Federal Register/Vol. 88, No. 172/Thursday, September 7, 2023

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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety

Administration

49 CFR Part 571

[Docket No. NHTSA–2023–0032]

RIN 2127–AL37

Federal Motor Vehicle Safety

Standards; Occupant Crash

Protection, Seat Belt Reminder

Systems

AGENCY

: National Highway Traffic

Safety Administration (NHTSA),

Department of Transportation (DOT).

ACTION

: Notice of proposed rulemaking

(NPRM).

SUMMARY

: The Moving Ahead for

Progress in the 21st Century Act of 2012

(MAP–21) directs NHTSA to initiate a

rulemaking proceeding to amend

Federal Motor Vehicle Safety Standard

(FMVSS) No. 208, ‘‘Occupant crash

protection,’’ to require a seat belt use

warning system for rear seats. Pursuant

to this mandate and following on an

earlier Advance Notice of Proposed

Rulemaking, NHTSA is proposing to

require a seat belt warning system for

the rear seats of passenger cars, trucks,

most buses, and multipurpose passenger

vehicles with a gross vehicle weight

rating of 4,536 kilograms (10,000

pounds) or less. This document also

proposes to enhance the existing front

seat belt warning requirements,

including requiring a seat belt warning

for the front outboard passenger seat

and increasing the duration of the

warning.

DATES

: You should submit your

comments early enough to be received

not later than November 6, 2023. In

compliance with the Paperwork

Reduction Act, NHTSA is also seeking

comment on a revision to an existing

information collection. For additional

information, see the Paperwork

Reduction Act section under the

Regulatory Notices and Analyses section

below. All comments relating to the

information collection requirements

should be submitted to NHTSA and to

the Office of Management and Budget

(OMB) at the address listed in the

ADDRESSES

section on or before

November 6, 2023.

DATES

: Proposed effective date: The first

September 1 that is one year after the

publication of the final rule for the front

seat belt warning system requirements

and the first September 1 that is two

years after the publication of the final

rule for the rear seat belt warning

system requirements, with optional

early compliance permitted. Multi-stage

manufacturers and alterers would have

an additional year to comply.

ADDRESSES

: You may submit comments

electronically to the docket identified in

the heading of this document by visiting

the Federal eRulemaking Portal at

https://www.regulations.gov. Follow the

online instructions for submitting

comments.

Alternatively, you can file comments

using the following methods:

• Mail: Docket Management Facility:

U.S. Department of Transportation, 1200

New Jersey Avenue SE, West Building

Ground Floor, Room W12–140,

Washington, DC 20590–0001.

• Hand Delivery or Courier: West

Building Ground Floor, Room W12–140,

1200 New Jersey Avenue SE, between 9

a.m. and 5 p.m. ET, Monday through

Friday, except Federal holidays. To be

sure someone is there to help you,

please call (202) 366–9826 before

coming.

• Fax: (202) 493–2251.

Regardless of how you submit your

comments, you should mention the

docket number identified in the heading

of this document.

Comments on the proposed

information collection requirements

should be submitted to: Office of

Management and Budget at

www.reginfo.gov/public/do/PRAMain.

To find this particular information

collection, select ‘‘Currently under

Review—Open for Public Comment’’ or

use the search function. It is requested

that comments sent to the OMB also be

sent to the NHTSA rulemaking docket

identified in the heading of this

document.

Instructions: All submissions must

include the agency name and docket

number or Regulatory Information

Number (RIN) for this rulemaking. For

detailed instructions on submitting

comments and additional information

on the rulemaking process, see the

Public Participation heading of the

Supplementary Information section of

this document. Note that all comments

received will be posted without change

to https://www.regulations.gov,

including any personal information

provided. Please see the Privacy Act

heading below.

Docket: For access to the docket to

read background documents or

comments received, go to https://

www.regulations.gov. You may also

access the docket at 1200 New Jersey

Avenue SE, West Building, Room W12–

140, Washington, DC 20590, between 9

a.m. and 5 p.m., Monday through

Friday, except Federal Holidays.

Telephone: 202–366–9826.

Confidential Business Information: If

you claim that any of the information in

your comment (including any additional

documents or attachments) constitutes

confidential business information

within the meaning of 5 U.S.C. 552(b)(4)

or is protected from disclosure pursuant

to 18 U.S.C. 1905, please see the

detailed instructions given under the

Public Participation heading of the

SUPPLEMENTARY INFORMATION

section of

this document.

Privacy Act: Please see the Privacy

Act heading under the Regulatory

Analyses section of this document.

FOR FURTHER INFORMATION CONTACT

: For

non-legal issues, you may contact Ms.

Carla Rush, Office of Crashworthiness

Standards, Telephone: (202) 366–4583;

Email: [email protected]; Facsimile:

(202) 493–2739. For legal issues, you

may contact Mr. John Piazza, Office of

Chief Counsel, Telephone: (202) 366–

2992; Email: [email protected];

Facsimile: (202) 366–3820. The address

of these officials is: the National

Highway Traffic Safety Administration,

1200 New Jersey Avenue SE,

Washington, DC 20590.

SUPPLEMENTARY INFORMATION

Table of Contents

I. Executive Summary

II. Background

III. Regulatory and Legislative History

IV. ECE Requirements and Euro NCAP

V. NHTSA Research on Effectiveness and

Acceptance of Seat Belt Warning

Systems

VI. Safety Need

VII. ANPRM

VIII. NHTSA’s Statutory Authority

IX. Overview of Proposed Requirements

X. Proposed Rear Seat Belt Warning

A. Overview

B. Applicability

C. Requirements

1. Visual Warning on Vehicle Start-Up

a. Compliance Options for the Type of

Information Conveyed

b. Triggering Conditions

c. Seat Occupancy Criteria and Interaction

With Child Restraint Systems

d. Minimum Duration

2. Audio-Visual Change-of-Status Warning

3. Telltale Location

4. Telltale Characteristics

5. Belt Use Criteria

6. Electrical Connections

7. Owner’s Manual Instructions

8. Interaction With Other Vehicle Warnings

D. Alternative Warning Signals

E. Resistance to Intentional and

Inadvertent Defeat and Deactivation

F. Consumer Acceptance

G. Technological and Economic Feasibility

XI. Warning Requirements for Front

Outboard Seats

A. Seat Belt Warning for Front Outboard

Passenger Seat

B. Driver’s Seat Belt Warning for Medium-

Sized Buses

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Stewart, T. (April 2023). Overview of Motor

Vehicle Traffic Crashes in 2021 (Report NO. DOT

HS 813 435. National Highway Traffic Safety

Administration, pg. 5.

Id. at pg. 2.

Id. at pg. 5.

Id.

Id. The 2021 fatality estimates are not entirely

final, and may change somewhat as NHTSA

receives further updates or corrections.

See https://www.transportation.gov/briefing-

room/nhtsa-estimates-2022-show-roadway-

fatalities-remain-flat-after-two-years-dramatic.

Though NHTSA acknowledges fatalities essentially

remained flat in 2022, NHTSA does not know if this

trend will continue to remain flat or if there will

be further increases in fatalities.

Seat belt use warning systems may also be

referred to in this preamble as seat belt ‘‘warning

systems’’ (or SBWS) or seat belt ‘‘reminder’’ systems

(or SBRSs).

Boyle, L.L. (2022, August). Occupant restraint

use in 2021: Results from the NOPUS Controlled

Intersection Study (Report No. DOT HS 813 344).

National Highway Traffic Safety Administration.

2016 MVOSS, p.7 (calculated from Fig. 5).

This research is identified and discussed in

Section V and Section XIV.A, as well as the

Preliminary Regulatory Impact Analysis docketed

with this NPRM.

C. Amendments to the Current Warning

Signal Requirements

1. Increasing the Duration of the Audio-

Visual Warning on Vehicle Start-Up

2. Requiring an Audio-Visual Change-of-

Status Warning

3. Audible Warning Characteristics

4. Visual Warning Characteristics

5. Other Warning Signal Features and

Criteria

XII. Other issues

A. Automatic Belts

B. Test Procedures

C. Considerations for Automated Driving

Systems

XIII. Regulatory Alternatives

A. ECE R16 and Euro NCAP

B. Occupant Detection and Enhanced

Warning Signals for the Rear Seat Belt

Warning

C. Non-Regulatory Alternatives

D. Requiring a Warning System for the

Front Center Seat

E. Requiring a 90 Second Duration Seat

Belt Warning System for the Front

Outboard Seating Positions

XIV. Overview of Benefits and Costs

A. Proposed Requirements

1. Rear Seat Belt Warning System

2. Front Seat Belt Warning System

3. Overall Benefits and Costs of Proposal

B. Regulatory Alternatives

1. Occupant Detection in Rear Seats

2. 90-Second Front Outboard Seat Belt

Warning

3. Seat Belt Warning for Front Center Seat

XV. Proposed Effective Date

XVI. Regulatory Analyses

XVII. Public Participation

Appendix A—Front Outboard Seat Belt

Warnings—Additional Data

Proposed Regulatory Text

I. Executive Summary

In 2020, there were 39,007 motor

vehicle traffic fatalities in the United

States.

This was 2,652 more fatalities

than in 2019 (when there were 36,355

fatalities).

In 2021, motor vehicle traffic

fatalities increased again to 42,939.

The

traffic fatality count in 2021 is the

highest since 2005 (43,510) and

represents the second year-to-year

increase since 2019.

The 10-percent

fatality increase from 2020 to 2021 is the

highest year-to-year percentage increase

since FARS started data collection in

1975.

NHTSA has preliminarily

estimated 42,795 fatalities in 2022,

representing a small decrease of about

0.3% from 2021.

The Moving Ahead

for Progress in the 21st Century Act

(MAP–21) directed NHTSA to initiate a

rulemaking to require a seat belt

warning for the rear seats in motor

vehicles. In addition, the Department of

Transportation has released a

comprehensive National Roadway

Safety Strategy to address the rise in

roadway fatalities and injuries. Part of

that strategy is to make vehicles safer.

Consistent with MAP–21 and the

National Roadway Safety Strategy, this

NPRM proposes to require a seat belt

use warning system

for the rear seats

of passenger cars, trucks, buses (except

school buses, for various reasons

detailed in the Applicability section of

the preamble, including practicability

and cost concerns), and multipurpose

passenger vehicles (MPVs) with a

GVWR of 4,536 kg (10,000 lb) or less.

This NPRM also proposes several

changes and enhancements to the

existing front seat belt warning

requirements, including increasing the

duration of the audio-visual seat belt

warning on vehicle start-up.

Safety Need for the Proposed Rule

Using a seat belt is one of the most

effective actions a motor vehicle

occupant can take to prevent death and

injury in a crash. Seat belts prevent

occupants from being ejected from the

vehicle, provide ‘‘ride-down’’ by

gradually decelerating the occupant as

the vehicle deforms and absorbs energy,

and reduce the occurrence of occupant

contact with harmful interior surfaces

and other occupants. Seat belts are

effective in most types of crashes, and

greatly reduce the risk of fatal and non-

fatal injuries compared to the risk faced

by unrestrained occupants.

While seat belt use is meaningfully

higher than it was a decade ago, there

is room for improvement. Usage rates

for seat belts in rear seats have

consistently been below those for the

front seats, and while front seat belt use

rates increased early in the previous

decade, for the last several years they

have plateaued. According to data from

NHTSA’s annual study of observed seat

belt use, from 2012 to 2021, seat belt use

was lower in the rear seat than in the

front seat, ranging from a difference of

about 9 percent in 2013 (78% vs. 87%)

to about 14 percent in 2017 (75% vs.

89%).

During that time, front seat belt

use rates ranged from about 86% in

2012 to 91% in 2019. In 2021, front seat

belt use was about 90%, and rear seat

belt use was about 78%. Accordingly,

every year, thousands of unrestrained

motor vehicle occupants are killed in

crashes, and tens of thousands of

unrestrained occupants are injured

(additional details on the target

population are provided in the summary

of benefits and costs later in this

executive summary).

Many of these unbelted occupants are

likely amenable to using a seat belt. Seat

belt nonusers can be categorized as

either ‘‘part-time’’ nonusers or so-called

‘‘hard-core’’ nonusers. Part-time

nonusers generally express positive

attitudes toward seat belts, but do not

always buckle up, due to a range of

reasons, such as short trips,

forgetfulness, and being in a rush. Hard-

core nonusers are those who generally

do not acknowledge the benefits of seat

belts and are opposed to their use.

Consumer research suggests that most

nonusers are part-time nonusers, not

hard-core nonusers. This is true even for

front seat occupants, for which there is

a relatively high rate of observed seat

belt use. For instance, NHTSA’s most

recent survey of seat belt use found that

approximately 83% of drivers who did

not always use a seat belt reported using

a seat belt most or some of the time, and

only 17% were hard-core nonusers who

used seat belts rarely or never.

The

same is true for rear seat passengers who

do not always use a belt, of whom 70%

used a belt most or some of the time,

while only 30% used a belt rarely or

never.

Seat belt warning systems encourage

seat belt use by reminding unbuckled

occupants to fasten their belts and/or by

informing the driver that a passenger is

unbelted so that the driver can request

the unbelted occupant to buckle up. The

warnings provided by seat belt warning

systems typically consist of visual and/

or audible signals. Research by NHTSA

and others shows that seat belt warning

systems are effective at getting

unbuckled occupants to fasten their seat

belt.

Federal Motor Vehicle Safety

Standard (FMVSS) No. 208, ‘‘Occupant

crash protection,’’ requires a short-

duration audio-visual seat belt warning

for the driver’s seat belt on passenger

cars, most trucks and MPVs with a

GVWR of 4,536 kg (10,000 lb) or less,

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and buses with a GVWR of 3,855 kg

(8,500 lb) or less. According to the

FMVSS No. 208 standard, the visual

component of the warning generally

must be at least sixty seconds long, and

the audible component must be at least

four seconds long.

In general, voluntary adoption of

warnings that go beyond this regulatory

minimum, while considerable, has been

mixed. Although the regulations do not

require seat belt warnings for any

seating position other than the driver’s

seat, almost all model year (MY) 2022

vehicles have a voluntarily-provided

seat belt warning for the front outboard

passenger seat. However, voluntary

adoption for rear seats has been much

slower, as only about 47% come

equipped with a voluntarily-provided

rear seat belt warning system (SBWS).

Most vehicles already provide a seat belt

warning for both front outboard seats

that is much longer than the minimal

required warning for the driver’s seat

belt, with the vast majority of vehicles

including an alert that is at least 90

seconds. This suggests that the front seat

belt warning minimum requirements in

the FMVSS are outdated, as consumers

seem clearly willing to accept audio-

visual reminders that are far longer than

the required four seconds.

In short, rear seat belt use rates have

persistently been below those for the

front seats, and progress on front seat

belt use rates have slowed. Moreover,

unbuckled occupants, in the front and

rear seats, continue to be

overrepresented in fatal crashes (51%),

given the lower exposure of unbelted

occupants relative to belted occupants

(because front seat belt use was about

90% and rear seat belt use was 80%).

Nevertheless, in spite of the

effectiveness of seat belts and seat belt

warnings, most new vehicles continue

to lack a rear seat belt warning.

Additionally, while most vehicles

provide some level of enhanced

reminders for the front seats, this level

of enhanced protection has not occurred

for all vehicles and is not standardized.

This suggests a need for a beneficial

safety technology that is not being met

in the vehicle market. This NPRM is

intended to meet this safety need and

advance NHTSA’s response to MAP–21.

Legal Authority and Prior Regulatory

History

This proposal is issued pursuant to

NHTSA’s authority under the National

Traffic and Motor Vehicle Safety Act (49

U.S.C. 30101 et seq.) (Safety Act), which

authorizes NHTSA to establish Federal

Motor Vehicle Safety Standards. The

statute requires safety standards to be

objective, practicable, and meet the

need for safety, among other things.

NHTSA has tentatively concluded that

the proposed requirements satisfy these

statutory criteria.

This NPRM also continues NHTSA’s

response to a rulemaking mandate in

MAP–21. MAP–21 required DOT

(NHTSA, by delegation) to initiate a

rulemaking proceeding to require rear

seat belt warnings and directed the

agency to issue a final rule unless the

rule would not meet the Safety Act

requirements for an FMVSS. In

accordance with MAP–21, in 2013

NHTSA initiated a rulemaking

proceeding when it submitted for public

comment a proposal to undertake a

study of the effectiveness of existing

rear seat belt warning systems. In 2019,

NHTSA continued with this rulemaking

proceeding by publishing an Advance

Notice of Proposed Rulemaking

(ANPRM) seeking comment on a variety

of issues related to potential rear seat

belt warning requirements. NHTSA

received 45 comments from a variety of

organizations and individuals. Most

commenters, including safety advocates,

vehicle manufacturers and suppliers,

and individual members of the public,

supported a rear seat belt warning

requirement.

This NPRM also responds to a

rulemaking petition. Public Citizen and

Advocates for Highway and Auto Safety

have petitioned NHTSA to require a seat

belt warning system for rear seats on

passenger cars and MPVs with a GVWR

of 4,536 kg (10,000 lb) or less. This

proposal is NHTSA’s further action on

its grant of this petition.

Summary of the Proposed Amendments

This NPRM proposes amending the

existing seat belt warning provisions in

FMVSS No. 208. This proposal has two

main components. The first proposes

requiring a rear seat belt reminder for

the rear seats. The second proposes

changes and enhancements to the seat

belt warning requirements for the front

outboard seats, most notably an audio-

visual warning that persists until the

seat belts at any occupied front outboard

seat are fastened. These proposed

requirements would apply to passenger

cars and trucks, buses (except school

buses), and multipurpose passenger

vehicles with a GVWR of 4,536 kg

(10,000 lb) or less.

1. Rear Seat Belt Reminder

Requirements

The first component of this NPRM is

a set of proposed requirements for a seat

belt warning for rear seats. The

proposed requirements have four main

elements.

• Visual warning on vehicle start-up

to inform the driver of the status of the

rear seat belts. We propose three

different compliance options from

which manufacturers could choose for

the rear seat belt warning system. The

first would require the system to

indicate how many or which rear seat

belts are in use (the ‘‘positive-only’’

option). The second would require the

system to indicate, for the occupied rear

seats, how many or which rear seat belts

are not in use (the ‘‘negative-only’’

option). The third would require the

system to indicate, for the occupied rear

seats, how many or which rear seat belts

are in use and how many or which rear

seat belts are not in use (the ‘‘full-

status’’ option). Certain features would

be required of all the options. Each

system would have to provide a

continuous or flashing visual warning,

consisting of either icons or text, visible

to the driver. The visual warning would

have to last for at least 60 seconds,

beginning when the vehicle’s ignition

switch is moved to the ‘‘on’’ or ‘‘start’’

position. The negative-only and full-

status compliance options would

require that the rear seats be equipped

with a belt latch sensor and an occupant

detection system (which facilitates these

more informative warnings), while the

positive-only option would only require

that the rear seats be equipped with a

belt latch sensor.

• Audio-visual change-of-status

warning. We propose an audio-visual

warning whenever a fastened rear seat

belt is unfastened while the ignition

switch is in the ‘‘on’’ or ‘‘start’’ position

and the vehicle’s transmission selector

is in a forward or reverse gear. The

warning would have to last for at least

30 seconds. We do not propose any

requirements for the volume or tone of

the warning. The intent of this warning

is to alert the driver or other occupants

to a change in belt status during a trip.

The warning would not be required if a

door is open, which would be the case

if a rear passenger unfastened their belt

in order to exit the vehicle.

• Requirements related to electrical

connections. Readily removable rear

seats would be required to either

automatically connect to the electrical

connections when the seat is put in

place, or, if a manual connection is

required, the connectors must be

readily-accessible. Further, vehicles

utilizing the negative-only compliance

option would be required to provide a

visual warning to the driver if a proper

electrical connection has not been

established for a readily removable rear

seat.

• Owner’s manual requirements. We

propose that the vehicle owner’s manual

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Based on data on total projected vehicle sales

in the United States for model year 2022 from the

agency’s New Car Assessment Program Purchasing

with Safety in Mind: What to Look For When Buying

a Vehicle program.

Children in booster seats are part of the target

population for this proposed rulemaking because

they should be restrained with the seat belt and so

would benefit from a seat belt reminder. The

transition to a booster seat typically occurs from

ages 4–7 years.

The Abbreviated Injury Scale (AIS) is a

classification system for assessing impact injury

severity developed and published by the

Association for the Advancement of Automotive

Medicine and is used for coding single injuries,

assessing multiple injuries, or for assessing

cumulative effects of more than one injury. MAIS

represents the maximum injury severity of an

occupant at an AIS level, i.e., the highest single AIS

for a person with one or more injuries. MAIS 1 &

2 injuries are considered minor injuries and MAIS

3–5 are considered serious injuries.

(which includes information provided

by the vehicle manufacturer to the

consumer, whether in digital or printed

form) describe the warning system’s

features, including the location and

format of the visual warnings. We also

propose that the owner’s manual

include instructions on how to make

any manual electrical connections for

readily removable seats.

2. Front Outboard Seat Belt Warning

Requirements

We propose several changes and

enhancements to the seat belt warning

requirements for the front outboard

seats. There are three main changes we

are proposing.

• Audio-visual warning on vehicle

start-up for front outboard passenger

seat. Currently, only the driver’s seat is

required to have a seat belt warning,

although almost all vehicles now

provide a seat belt warning for the front

outboard passenger seat as well.

propose to require a seat belt warning

for the front outboard passenger seat.

• Increasing the duration of the

audio-visual warning on vehicle start-

up. We propose enhancing the front seat

warning requirements by requiring an

audio-visual warning that remains

active until the seat belt at any occupied

front outboard seat is fastened. We are

proposing this in light of a variety of

factors, including the increase in

roadway fatalities, the lack of

improvement in front seat belt use rates,

and the fact that the audio-visual

warnings with which vehicle

manufacturers are currently equipping

vehicles significantly exceed the 4-

second regulatory minimum (including

a non-trivial share of currently sold

vehicles with an indefinite-duration

reminder). Vehicle manufacturers can

adjust warning signal characteristics

(such as frequency and volume) to make

the warning both effective and

acceptable to consumers.

• Audio-visual change-of-status

warning. We also propose to require an

audio-visual change-of-status warning

whenever a front outboard seat belt is

unbuckled during a trip (unless a front

door is open, to account for an occupant

unfastening the belt to exit the vehicle).

The warning would be required to

remain active until the seat belt is

refastened.

Proposed Effective Date

We propose an effective date of the

first September 1 that is one year after

the publication of the final rule for the

front seat belt warning system

requirements and the first September 1

that is two years after the publication of

the final rule for the rear seat belt

warning system requirements, with

optional early compliance (See Section

XV for details). Consistent with 49 CFR

571.8(b), multi-stage manufacturers and

alterers would have an additional year

to comply.

Regulatory Alternatives

NHTSA considered a wide range of

alternatives to the proposed

requirements. The main alternatives

NHTSA considered were the seat belt

warning requirements in Economic

Commission for Europe (ECE)

Regulation R16 and Euro New Car

Assessment Programme (NCAP). The

proposed requirements are identical or

similar to ECE R16 and Euro NCAP in

many respects but differ from them in

several ways. For instance, while the

ECE rear seat belt warning regulations

allow a warning for an unfastened seat

belt at an unoccupied seat, this proposal

would not allow this, because we

tentatively believe that the resulting

‘‘false’’ warning would potentially

annoy drivers and lead to behaviors that

would decrease system effectiveness.

Another way the proposal differs from

ECE R16 is the duration of the front seat

belt warning on vehicle start-up: R16

generally requires only a 30–60 second

audio-visual warning; we propose a

warning that lasts until the seat belt is

buckled. The regulatory analysis

quantifies the costs and benefits of three

specific regulatory alternatives:

requiring occupant detection for the rear

seat belt warning system; requiring (for

the front outboard seats) an audio-visual

warning on vehicle start-up with a

duration of 90 seconds; and requiring a

seat belt warning for front center seats.

Benefits and Costs of the Proposed

Requirements

NHTSA estimates the target

population and the benefits and costs of

the proposed requirements in the stand-

alone preliminary regulatory impact

analysis (PRIA) that is being placed in

the docket with this NPRM and is

summarized in the NPRM.

Based on NHTSA’s data on fatalities

and injuries from motor vehicle crashes,

adjusted to account for the benefits of

other mandatory safety technologies,

there are, on average, 475 fatalities and

7,036 injuries to unrestrained rear seat

occupants and 6,733 fatalities and

47,952 injuries to unrestrained front

outboard seat occupants each year. This

is the overall target population—the

annual deaths and injuries that the

proposed requirements are aimed at

reducing.

NHTSA estimates the benefits it

expects from the proposed seat belt

warning requirements. The benefits are

the fatalities and injuries that would be

prevented by these proposed

requirements. The benefits depend,

principally, on the expected increase in

seat belt use and the effectiveness of

seat belts in preventing deaths and

injuries.

For the rear seat belt warning system

analysis, NHTSA used a ‘‘low’’ and a

‘‘high’’ estimate for the increase in rear

belt use with the proposed warning

system. For occupants 11 years and

older, these were 3 and 5 percentage

points, and for occupants from 6 to 10

years old, 0.3 and 0.4 percentage

points.

For simplicity, NHTSA refers

to these scenarios as ‘‘Low’’ and ‘‘High,’’

or ‘‘3%’’ and ‘‘5%.’’ The estimated

annual benefits are presented in table

Another way to measure benefits is by

calculating equivalent lives saved (ELS).

Equivalent lives saved are the number of

prevented fatalities added to the number

of prevented injuries, with the

prevented injuries expressed in terms of

fatalities (that is, with an injury

expressed as a fraction of a fatality, so

that the more serious the injury, the

higher the fraction). The estimated

equivalent lives saved assuming either a

3% or 7% discount rate are presented in

table 2.

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ABLE

1—E

STIMATED

NNUAL

ENEFITS

—P

OTENTIAL

IVES

AVED AND

NJURIES

REVENTED FOR

OSITIVE

-O

NLY

SBWS (R

EAR

EATS

), W

ITH

STIMATED

3% & 5% I

NCREASE IN

ELT

Injury level

(Low)

(High)

MAIS 1 ..................................................................................................................................................................... 23.2 34.3

MAIS 2 ..................................................................................................................................................................... 40.2 60.3

MAIS 3 ..................................................................................................................................................................... 5.6 8.4

MAIS 4 ..................................................................................................................................................................... 5.5 8.2

MAIS 5 ..................................................................................................................................................................... 0.2 0.3

Total Injuries ..................................................................................................................................................... 74.7 111.5

Fatal ......................................................................................................................................................................... 22.3 33.6

ABLE

2—E

STIMATED

NNUAL

ENEFITS

—E

QUIVALENT

IVES

AVED

—P

OSITIVE

-O

NLY

SBWS (R

EAR

EATS

)

Belt use increase

3% Discount

rate

7% Discount

rate

3% increase (Low) ................................................................................................................................................... 21.9 17.7

5% increase (High) .................................................................................................................................................. 32.9 26.7

NHTSA also estimates the costs of the

proposed requirements for rear seat belt

warnings. NHTSA estimates that the

minimum cost to comply with the rear

seat belt warning requirements (the

positive-only system) is $166.44 million

(M). This is based on a per-vehicle cost

of $19.59 for 53.1% of 16M affected new

vehicles.

Based on the forgoing, NHTSA

performed benefit-cost and cost-

effectiveness analyses. A benefit-cost

analysis calculates the net benefits,

which is the difference between the

benefits flowing from injury and fatality

reductions and the cost of the rule. The

net benefit estimates are presented in

table 3. The cost-effectiveness analysis

derives the cost per equivalent life

saved, which is equal to the total cost

of the rule divided by the total fatal

equivalents that it prevents. These

estimates are presented in table 4.

ABLE

3—N

ENEFITS

—P

ROPOSED

OSITIVE

-O

NLY

EAR

SBWS

[2020 Dollars, in millions]

Seat position & belt use increase

Benefits

3% discount

Benefits

7% discount

Cost

Net benefits

3% discount

rate

Net benefits

7% discount

rate

3% increase (Low) ............................................................... $262.1 $212.7 $166.4 $95.6 $46.2

5% increase (High) .............................................................. 394.8 320.4 166.4 228.3 153.9

ABLE

4—C

OST

-E

FFECTIVENESS

NALYSIS

OST PER

QUIVALENT

IFE

AVED

)—P

ROPOSED

OSITIVE

-O

NLY

YSTEM

EAR

EATS

)

[2020 Dollars, in millions]

Seat position & belt use increase

ELS

3% discount

ELS

7% discount

Cost

Cost/ELS

3% discount

Cost/ELS

7% discount

3% increase (Low) ............................................................... 21.9 17.7 $166.4 $7.6 $9.4

5% increase (High) .............................................................. 32.9 26.7 166.4 5.0 6.2

NHTSA is also proposing enhancing

the driver seat belt warning

requirements by requiring an audio-

visual warning that remains active until

the driver’s seat belt is buckled and

extending the driver’s seat belt warning

requirements, as modified by this

NPRM, to the front outboard passenger

seat. NHTSA estimated the annual

benefits of a seat belt warning for the

driver and outboard front passenger that

remains active until the occupant’s seat

belt is buckled as shown in table 5 and

table 6.

ABLE

5—E

STIMATED

NNUAL

ENEFITS

—L

IVES

AVED AND

NJURIES

REVENTED

—I

NDEFINITE

URATION

SBWS

RONT

UTBOARD

EATS

)

Injury level Driver

Front

passenger

Total

MAIS 1 ......................................................................................................................................... 20.7 3.7 24.4

MAIS 2 ......................................................................................................................................... 120.0 20.5 140.5

MAIS 3 ......................................................................................................................................... 21.6 3.9 25.5

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Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules

Based on data on total projected vehicle sales

in the United States for model year 2022 from the

agency’s New Car Assessment Program Purchasing with Safety in Mind: What to Look For When Buying

a Vehicle program.

ABLE

5—E

STIMATED

NNUAL

ENEFITS

—L

IVES

AVED AND

NJURIES

REVENTED

—I

NDEFINITE

URATION

SBWS

RONT

UTBOARD

EATS

)—Continued

Injury level Driver

Front

passenger

Total

MAIS 4 ......................................................................................................................................... 17.4 3.1 20.5

MAIS 5 ......................................................................................................................................... 0.5 0.1 0.6

Total Injuries ......................................................................................................................... 180.2 31.2 211.4

Fatal ............................................................................................................................................. 65.9 11.4 77.3

ABLE

6—E

STIMATED

NNUAL

ENEFITS

—E

QUIVALENT

IVES

AVED

—I

NDEFINITE

SBWS (F

RONT

UTBOARD

EATS

)

Undiscounted

3% Discount

rate

7% Discount

rate

Driver ........................................................................................................................................... 78.7 65.2 52.8

Front Passenger .......................................................................................................................... 13.6 11.3 9.2

Total ...................................................................................................................................... 92.3 76.5 62.0

NHTSA estimates that the

incremental cost of the enhanced seat

belt warning would be no greater than

the currently available seat belt

warning. Although a seat belt warning is

currently not required for the front

outboard passenger seats, we estimate

that 96 percent of new vehicles are

equipped with them.

NHTSA

estimates that the cost for equipping a

front outboard passenger seat with a seat

belt warning system is about $2.13 per

vehicle. To equip a seat belt warning

system in the front outboard passenger

seat positions on the remaining 4

percent of new vehicle fleet (16 million)

without such a warning is $1.36 million

(= $2.13 × 0.04 × 16 million).

The total monetized benefits, costs,

and net benefits (total monetized

benefits—total cost) of the enhanced

seat belt warning system for the driver

and front passenger is shown in table 7.

ABLE

7—A

NNUAL

ONETIZED

ENEFITS

, C

OSTS AND

ENEFITS

—I

NDEFINITE

SBWS (F

RONT

UTBOARD

EATS

)

[2020 Dollars, in millions]

Driver Front Passenger Driver and Front Passenger

Undiscounted 3% 7% Undiscounted 3% 7% Undiscounted 3% 7%

Passenger car Benefits ................... $422.5 $353.0 $288.0 $79.9 $66.7 $54.4 $502.4 $419.7 $342.4

Light Truck & Van Benefits ............. 520.4 427.6 344.8 83.4 68.5 55.2 603.8 496.1 400

Total Benefits ........................... 942.9 780.5 632.8 163.3 135.2 109.7 1,106.2 915.8 742.5

Total Costs ............................... 0 0 0 1.36 1.36 1.36 1.36 1.36 1.36

Net Benefits ..................................... 942.9 780.5 632.8 161.9 133.9 108.3 1,104.8 914.4 741.1

The net benefits of the proposed rule

requiring seat belt warning for rear

seating positions and the enhanced seat

belt warning for the front outboard seats

are shown in table 8.

ABLE

8—N

ENEFITS

ROM THE

ROPOSAL

(SBWS

FOR

EAR

EATING

OSITIONS AND

NDEFINITE

SBWS

FOR

RONT

UTBOARD

EATING

OSITIONS

)

[2020 Dollars, in millions]

3% Discount

rate

7% Discount

rate

Front Outboard Seats .............................................................................................................................................. $914.4 $741.1

Rear Seats (3% increase in rear seat belt use) ...................................................................................................... 95.6 46.2

Rear Seats (5% increase in rear seat belt use) ...................................................................................................... 228.3 153.9

Total Net Benefits (3% increase in rear belt use) ............................................................................................ 1,010.0 787.4

Total Net Benefits (5% increase in rear belt use) ............................................................................................ 1,142.7 895.0

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Stewart, T. (April 2023). Overview of Motor

Vehicle Traffic Crashes in 2021(Report NO. DOT HS

813 435. National Highway Traffic Safety

Administration, pg. 5.

Id. at pg. 2.

Id. at pg. 5.

Id.

Id. The 2021 and 2022 fatality estimates are not

entirely final, and may change somewhat as NHTSA

receives further updates or corrections.

See https://www.transportation.gov/briefing-

room/nhtsa-estimates-2022-show-roadway-

fatalities-remain-flat-after-two-years-dramatic.

Though NHTSA acknowledges fatalities essentially

remained flat in 2022, NHTSA does not know if this

trend will continue to remain flat or if there will

be further increases in fatalities.

https://www.transportation.gov/sites/dot.gov/

files/2022-02/USDOT-National-Roadway-Safety-

Strategy.pdf.

See, e.g., 68 FR 46262 (Aug. 5, 2003). See also

Buckling Up: Technologies to Increase Seat Belt

Use. Special Report 278 at 18, Committee for the

Safety Belt Technology Study, Transportation

Research Board of The National Academies (2003)

[hereinafter ‘‘Transportation Research Board

Study’’].

Charles J. Kahane, Lives Saved by Vehicle

Safety Technologies and Associated Federal Motor

Vehicle Safety Standards, 1960 to 2012—Passenger

Cars and LTVs—With Reviews of 26 FMVSS and

the Effectiveness of Their Associated Safety

Technologies in Reducing Fatalities, Injuries, and

Crashes. 89 DOT HS 812 069 at 89, Department of

Transportation, National Highway Traffic Safety

Agency (2015) [hereinafter ‘‘DOT Lives Saved

Study’’].

See the Preliminary Regulatory Impact

Analysis (PRIA) (in the docket for this rulemaking)

for these effectiveness estimates.

Boyle, L.L. (2022, August). Occupant restraint

use in 2021: Results from the NOPUS Controlled

Intersection Study (Report No. DOT HS 813 344).

National Highway Traffic Safety Administration.

NOPUS is the only nationwide probability-based

observational survey of seat belt use in the United

States. The survey observes seat belt use as it

actually occurs at randomly-selected roadway sites,

and involves a large number of occupants (68,804

in 2021). NOPUS observations are made during

daylight hours and are not necessarily

representative of high-risk driving times when belt

use may be lower.

Id.

II. Background

In 2020, there were 39,007 motor

vehicle traffic fatalities in the United

States.

This was 2,652 more fatalities

than in 2019.

In 2021, motor vehicle

traffic fatalities increased again to

42,939.

The traffic fatality count in

2021 is the highest since 2005 (43,510)

and represents the second year-to-year

increase since 2019.

The 10-percent

fatality increase from 2020 to 2021 is the

highest year-to-year percentage increase

since FARS started data collection in

1975.

NHTSA has preliminary

estimated 42,795 fatalities in 2022,

representing a small decrease of about

0.3% from 2021.

The Department of

Transportation has released a

comprehensive National Roadway

Safety Strategy to address this rise in

roadway fatalities and injuries.

Part of

that strategy is making vehicles safer.

This NPRM proposes to require a seat

belt use warning system for the rear

seats of passenger cars, trucks, buses

(except school buses), and multipurpose

passenger vehicles (MPVs) with a

GVWR of 4,536 kg (10,000 lb) or less.

This NPRM also proposes to enhance

the existing front seat belt warning

requirements, including requiring a seat

belt warning for the front outboard

passenger seat and increasing the

duration of the warning. This section

provides a brief introduction to seat belt

technology, evidence on seat belt use by

vehicle occupants, and strategies to

increase belt use.

Using a seat belt is one of the most

effective actions a motor vehicle

occupant can take to prevent death and

injury in a crash.

Seat belts protect

occupants in various ways. They

prevent occupants from being ejected

from the vehicle, gradually decelerate

the occupant as the vehicle deforms and

absorbs energy, and reduce the

occurrence of occupant contact with

harmful interior surfaces and other

occupants.

Seat belts are effective in

most types of crashes (although

effectiveness varies for different types of

crashes). Research has found that seat

belts greatly reduce the risk of fatal and

non-fatal injuries compared to the risk

faced by unrestrained occupants. For

rear seat occupants, seat belts reduce the

risk of fatality by 55% (for passenger

cars) and 74% (for light trucks and

vans). For front seat occupants, drivers

and right front passengers, seat belts

reduce the risk of fatality by 44% (for

passenger cars) and 63% to 73% (for

light trucks and vans). Seat belts reduce

the risk of injuries by up to 63%.

While the PRIA makes use of these

effectiveness rates, we note that the

effectiveness of seat belts is not

impacted by the proposed rule. Instead,

benefits from the proposed rule are the

result of the increase in seat belt use

resulting from the warning.

While seat belt use is meaningfully

higher than it was a decade ago, there

is room for improvement. Usage rates

for rear belts have consistently been

below those for the front seats, and

while front seat belt use rates increased

early in the previous decade, for the last

several years they have plateaued.

According to data from NHTSA’s

National Occupant Protection Use

Survey (NOPUS), from 2012 to 2021,

seat belt use was lower in the rear seat

than in the front seat, ranging from a

difference of 8.8 percent in 2013 (78.3%

vs. 87.1%) to 14.3 percent in 2017

(75.4% vs. 89.7%).

During that time,

front seat belt use rates ranged from

86.1% in 2012 to 90.7% in 2019. In

2021, front seat belt use was 90.4% and

rear seat belt use was 77.9 percent.

See

Figure 1.

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See, e.g., Transportation Research Board Study

at 3.

See, e.g., Transportation Research Board Study

at 32; Spado, D., Schaad, A., & Block, A. (2019,

December). 2016 motor vehicle occupant safety

survey; Volume 2: Seat belt report (Report No. DOT

HS 812 727). National Highway Traffic Safety

Administration, at p. 71 (Fig. 53); p. 76 (Fig. 54).

This is a national telephone survey periodically

conducted by NHTSA. Because, unlike NOPUS, it

is not observational, the MVOSS is not the best

indicator of national belt use. In addition, because

of respondent bias, the large number of part-time

users, and the tendency for survey respondents to

over-report belt use, MVOSS use rates have

typically been about 10 percentage points higher

than those from NOPUS, which is an observational

study, and therefore a more objective and accurate

measure of belt use. MVOSS does, however,

provide demographic detail that cannot be observed

and insight into the reasons people do and do not

use seat belts.

Transportation Research Board Study at 40.

2016 MVOSS, p.7 (calculated from Fig. 5).

Id. at p. 12 (calculated from Fig. 10).

Id. at p. 13 (calculated from Fig. 11).

Id. at p. 64 (Table 15). The MVOSS results are

consistent with, though differ somewhat from, those

in a similar survey conducted by the Agency for

Healthcare Research and Quality. Chu, M.

Characteristics of Persons Who Seldom or Never

Wear Seat Belts, 2002. Statistical Brief #62.

December 2004. Agency for Healthcare Research

and Quality, Rockville, MD. http://meps.ahrq.gov/

mepsweb/data_files/publications/st62/stat62.pdf.

The reader is referred to the discussion in Section

XIV.A.2 and in the PRIA, section 4.3.

NHTSA runs a Congressionally mandated High

Visibility Enforcement (HVE) annual campaign

focused on increasing seat belt use. The Click It or

Ticket (CIOT) nationwide campaign has been in

effect for about 20 years. It runs every year from

Mid-May through the Memorial Day weekend, into

the first week in June.

Akamatsu, M., Hashimoto, H., and Shimaoka,

S., ‘‘Assessment Method of Effectiveness of

Passenger Seat Belt Reminder,’’ SAE Technical

Paper 2012–01–0050, 2012, doi:10.4271/2012–01–

0050.

See, e.g., Transportation Research Board Study

at 8, 25; Mark Freedman et al., Effectiveness and

Acceptance of Enhanced Seat Belt Reminder

Systems: Characteristics of Optimal Reminder

Systems Final Report. DOT HS 811 097 at 2 (Feb.

2009) (hereinafter ‘‘DOT 2009 Seat Belt Study’’).

See Section XI.C.1, Increasing the duration of

the audio-visual warning on vehicle start-up.

Consumer survey research by NHTSA

and others (such as the Insurance

Institute for Highway Safety and

academic researchers) suggests that

many unbelted occupants are likely

amenable to using a seat belt. Seat belt

nonusers can be categorized as either

‘‘part-time’’ nonusers or so-called ‘‘hard-

core’’ nonusers.

Part-time nonusers

generally express positive attitudes

toward seat belts, but do not always

buckle up, due to a range of reasons,

such as short trips, forgetfulness, and

being in a rush.

Hard-core nonusers

are those who ‘‘generally do not

acknowledge the benefits of seat belts

and are opposed to their use.’’

Research by NHTSA and others suggests

that most nonusers are part-time

nonusers, not hard-core nonusers. This

is true even for front seat occupants, for

which there is a relatively high rate of

observed seat belt use. For instance,

NHTSA’s most recent survey of seat belt

use found that approximately 83% of

drivers who did not always use a seat

belt reported using a seat belt most or

some of the time, and only 17% were

hard-core nonusers who used seat belts

rarely or never.

Similarly, for those

who did not always use a seat belt when

riding as a passenger in the front, 89%

used seat belts most or some of the time

while only 11% used a seat belt rarely

or never.

The same was true for rear

seat passengers who did not always use

a belt, of whom 70% used a belt most

or some of the time, while only 30%

used a belt rarely or never.

Moreover,

of the survey respondents who reported

‘‘always’’ using a seat belt while driving,

only 66% ‘‘always’’ used a seat belt

when riding as a passenger in the rear

seat.

NHTSA has, over time, tried a variety

of such strategies, including sponsoring

national media campaigns, supporting

the enactment of state seat belt use laws

and high-visibility enforcement, and

facilitating or requiring vehicle-based

strategies.

Some of these strategies are

non-regulatory; some are regulatory.

One example of a non-regulatory

strategy is NHTSA’s annual Click It or

Ticket mobilization, which includes a

national advertising campaign backed

up by high-visibility local enforcement

of state seat belt laws. Adult rear-seat

passengers are covered by seat belt laws

in 32 states and the District of

Columbia. Some of these states with

mandatory rear seat belt laws include

rear-seat specific messaging in their

media campaigns. While such measures

have helped make enormous progress,

the persistent gaps in seat belt use

suggest that additional approaches may

be necessary.

Seat belt warning systems are a

vehicle-based strategy to increase belt

use. Seat belt warning systems

encourage seat belt use by reminding

unbuckled occupants to fasten their

belts and/or by informing the driver that

a passenger is unbelted, so that the

driver can request the unbelted

occupant to buckle up.

The warnings

provided by seat belt warning systems

typically consist of visual and/or

audible signals. An optimized warning

system balances effectiveness and

annoyance, so that the warning is

noticeable enough that the occupants

will be motivated to fasten their belts,

but not so intrusive that an occupant

may attempt to circumvent or disable it

or the public will not accept it.

Research by NHTSA and others shows

that seat belt warning systems are

effective at getting unbuckled occupants

to fasten their seat belt. (We take a

closer look at this research in Section V

and Section XIV.A, as well as the PRIA.)

Federal Motor Vehicle Safety

Standard (FMVSS) No. 208, ‘‘Occupant

crash protection,’’ requires a short-

duration audio-visual seat belt warning

for the driver’s seat belt on passenger

cars and most light- and medium-duty

trucks, MPVs, and buses. (Later in this

section we discuss the current

requirements in more detail.) The visual

component of the warning generally

must be at least sixty seconds long, and

the audible component must be at least

four seconds long. The regulations do

not require seat belt warnings for any

seating position other than the driver’s

seat.

Although not required by NHTSA’s

regulations, most currently produced

vehicles have a seat belt warning for the

front outboard passenger seat. Almost

all (96.6%) MY 2022 vehicles offered for

sale in the United States are equipped

with a seat belt warning for the front

outboard passenger seat. Further, almost

all vehicles already provide an audio-

visual seat belt warning for both front

outboard seats that is longer than the

minimum warning for the driver’s seat

belt currently required in FMVSS No.

208. However, the persistence of the

front seat belt warning, while greater

than the very minimal durations

required by FMVSS No. 208, is not

consistent across currently produced

vehicles. Specifically, a little over half

of MY 2022 vehicles provide a visual

warning that lasts until the belts at any

occupied front outboard seat are

fastened, and while almost all (about

93%) have an audible warning lasting at

least a minute and a half, less than half

have an audible warning that lasts at

least two minutes.

This means that

while many currently produced vehicles

have significantly enhanced reminders,

many do not. This, along with the

plateauing front seat belt use numbers

suggests that the current regulatory

minima are too short, and that in the

absence of a requirement, persistent

audible reminders that could improve

front seat belt use may not be widely

provided in the market.

On the other hand, while almost all

model year MY 2022 vehicles have a

seat belt warning for the front outboard

passenger seat, under half come

equipped with a rear seat belt warning

system. Rear seat belt warnings were

first introduced in the United States by

Volvo around 2009. Based on data on

total projected vehicle sales in the

United States for model year (MY) 2022

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Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules

Through the NCAP program, NHTSA sends

annual requests for safety information about new

vehicles to vehicle manufacturers. This includes

specific questions on seat belt reminder systems.

The focus of this request for information is for

vehicle models that will be sold in the upcoming

model year that have a GVWR of 4,536 kg (10,000

lbs.) or less, and this data generally covers all such

vehicles offered for sale in the U.S. for MY 2022.

Throughout this document we will refer to this data

as our ‘‘NCAP data’’ or ‘‘Purchasing with Safety in

Mind: What to Look For When Buying a Vehicle’’

data or information.

Transportation Research Board Study at 19

(citing Donna Glassbrenner. 2002. Safety Belt and

Helmet Use in 2002—Overall Results. DOT HS 809

500. Washington, DC: U.S. Department of

Transportation, National Highway Traffic Safety

Administration).

Matthew J. Trowbridge & Richard Kent, Rear-

Seat Motor Vehicle Travel in the U.S.: Using

National Data to Define a Population at Risk. Am.

J. Prev. Med. 37(4), 321–3 (2009).

Trowbridge & Kent at 322.

32 FR 2408, 2415 (Feb. 3, 1967).

S4.1.5.1(a)(3); S7.3.

S4.2.6; S7.3.

S4.2.6 (with the exception of some compliance

options).

See, e.g., Interpretation Letter from NHTSA to

R. Lucki, July 24, 1985 (‘‘Thus, the intent was to

require a warning system for only the driver’s

position.’’). All NHTSA interpretation letters cited

in this preamble are available at http://

isearch.nhtsa.gov/search.htm.

49 CFR 571.208, S7.3.

The warning requirements for automatic belts

in S4.5.3 mirror, with some differences, the first

compliance option. Automatic belts are rarely, if

ever, installed in current production vehicles, and

NHTSA’s regulations limit the seating positions for

which automatic belts may be used to rear seats.

‘‘Active protection’’ refers to features, such as

manual seat belts, that require action by the

occupant, while ‘‘automatic protection’’ or ‘‘passive

protection’’ refers to safety features that do not

require any action by the occupant other than

sitting in a designated seating position. Seat belt

interlocks prevent starting or operating a motor

vehicle if an occupant is not using a seat belt. For

a fuller discussion of the history of the active and

passive protection requirements in FMVSS No. 208,

see Stephen R. Kratzke, Regulatory History of

Automatic Crash Protection in FMVSS 208. SAE

Technical Paper 950865, International Congress and

Exposition, Society of Automotive Engineers,

Detroit, Michigan, Feb. 27–March 2 (1995).

36 FR 4600 (May 10, 1971).

37 FR 3911 (Feb. 24, 1972).

These amendments were codified at 49 U.S.C.

30124. As explained below, the provisions were

amended in 2012 by the Moving Ahead for Progress

in the 21st Century Act.

from the agency’s New Car Assessment

Program (NCAP) Purchasing with Safety

in Mind: What to Look For When Buying

a Vehicle program, about 46.9 percent

are equipped with a rear seat belt

warning system.

Based on this MY

2022 data, fifteen vehicle manufacturers

offer vehicles for sale in the United

States with rear seat belt warning

systems. Thus, while rear seat belt

warnings have become more widely

deployed in recent years, the majority of

the current fleet still is not equipped

with them.

The benefits of increasing seat belt

use could be sizable. The National

Academy of Sciences has noted that

‘‘even a small increase in belt use

should have large benefits.’’

The size

of the unbelted fatality problem for front

seats means that even a very modest

improvement in seat belt use will have

a meaningful benefit. Our analysis

found that even a 1% increase in belt

usage for the driver’s seat resulted in a

significant number of lives saved. With

respect to the rear seats, ‘‘while the

overall proportion of person-trips taken

as a rear-seat occupant in the U.S. is

relatively low (12.9%), at-risk travel

exposure by rear-seat passengers at a

national level is substantial

(approximately 39 billion annual

person-trips).’’

Moreover, children are

proportionally much more likely to be

rear seat passengers than adults,

and

the increased prevalence of ridesharing

services has likely increased the

prevalence of rear-seat passengers.

In short, front seat belt use rates

appear to have plateaued, and rear seat

belt use rates have persistently been

below those for the front seats.

Moreover, unbuckled occupants

continue to be overrepresented in fatal

crashes (51%), given the lower exposure

of unbelted occupants relative to belted

occupants (because front seat belt use

was about 90% and rear seat belt use

was 80%). Nevertheless, in spite of the

effectiveness of seat belts and seat belt

warnings, most new vehicles continue

to lack a rear seat belt warning, and,

while many provide significantly

enhanced reminders for the front seats,

many do not. This suggests a need for

a beneficial safety technology that is not

being met in the vehicle market. This

NPRM is intended to meet that need.

In Section VI and Section XIV below,

and in the PRIA, we take a detailed look

at the estimated target population,

effectiveness of front and rear belt

warnings, and benefits and costs of this

proposal.

III. Regulatory and Legislative History

Current Driver’s Seat Belt Warning

Requirements

FMVSS No. 208 is intended to reduce

the likelihood of occupant deaths and

the likelihood and severity of occupant

injuries in crashes. The standard took

effect in 1968 and from its inception

required seat belts in passenger cars.

The standard currently requires a seat

belt warning for the driver’s seat belt on

passenger cars;

trucks and MPVs with

a GVWR of 4,536 kg (10,000 lb) or less

(except for some compliance options

which do not require the warning);

and buses with a GVWR of 3,855 kg

(8,500 lb) or less and an unloaded

weight less than or equal to 2,495 kg

(5,500 lb).

The regulations do not

require seat belt warnings for any

seating position other than the driver’s

seat.

Manufacturers have two compliance

options for the driver’s warning.

The

first option requires that if the key is in

the ‘‘on’’ or ‘‘start’’ position and the seat

belt is not in use, the vehicle must

provide a visual warning for at least 60

seconds, and an audible warning that

lasts 4 to 8 seconds. Under the second

option, when the key is turned to the

‘‘on’’ or ‘‘start’’ position, the vehicle

must provide a visual warning for 4 to

8 seconds (regardless of whether the

driver seat belt is fastened) and an

audible warning lasting 4 to 8 seconds

if the driver seat belt is not in use.

Early NHTSA Experiences With Seat

Belt Warnings

Between 1967 and 1974, NHTSA

promulgated a series of different

occupant protection regulations that

specified as compliance options various

combinations of active and passive

occupant crash protection, seat belt

interlocks, and seat belt warnings.

seat belt warning was first required in

1971, when NHTSA sought to increase

seat belt use by adopting occupant

protection compliance options that

included the use of a seat belt warning

for the front outboard seating

positions.

This seat belt warning

option required audible and visible

warning signals that lasted for as long as

the occupant was unbelted, the ignition

was ‘‘on,’’ and the transmission was in

forward or reverse. In 1972, NHTSA

adopted occupant protection options for

passenger cars that included (for cars

that did not provide automatic

protection) an interlock system that

would prevent the engine from starting

if any of the front seat belts were not

fastened.

Contrary to the agency’s

expectations, the initial vehicle

introduction of these systems in the

early 1970s was not well-received by the

public. In particular, continuous

buzzers and ignition interlocks annoyed

many consumers to the point of their

disabling or circumventing the systems.

As a result of the negative consumer

reaction, Congress adopted a provision,

as part of the Motor Vehicle and School

Bus Safety Amendments of 1974,

prohibiting NHTSA from prescribing a

motor vehicle safety standard that

required, or permitted as a compliance

option, seat belt interlocks or audible

seat belt warnings lasting longer than

eight seconds.

In response, NHTSA

amended FMVSS No. 208 in 1974 to

require that only the driver seating

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39 FR 42692 (Dec. 6, 1974).

House Report 107–108, June 22, 2001.

Transportation Research Board Study at 9.

See Docket No. NHTSA–2002–13226.

See Docket Nos. NHTSA–2001–9899, NHTSA–

2002–13379, NHTSA–2003–14742, NHTSA–2003–

15006, and NHTSA–2003–15156.

Public Law 109–59, 10306 (2005).

Docket No. NHTSA–2010–0061–0002.

84 FR 51076 (Sept. 27, 2019).

75 FR 37343 (June 29, 2010) (Docket No.

NHTSA–2010–0061).

The Association of International Automobile

Manufacturers subsequently became the

Association of Global Automakers (Global). The

Alliance and Global have merged to become the

Alliance for Automotive Innovation.

Public Law 112–141 (2012).

Id. at section 31202(a)(2) (repealing portion of

49 U.S.C. 30124).

Id. at section 31503. Authority has been

delegated to NHTSA. 49 CFR 1.95.

Section 30111 requires that a Motor Vehicle

Safety Standard meet the need for safety, be stated

in objective terms, and be practicable, among other

requirements. See infra Section VIII.

78 FR 5865 (Jan. 28, 2013).

position be equipped with a seat belt

warning system providing a visual and

audible warning, with the audible

warning not lasting longer than eight

seconds.

The limited-duration driver’s

seat belt warning requirement has

remained in the standard, with some

changes, since 1974. Since that time

FMVSS No. 208 has not been amended

to require seat belt warnings for any

passenger seating positions.

Recent Regulatory History

In 2001, the House Committee on

Appropriations directed NHTSA to

contract with the Transportation

Research Board (TRB) of the National

Academy of Sciences to conduct a study

on the benefits and acceptability of

minimally intrusive vehicle

technologies to increase seat belt use.

The Committee also requested that the

study consider potential legislative and

regulatory actions to facilitate

installation of devices to encourage seat

belt use. The TRB report (published in

2004) found that new seat belt use

technologies existed that could increase

belt use without being overly

intrusive.

It recommended that rear

seat belt warning systems be developed

and that NHTSA undertake a broad,

multi-year program of research on the

effectiveness and acceptability of

different seat belt warning systems to

establish a basis for future regulation. It

also recommended that Congress amend

the Safety Act to eliminate the 8-second

limit on the length of the audible

warning.

In 2002 and 2003, NHTSA sent letters

to several vehicle manufacturers

encouraging them to enhance seat belt

warning systems beyond the FMVSS

No. 208 minimum requirements.

The

agency facilitated the voluntary

adoption of enhanced warnings through

a series of legal interpretations that

determined that the Safety Act did not

prohibit manufacturers from

implementing enhanced warning

systems as long as the manufacturer

provided some means of differentiating

the voluntarily-provided signal from the

required signal (for example, by a

clearly distinguished lapse in time

between the two signals).

(An

‘‘enhanced’’ system is one with visual

and/or audible warning signals that

exceed the durations specified in

FMVSS No. 208, S7.3, and/or that

applies to seating positions other than

the driver’s seat. A ‘‘basic’’ system is

one that simply meets the minimum

requirements in FMVSS No. 208.) Many

vehicle manufacturers subsequently

implemented enhanced seat belt

warnings for the driver and right front

outboard seating positions. Based on

information submitted to the agency in

connection with NCAP, for MY 2022,

99.6 percent of participating vehicle

models offered for sale in the United

States had an enhanced warning

(audible and/or visual) for the driver,

right front passenger, or both.

In 2005, Congress passed legislation—

the Safe, Accountable, Flexible, and

Efficient Transportation Equity Act—a

Legacy for Users (SAFETEA–LU)

—

that required NHTSA to evaluate the

effectiveness and acceptability of

several different types of enhanced seat

belt warnings offered by a number of

manufacturers. In response, the agency

conducted a comprehensive multi-phase

research study (explained in Section V

below).

On November 21, 2007, Public Citizen

and Advocates for Highway and Auto

Safety (Advocates, and, collectively,

petitioners) petitioned NHTSA to

amend FMVSS No. 208 to require a seat

belt warning system for rear seats on

passenger cars and MPVs with a GVWR

of 4,536 kg (10,000 lb) or less.

The

petitioners noted that primary

enforcement laws typically do not cover

rear seat occupants and that studies

have indicated that warnings for rear

seat belts would significantly increase

rear passenger seat belt use. The

petitioners stated that rear seat belt

warnings are technologically feasible

and would be less costly if they were

required in all vehicles. The petitioners

provided a range of estimates of how

much a rear seat belt warning system

could increase rear belt use. The

petitioners stated that rear seat belt

warnings would save hundreds of lives

each year and that a large percentage of

the lives saved would be children. As

noted in the ANPRM,

NHTSA granted

the petition.

On June 29, 2010, the agency

published a Request for Comments

document (RFC) on the petition.

The

RFC discussed the agency’s research

and findings regarding requiring rear

seat belt warnings and solicited

comments.

The agency received 26 comments.

Five commenters opposed requiring rear

seat belt warnings: Ford Motor

Company, General Motors, the Alliance

of Automobile Manufacturers (Alliance),

the Association of International

Automobile Manufacturers,

and a

commenter from the general public.

These commenters believed that a

requirement for rear seat belt warnings

was premature and that it should

remain voluntary, and some supported

using NCAP to encourage their

penetration in the market. Among those

that supported requiring rear seat belt

warnings were IEE S.A., Consumers

Union, the Insurance Institute for

Highway Safety (IIHS), the Automotive

Occupant Restraint Council (now

known as the Automotive Safety

Council), and the American Academy of

Pediatrics.

In 2012, Congress passed the Moving

Ahead for Progress in the 21st Century

Act (MAP–21).

That legislation

contains two provisions regarding seat

belt warning systems. First, it repeals

the 8-second durational limit for the

driver’s seat belt audible warning.

Second, it requires the Secretary of DOT

to initiate a rulemaking proceeding to

amend FMVSS No. 208 to provide a

safety belt use warning system for

designated seating positions in the rear

seat.

It directs the Secretary to either

issue a final rule, or, if the Secretary

determines that such an amendment

does not meet the requirements and

considerations of 49 U.S.C. 30111,

submit a report to Congress describing

the reasons for not prescribing such a

standard.

In accordance with MAP–21, in early

2013 NHTSA initiated a rulemaking

proceeding when it submitted for public

comment a proposal to undertake a

study regarding the effectiveness of

existing rear seat belt warning

systems.

(The results of this study are

discussed in Section V below.) In 2017,

the Center for Auto Safety and Kids and

Cars filed a petition for a writ of

mandamus in the United States Court of

Appeals for the District of Columbia

Circuit to compel DOT to initiate and

complete a rulemaking to require a rear

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In re Kids and Cars, Inc., No. 17–1229, Doc.

1702061 (D.C. Cir. filed Oct. 30, 2017).

In re Kids and Cars, Inc., No. 17–1229 (D.C. Cir.

June 5, 2018).

ECE Regulation No. 16, Revision 10.

The regulation was introduced in two phases:

September 1, 2019 for new vehicle types (i.e.,

applied to all vehicle models that get a new type

approval) and September 1, 2021 for all newly

produced and registered vehicles.

European New Car Assessment Programme

Assessment Protocol—Safety Assist, Version 9.1,

November 2021.

For front seat belts, the assessment protocol

requires both a visual and an audible warning

signal. The front occupant visual signal must

remain active until the seat belt is fastened. The

audible signal for the front occupants has two

stages, an initial and final audible signal, which

have different onset criteria. The initial audible

signal must not exceed 30 seconds and the final

audible signal must be at least 90 seconds. To

prevent unnecessary signals, the system must also

be capable of detecting whether the front passenger

seat is occupied.

Sction 3.4.2.1.

See 68 FR 46262 (Aug. 5, 2003).

U.S. Department of Transportation, National

Highway Traffic Safety Administration. July 2003.

Initiatives to Address Safety Belt Use, available at

www.regulations.gov (docket NHTSA–2003–14621).

Mark Freedman et al. The Effectiveness of

Enhanced Seat Belt Reminder Systems Draft Report:

Observational Field Data Collection Methodology

and Findings. 2007. DOT HS–810–844. Washington,

DC: National Highway Traffic Safety

Administration.

seat belt warning.

The Court

subsequently denied the petition

without prejudice to renewal in the

event of significant additional agency

delay.

In 2019, NHTSA published an

Advance Notice of Proposed

Rulemaking seeking comment on a

variety of issues related to potential rear

seat belt warning requirements. The

ANPRM is discussed in Section VII.

IV. ECE Requirements and Euro NCAP

ECE Requirements

The European Union has issued an

updated version of Regulation No. 16

of the Economic Commission for Europe

of the United Nations (UNECE) that

requires seat belt reminder systems in

all front and rear seats on new cars.

The seat belt reminder system is

required to have both a start-of-trip

warning and a change-of-status warning

for both the rear and front seats, though

the exact requirements differ somewhat

for rear and front seats.

Rear seat requirements. R16 specifies

a two-level warning. The first-level

warning is a visual warning and the

second-level warning is an audio-visual

warning. The first-level warning applies

at the start of a trip and the second-level

warning applies when a fastened belt

becomes unfastened during a trip. The

first-level warning must activate when

the seat belt of any of the rear seats is

not fastened and the ignition switch or

master control switch is activated. The

first-level warning must last at least 60

seconds or until the belt is fastened (or

the seat is no longer occupied, if

equipped with occupant detection). The

second-level warning must activate

when a belt becomes unfastened and

certain specified speed or distance

thresholds are met and must last for 30

seconds unless other specified criteria

are met (e.g., the belt is re-fastened).

Front seat requirements. The front

seat belt warning requirements are

similar to the rear seat warnings, with

some differences. First, the first-level

visual warning is only required to last

30 seconds, not 60 seconds. Second, the

second-level warning applies to

unfastened belts at the start of the trip

as well as to changes in belt status.

The regulation also contains a variety

of other requirements relating to the seat

belt warning systems (e.g., telltales,

exemptions for certain vehicles and

seating positions). R16 also allows for

short and long-term deactivation of both

front and rear warnings.

The ECE requirements are discussed

in more detail where relevant in later

sections of this preamble.

Euro NCAP

Euro NCAP introduced bonus points

for seat belt warnings in 2002. The Euro

NCAP protocol for Safety Assist systems

describes which features a seat belt

reminder must have to qualify for extra

points.

Rear seat warnings. For rear seats, a

visual signal must start once the ignition

switch is engaged. The visual signal

must be at least 60 seconds long.

Occupant detection is not required for

rear seats, but systems that feature rear

seat occupant detection are eligible for

higher scores. For systems without

occupant detection, the visual signal

must clearly indicate to the driver

which seat belts are in use and not in

use. For systems with occupant

detection on all rear seating positions,

the visual signal does not need to

indicate the number of seat belts in use

or not in use, but the signal must remain

active if a seat belt remains unfastened

on any of the occupied seats in the rear.

No visual signal is required if all the

rear occupants are belted. For systems

with rear seat occupant detection, a 30-

second audible signal needs to activate

before the vehicle reaches a speed of 25

km/h or before it travels 500 meters

when any occupied seat has an

unbuckled belt.

When any seat belt

experiences a change of status at vehicle

speeds above 25 km/h, an audio-visual

signal is required, with the visual signal

lasting 60 seconds and the audible

warning lasting 30 seconds, unless

certain conditions are met.

Front seat warnings. The Euro NCAP

protocol requires that, in order to

receive points, at the start of a trip the

system must provide a visual seat belt

warning that lasts until the belt is

fastened

and an audible warning that

activates when certain conditions are

met and generally must last at least

about 90 seconds (the exact duration

depends on a variety of specified

criteria, such as vehicle speed or

distance travelled). It also specifies an

audio-visual change-of-status warning

that meets the requirements of the

initial start of trip warning.

V. NHTSA Research on Effectiveness

and Acceptance of Seat Belt Warning

Systems

NHTSA has taken a variety of actions

to research the effectiveness and

acceptance of seat belt warnings.

In 2002 the agency chartered an

integrated project team to recommend

strategies for increasing seat belt use.

The team’s report, issued in 2003,

observed that ‘‘[d]espite the significant

increases over the past twenty years,

safety belt use in the United States falls

short of that in some industrialized

nations.’’

The report also noted that

there are a ‘‘wide range of initiatives

. . . that have the potential to raise and/

or sustain safety belt use rates.’’ The

report went on to identify several such

initiatives, which it classified as either

behavioral or vehicle-based. The

behavioral strategies included

upgrading existing State seat belt laws,

high-visibility enforcement campaigns,

a national communications plan,

employer policies and regulation, and

insurance industry collaboration. The

vehicle-based strategies included

encouraging vehicle manufacturers to

voluntarily install enhanced seat belt

warning systems, providing consumer

information on vehicles equipped with

enhanced warning systems as part of

NCAP, and continued monitoring and

assessment of the effectiveness and

acceptability of enhanced seat belt

warnings through research.

In response to the 2005 SAFETEA–LU

mandate, NHTSA undertook a multi-

phase research study of seat belt

warnings. NHTSA published several

reports on these studies. Three are

particularly relevant to this’s NPRM.

The first is a large-sample

(approximately 40,000 observations)

national observational study on the

effectiveness of front seat belt

warnings.

The study covered several

states in different parts of the country.

The vehicles in the study sample had a

wide variety of seat belt warning

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N. Lerner et al. 2007. Acceptability and

Potential Effectiveness of Enhanced Seat Belt

Reminder System Features. DOT HS 810 848.

Washington, DC: National Highway Traffic Safety

Administration [hereinafter DOT 2007

Acceptability Study].

DOT 2009 Belt Warning Study, supra note 36.

Paul Schroeder & Melanie Wilbur. 2015.

Survey of Principal Drivers of Vehicles with a Rear

Seat Belt Reminder System. Washington, DC:

National Highway Traffic Safety Administration.

Polson, A., Lerner, N., Burkhardt, E., Piesse, A.,

Zador, P., & Janniello, E. (2021, October). Enhanced

seat belt reminder systems: An observational study

examining the relationship with seat belt use

(Report No. DOT HS 812 808). National Highway

Traffic Safety Administration, Pg. 40.

See NHTSA, NCSA Reports and Publications,

https://www.nhtsa.gov/FARS. FARS contains data

on a census of fatal traffic crashes within the 50

States, the District of Columbia, and Puerto Rico. To

be included in FARS, a crash must involve a motor

vehicle traveling on a traffic way customarily open

to the public, and must result in the death of an

occupant of a vehicle or a non-occupant within 30

days of the crash.

The CDS target population is defined as police-

reported motor vehicle traffic crashes involving at

least one passenger car, pickup, van, or SUV (also

called CDS applicable vehicles) that was towed

from the scene due to damage.

DOT Lives Saved Study at 106 (front seats); Id.

at 112 (rear seats). Seat belts are less effective in

severe near-side impacts or other catastrophic

crashes. Id. at 112.

See PRIA, Appendix D.

84 FR 51076 (Sept. 27, 2019).

systems. These included warning

systems that had only the minimum

features required by FMVSS No. 208, as

well as twenty different enhanced

warning systems. Because of the detail

of the data gathered (e.g., occupant

demographic and vehicle-specific

information), the analysis was able to

control for confounding factors. The

second study uses an experimental or

focus-group-based approach to study

consumer acceptance as well as

effectiveness.

The third report

summarized and extended the analyses

from the previous two reports.

This

series of research studies shows, among

other things, that the presence of an

enhanced front seat belt reminder

system increased front outboard

passenger seat belt use by about 3 to 4

percentage points more than in vehicles

with only a driver seat belt warning

system meeting the minimum

requirements in S7.3.

In 2015 the agency completed an

additional report on a study of the

effectiveness and consumer acceptance

of rear seat belt warnings.

This study

utilized a telephone survey of the

drivers of vehicles with and without

rear seat belt warning systems. The

study found that overall, drivers of

vehicles with a rear seat belt warning

system were satisfied with the system

and noticed an increase in rear seat belt

use. For example, among drivers of

vehicles with a rear seat belt warning,

approximately 80% were satisfied with

the system and 65% reported that the

rear seat belt warning made it easier to

encourage rear seat passengers to buckle

up. About one-quarter of drivers (24%)

of vehicles equipped with a rear seat

belt warning system noticed an increase

in rear seat belt use. When asked about

their experience with the change of seat

belt buckle status alert, close to half of

the drivers of vehicles with a rear seat

belt warning system (49%) said that

their system had indicated, within the

past year, that a passenger had

unfastened his/her seat belt. Overall, of

those who reported experiencing a

change of seat belt status alert (49%),

over three-quarters of these drivers

(77%) said that the unbuckled passenger

eventually did refasten her seat belt,

either on her own or at the driver’s

request.

In 2021, NHTSA published an update

of the 2009 Belt Warning Study.

The

purpose of the report was to examine

the front seat belt warning system

features associated with greater

effectiveness in increasing seat belt use.

Because of limitations with the

collected data, the findings of the report

were relatively limited. However, the

report found (consistent with the earlier

research) that ‘‘systems with sound,

icon, and text had generally higher seat

belt use rates than systems without all

of these features.’’

The results of this research are

discussed in more detail throughout the

preamble. The relevant research reports

have also been placed in the docket for

this rulemaking.

VI. Safety Need

As noted earlier, rear seat belt use has

consistently been lower than front seat

belt use. NHTSA estimated the target

populations for rear and front outboard

passenger seat belt warnings, as well as

the effectiveness of the warnings. This

section provides a summary of these

estimates. For additional discussion of

the methodology used to derive these

estimates, see the discussion in the

Preliminary Regulatory Impact Analysis

as well as the studies placed in the

docket.

To estimate the target populations for

the rear and front passenger seats—that

is, the number of unrestrained

occupants who could be expected to

potentially benefit from the proposed

seat belt warning requirements—

NHTSA examined data from the Fatality

Analysis Reporting System (FARS)

and the National Automotive Sampling

System (NASS) Crashworthiness Data

System (CDS)

from 2011 to 2015.

Because seat belts are effective at

preventing deaths and injuries in all

types of motor vehicle crashes,

the

target populations include fatalities and

injuries from different crash modes. We

examined fatalities and injuries for

occupants in passenger cars, trucks,

buses, and MPVs with a GVWR of 4,536

kg (10,000 lb) or less (the vehicles [with

some exceptions] to which the proposed

requirements would apply). We

adjusted these to account for future

decreases in fatalities and injuries

projected to occur in the absence of the

proposed requirements due to the

introduction of other mandatory safety

technologies (e.g., electronic stability

control, ejection mitigation side curtain

air bags).

Based on FARS and NASS–CDS data

from 2011 to 2015, on average 1,002

unrestrained rear occupants were killed

in crashes and 7,821 were injured

annually.

After adjusting these to

account for future decreases in fatalities

and injuries projected to occur in the

absence of the proposed requirements

due to the introduction of other

mandatory safety technologies, there

were, on average, 475 fatalities and

7,036 injuries to unrestrained rear seat

occupants each year. This is the overall

target population for the proposed rear

seat belt warning requirements.

Turning to the target population for

the driver and front outboard passenger

seat, from 2011 to 2015, annually an

average of 7,503 unrestrained drivers

were killed in crashes and an average of

1,453 unrestrained front outboard

passenger seat occupants were killed in

crashes and 63,436 unrestrained drivers

and front outboard passenger occupants

were injured.

After adjusting these to

account for future decreases in fatalities

and injuries projected to occur in the

absence of the proposed requirements

due to the introduction of other

mandatory safety technologies, there

were, on average, 6,733 fatalities and

47,952 injuries to unrestrained front

outboard seat occupants each year. This

is the overall target population for the

proposed front outboard passenger seat

belt warning requirements.

VII. ANPRM

On September 27, 2019, in accordance

with the grant of the petition from

Public Citizen and Advocates for

Highway and Auto Safety and

continuing with the proceeding that

MAP–21 required to be initiated,

NHTSA published an ANPRM for

requiring rear seat belt warning

systems.

The ANPRM sought

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49 U.S.C. 30111(a).

49 U.S.C. 30102(a)(9).

Section 30102(a)(10).

Section 30111(b)(1).

Section 30111(b)(3)–(4).

See 49 CFR 1.95.

comment on a variety of issues related

to a requirement for a rear seat belt

warning system, including potential

requirements for such systems, the

vehicles to which they should apply,

their effectiveness, the likely consumer

acceptance, and the associated costs and

benefits. It also sought comment on

removing the 8-second maximum

duration for the driver’s seat belt

warning specified in FMVSS No. 208

S7.3 to reflect MAP–21’s repeal of the

statutory limitation that was the basis

for this provision.

The comment period closed on

November 26, 2019. NHTSA received 45

comments: five comments from vehicle

manufacturers; two from school

transportation associations; two from

vehicle manufacturer associations;

seven from safety advocacy groups;

seven from automotive industry

suppliers and trade associations; one

comment each from a foreign country,

insurance institute, consumer program,

and bus manufacturer; and eighteen

comments from individual members of

the public.

Most commenters, including safety

advocates, vehicle manufacturers and

suppliers, and individual members of

the public, supported a rear seat belt

warning requirement. Some commenters

(including a bus manufacturer, a bus

supplier, an association of school bus

operators, and some individual

commenters) recommended that the

requirements not apply to heavy

vehicles such as buses or school buses,

citing concerns with installation, costs,

the driver’s role, and maintenance.

Vehicle manufacturers and suppliers

commented that the requirements

should harmonize with ECE R16, while

some other commenters (predominantly

safety advocacy groups) supported

departures from the ECE R16

requirements, arguing that

harmonization should not come at the

expense of safety. Thus, while most

commenters supported requiring a

visual warning on vehicle start-up and

an audio-visual change-of-status

warning for a belt that is unfastened

when the vehicle is moving, some

commenters favored requiring enhanced

features such as an audio-visual

warning on vehicle start-up and

occupant detection.

A few commenters (Advocates, Kids

and Cars, Center for Auto Safety)

pointed out the delays with this

rulemaking and the urgency for a final

rule. Most vehicle manufacturers

supported removing the upper limit on

the duration of the audible warning for

the driver’s seat belt.

VIII. NHTSA’s Statutory Authority

NHTSA is proposing this’s NPRM

pursuant to its authority under the

National Traffic and Motor Vehicle

Safety Act.

Under 49 U.S.C. chapter 301, Motor

Vehicle Safety (49 U.S.C. 30101 et seq.),

the Secretary of Transportation is

responsible for prescribing motor

vehicle safety standards that are

practicable, meet the need for motor

vehicle safety, and are stated in

objective terms.

‘‘Motor vehicle

safety’’ is defined in the Motor Vehicle

Safety Act as ‘‘the performance of a

motor vehicle or motor vehicle

equipment in a way that protects the

public against unreasonable risk of

accidents occurring because of the

design, construction, or performance of

a motor vehicle, and against

unreasonable risk of death or injury in

an accident, and includes

nonoperational safety of a motor

vehicle.’’

‘‘Motor vehicle safety

standard’’ means a minimum

performance standard for motor vehicles

or motor vehicle equipment.

When

prescribing such standards, the

Secretary must consider all relevant,

available motor vehicle safety

information.

The Secretary must also

consider whether a proposed standard is

reasonable, practicable, and appropriate

for the types of motor vehicles or motor

vehicle equipment for which it is

prescribed and the extent to which the

standard will further the statutory

purpose of reducing traffic accidents

and associated deaths.

The

responsibility for promulgation of

Federal motor vehicle safety standards

is delegated to NHTSA.

In making the

proposals in this’s NPRM, the agency

carefully considered all the

aforementioned statutory requirements.

They are discussed in more detail

throughout the preamble and in the

regulatory analyses. In addition, MAP–

21 directed NHTSA to initiate a

rulemaking to require a seat belt

warning for the rear seats in motor

vehicles (see Section III, Regulatory and

Legislative History).

IX. Overview of Proposed Requirements

As previously mentioned, this NPRM

proposes amending the existing seat belt

warning provisions in FMVSS No. 208.

This proposal has two main

components. The first proposes

requiring a seat belt reminder for the

rear seats. The second proposes changes

and enhancements to the seat belt

warning requirements for the front

outboard seats. These proposed

requirements would apply to passenger

cars and trucks, buses (except school

buses), and multipurpose passenger

vehicles with a GVWR of 4,536 kg

(10,000 lb) or less.

Rear Seat Belt Reminder Requirements

The first component of this NPRM is

a set of proposed requirements for a seat

belt warning for rear seats. The

proposed requirements have four main

elements.

• Visual warning on vehicle start-up

to inform the driver of the status of the

rear seat belts. We propose three

different compliance options for the rear

seat belt warning system. The first

would require the system to indicate

how many or which rear seat belts are

in use (the ‘‘positive-only’’ option). The

second would require the system to

indicate, for the occupied rear seats,

how many or which rear seat belts are

not in use (the ‘‘negative-only’’ option).

The third would require the system to

indicate, for the occupied rear seats,

how many or which rear seat belts are

in use and how many or which rear seat

belts are not in use (the ‘‘full-status’’

option). Certain features would be

required of all the options. Each system

would have to provide a continuous or

flashing visual warning, consisting of

either icons or text, visible to the driver.

The visual warning would have to last

for at least 60 seconds, beginning when

the vehicle’s ignition switch is moved to

the ‘‘on’’ or ‘‘start’’ position. The

negative-only and full-status

compliance options would require that

the rear seats be equipped with a belt

latch sensor and an occupant detection

system (which facilitates these more-

informative warnings), while the

positive-only option would only require

that the rear seats be equipped with a

belt latch sensor.

• Audio-visual change-of-status

warning. We propose an audio-visual

warning whenever a fastened rear seat

belt is unfastened while the ignition

switch is in the ‘‘on’’ or ‘‘start’’ position

and the vehicle’s transmission selector

is in a forward or reverse gear. The

warning would have to last for at least

30 seconds. We do not propose any

requirements for the volume or tone of

the warning. The intent of this warning

is to alert the driver or other occupants

of a change in belt status during a trip.

The warning would not be required if a

door is opened, which would be the

case if a rear passenger unfastened their

belt in order to exit the vehicle.

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Comments are from the ANPRM unless

otherwise noted. As discussed in more detail in the

regulatory alternatives section, many commenters

(OEMs and trade groups) generally recommended

harmonizing with R16 and/or other NCAP

programs. In the following sub-sections, we include

comments that specifically recommended

harmonizing with R16 or Euro NCAP with respect

to the particular issue being discussed.

See 76 FR 53102 (Aug. 25, 2011) (denial of a

petition for rulemaking to mandate the installation

of three-point seat belts for all seating positions on

all school buses).

§ 8.4.1.2.

• Requirements related to electrical

connections. Readily removable rear

seats would be required to either

automatically connect the electrical

connections when the seat is put in

place, or, if a manual connection is

required, the connectors must be

readily-accessible. Further, vehicles

utilizing the negative-only compliance

option would be required to provide a

visual warning to the driver if a proper

electrical connection has not been

established for a readily removable rear

seat.

• Owner’s manual requirements. We

propose that the vehicle owner’s manual

(which includes information provided

by the vehicle manufacturer to the

consumer, whether in digital or printed

form) describe the warning system’s

features, including the location and

format of the visual warnings. We also

propose that the owner’s manual (which

includes information provided by the

vehicle manufacturer to the consumer,

whether in digital or printed form)

include instructions on how to make

any manual electrical connections for

readily removable seats.

Front Outboard Seat Belt Warning

Requirements

We propose several changes and

enhancements to the seat belt warning

requirements for the front outboard

seats:

• Audio-visual warning on vehicle

start-up for front outboard passenger

seat. Currently, only the driver’s seat is

required to have a seat belt warning,

although almost all vehicles now

provide a seat belt warning for the front

outboard passenger seat as well.

Accordingly, we propose to require a

seat belt warning for the front outboard

passenger seat. In addition, for an ADS-

equipped vehicle that has no manually-

operated driving controls, we are

proposing that the front passenger

warning apply to ‘‘any’’ front outboard

passenger.

• Increasing the duration of the

audio-visual warning on vehicle start-

up. We propose enhancing the front seat

belt warning duration by requiring an

audio-visual warning that remains

active until the seat belt at any occupied

front outboard seat is fastened. We are

proposing this in light of a variety of

factors, including the increase in

roadway fatalities, the lack of

improvement of front seat belt use rates,

and the fact that the audio-visual

warnings with which vehicle

manufacturers are currently equipping

vehicles significantly exceed the

4-second regulatory minimum

(including a non-trivial share of

currently sold vehicles with an

indefinite-duration reminder). Vehicle

manufacturers can adjust warning signal

characteristics (such as frequency and

volume) to make the warning both

effective and acceptable to consumers.

We are also proposing some additional

requirements for the warning related to

increasing the duration (for example,

specifying at least a 20 percent duty

cycle for the warning).

• Audio-visual change-of-status

warning. We also propose to require an

audio-visual change-of-status warning

whenever a front outboard passenger

seat belt is unbuckled during a trip

(unless a front door is opened, to

account for an occupant unfastening the

belt to exit the vehicle). The warning

would be required to remain active until

the seat belt is refastened.

• Driver seat belt warning for

medium-sized buses. FMVSS No. 208

currently does not require a driver seat

belt warning for medium-sized buses

(roughly, buses that weigh between

3,855 kg (8,500 lb) and 4,536 kg (10,000

lb)). We are now proposing to require

that these buses be equipped with a

driver seat belt warning. NHTSA is

unaware of any such buses that do not

already have an FMVSS No. 208-

compliant driver seat belt warning.

Effective Date

We propose an effective date of the

first September 1 that is one year after

the publication of the final rule for the

front seat belt warning system

requirements and the first September 1

that is two years after the publication of

the final rule for the rear seat belt

warning system requirements, with

optional early compliance. For example,

if the final rule were published on

October 1, 2022, the effective date

would be September 1, 2024 for the

front seat belt warning system

requirements and September 1, 2025 for

the rear seat belt warning system

requirements. Consistent with 49 CFR

571.8(b), multi-stage manufacturers and

alterers would have an additional year

to comply.

X. Proposed Rear Seat Belt Warning

A. Overview

The proposed rear seat belt warning

requirements have four main

components: a visual warning on

vehicle start-up to alert and inform the

driver of the status of the rear seat belts;

an audio-visual change-of-status

warning when a rear seat belt is

unbuckled during a trip; requirements

for the electrical connections for readily

removable seats; and owner’s manual

requirements. We also propose

requirements for several characteristics

of this warning, such as duration and

triggering conditions. We also discuss

related issues such as hardening the

system against user circumvention,

consumer acceptance, and technological

and economic feasibility.

The proposed changes would apply to

all rear designated seating positions in

passenger cars, trucks, buses (except

school buses), and MPVs with a GVWR

of 4,536 kg (10,000 lb) or less.

B. Applicability

The ANPRM sought comment on the

vehicles to which a rear seat belt

warning requirement should apply. The

current FMVSS No. 208 generally

requires rear seat belts in passenger cars,

trucks, MPVs, buses less than 10,000 lb,

over-the-road buses between 10,000 lb

and 26,000 lb, and buses greater than

26,000 lb (except school, perimeter-

seating, and transit buses). We observed

that high-occupancy vehicles might

pose challenges for implementing a rear

warning system due to the potential

complexities of the visual signal,

number of seats, and other issues. At the

same time, such vehicles could be at

least as likely—if not more likely—to

have rear occupants. With respect to

school buses, a rear seat belt warning

requirement might place additional cost

burdens on school systems, potentially

leading to reductions in school bus

service, with a concomitant increased

risk to students.

We also noted that

school buses utilize

compartmentalization to reduce the risk

of crash injury, even to the unbelted.

The ECE R16 rear belt warning

requirements apply to M1 and N1

vehicle categories (passenger cars,

multipurpose passenger vehicles, vans,

pick-ups and light trucks), with

exemptions for ambulances, hearses,

and motor-caravans, as well as for all

seats for vehicles used for transport of

persons with disabilities, vehicles

intended for use by the armed services,

civil defense, fire services and forces

responsible for maintaining public

order.

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A Type 1 seat belt assembly is a lap belt for

pelvic restraint, and a Type 2 seat belt assembly is

a combination of pelvic and upper torso restraints

(3-point belt). Type 2 belts are required for most

rear seats in passenger cars. S4.1.5.5. Type 2 belts

are also required for most rear seats on buses

required to have rear seat belts. Type 2 belts are also

required on most rear seats in trucks and MPVs less

than or equal to 10,000 lb. Type 2 belts generally

are not required on side-facing seats.

Blue Bird’s comment was unclear, because it

also specifically commented that it was opposed to

any changes which expand the requirements of

FMVSS No. 208 for buses with a GVWR greater than

3,855 kg (8,500 lb), including the proposed

requirement for rear passenger seat belt warning

systems.

We assume that this refers to traditional

motorcoaches which are over 10,000 lb.

Comments

Advocates commented that the

requirements should apply, at a

minimum, to all passenger vehicles, and

should apply in all vehicles in which

data indicates belt non-use is occurring.

Freedman Seating Company (a

manufacturer of seating for the

transportation industry) favored a

requirement for all vehicles (and,

presumably, seating positions) requiring

Type 2 seat belts.

A number of

commenters recommended that the

requirements harmonize with R16. Two

commenters stated that, consistent with

ECE R16–07, vehicles such as

ambulances, hearses, and police cars

should be exempt from any

requirements. Two commenters

similarly stated that the rule should

only apply to vehicles under 10,000

pounds GVWR (with some specific

exclusions for certain vehicle types). A

commenter argued that while there

might be benefits to a requirement for

commercial vehicles and buses, it could

pose considerable challenges for those

vehicles, so any requirements for larger

vehicles should be considered in a

separate rulemaking.

We also received several comments

specifically about applicability to buses.

One comment stated that seat belt

reminder systems should be included in

vehicles 10,000 lb and under, including

high-occupancy vehicles such as 15-

passenger vans and school buses, given

the likelihood of vulnerable (e.g.,

children) rear seat passengers and the

difficulty for the driver to determine if

occupants are belted. Other commenters

opposed a requirement for some or all

buses. A commenter opposed

requirements for any buses based on

what it characterized as the complexity,

cost, potential for driver distraction, and

lack of data supporting effectiveness.

A commenter stated that rear seat belt

warnings should not be required in

motorcoaches;

while technically

feasible, such a requirement would be

costly and not suitable. The

commenter’s concerns were similar to

those that detailed for school buses (see

below).

Several commenters argued that

school buses should be excluded from

any requirements. They made a variety

of arguments on this point.

The commenters argued that a

requirement for school buses would be

prohibitively expensive. One

commenter stated that it could dissuade

pupil transporters from voluntarily

equipping large buses with seat belts, as

well as provoke objections to laws that

require them. Several comments

questioned the technical feasibility and

the potential for malfunctions and false

alarms. A commenter stated that

because of the complexity of any system

required for a vehicle with a large

number of rear seating positions,

improper detection is a real possibility.

Two commenters similarly said that the

sensors might not be sophisticated

enough to deal with the variations

found in the school bus operating

environment, because children that ride

in school buses are of varying ages and

sizes, with NSTA noting the possibility

of false alarms. A commenter stated that

the school bus interior is a harsh

environment and the necessary wiring

and connections are subject to failure by

exposure or tampering; this failure for

hardwired systems could be eliminated

through use of wireless technology, but

transmitting devices are also subject to

failure, and require power. However,

some commenters noted that rear

warnings for school buses may be

technically feasible and are, to some

extent, currently available.

Two commenters also raised potential

unintended consequences of school bus

driver distraction. A commenter brought

up that driver distraction is perhaps the

greatest concern for the implementation

of warning device technology in school

buses. The primary function of the

school bus driver is to safely transport

the student passengers; the bus driver

must be able to fully focus on driving,

so each activation of a warning would

require a bus driver to transfer focus to

the display source to read the data,

understand the data, then interpret the

data to the exact student/location in the

bus. At that point, the driver would

need to direct the student to buckle up

if that is the actual need. This situation

could occur simultaneously with several

students. In driving situations with

high-density urban traffic or high-speed

rural two-lane roads with much

commercial vehicle traffic, the potential

for a crash could significantly increase.

A couple of commenters questioned

the ability of school bus drivers to

ensure that student occupants use the

seat belts. A commenter questioned

what a driver faced with a seat belt

warning should do: Would the driver be

required to walk the aisle like an

airplane flight attendant inspecting the

entire bus and requiring students to

buckle up? Would the driver be required

to refuse to move the bus until all belts

are buckled? The commenter also

questioned whether it is the

responsibility of the driver or the

passenger to obey any applicable state

law (along with parental and school

information and encouragement) and

ensure the belt is fastened. Another

commented similarly stated that the

driver’s ability to ensure seat belt use is

limited; the student passengers’ failure

to comply often comes after repeated

requests to do so from school bus

drivers or aides. A few commenters also

had concerns about potential legal

liability for operators and drivers. A

commenter stated that school districts

would need to determine if the failure

of a warning system to properly

function would require that the seating

position be rendered unusable, and

another commenter said that it was

unclear if the presence of a seat belt

warning system would make the driver

legally liable in a crash for injuries to

unbelted students. The commenter

further wondered whether the addition

of such a system would force school

systems to hire bus monitors to

supervise belt use, adding a significant

cost to state and local budgets. Along

these lines, the commenter

recommended a hold-harmless

provision in the regulations to cover

school bus operators for instances where

a student passenger evades a seat belt

restraint system and sustains injuries.

Related to this, two commenters

mentioned the possibility of

circumvention in school buses. One

commenter noted the ability of

passengers to defeat the systems (either

intentionally or unintentionally);

sophisticated sensor design would be

required to warn the driver of non-use

in these cases. Another commenter said

that an occupant could buckle the belt

behind him/her, thus turning off the

alarm without having complied with the

purpose of the alarm.

A commenter stated that a seat belt

warning on school buses would lead to

routing delays, due to additional time

required at each stop to ensure that

students were belted. The commenter

also noted the potential effects of

stopped buses (especially during rush

hours). Another commenter said that

system malfunctions would result in a

school bus being removed from service

and raised the possibility of a

malfunction occurring mid-trip, which

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100

Buses with GVWRs greater than 8,500 lb and

less than or equal to 10,000 lb are currently not

required to have a driver’s seat belt warning. See

FMVSS 208, S4.4.3.1. We propose to close this

loophole. See Section XI.B.

101

S4.2.7.1.

102

S4.4.3.3; S4.4.5.1.

103

See 49 U.S.C. 30112(b)(1) (a FMVSS does not

apply to, among other things, ‘‘the sale, offer for

sale, or introduction or delivery for introduction in

interstate commerce of a motor vehicle or motor

vehicle equipment after the first purchase of the

vehicle or equipment in good faith other than for

resale’’).

104

Fifteen-passenger vans are classified as buses

under the FMVSS because they are designed for

carrying more than ten persons. See 49 CFR 571.3

(‘‘Bus means a motor vehicle with motive power,

except a trailer, designed for carrying more than 10

persons.’’) (italics in original).

105

More discussion of occupant detection

systems is provided in Section XIV.B.

would present the operator the issue of

whether to continue operating the bus

or not.

Agency Response

This proposal applies to all rear

designated seating positions in

passenger cars and all rear designated

seating positions certified to a

compliance option requiring a seat belt

in trucks, buses, and MPVs with a

GVWR of 4,536 kg (10,000 lb) or less,

except for school buses and law

enforcement vehicles. We propose to

apply the proposed requirements to

these categories of vehicles because

these vehicles are required to have seat

belts at all rear designated seating

positions and (except for some buses) a

seat belt warning for the driver’s seat.

100

We note that some types of trucks and

MPVs (motor homes, walk-in van-type

trucks, vehicles designed to be sold

exclusively to the U.S. Postal Service, or

vehicles between 8,500–10,000 lbs

carrying a chassis-mount camper)

101

and over-the-road buses that are also

prison buses

102

are not required to have

rear seat belts. The proposed

applicability is largely consistent with

ECE R16, except that we are not

proposing to exempt special-purpose

vehicle types such as ambulances

because they are typically customized

after first sale.

103

We believe it is particularly important

to include vehicles with a GVWR greater

than 3,855 kg (8,500 lb), but less than

or equal to 4,536 kg (10,000 lb)—

including buses other than school

buses—because this includes high

occupancy vehicles (e.g., large capacity

passenger vans and large sport utility

vehicles [SUVs]).

104

We also believe an

increasing number of large trucks and

vans are used as personal vehicles and

are not solely used for work-related

purposes. In addition, multiple rear

seats or rows make it more difficult for

the driver to ascertain rear seat belt use,

so a warning could prove especially

useful in these vehicles. We also

recognize that the intent of the MAP–21

mandate is to improve protection for

rear occupants; given the proven

benefits of seat belts, we tentatively

believe the warning should be broadly

applied. We acknowledge that vehicles

with a larger number of rear seats may

encounter visual signal complexities.

Accordingly, our intent is to propose

performance requirements that provide

manufacturers with the flexibility to

design a warning system that is

appropriate for each vehicle type. We

chose to limit the application of the

passenger seating requirements to light-

duty vehicles (less than or equal to

10,000 lb). Several commenters were all

in agreement with excluding vehicles

over 10,000 lb; it is consistent with the

petition and with the applicability of

the current seat belt warning system

requirements.

We have tentatively decided to

exclude all school buses (including

those weighing under 10,000 lb [small

school buses]) because of practicability

issues. First, the agency is concerned

about the costs to school systems, which

could lead to reductions in school bus

service, resulting in greater risk to

students. Second, we are concerned

about the burdens such systems might

place on the driver. For example, with

a rear seat belt warning system without

occupant detection (the minimum

compliance option that we are

proposing in this NPRM), the school bus

driver would have to verify that all the

passengers are using their seat belts

based on the system’s visual signal that

identifies how many or which rear seat

passengers are belted. We tentatively

agree with the commenters who argued

that is not practicable. This concern

might be mitigated, in part, by a more

robust system utilizing occupant

detection, but we do not believe that

would be practicable at this time.

105

Third, school buses of all sizes offer

passengers compartmentalization

protection to reduce the risk of crash

injury, even to the unbelted. Such

protection is not offered in other

vehicles. Finally, we note various other

concerns raised by the commenters and

summarized above, including the

possibility of school buses being out of

service due to malfunctioning reminder

systems, and potential liability issues

for school districts.

Law enforcement vehicles would also

be exempt from the proposed

requirements because of concerns with

practicability: the rear seats are mainly

used to transport passengers that are

under arrest and normally handcuffed,

so if the policy of the police agency is

that prisoners be transported with their

seat belts fastened then the officer

would be responsible for fastening the

seat belt around the prisoner(s) and thus

would already be aware of the belt

status of the rear seat occupants. The

term ‘‘law enforcement vehicle’’ is

already defined in FMVSS No. 208 to

mean ‘‘any vehicle manufactured

primarily for use by the United States or

by a State or local government for police

or other law enforcement purposes.’’

We seek comment on our proposed

applicability requirements.

C. Requirements

This NPRM proposes a visual warning

on vehicle start-up and an audio-visual

change-of-status warning if a belt is

unbuckled during a trip. We also

propose a variety of requirements with

respect to the warning triggering

conditions, duration, telltale, and

electrical connections, among other

things.

1. Visual Warning on Vehicle Start-Up

This NPRM proposes a visual warning

to alert and inform the driver, upon

vehicle start-up, to the status of the rear

seat belts. We also propose minimum

performance requirements for several

aspects of this warning.

a. Compliance Options for the Type of

Information Conveyed

The ANPRM sought comment on

whether NHTSA should require a

warning at the start of the trip, whether

such a warning should be visual-only or

audio-visual, and what type of

information the visual warning should

convey. NHTSA identified three

potential types of warnings. One would

require the system to indicate how

many or which rear seat belts are in use

(a ‘‘positive-only’’ system). The second

would require the system to indicate, for

the occupied rear seats, how many or

which rear seat belts are not in use

(‘‘negative-only’’). The third requires the

system to indicate, for the occupied rear

seats, how many or which rear seat belts

are in use and how many or which rear

seat belts are not in use (‘‘full-status’’).

The second and third types of warnings

identified would require that the system

be capable of determining which rear

seating positions are occupied (i.e.,

would require an occupant detection

system). NHTSA also sought comment

on whether some or all of the

compliance options should require

occupant detection.

ECE R16 requires a visual warning at

the start of a trip, but not an audible

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Section 8.4.4.1; Section 8.4.2.3.1.

107

Section 8.4.2.3.1; § 8.4.2.3.2.

108

Section 8.4.4.2.

109

Section 8.4.4.2.

110

Section 8.4.4.3.

111

Section 3.4.3.1.4.

112

Section 3.4.3.1.3.

113

Section 3.4.3.1.1.

114

Section 3.4.3.2.3. The thresholds are (at the

choice of the OEM) either a forward speed of 25

km/h or forward motion for 500 m.

115

Section 3.4.3.2.3. For front seat belts, the

assessment protocol requires both a visual and an

audible warning signal (see Section 3.4.2). The

visual signal must remain active until the seat belt

is fastened. The audible signal has two stages, an

initial and final audible signal, which have different

onset criteria. The initial audible signal must not

exceed 30 seconds and the final audible signal must

be at least 90 seconds. To prevent unnecessary

signals, the system must also be capable of

detecting whether the front passenger seats are

occupied.

signal.

106

The visual warning must

remain active until none of the belts that

triggered the warning are unfastened,

the seat(s) which triggered the warning

are no longer occupied, or 60 seconds

has elapsed.

107

The visual warning must

‘‘indicate at least all rear seating

positions to allow the driver to identify,

while facing forward as seated on the

driver seat, any seating position in

which the safety-belt is unfastened.’’

108

Occupant detection is not required, but

in vehicles that do have occupant

detection the warning does not need to

indicate unfastened belts for

unoccupied seating positions.

109

This

warning may be canceled by the

driver.

110

Euro NCAP’s rating protocol also

requires a visual warning at the start of

a trip. The requirements are similar to

ECE R16. Euro NCAP’s rating protocol

does not require occupant detection but

incentivizes systems that use occupant

detection by awarding additional points

for this feature. For systems without

occupant detection, the visual signal

must show belts in use and not in

use.

111

For systems with occupant

detection, the visual signal does not

need to indicate the number of seat belts

in use or not in use, but the signal must

remain active as long as the seat belts

remain unfastened on any of the

occupied seats in the rear;

112

no visual

signal is required if no rear occupants

are detected.

113

Systems with occupant

detection must also provide a 30-second

audible signal at the start of the trip

before specified speed or distance

thresholds have been crossed.

114

Alternatively, if occupant detection is

provided the manufacturer may use the

same warning strategy as specified for

the front seats.

115

Comments

Most commenters explicitly endorsed

a warning on start-up, and none

opposed it, although the comments

differed on whether it should have an

audible component. Two comments

recommended harmonizing with the

ECE R16 requirement for a visual-only

warning on start-up. A commenter

stated that NHTSA should provide

flexibility in terms of the type of

information that is required to be

communicated by the reminder system,

including positive-only, negative-only,

and full-status systems, with

consideration for both occupant-

detection and non-occupant-detection

centric approaches. Based on the

definitions provided within the

ANPRM, the baseline standard for R16

could be met through a non-occupant

detection, positive-only system, but

would not prohibit additional

technology features to provide

additional functionality. Another

commenter agreed that positive-only,

negative-only, and full-status systems

each could have strengths and

limitations; the priority should be that

all of these variations effectively allow

the driver to identify which seats are

unfastened (in the case without

occupant detection), or if any occupied

seats are unfastened (with occupant

detection). The commenter noted that

R16 does not establish such definitions

of systems, but rather specifies the base

requirement that the driver should be

able to identify which seats are

unfastened. The comment stated that

NHTSA should not set criteria too

broadly, which could restrict

manufacturers to implementing a full-

vehicle display, even if occupant

detection is applied, in which case a

single seat belt telltale indicator is

sufficient.

Three commenters recommended a

visual-only warning. A commenter

stated that a visual warning, such as a

telltale, should exist as an initial

warning, and a combination of audible

and visual warnings could exist as a

‘‘second-level’’ warning. Another

commenter stated that visual displays

are efficient at conveying information

that is complex, that deals with

locations in space, or that does not

require immediate action. The comment

stated that, while audio-visual warnings

are more effective than visual-only

warnings, visual displays are less

intrusive and perceived as less annoying

than audible warnings, so that a visual-

only warning would minimize the

impact of false warnings that could

negatively impact consumer acceptance.

The commenter also stated that, while

visual displays alone have not been

found to be effective for motivating

occupants to use a seat belt, the driver

may use this information to encourage

unbuckled rear occupants to use a seat

belt.

Several commenters favored requiring

an audio-visual warning at the start of

the trip. Four commenters supported the

specification of the most effective

warnings and noted that audio-visual

warnings are more effective than visible

warnings alone. Two commenters stated

that a visual-only warning would be

easily missed by a driver who is focused

on driving safely.

Three commenters recommended

requiring a ‘‘negative’’ warning with

occupant detection. A commenter said

that such systems would reduce false

signals and annoyance. Another

commenter similarly supported a

warning on startup and commented that

while a positive-only warning icon at

the start of a ride would be helpful, it

would not be as valuable as a warning

triggered by negative-only status as a

way to change the behavior of those

occupants who are lax or reluctant to

buckle up.

Agency Response

This rule proposes to require a visual

warning (without an audible

component) upon vehicle start-up.

NHTSA decided to propose the three

compliance options identified in the

ANPRM for the type of information the

warning must convey. Each proposed

system has strengths and limitations.

The positive-only system would be the

least technically complex of the three

proposed options. Since it would only

need to detect whether a seat belt is in

use, it would only require a seat belt

latch sensor. With a positive-only

system, the driver would need to

determine how many rear seat

occupants there are and then determine

if that number equals the number of seat

belts that are reported by the warning

system as buckled. This compliance

option would not necessitate occupant

detection; we tentatively believe that

there are still design and technological

challenges associated with

implementing occupant detection

technology in rear seats (this is

discussed in more detail in Section XIII,

Regulatory Alternatives).

The negative-only and full-status

systems would provide the driver with

more information, and thus might be

more effective than the positive-only

system for at least two reasons. First,

they would directly inform the driver

whether any rear seat occupants were

unbuckled, without the driver having to

compare the number or location of

occupants and fastened belts. Second, as

discussed in more detail below, warning

systems equipped with occupant

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Approximately 70% of Euro NCAP-tested

vehicles had occupant detection in the rear seats.

117

Section 3.4.3.1.3.

118

See Euro NCAP section 3.4.3.1.4.

detection are more amenable to audible

warnings and enhanced warning

features. However, we tentatively

believe that systems such as these that

provide a negative warning—that is, a

warning for an unfastened belt—are

only appropriate for systems utilizing

occupant detection. This is because we

tentatively believe that it is not

appropriate to provide a warning for an

unfastened seat belt at an unoccupied

seat because such ‘‘false positives’’

could be a nuisance for the driver and

might either desensitize the driver to the

warning signal or lead them to

circumvent or defeat the system—

especially since the majority of trips do

not have rear seat occupants. The

proposal would therefore permit a

warning for an unfastened belt only if

the seating position were equipped with

occupant detection. Accordingly, it

would not, for example, permit a system

without occupant detection that

displayed the status of all the rear seat

belts to be certified as a positive-only

system coupled with a voluntary

warning for unfastened seat belts.

With respect to comments in favor of

requiring audio-visual warnings, we

agree that warnings with an audible

component are generally more effective.

However, requiring an audio-visual

warning would necessitate requiring

occupant detection because the

resulting ‘‘false positives’’—having an

audible warning activate for an

unfastened belt at an unoccupied seat—

would annoy the driver and could

decrease the effectiveness of the

warning. Thus, this NPRM does not

require an audible warning on startup.

However, manufacturers would be free

to provide an audible warning on

startup if they so choose, especially if

the vehicle is equipped with occupant

detection in the rear. This approach

harmonizes with R16 and Euro NCAP.

We acknowledge that there are

systems currently deployed in both the

United States and Europe that would

not comply with the proposed

compliance options. In particular,

manufacturers appear to be deploying

systems without occupant detection that

provide a warning for an unfastened

belt. When the ANPRM was published,

the rear seat belt warning systems in

vehicles sold in the United States used

what would be classified in this

proposal as a positive-only warning

system. Our current, preliminary

review, however, indicates that

manufacturers are now providing visual

warnings that indicate unfastened seat

belts, and not necessarily with occupant

detection. For example, the visual

warning displays on some MY2022

Honda and Porsche vehicles appear to

indicate the status of all the rear seat

belts, but the owner’s manual does not

indicate that the vehicle is equipped

with occupant detection in the rear

seats. This information is consistent

with Honda’s comment that the

compliance options should allow the

driver to identify which seats are

unfastened (in the case without

occupant detection).

Similarly, it appears that, as suggested

in the comments, European vehicle

manufacturers are deploying systems

that indicate seat belts that are fastened,

seat belts that are not fastened, or the

status of all rear seat belts, both with

and—importantly—without occupant

detection.

116

For example, the MY 2021

Peugeot 3008 appears to have a system

that indicates the status of all the rear

seat belts but does not indicate in its

owner’s manual that it has occupant

detection in the rear seats. Both ECE

R16 and Euro NCAP appear to permit a

broad range of systems, including those

providing warnings for unfastened belts

at unoccupied seats. R16 requires that

the visual warning ‘‘indicate at least all

rear seating positions to allow the driver

to identify, while facing forward as

seated on the driver seat, any seating

position in which the safety-belt is

unfastened.’’ Euro NCAP similarly

requires systems without occupant

detection to provide a visual warning

showing both the belts in use and not

in use. Nevertheless, we tentatively

believe that the proposed deviation from

R16 and some current United States and

European systems is warranted because

we tentatively believe it is not

appropriate to provide a warning for an

unfastened belt at an unoccupied seat.

Although the three proposed

compliance options are not identical to

the R16 and Euro NCAP requirements,

we believe that a system that complies

with the proposed requirements could

also comply with R16 and Euro NCAP.

With respect to R16, each of the three

proposed compliance options would

‘‘allow the driver to identify, while

facing forward as seated on the driver

seat, any seating position in which the

safety-belt is unfastened.’’ While the

reference to an ‘‘unfastened’’ belt might

be read to preclude a positive-only

system—that is, it might be read to

mean that the system must explicitly

inform the driver of an unfastened belt,

such as would be the case in the

systems we are calling ‘‘negative-only’’

or ‘‘full-status’’—after reviewing the

types of systems available in the

European market we believe this is not

the case. Similarly, the negative-only

and full-status compliance options

appear consistent with Euro NCAP

because they would provide a warning

for an unfastened seat belt at an

occupied seat.

117

However, the positive-

only compliance option does not appear

to be consistent with Euro NCAP

because Euro NCAP requires that

systems without occupant detection

show the rear seat belts in use and not

in use, and the positive-only

compliance option would not permit a

visual signal for an unfastened seat

belt.

118

NHTSA seeks comment on all of these

issues. While we have tentatively

concluded that the proposed

compliance options would help mitigate

false warnings and the possibly

attendant consumer acceptance issues,

we are considering altering the

proposed compliance options to

accommodate systems that are currently

being deployed, or that manufacturers

may wish to deploy in the future. For

example, we are considering allowing

visual warnings that indicate which seat

belts are unfastened without occupant

detection. We therefore seek comment

on what visual warnings vehicle

manufacturers are using in the United

States and Europe and whether they

employ occupant detection. We also

seek comment on why vehicle

manufacturers have decided to use

visual warnings that indicate unfastened

seat belts without the use of occupant

detection and whether they have

received complaints from consumers

about false warnings, or requests to

deactivate the system. Is there any

consumer acceptance data to support or

oppose allowing visual warnings that

indicate unfastened seat belts without

the use of occupant detection in the rear

seats? We also seek comment on

whether there are any other aspects of

the proposed compliance options with

which current or anticipated future

systems would not comply. Is there a

preferable set of options that is

sufficiently objective to satisfy the

Safety Act? NHTSA also seeks comment

on how manufacturers interpret the R16

requirements, to the extent that the

agency’s characterization of them is

contrary to industry understanding or

practice. NHTSA also seeks comment on

whether the proposed regulatory text is

sufficiently objective and unambiguous.

b. Triggering Conditions

In the ANPRM we indicated that

requiring the warning at the beginning

of each journey or trip the vehicle

makes is intuitively appealing because it

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Section 8.4.2.3.1.

120

Section 3.4.1; Section 3.4.3.1.1.

121

Section 3.4.1.

122

Section 8.4.4.2 (R16; section 3.4.3.1.1 (Euro

NCAP).

123

See DOT 2009 Seat Belt Study at 65.

would help assure that occupants are

safely restrained prior to any potential

vehicle crash. However, we sought

comment on the possible advantages of

delaying the warning to a time when the

driver or occupants are less distracted

and therefore might pay more attention

to the warning.

R16 requires that the visual warning

activate when a belt is not fastened and

the ignition or master control switch

activated.

119

Euro NCAP similarly

requires that the warning start at the

commencement of a journey when the

ignition switch is engaged (whether or

not the engine is running) and any of

the rear belts are not fastened.

120

However, Euro NCAP allows for short

breaks in the journey (up to 30 seconds)

to account for events such as engine

stalling where the reminder is not

required to start again.

121

For both R16

and Euro NCAP, for vehicles that have

occupant detection in the rear seats, the

visual warning does not need to indicate

unfastened seat belts for unoccupied

seating positions.

122

Comments

Many ANPRM commenters either

specifically recommended harmonizing

with R16 or recommended triggers that

harmonized with R16. Three

commenters specifically recommended

harmonizing with R16. Many other

commenters recommended that the

trigger be based on the ignition switch.

One commenter explained that this

would provide flexibility for novel

approaches for classifying vehicle

motion. A few commenters stated that it

was necessary for the warning to

activate before the vehicle was in

motion; for example, it was noted that

vehicle crashes can happen quickly

(e.g., backing out of a parking spot), so

vehicle occupants should be buckled up

anytime the vehicle is in motion. A

commenter also stated that delaying the

warning until the vehicle is in drive

mode could leave drivers unable to

ensure all passenger belts are fastened.

Delaying the warning might warrant

additional study, but if the study

suggests changing the warning timing, it

should do so for all vehicle occupants.

A commenter stated that any triggering

condition other than initiation at the

beginning of a trip when the ignition

switch is moved to the ‘‘on’’ or ‘‘start’’

position would necessitate occupant

detection.

However, a few commenters

suggested alternative approaches. One

commenter recommended against

requiring a warning before a driver

shifts a vehicle into drive because a

transmission-less electric vehicle can

quickly shift to drive. Requiring the

warning before the vehicle is shifted to

drive would potentially amount to a seat

belt drive interlock and potentially

delay shifting into drive. The

commenter believed this is unnecessary,

could result in driver frustrations that

diminish acceptance, and lead to hasty

detection that increases the potential for

error. Another commenter stated that

the warning would be most effective if

it were triggered when the seat is

occupied, the belt is unfastened, and the

vehicle’s power is on. Yet another

commenter stated that the triggering

condition should be vehicle unlocking

and for a period following relocking.

Finally a commenter stated that the

warning should be deactivated or

disallowed if all occupants are properly

buckled.

Agency Response

NHTSA proposes that the warning

begin when the vehicle’s ignition switch

is moved to the ‘‘on’’ or ‘‘start’’ position.

This same condition appears in the

existing driver seat belt warning

requirements and is similar to ECE R16

and Euro NCAP. We are not proposing

to follow R16 and refer to a ‘‘master

control switch’’ because we do not

believe it is necessary to introduce this

new term into FMVSS No. 208 for the

proposed amendments to the standard.

Also similar to those protocols, if the

system has occupant detection, no

warning is required for unoccupied

seats under the full-status and negative-

only compliance options. As a

commenter suggests, this would likely

lead to more effective warnings because

it mitigates false warnings and eases the

burden on the driver to reconcile what

the warning depicts with the actual

status of the rear seat passengers. We

believe basing the trigger on the ignition

switch is preferable to delaying the

warning until the vehicle is placed in

gear because the proposed requirement

would make it more likely that the

occupants fasten their belts before the

vehicle is in motion.

123

With respect to the commenter on

transmission-less electric vehicles

quickly shifting to drive, the warning is

triggered by the ignition, not the

transmission gear position and would

not impede the driver from shifting to

drive. NHTSA also disagrees with the

commenter that the system would be

triggered by the vehicle being unlocked.

This could require a warning before any

occupants had entered the vehicle, and

thus would likely not serve its purpose

of warning the driver and occupants

given the limited duration of the

warning. Such a requirement would also

not harmonize with the existing driver

belt warning system and the ECE R16

and Euro NCAP requirements.

For the negative-only system, we

propose to require a visual warning

indicating which occupied seats have an

unfastened seat belt for the required

duration or until the belts at all

occupied rear seating positions are in

use. Therefore, like the R16

requirement, if all occupied seats have

fastened seat belts no visual warning

would be required.

c. Seat Occupancy Criteria and

Interaction With Child Restraint

Systems

The negative-only and full-status

compliance options would require the

warning system to determine whether a

seat position is occupied. Because the

existing seat belt warning requirements

in FMVSS No. 208, S7.3 apply only to

the driver seat, they do not contemplate

an occupant detection system (because

driver seat occupancy could

traditionally be assumed).

There are three main detection

scenarios an occupant detection system

would be exposed to in the rear seats:

adults, teenagers, and older children of

various heights and weights; children

seated in a child restraint system (CRS);

and objects such as packages, pets, or

unoccupied CRSs. This section will

discuss how the occupant detection

capability for negative-only and full-

status systems should perform for these

different scenarios and our proposed

weight and height criteria for

compliance testing of rear seat belt

warning systems certified to either the

negative-only or full-status compliance

options.

The ANPRM identified a need to

objectively specify when a seat is

occupied for the purposes of testing

negative-only and full-status rear seat

belt warning systems for compliance.

The ANPRM requested comment on

several options for seat occupancy

criteria based on those specified in

FMVSS No. 208 for compliance testing

of low-risk deployment and suppression

air bag systems in the presence of

children or small-stature adults. These

fall into three main categories. First,

FMVSS No. 208 specifies 1-, 3-, and 6-

year-old child anthropomorphic test

devices (test dummies) (weighing,

respectively, 22 lb [10 kg], 36 lb [16.3

kg], and 52 lb [23.6 kg]). Second, it

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FMVSS No. 208 S29.1(e).

125

Annex 18.

126

Section 3.4.1.3.

127

Safe Ride News also appeared to suggest that

in conjunction or in the alternative, the system

should be able to be deactivated or allow the driver

to dismiss (acknowledge) the warning. NHTSA’s

tentative conclusion to not adopt these approaches

is explained in Section X.E, Resistance to

intentional and inadvertent defeat and deactivation.

specifies a 5th percentile female test

dummy (weighing 108 lb [50 kg]). Third,

it specifies height and weight

requirements for a child used as an

alternative for the 6-year-old child test

dummy for compliance testing of

advanced air bag systems utilizing static

suppression (weighing between 46.5 lb

and 56.5 lb [21 kg and 25.6 kg] and

between 45 in and 49 in [114 cm and

124.5 cm] tall).

124

ECE R16 specifies three alternative

methods for testing rear seats with

occupant detection: placing a load of 40

kg (88 lb) on the seat; placing an object

or human representing a 5th percentile

adult female (the HIII–5F specified in 49

CFR part 572, as adjusted for the ECE

test); or an alternative method specified

by the vehicle manufacturer.

125

Euro

NCAP defines occupancy as the use by

an occupant larger, taller, or heavier

than a 5th percentile female.

126

The ANPRM also sought comment on

whether a rear seat belt warning would

reliably detect a child restraint system

attached by a child restraint anchorage

system, or LATCH. The intent of this

question was to determine whether a

seat belt warning system might register

a false alarm for a LATCH-installed

CRS. Neither R16 nor Euro NCAP have

requirements with respect to the

system’s interaction with LATCH-

installed CRSs.

Comments

We received a number of comments

related to seat occupancy criteria and

the detection capabilities the system

should have.

With respect to seat occupancy

criteria, several commenters supported

harmonizing with ECE R16 and/or

basing the criteria on a 5th female

dummy (88 lb–105 lb). Several

commenters suggested harmonizing

with the ECE R16 criteria. A commenter

stated that the occupant size that the

system is required to detect should not

be less than the occupant size that

would use the seat belt as the only

restraint. Another commenter stated that

for children seated in booster seats or

high-back boosters (with belt

positioning guides), the CRS often

directly utilizes the belt provided in the

vehicle. In these cases, a rear belt

reminder system may be useful for

reminding the driver to ensure the child

seated in that seating position is either

restrained or providing an alert that the

restraint status has changed during a

trip (i.e., belt became unbuckled). A

commenter recommended specifying

the 5th percent female detection criteria

for several reasons: starting with the 5th

female would cover a large share of the

target population; belt usage is high for

children as long as they are in a CRS (so

a warning system appears less needed);

the 5th percent female includes a large

share of the teenage population; it

would harmonize with FMVSS No. 208

and international NCAP programs; and

it would result in more robust systems

with respect to false positives.

On the other hand, various

commenters recommended that the

occupancy criteria be based on children

that might reasonably be expected to use

seat belts. Two commenters suggested

that the occupancy criteria be based on

the smallest weight of a child that can

reasonably be expected to be restrained

by a seat belt rather than a CRS. One of

the commenters stated that a weight of

20 lb (9 kg) is consistent with all state

laws for CRS use. Another commenter

stated that the criteria should reflect a

minimum weight equal to that of a

Hybrid III 6-year old child (about 52 lb).

However, as noted below, commenters

believed that using weight alone was

not enough. A commenter did not agree

with criteria based on a 6-year-old, and

instead suggested the HIII 3-year-old

dummy (36 pounds, or 16 kg) as the

minimum weight threshold, stating that

this dummy’s weight roughly represents

the 95th percentile 2-year-old and the

5th percentile 5-year-old. The

commenter stated a 6-year-old was not

appropriate as nearly 60% of 4- and 5-

year-old children do not ride in a CRS

with a harness, so many of the most

vulnerable seat belt users (very young

children using the belt alone or in

conjunction with a booster) would fail

to trigger the alarm if unbuckled. A

commenter stated that the specifications

should represent the occupant

population at risk from non-use of rear

seat belts, and stated that NHTSA’s 2017

passenger vehicle fatality data indicates

that restraint non-use exceeds the

national average (47%) in the

population of occupants starting at age

8–12; the unrestrained percentage for

younger occupants is 36% for 4–7-year-

olds and 22% for occupants less than 4

years old. A commenter suggested that

the criteria should register children that

would presumably be placed in a child

restraint system (i.e., children as young

as 4 years old). Another commenter

recommended that NHTSA’s testing

reflect the full range of body types as

well as child restraint systems that

could be present in rear seats.

We also received a variety of

comments about the detection

capabilities the system should have.

Several commenters argued that the

system should be required to detect

CRSs. Three commenters supported

requiring LATCH detection. Two of

those commenters stated that the

reminder system should be able to

recognize when a car safety seat is

installed with LATCH instead of the

seat belt and should not activate under

those conditions in order to avoid

nuisance (false) warnings. A commenter

said that when a CRS is installed using

the lower anchors of the LATCH system,

the seat belt is typically not in use, so

a non-discerning sensor would conclude

that an unbuckled occupant is present

(because a CRS is heavy enough to be

classified as an occupant by an

occupant detection system).

127

commenter recommended that the

occupant detection system provide a

warning if the CRS is improperly

latched.

On the other hand, several

commenters believed that the system

should not be required to detect a CRS.

Three commenters stated that the

system should not be required to detect

a CRS, with two of the commenters

noting variation in CRS designs and the

fact that neither ECE R16 nor Euro

NCAP require CRS detection

capabilities. These three commenters

opposed requiring LATCH detection

because it would provide little benefit

with significant added costs. One of the

commenters added that LATCH systems

are not typically latched/unlatched

frequently, so it is far more uncommon

to be in the unlatched state.

Additionally, as only the latch could

potentially be detected, and yet the

remaining parts of the child restraint are

unmonitored, it may give a false

assurance to the user that the child is

fully restrained. Two of the commenters

said that if this were required, the

system would need to distinguish

different types of CRS available in the

market, which would be difficult to

implement. A commenter that opposed

requiring occupant detection on buses,

commented that buses with LATCH

seats would require a detection system

capable of differentiating whether an

occupant is unbuckled or secured using

the LATCH attachments; whether an

occupant is unbuckled or secured using

the securement harness provided with

the seat; and between removed seats and

those with incorrect electrical

connections. Another commenter stated

that CRSs pose a challenge to occupant

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All 50 states, the District of Columbia, and all

United States territories have laws requiring

children to be secured in the appropriate car seats

or booster seats for their ages and sizes while riding

in vehicles. Most states now require children to ride

in appropriate car seats or booster seats until as old

as age eight (Alaska covers children up to 15 years

old as long as they fall within their specified height

and weight criteria).

129

Within these types are CRS designs that can

be used for multiple purposes, such as convertible

CRSs that can be used as a rear-facing and forward-

facing CRS and combination CRSs that can be used

as a forward-facing CRS and booster seat.

130

Many in the child passenger safety community

refer to the child restraint anchorage system as the

‘‘LATCH’’ system, an abbreviation of the phrase

‘‘Lower Anchors and Tethers for Children.’’ The

term was developed by a group of manufacturers

and retailers for use in educating consumers on the

availability and use of the anchorage system and for

marketing purposes.

131

Some boosters can also be secured to the seat

with LATCH so that it stays in place when in use

and not in use.

132

For the NHTSA recommendations discussed

here, see https://www.nhtsa.gov/equipment/car-

seats-and-booster-seats (last accessed Apr. 7, 2022).

133

See https://www.healthychildren.org/English/

safety-prevention/on-the-go/Pages/Car-Safety-Seats-

Product-Listing.aspx.

134

About 16.6 percent of children 4 to 7 years old

were prematurely transitioned to seat belts in the

‘‘2019 National Survey of the Use of Booster Seats’’

(DOT HS 813 033).

135

For anthropomorphic test devices, this would

include the 50th percentile male, 5th percentile

female, and the 6-year-old and 10-year-old child

dummies.

detection systems, which would need to

account for all of the different uses of

the rear seat; a false-positive warning on

a child properly restrained using the

LATCH system (who would not be

buckled in with the seat belt) could

discourage the consumer from using

LATCH.

Finally, some commenters advocated

requiring more sophisticated detection

capabilities in order to limit false

positives. Two of these commenters

suggested that the system should be able

to discern the difference between an

occupant and objects such as packages.

Another commenter said that NHTSA

should also limit false activations when

seats are occupied by child seats or

other items. A commenter stated that

NHTSA should allow for a child seat

mode that suppresses the warning.

Agency Response

As an initial matter, it is important to

understand the different types of CRSs,

how seat belts are used with them, and

the size/age of the children for which

each type of CRS is typically

appropriate.

128

There are essentially three types of

CRSs: rear-facing CRSs, forward-facing

CRSs, and booster seats.

129

Rear-facing

and forward-facing CRSs are child seats

that are installed using either LATCH

130

or a seat belt to secure it in place.

131

Booster seats raise and position a child

so the vehicle’s lap-and-shoulder belt

fits properly.

NHTSA recommends that children

remain in a rear-facing CRS until they

reach the top height or weight limit

allowed by the CRS manufacturer.

132

NHTSA also recommends that children

remain in a forward-facing car seat with

a harness and tether until they reach the

top height or weight limit allowed by

the car seat’s manufacturer. Most

forward-facing CRS are rated for

children up to 49 in (124 cm) and 65 lb

(29 kg).

133

Once a child outgrows the

forward-facing car seat with a harness,

the child can travel in a booster seat and

use a seat belt. NHTSA identifies an age

range of 4–7 years old for when this

transition to a booster typically occurs,

depending on the height and weight of

the child and the respective limits of

their forward-facing car seat. Once a

child outgrows the booster seat they can

sit directly in the seat and use the seat

belt alone; NHTSA identifies an age

range of eight to thirteen and older for

when this typically occurs.

In the remainder of this section we

discuss, first, the proposed weight and

height criteria NHTSA proposes to use

in compliance testing of rear seat belt

warning systems certified to the

negative-only or full-status compliance

options and, second, what ability (if

any) such systems should have to detect

a CRS.

Weight and Height Criteria

NHTSA believes the rear seat belt

warning system should be able to detect

an occupant that should be restrained

with a seat belt alone and provide seat

belt use information to the driver that is

appropriate for that type of system. This

target population is comprised of adults,

teenagers, and children in booster seats.

Children in booster seats are part of the

target population because they should

be restrained with the seat belt and so

would benefit from a seat belt reminder.

As mentioned above, the transition to a

booster seat typically occurs from ages

4–7 years. Children in rear-facing and

forward-facing CRSs are not part of the

target population because these children

are restrained by the CRS harness, not

the seat belt. The intent of the reminder

is not to warn of CRS misuse, but to

warn of occupants not restrained by a

belt alone.

Accordingly, we are proposing that a

rear designated seating position would

be considered ‘‘occupied’’ when an

occupant who weighs at least 46.5 lb (21

kg), and is at least 45 in (114 cm) tall,

is seated there. These criteria are

proxies for a six-year-old child, which

roughly corresponds to a typical age at

which a child would transition from a

forward-facing CRS to a booster seat. We

have taken these criteria from FMVSS

No. 208, which uses them to specify the

smallest child that may be used as an

alternative to the 6-year-old dummy in

static suppression tests under FMVSS

No. 208. The proposed test does not

specify the use of a booster seat because

we are aware that children can be

prematurely transitioned to a seat belt

without the use of a booster,

134

and we

believe it is desirable to test the lower

end of the possible weight range that

encompasses children that could

conceivably be restrained with a seat

belt alone. As we explain below in

Section XII.B, Test Procedures, the

agency proposes using either a person or

any anthropomorphic test device

specified in part 572 that meets these

proposed weight and height criteria.

135

These criteria specify a smaller

occupant than does R16. We tentatively

believe that harmonizing with R16 and

using a heavier dummy would not

capture the child segment of the

population that is in booster seats; that

is, seat belt use may occur for occupants

smaller than the criteria specified by

R16. We also do not believe it is

necessary to use a larger-size occupant

because a system capable of recognizing

a six-year-old should also be capable of

recognizing larger occupants.

At the same time, we tentatively

believe that the proposed criteria are

preferable to criteria reflecting a

younger occupant (lower weight). The

smallest dummy that would meet the

proposed weight and height criteria is

the 6-year-old dummy specified in part

572. The next smallest dummy

represents a 3-year-old child (i.e., the

Hybrid III three-year-old), but we

believe it would not be appropriate to

specify the use of the 3-year-old because

a child represented by this ATD should

be seated in a forward- or rear-facing

CRS, not a booster seat.

Ability of the System To Detect a CRS

NHTSA also does not propose to

require any sort of CRS detection

capabilities at this time.

We tentatively believe that a forward-

or rear-facing CRS installed with the

seat belt would not cause problematic

false warnings; rather it would just

Similarly, we believe that a forward-

or rear-facing CRS installed with

LATCH would not pose issues

necessitating any specific requirements

related to the LATCH system, such as

LATCH sensors. There are a few reasons

for this. First, we do not believe

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https://www.nhtsa.gov/road-safety/child-

safety.

137

DOT 2009 Belt Warning Study, supra n. 36.

138

Global suggested not adopting the Euro NCAP

duration requirement (90 seconds) because the

warning must balance effectiveness and consumer

acceptance, but NHTSA understands the Euro

NCAP minimum duration to be 60 seconds.

139

NSC cited an IIHS study finding that an

indefinite reminder and a 100 second constant

reminder increased seat belt use by 30–34 percent

over an intermittent reminder.

140

We are also proposing that these visual

displays should not be overridden by other visual

warnings for the required duration.

LATCH-installed CRSs would lead to

false warnings or driver confusion about

the belt status of any rear occupants,

because NHTSA recommends buckling

unused seat belts that are within reach

of children to prevent seat belt

entanglement and/or strangulation.

136

This includes, for forward- or rear-

facing CRSs installed with LATCH,

buckling the unused belt behind the

CRS. (Fastening the unused seat belt

behind the CRS when installing a CRS

with LATCH should not be mistaken for

installing a CRS with both the seat belt

and LATCH; a CRS installed with

LATCH is not also installed with the

seat belt unless it is approved by both

the car seat and vehicle manufacturers.)

If users follow NHTSA’s

recommendation and buckle the belt

behind the CRS, the positive-only

system would simply consider those

belts to be fastened, and the negative-

and full-status systems would not

buckled as NHTSA recommends, with a

positive-only system, the driver would

simply see that there were no buckled

belts, so there would be no false

warnings. For the negative-only and

full-status systems (which utilize

occupant detection), the system could

occupant depending on the weight of

the child and CRS. We are aware of at

least one vehicle manufacturer that uses

occupant detection for its rear seat belt

warnings and it recommends fastening

the unused seat belt if the CRS is

installed with LATCH to avoid such a

false warning. (In the owner’s manual

section of this preamble we seek

comment on including such guidance in

the owner’s manual, which includes

information provided by the vehicle

manufacturer to the consumer, whether

in digital or printed form.) Again, if the

belt is not buckled as NHTSA

recommends, the driver would need to

take these facts into account when

comparing the number of rear seat

occupants against how many or which

rear seat belts are reported to be in use

by the warning system. Second, we are

not proposing to require a warning for

CRSs improperly attached to the LATCH

because the focus of this rulemaking is

on providing a seat belt warning, not on

providing warnings for improperly

installed LATCH child seats. Third, this

approach is consistent with ECE R16

and Euro NCAP, neither of which have

provisions for addressing LATCH-

installed child restraints. Finally,

requiring LATCH sensors would add

extra complexity and cost.

We also do not believe a booster seat

would present any special challenges to

a seat belt warning system. If an

(un)belted child is in a booster seat, the

system would register the belt as not

(un)fastened and (if equipped with

occupant detection) that the seat was

occupied. This would not necessitate

the system to specifically detect the

booster seat because the performance

criteria are weight-based. In addition,

we would not expect an occupant

detection system to provide a false

warning for an unoccupied booster seat

because the proposed seat occupancy

criteria (roughly equivalent to a 6-year-

old) is heavier than an unoccupied

booster seat.

We are also not proposing to require

more sophisticated features to test how

well the system avoids false positives—

e.g., the ability of the system to

distinguish packages or pets from

occupants or a child seat mode. A

detection system that can differentiate

between cargo and occupants would

require additional sensor technology in

comparison to a weight-based sensor

and would be more costly. This issue

can be mitigated by moving the cargo to

the floor or trunk of the vehicle or by

buckling the unused belt and would not

be an issue for the positive-only

compliance option. Tesla’s ‘‘child seat

mode’’ allows the driver to acknowledge

the warning triggered by a CRS installed

with LATCH for that trip. With respect

to Tesla’s comment regarding a child

seat mode, neither ECE R16 nor Euro

NCAP contemplate this and we are not

aware of other manufacturers that have

employed this feature. Given that a

child seat mode feature could be used

to circumvent the warning (i.e., a belt

use warning could be prevented or

dismissed by use of the child seat

mode), and the limited information

NHTSA has on it, we have tentatively

decided not to permit this feature.

We seek comment on all these issues.

d. Minimum Duration

The ANPRM also sought comment on

the minimum duration of the warning.

NHTSA’s front seat belt warning

research suggests that longer-duration

warnings are more effective, but also

more annoying.

137

The current driver’s

seat belt visual warning in FMVSS No.

208 is required to last at least 60

seconds under the second compliance

option in FMVSS No. 208, S7.3(a)(2).

Both R16 and Euro NCAP specify a 60-

second visual warning (which may end

sooner if the belt is fastened or the seat

becomes unoccupied).

Comments

Many commenters recommended

harmonizing with R16 and adopting 60

seconds.

138

A few commenters advocated a longer

warning. Two commenters

recommended the warning should last

until all occupants are buckled. One

commenter said that systems with long

single-cycle durations and those that

cycle audible/visual reminders

throughout the entirety of the drive are

more effective than systems that cycle

for a limited number of times.

139

Another commenter said that the

visual warning duration should be

based on evidence of effectiveness while

maintaining a balance with annoyance.

Agency Response

NHTSA is proposing that the warning

last for at least 60 seconds. We believe

that 60 seconds is sufficient to capture

the driver’s attention, and that a longer

warning would have the potential to

become distracting or a nuisance.

140

This would be a shorter warning than

we are proposing for the front outboard

seats (see Section XI.C). There are a

couple of reasons for our tentative

decision that a shorter warning is

warranted for the rear seats. First, we

are not proposing to require occupant

detection for the rear seat belt warning

system; the positive-only compliance

option would require that the driver be

informed of which rear seat belts are

fastened. This type of ‘‘warning’’

functions more to provide information

to the driver, rather than a true warning

(because it will be providing

information to the driver even if all rear

occupants have fastened their seat

belts), so we tentatively think that it is

not necessary to require that this be

particularly long-lasting. Second, and

related, even for the compliance options

that would entail occupant detection,

the complexities of occupant detection

in the rear seats and the possibilities for

false positives provide another reason

for not requiring an extremely long-

lasting warning. Manufacturers would

be free to provide a longer warning if

they wished. The proposed compliance

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Defined as forward motion at a speed greater

than 10 km/h. § 2.47.

142

Section 8.4.4.5.

143

These summaries simplify the requirements

somewhat. They will be discussed in greater detail

later in the preamble where relevant.

144

Section 3.4.1.5.

145

Section 3.4.1.5.

146

Section 3.4.1.5.

147

Section 3.4.3.1.1.

148

Section 3.4.1.6.

149

Section 3.4.3.2.

150

Section 3.4.1.6. The audio signal must resume

when the speed goes above 25 km/h and no doors

have been opened and the seat belt(s) remain

unbuckled. In addition, the audible signal may

instead meet the requirements for the front seating

positions, if the vehicle is equipped with occupant

detection.

151

Section 8.4.2.2.1.

152

In the proposed regulatory text, we use the

term ‘‘symbol’’ instead of ‘‘icon’’ in order to be

consistent with the current usage in FMVSS Nos.

101 and 208.

options requiring occupant detection

would not require a warning for

occupants with fastened belts.

This is consistent with ECE R16 and

Euro NCAP and with systems currently

deployed in the United States. Our

preliminary analysis found that, of the

15 manufacturers that provide vehicle

models with a rear seat belt warning

system in the United States, 8 appear to

provide systems with initial visual

warnings that are active for at least 60

seconds. An additional three

manufacturers appear to provide visual

warnings until the seat belt is fastened.

2. Audio-Visual Change-of-Status

Warning

The ANPRM sought comment on

requiring a change-of-status warning for

when a fastened seat belt is unfastened,

including an audio-visual change-of-

status warning. We also sought

comment with respect to potential

requirements for an audible warning,

including the duration of the warning

and whether NHTSA should specify

additional warning characteristics (such

as sound level).

R16 specifies an audio-visual change-

of-status warning for the rear seats. If a

fastened rear belt becomes unfastened

when the vehicle is in ‘‘normal

operation,’’

141

R16 specifies an audio-

visual warning (second level) when

certain distance, time and/or speed

threshold(s) (at the choice of the

manufacturer) are exceeded.

142

The

additional thresholds are distance

traveled (not to exceed 500 meters),

vehicle speed (not to exceed 25 km/h,

and/or travel time (not to exceed 60

sec). This warning must last for at least

30 seconds unless the unfastened belt

becomes fastened, the seat associated

with the unfastened belt is no longer

occupied, or the vehicle is no longer in

normal operation.

143

This warning may

not be canceled by the driver.

Euro NCAP also requires (in order to

earn bonus points) an audio-visual

change-of-status warning at vehicle

speeds of 25 km/h and above.

144

If the

change-of-status occurs below 25 km/h

and no doors are opened, the signal may

be delayed until the vehicle has been in

forward motion for 500 meters or has

reached a forward speed of 25 km/h.

145

A warning is not required if the system

has occupant detection as long as all

doors remain closed and the number of

buckled positions remains the same, in

order to minimize the number of false

positives (e.g., children remaining in the

vehicle but swapping seats in the rear

while at a traffic light).

146

The warning

duration differs for the visual and

audible warnings. With respect to the

visual warning, if the system does not

have occupant detection, the warning

must last until the seat belt is fastened

or 60 seconds have elapsed.

147

If the

system does have occupant detection,

the signal must remain on until the belt

is fastened. The audible warning must

last until the belt is fastened,

148

seconds have elapsed,

149

or the vehicle

speed falls below 10 km/h.

150

Comments

Many commenters specifically

supported requiring an audio-visual

change-of-status warning. One

commenter cited a survey of adult

passengers who do not routinely use a

seat belt in the rear in which 62% of

respondents said they would be more

likely to use a seat belt if there was an

audible warning compared with only

50% who said the same about a visual

warning.

With respect to the triggers for the

warning, two commenters stated that a

change-of-status warning should

activate regardless of the speed.

Several comments also discussed the

duration of an audible alert. Several

commenters recommended harmonizing

with the 30 seconds required by R16.

Other commenters argued for a longer

audible warning, including: 60 seconds,

90 seconds, and until all occupants are

buckled. One comment noted that

audio-visual warnings that continue to

cycle throughout the drive are more

effective than limited-duration

warnings. Another commenter

recommended consistency with existing

FMVSS No. 208 audible warning

systems for front occupants.

Commenters stated that the duration

should be based on evidence of

effectiveness while maintaining a

balance with annoyance. A commenter

stated that, while information about the

effect of an audio-visual rear seat belt

warning on rear seat belt use is sparse,

research on front seat belt warning

systems suggests that an audio-visual

warning lasting longer than 8 seconds

would be expected to motivate an

unbelted rear occupant to refasten the

seat belt.

With respect to other warning

characteristics, three commenters

recommended that the audible warning

be heard throughout the vehicle. A

commenter suggested following R16’s

requirement that the warning ‘‘consist of

a continuous or an intermittent (pauses

shall not exceed 1 second) sound signal

or of continuous vocal information.’’

151

Two commenters said that specifying

additional audible warning

characteristics would be burdensome

and unnecessary. A commenter said that

there should be a balance of the sound

level so that consumers would accept

and react positively to the warning, and

suggested it be the same as that for the

driver. Another commenter

recommended that the audible warning

specification be based on evidence of

effectiveness and suggested that

maintaining consistency with other seat

belt warning signals would be desirable.

A commenter recommended

consistency with existing FMVSS No.

208 audible warning systems for front

occupants. And yet another commenter

recommended a warning that is

enhanced but does not rattle the driver.

Agency Response

The agency proposes to require an

audio-visual warning when a rear seat

belt is unbuckled during a trip. We

propose that when the vehicle’s ignition

switch is in the ‘‘on’’ or ‘‘start’’ position,

the vehicle’s transmission selector is in

a forward or reverse gear, and a rear seat

belt in use changes to not being in use,

the vehicle must activate a continuous

or flashing visual warning consisting of

icons

152

or text visible to the driver, as

well as a continuous or intermittent

audible signal for a period of not less

than 30 seconds, beginning when a seat

belt in use changes to not being in use.

The warnings could cut off sooner if the

belt is refastened before the minimum

time limit has been reached. Comments

from vehicle manufacturers were largely

in support of harmonizing with the ECE

R16 requirements, and the proposed

requirements are comparable to the

change-of-status warnings on vehicles

currently equipped with rear seat belt

warnings. For example, Volvo vehicles

provide an audio-visual warning lasting

until the belt is refastened.

We believe this warning will be an

effective way to reduce the risk of injury

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Paul Schroeder & Melanie Wilbur. 2015.

Survey of Principal Drivers of Vehicles with a Rear

Seat Belt Reminder System. Washington, DC:

National Highway Traffic Safety Administration,

[Found in the docket for this ANPRM.]

154

Id. at 10. This percentage is based on a fairly

small number (15) of drivers who reported that their

children do not always use seat belts.

155

Features of the change-of-status warning that

are common with the start of trip warning—for

example, the telltale characteristics—are discussed

later in the preamble.

156

Section 8.4.2.4.1.

157

Section 3.4.3.2.3.

to rear seat occupants by alerting the

driver when a passenger unbuckles

during a trip. NHTSA’s 2015 consumer

survey found that a change-of-status

warning is effective in getting

passengers to refasten their seat belt.

153

This may be an especially beneficial

feature for drivers transporting children

in the back seat. Such a warning may

reduce the risk of injury to children by

alerting the driver that a child has

unbuckled his or her seat belt, providing

the driver an opportunity to direct the

child to re-buckle the belt. Fifty-five

percent of the drivers surveyed by

NHTSA who transport children in the

rear seat and who said their children do

not always use seat belts, have had the

experience of their child unbuckling

during a trip.

154

The proposed requirements follow

ECE R16 and Euro NCAP in that both of

those protocols include an audio-visual

rear belt change-of-status warning with

specified trigger criteria.

155

tentatively agree with a commenter that

a duration longer than 8 seconds is

warranted because it will be more

effective and believe that a 30-second

minimum duration appropriately

balances effectiveness and acceptance.

We note that this is shorter than the

duration we are proposing for the

change-of-status warning for the front

outboard seats (until the belt is re-

fastened—see Section XI.C.2) because

we tentatively believe that a longer

warning for the rear seats is more likely

to lead to driver distraction, especially

with children in the rear seats.

The proposal differs from R16 and

Euro NCAP in a few ways:

• Triggers. The warning would be

required as long as the ignition is on

and the transmission selector is in the

drive or reverse position, with no

additional thresholds or triggers, such as

the vehicle having to reach a forward

speed of 25 km/h. We tentatively

believe this departure from R16 and

Euro NCAP is justified. Seat belts

provide a safety benefit even at lower

speeds, and regardless of the direction

of motion. We also believe a warning

would be beneficial even if the vehicle

is not moving. A driver may want to

know if any rear seat occupants—

especially children—have been

unbuckled while the vehicle is

temporarily stopped (e.g., at a traffic

light) or slowed (e.g., in a parking lot),

because the vehicle could soon be

resuming travel. In addition, providing

a warning when the vehicle is stationary

would allow the driver to attend to the

unbuckled passengers before having to

focus attention on the driving task. We

similarly believe that a warning would

be useful before the vehicle has reached

any distance or trip time threshold. We

do not adopt the Euro NCAP allowance

for not requiring a change-of-status

warning when all doors remain closed

and the number of buckled positions

remains the same because this would

require a delay in the activation of the

change-of-status warning; also, these

types of events are likely limited and

require very little time so exposure to

the warning would be very limited. We

do, however, adopt the Euro NCAP

requirement that if a change-of-status

occurs and a door is open, the system

should consider that as the start of a

new trip. This would allow for

passengers to exit the vehicle when the

driver does not shift into the park gear

without activating the change-of-status

warning for the full duration

requirement.

• Duration. The proposed 30-second

duration harmonizes with ECE R16

(though it is shorter than the 60-second

duration for the visual signal specified

in Euro NCAP, but consistent with the

30-second duration for the audible

signal). We propose that the audible

signal may be ‘‘intermittent’’ (i.e., not

continuous), which mirrors the

longstanding requirements for the

driver’s seat belt warning. ECE R16

156

and Euro NCAP

157

do not count periods

in which the warning stops for longer

than 3 seconds as part of the overall

duration, and we have tentatively

decided to propose a similar

requirement for the rear audible change-

of-status warning. (In contrast, we are

specifying additional signal

characteristics for the front seat belt

change-of-status warning because we are

proposing to require a longer duration

for that warning. This is discussed in

Section XI.C.2)

• Audible warning characteristics.

ECE R16 specifies that for intermittent

audible warnings, the pauses shall not

exceed 1 second, and that gaps longer

than 3 seconds would not count toward

the required 30 second duration. Euro

NCAP specifies that there must be no

gaps greater than 10 seconds, and that

gaps longer than 3 seconds would also

not count toward their required

duration. We have tentatively decided

to propose a requirement that specifies

that periods of time when the audible

warning is not active for longer than 3

seconds would not count toward the

required 30 second duration. Given the

very limited duration of the rear seat

change-of-status audible warning for the

rear seats we believe this is a sufficient

constraint for achieving an adequate

warning. We have not further specified

audible warning characteristics, such as

volume or tone, in order to provide

manufacturers design flexibility. The

standard has required an audible

driver’s seat belt warning with no

additional audible warning

requirements since the early 1970s, so

we believe manufacturers are familiar

with designing and implementing

optimal audible seat belt warnings. As

mentioned above, we are specifying

additional signal characteristics for the

front seat belt change-of-status warning

because we are proposing to require an

indefinite duration for that warning,

which requires more thought about the

warning characteristics to mitigate the

use of ineffective audible warnings (See

Section XI.C.2).

We seek comment on all aspects of

the proposed change-of-status warning.

Are there situations when the warning

at a low speed would result in an

unnecessary or unwanted warning, and

how frequently would such situations

occur? Are any of the deviations from

R16 and/or Euro NCAP unwarranted,

and what is the basis for such a

conclusion? We acknowledge that the

proposed requirements may still trigger

the change-of-status warning for a short

period of time until a door is opened

when a passenger exits the vehicle and

the vehicle is not in the park gear;

however, we believe exposure to a very

limited warning in these scenarios is

necessary in order to capture other

change-of-status events that occur when

a vehicle is stopped but not in the park

gear. We seek comment on how vehicle

manufacturers are currently handling

(e.g., what type of warning if any is

provided) rear seat change-of-status

events that occur when the vehicle is

stopped, but not in the park gear, or at

low speeds (e.g., what type of warning,

if any, is provided when passengers exit

the vehicle without the vehicle being in

the park gear)? As will be discussed

later, we are proposing that the change-

of-status warning for the front outboard

seats be active until the seat belt that

triggered the warning is refastened, so

we seek comment on whether the

proposed limited duration change-of-

status warning for the rear seats should

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DOT 2007 Acceptability Study, supra n.78.

159

Section 8.4.2.1.1.

160

Section 3.4.1.1.

161

FMVSS No. 208 S7.3(a) and FMVSS No. 101,

table 2.

162

FMVSS No. 208 S7.3; FMVSS No. 101 S5.1.2.

163

FMVSS No. 101, S5.3.3(a).

164

See Table 2.

165

S5.5.2. These are: air bag malfunction, low tire

pressure, electronic stability control malfunction,

passenger air bag off, high beam, turn signal, and

any brake system malfunction required by table 1

to be red.

166

See FMVSS No. 101 S4 (‘‘Common space’’ is

‘‘an area on which more than one telltale, indicator,

identifier, or other message may be displayed, but

not simultaneously’’).

167

FMVSS No. 101, S5.5.5.

168

FMVSS No. 101, S5.2.3.

169

Section 8.4.2.1.2.

170

Section 8.4.2.1.1.

171

Section 8.4.4.3.

172

Section 8.4.4.3. A common telltale may be

used for both the front and rear seat belt reminders.

Section 8.4.4.4. The front reminder is required to

utilize the symbol specified in Regulation 121,

which is the same symbol specified in FMVSS No.

101 and depicted in Figure 2.

173

Section 8.4.4.2 (‘‘The visual warning shall

indicate at least al rear seating positions to allow

the driver to identify, while facing forward as

seated on the driver seat, any seating position in

which the safety-belt is unfastened.’’).

174

Section 3.4.1.1.

also be required to last indefinitely until

the rear seat belt is refastened.

3. Telltale Location

A seat belt warning can function by

alerting the driver that a rear seat belt

is unbuckled, leaving it to the driver to

request the rear passenger to buckle up.

However, many other strategies are

possible. For example, in addition to

warning the driver, the front seat

passenger could also be warned on the

premise that, if the driver was occupied

by other matters, the front seat

passenger could direct the rear seat

passengers to buckle up. Another

strategy could be to warn the rear

passenger(s) directly that their belt is

unbuckled. Finally, in addition to

warning the rear passenger(s), the driver

and/or the front passenger could be

warned. Some research suggests that

having the warning visible to the

unbelted occupant may increase

effectiveness.

158

ECE R16 requires that the visual

warning be visible to the driver when

they are facing forward,

159

and Euro

NCAP similarly requires that the visual

signal be clearly visible to the driver

without the need for the head to be

moved from the normal driving

position.

160

Comments

Most commenters recommended that

the signal be visible to the driver, while

one suggested the signal be visible to the

rear seat passengers to avoid relying on

the driver to enforce belt use, especially

as rear-seat occupancy increases due to

the increased use of for-hire vehicles

(and, possibly at some time in the

future, autonomous vehicles).

Another commenter stated that it is

impractical to provide a warning to rear

passengers on buses due to wiring costs,

customization, and FMVSS No. 222

requirements for head impact

performance (for school buses).

Agency Response

We agree with the majority of

commenters and propose that the

warning signal be visible to the driver.

Although some research may suggest

that having the warning visible to the

unbelted occupant may increase

effectiveness, we tentatively believe that

the increased cost, complexity, and re-

design such a requirement would entail

would not be justified. However,

manufacturers would have the

flexibility to place the visual warning

where it would be seen by some or all

rear seat occupants. In Section XII.C we

discuss the implications of the telltale

location as it relates to automated

vehicles.

4. Telltale Characteristics

The ANPRM sought comment on

whether we should propose

requirements for telltale characteristics

such as color and required text.

For the current driver’s seat belt

warning, FMVSS No. 208 requires a

continuous or flashing warning light

displaying (at the choice of the

manufacturer) either the telltale

specified in FMVSS No. 101 (see Figure

2) or the words ‘‘Fasten Seat Belts’’ or

‘‘Fasten Belts.’’

161

The telltale must be

visible to the driver

162

in both daytime

and nighttime.

163

There are no color or

illumination requirements for the

telltale.

164

The seat belt telltale may

share a common space with other

telltales except several specific telltales

identified in FMVSS No. 101.

165

Telltales in the same common space,

however, may not be displayed

simultaneously.

166

The seat belt telltale

must displace any other symbol or

message in that common space while

the underlying condition for the

telltale’s activation exists.

167

Supplementary symbols or words may

be used in conjunction with the

required telltale or words.

168

Figure 2—Seat Belt Telltale From

FMVSS No. 101

The rear reminder requirements in

ECE R16 mirror the FMVSS driver’s

warning requirements in several

respects: the telltale may be flashing or

steady;

169

it must be recognizable in the

daylight and at nighttime and

distinguishable from other alerts;

170

and

there are no color requirements.

171

However, R16 differs from the FMVSS

requirements in that there is no required

telltale symbol.

172

R16 also appears to

require a visual warning that depicts all

the rear seating positions.

173

Euro NCAP specifies that as soon as

the audible part of the seat belt

reminder signal starts, the visual signal

needs to flash and be synchronized with

the audible part.

174

Comments

Several commenters favored

standardized warnings. Two

commenters stated that standardized

telltales would help drivers recognize

the icons when driving different/

multiple vehicles (rentals, etc.).

In contrast, other commenters urged

NHTSA to provide manufacturers with

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Honda’s comment seems ambiguous. It urges

harmonization with R16, which does not require a

specific telltale, but also states that the existing seat

belt telltale in FMVSS No. 101 is a universally-

recognized warning that can be used to provide a

consistent link to additional seat belt information,

and advocates using the FMVSS No. 101 telltale as

a ‘‘baseline warning’’ to ensure that an active safety

belt warning continues to be provided if an

additional seat belt warning visual display needs to

give priority to a more important safety warning.

176

https://public.servicebox.peugeot.com/APddb/

modeles/3008/eGuide_ed02-16/pdfs/

9999_9999_091_en-GB.pdf, pg. 144.

177

https://www.cupraofficial.com/content/dam/

public/cupra-website/owners/cupra-car-model-

manuals/brochures/

CUPRA_FORMENTOR_06_21_EN.pdf, pg. 17.

flexibility and not require a specific

telltale. Two commenters specifically

suggested harmonizing with ECE R16, in

addition to the many commenters who

generally urged harmonization with

R16. A commenter requested flexibility

to choose the indication method for

each seating position, such as a telltale

or a graphic or rendering of the vehicle

seating positions in a more advanced

display screen.

175

Another commenter

urged NHTSA to defer regulatory action

on the establishment of a specific

symbol and simply require that any

telltale provided be communicated in

the owner’s manual because additional

research is needed to determine which

approaches may be most effective in

communicating reminder status for a

particular row or specific designated

seating position, and emphasized its

belief that NHTSA should not mandate

specific indicators or display

characteristics in order to provide OEMs

with flexibility. Two commenters

similarly suggested allowing the

telltales for the rear seat belt reminder

to differ (e.g., different colors, symbols)

from those currently used for the front.

On the other hand, some commenters

did not oppose requiring use of the

current driver’s seat belt telltale. A

commenter said that a typical approach

for rear seat belt warnings is to include

a separate area on the instrument panel

for separate telltale(s) for the rear

seating position. These telltales could be

specific to the actual seating position to

inform the driver of the actual position

that is buckled or unbuckled.

A commenter said that the rear seat

warning system should be coordinated

with the driver warning, and that an

ideal approach would be to provide a

pictogram of the vehicle that has icons

showing the seat belt status for each

seating position. The commenter

suggested this dashboard image could

be combined with the door-ajar image,

and it could even be enhanced to

indicate whether a door’s child safety

lock feature is engaged. Similarly, a

commenter stated that the warning

should convey the location of each

unbuckled occupant (negative-only

system for which occupant detection

would be necessary).

Agency Response

We are proposing that the visual

warning be continuous or flashing and

consist of icons or text and indicate how

many or which rear seat belts are in use

or not in use depending on the type of

warning system. If icons are used to

indicate how many or which rear belts

are in use, we propose that icon(s) must

be green; if icons are used to indicate to

the driver how many or which belts are

not in use, we propose that the icon(s)

be red. If text is used to indicate to the

driver how many or which rear seat

belts are in use or not in use, we

propose that the text contain the words

‘‘rear belt(s) in use’’ or ‘‘rear belt(s) not

in use.’’ We also propose to amend table

2 in FMVSS No. 101, Controls and

displays, to clarify that the ‘‘Seat Belt

Unfastened Telltale’’ depicted there

does not apply to the rear seat belt

reminder. We also propose to amend

able 1 in FMVSS No. 101 by adding in

a row for the proposed rear seat belt

warning. We agree with the merits of

standardized warnings, but also seek to

provide manufacturers flexibility to

address their vehicle designs.

The requirement that the visual

warning be continuous or flashing

mirrors the current driver’s seat belt

visual warning requirement and is also

consistent with R16. However, we

propose to depart from the current

driver’s warning and from R16 and

standardize the color of the icons and

text for the warnings to increase the

likelihood that consumers would notice,

recognize, and respond to the warnings.

We believe that standardized colors and

text will facilitate the interpretation of

the signal. We are departing from the

current driver’s warning requirements

and following R16 by not requiring

specific icons because we believe the

choice of icons would largely depend on

whether the system displayed the

number of seat belts in use or which

seat belts are in use; this NPRM

provides manufacturers flexibility in

choosing which icons to use.

Another difference between the

proposal and R16 is that R16 requires

that the visual warning ‘‘indicate at least

all rear seating positions.’’ We

understand this to mean that the visual

warning must depict all the rear seating

positions. For instance, on some

vehicles, Peugeot employs a visual

warning that uses a schematic of the

whole vehicle to indicate seat belt non-

use or change-of-status for each seating

position.

176

Another manufacturer,

Cupra, uses a visual warning, on some

of its European vehicles, which depicts

the status of all the seat belts in the rear

seats without using a schematic of the

whole vehicle.

177

In order to give manufacturers design

flexibility, we do not propose to require

that the warning depict all rear seating

positions. Our proposed requirements

would allow the visual warning to

consist of text or icons indicating how

many or which rear seats are fastened or

unfastened. For example, the warning

text might consist of ‘‘Middle and Right

rear seat belts fastened.’’ Another visual

warning option would be the seat belt

icon with an adjacent numeral

indicating the number of rear seat belts

fastened. Accordingly, the proposal

would allow, but not require, use of a

pictogram as recommended by Safe Ride

News. We are not requiring this because

we believe it would be difficult to

implement on vehicles such as

passenger vans with many rear seats.

(We also note that R16, which requires

the visual warning to indicate all rear

seats, does not apply to vehicles that

transport more than eight passengers.)

We acknowledge that vehicles with a

larger number of rear seats, such as

passenger vans/buses, may encounter

visual signal complexities; however, we

are not dictating specific types of signals

in the proposed requirements in order to

ensure manufacturers have adequate

flexibility to address these types of

issues. We think these vehicles, in

particular, would benefit from the

option to indicate how many rear seats

are fastened.

We seek comment on all of these

issues, including the type of visual

warnings that rear seat belt reminder

systems employ currently or may

employ in the future. We also seek

comment on whether we should

consider further aligning with R16 by

requiring the visual warning to indicate

all rear seating positions, which features

of a visual warning would be

appropriate for buses, and whether any

further amendments to FMVSS No. 101

are necessary (e.g., the common space

requirements in S5.5).

5. Belt Use Criteria

The ANPRM sought comment on

whether NHTSA should retain, for a

rear seat belt warning, the criteria used

for the current driver’s seat belt warning

to determine if the occupant is belted.

The current driver’s belt warning

requirements specify that a belt is ‘‘not

in use’’ when, at the option of the

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S7.3(c). These are the definitions for manual

belts. For automatic belts, see infra Section XII.A.

179

Section 2.46.

180

See Docket No. NHTSA–2010–0061

(comments of IEE S.A., Alliance of Automobile

Manufacturers, Association of Global Automakers,

and Automotive Safety Council).

181

We consider readily removable seats to be

seats designed to be easily removed and replaced

by means installed by the manufacturer for that

purpose (see FMVSS No. 208 S4.1.4.2.2.), and do

not require any special tools for their removal.

182

See Sections 8.4.1.3 and 15.4.2.

manufacturer, either the seat belt latch

mechanism is not fastened or the belt is

not extended at least 10.16 centimeters

(cm) (4 inches (in)) from its stowed

position.

178

ECE R16 defines an ‘‘unfastened’’ belt

to mean ‘‘either the safety-belt buckle of

any occupant is not engaged or the

length of the pulled out webbing is less

than the length of the webbing which is

needed to buckle an un-occupied seat in

the rear most seating position.’’

179

Euro

NCAP does not specify a webbing spool-

out criteria, and only refers to the status

of the belt buckle.

Comments

Three commenters supported using

the existing FMVSS No. 208 criteria.

A commenter suggested harmonizing

with ECE R16, regardless of the type of

system, in order to provide flexibility

for vehicles that may have different

characteristics with respect to rear row

seating positions; for example, for rear

seats that can be removed from a

vehicle, providing an option whereby

belt spooling can be used as an

alternative to buckle latching may

reduce challenges associated with any

electrical connections that might be

otherwise needed to provide

functionality.

Other commenters suggested using

different belt use criteria considering

the wide range of possible occupants,

devices (e.g., car seats), and objects in

rear seats, but did not offer possible

solutions. One commenter stated that

any seat belt use criteria should take

into account whether a bypass system

for CRS installation would be employed

to prevent false warnings caused by

using the lower anchors. Another

commenter stated that the prolific use of

LATCH seats and integrated child seats

on buses will necessitate an alternate

means of seat belt use detection.

Agency Response

The current FMVSS No. 208 belt use

criteria for the driver’s seat belt warning

requirements have been in place since

1974 and allow for the use of a belt latch

or spool-out sensor. While these criteria

would be effective for determining belt

use for the initial seat belt warning, we

believe the use of a spool-out sensor

would not allow for an objective or

reliable criterion for the proposed

change-of-status warning. There may be

instances where the webbing may not

readily spool back in when the seat belt

is unbuckled (e.g., due to the use of

shoulder belt routing features or the use

of a belt positioning booster seat), and

thus would not reliably trigger the

change-of-status warning. Therefore, we

are proposing amending the belt use

criteria in FMVSS No. 208, for the seat

belt warning requirements, to rely on

the use of a belt latch sensor, and not

provide requirements that would

accommodate the use of a spool-out

sensor. We believe this is consistent

with Euro NCAP. We invite comment on

this tentative decision to not

accommodate the use of spool-out

sensors for the belt use criterion and

request any data on the prevalence of

the use of spool-out sensors in the fleet.

Concerns about false alarms triggered

by LATCH use for the installation of

child restraints are already addressed by

the simple approach, in line with

NHTSA’s recommendations, that

parents and caregivers fasten and lock

the unused seat belts for the seat where

the child restraint is being installed.

This is an already existing agency

recommendation to prevent seat belt

entanglement and would prevent false

warnings related to LATCH use.

6. Electrical Connections

In the ANPRM, we explained that a

rear seat belt warning system might

require an electrical connection between

the seat and the vehicle to relay the

information gathered by a belt latch or

webbing spool-out sensor to the rest of

the warning system. A rear-belt warning

system may therefore, as several

commenters to the RFC noted,

180

present potential wiring complexities,

particularly in vehicles with removable,

folding, rotating, or stowable seats.

These types of seats might present an

issue for a rear seat belt warning system

because the electrical connection might

not be automatically reestablished for

these seats when the seat is reinstalled.

There could be instances with manual

connection seats where the driver either

forgets to make the connection or makes

an improper connection. Even for seats

where the connections are automatically

established when the seat is reinstalled,

the automatic connectors might

malfunction. If the electrical connection

is not reestablished, the warning system

could malfunction or provide inaccurate

information. Removable seats are

mainly found in the second row of

minivans.

181

Foldable, rotating or

otherwise stowable seats (e.g., Stow-n-

Go, Flip and Fold) are prominent in the

third row of minivans or large SUVs.

Foldable or stowable seats in the second

row are not as prominent in minivans.

Neither Euro NCAP nor ECE R16 have

any requirements that address the

potential for improper electrical

connections for such seats. The ECE

regulations provide that the rear seat

belt warning requirements would not

apply to folding rear seats or to seats

fitted with an s-type belt (including a

harness belt) until September 2022.

182

Euro NCAP does not exclude folding

seats and includes all seating positions

including optional and removable seats,

but does not require the monitoring of

the buckle status for rear seat belt

secondary buckles that require a tool to

unlock.

Comments

Three commenter stated that

removable, suspension and folding seats

are complex and raise reliability and

technological readiness concerns and

should be exempted from the warning

requirements until it would be

practicable. Two of these commenters

said that if a seat belt warning were

required for such seats, significant lead

time or a phase-in (e.g., until the vehicle

platform was updated) would be

necessary.

Commenters stated that a rule should

include some or all of these seat types.

A commenter stated that, although these

seats may present challenges for rear

seat belt warning systems, NHTSA has

provided no evidence that, in cases

other than removable seats, the

challenges would be insurmountable, or

quantified the portion of the target

population represented by occupants of

these types of seats, which likely

includes many children. Another

commenter stated that removable seats

would not need to be exempted from the

requirements (as they currently are from

ECE R16) if specific types of electrical

connections or technology (e.g., wired

buckle switch, wireless buckle switch,

belt extension) were not required.

Commenters said that electrical

connections for removable, rotating,

flipping and folding seats should not

require any action on the part of the

consumer because vehicles with these

seats frequently transport children, and

believed that NHTSA should also

consider requiring wireless connections

and a warning for an improper

connection.

Commenters were against any

prescriptive design requirements related

to the connection between the vehicle

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As we note in Section X.C.7 below, we also

propose that the owner’s manual (which includes

information provided by the vehicle manufacturer

to the consumer, whether in digital or printed form)

include instructions on how to make any manual

electric connections for readily removable seats.

184

We estimate that minivans make up 3.6% of

vehicles produced based on MY 2015 WardsAuto

production data. The number of minivans that

would potentially be affected by this proposed

requirement is less than 3.6%, because some

minivans only have foldable/stowable rear seats,

not removable seats.

and any removeable, folding, rotating, or

stowable seats, and in favor of a robust

set of compliance options to facilitate

new technology (although one

commenter also said that any additional

time it would take NHTSA to develop

such options would not be justified by

the limited benefits and relatively small

number of affected vehicles). A

commenter said that NHTSA should

instead include a reliability requirement

(e.g., lifetime warranty).

Two commenters expressed concerns

with wiring complexities associated

with buses. One of these commenters

specifically noted track-mounted seats,

which can be repositioned by the end

user, which are also subject to improper

connections and for which wireless

communication technology is not

currently available.

Agency Response

We have tentatively decided not to

exempt any of these seat types from the

proposed requirements. We are not

exempting suspension and/or folding

seats; the electrical connections should

not be disturbed because these seats are

not readily removable, and they would

potentially just require additional

wiring to accommodate the folding or

stowing process. We are also not

exempting removable seats because we

tentatively believe that concerns with

improper electrical connections will be

addressed by the proposed warning

requirement discussed below. Applying

the requirements to these seats also

harmonizes with ECE R16 (which will

soon fully phase in the rear belt

requirements for these seats) and Euro

NCAP. We do not consider a phase-in

necessary for suspension and/or folding

seats because we believe the solution for

these seats is simple. For removable

seats a phase-in is unnecessary because

readily attachable electrical connections

appear feasible. We do not believe buses

would be subject to these requirements,

given our definition of readily

removable seats.

We have tentatively decided not to

propose any requirements with respect

to the electrical connections for folding,

rotating, or stowable seats. Because

these seats are not readily removable,

the electrical connections should not be

disturbed and could be accommodated

with additional wiring. We are,

however, proposing two requirements

related to the electrical connections for

readily removable seats.

First, we are proposing that readily

removable seats must either

automatically connect the electrical

connections when the seat is put in

place (i.e., not require the vehicle user

to take any additional action to

reconnect the electrical connections

other than re-installing the seat) or, if a

manual connection is required (i.e., the

user must reconnect the electrical

system), the connectors must be readily-

accessible.

183

By readily-accessible

connectors we mean connectors that are

easy for an ordinary consumer to see

and access. A system utilizing a wireless

connection could be classified as either

automatic or manual, depending on

whether the user needs to take any

additional actions to establish the

wireless connection. We agree with the

commenters who recommended no

prescriptive requirements in order to

ensure OEMs have flexibility in system

design. We think the proposal balances

flexibility and the need to ensure that a

proper connection is made.

Second, we are proposing that

vehicles utilizing the negative-only

compliance option provide a visual

warning to the driver if a proper

electrical connection has not been

established for a readily removable seat.

We are concerned that consumers could

reinstall removable seats (with either

automatic or manual connections)

without making a proper electrical

connection. There could be instances for

manual connection seats where the

driver either forgets to make the

connection or makes an improper

connection. Even for seats where the

connections are automatically

established when the seat is reinstalled,

the automatic connectors might

malfunction (e.g., debris, broken

connector) and a proper connection may

not be made. If the electrical connection

is not reestablished, the warning system

could malfunction or provide inaccurate

information. We are only proposing to

require the warning for negative-only

systems because a faulty connection

would result in the system not triggering

any warning of an unbelted rear seat

occupant. Moreover, the driver would

otherwise have no reason to suspect that

the system was malfunctioning, and so

might mistake the lack of a warning as

an indication that the rear seat occupant

was belted.

These potentially serious problems

are not present in full-status or positive-

only warning systems. First, it is our

expectation that a faulty connection for

a full-status system would affect both

the occupant detection and belt status.

However, if for some reason this is not

the case and the occupant detection of

a full-status system is working properly,

but the seat belt buckle sensor is not

connected properly, then no visual

warning should activate without input

from the buckle sensor and the driver

should easily recognize the system is

not working properly. If for this same

scenario, the system interprets a lack of

input from the seat belt sensor as an

unbuckled seat belt when the driver

verifies or requests the rear seat

occupant to buckle their seat belt and

the occupant is already buckled, then

the driver would again be aware the

system is not working properly. If the

occupant detection sensors are not

connected properly, the driver would be

aware of the number of rear seat

occupants being transported, and would

thus be aware that the system is not

operating correctly when there is not a

warning for each occupant. Similarly, if

there were not a good connection in a

vehicle with a positive-only system, an

unbelted rear seat occupant would not

accurate; a belted passenger would also

not register as belted, but since the

passenger would be belted, there would

be no adverse consequences from the

system error if a crash were to occur.

We believe that both of these

requirements would mainly affect

minivans, which make up a small

percentage of the fleet.

184

We believe it

might be possible to utilize the rear seat

belt visual warning signal, with slight

modifications (e.g., a different color).

The agency seeks comments on this

proposal, particularly on the safety need

for such warnings, costs, and feasibility

of the proposed warning. We also seek

comment on whether this telltale should

be added to table 2 of FMVSS No. 101,

Controls and displays.

None of the regulations or statutes

administered by NHTSA require

manufacturers to provide a lifetime

warranty. However, if a vehicle or item

of equipment is determined (by the

manufacturer or NHTSA) to have a

safety-related defect or fails to meet an

applicable FMVSS, the Safety Act

requires the manufacturer to notify the

owner of the defect or noncompliance

and (if the vehicle or item is not more

than 15 years old) remedy the vehicle or

item without charge to the vehicle

owner.

7. Owner’s Manual Instructions

The ANPRM sought comment on

requiring the owner’s manual to provide

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The National Child Restraint Use Special

Study found that only 13 percent of drivers

reported reading the vehicle owner’s manual.

Nathan K. Greenwell. 2015. DOT HS 812 142.

Washington, DC: U.S. Department of

Transportation, National Highway Traffic Safety

Administration, p. 10.

186

As noted earlier, NHTSA recommends

buckling unused seat belts that are within reach of

children to prevent seat belt entanglement and/or

strangulation.

187

FMVSS No. 101, S5.5.5. See discussion supra,

Section X.C.4, Telltale characteristics.

information on the warning system’s

features, including the location, format,

and meaning of the visual warnings.

Because the owner’s manual readership

may be relatively low,

185

we also sought

comment on whether this information

should be displayed in the vehicle

instead of (or in addition to) the owner’s

manual.

Comments

None of the commenters opposed

such a requirement. Several commenters

supported including such information

in the owner’s manual. Some

commenters requested flexibility in

describing the functionality of the

system. One commenter suggested that

the owner’s manual could include

information on the seating positions

where a rear-seat reminder is provided,

a description of the visual and audible

warning(s), an indication of whether the

system incorporates driver monitoring

(including any limitations), instructions

for deactivating or cancelling any

warning(s), any limitations related to

CRS, and information related to the

connection of removable, folding,

rotating, or stowable seats.

A commenter believed that

information should also be displayed in-

vehicle, especially for one-time vehicle

users (renters, friends, family), and

especially with respect to electrical

connections for removable/stowable

seats. Another commenter believed that

more research on the best way to

communicate this to owners is needed.

A commenter stated that information

on how a rear seat belt reminder affects

CRS installation should be provided,

including whether the system is able to

detect a CRS (and avoid false warnings).

Agency Response

We propose that the owner’s manual

(which includes information provided

by the vehicle manufacturer to the

consumer, whether in digital or printed

form) describe the warning system’s

features, including the location, format,

and meaning of the visual warnings. We

also propose that the owner’s manual

include instructions on how to make

any manual electrical connections for

readily removable seats. This will

provide manufacturers flexibility for

how they describe the functionality of

the system. These proposed additions to

the owner’s manual requirements in

FMVSS No. 208 would require a

revision to the approved collection of

information OMB No. 2127–0541. Later

in this proposed rule, we seek comment

on this revision.

With regard to including system

functionality information in the vehicle

itself, these types of vehicle features are

not normally explained visually in the

vehicle, other than information on air

bags which pose safety risks. This level

of detail is best described in the owner’s

manual.

We are aware of at least one

manufacturer that provides information

in the owner’s manual on how their rear

belt warning system with occupant

detection functions when a CRS is

installed with LATCH and guidance on

how to avoid activating the warning (for

example, it informs the consumer that

fastening the seat belt prior to installing

a CRS with LATCH will avoid activating

the warning system for that seat).

186

seek comment on whether we should

require including such information in

the owner’s manual (which includes

information provided by the vehicle

manufacturer to the consumer, whether

in digital or printed form).

8. Interaction With Other Vehicle

Warnings

The ANPRM also solicited comment

on whether a rear seat belt warning

could conflict with other in-vehicle

warnings, and how this might be

addressed.

Comments

A few commenters believed that the

rear belt reminder could conflict with

other warnings. One commenter

believed that there are conflicts and that

the rear seat belt warnings should be

given priority over other warnings. Two

commenters recommended that NHTSA

provide flexibility for rear-seat reminder

system alerts (or aspects of the alert) to

be temporarily suppressed or paused

where it is necessary to alert or redirect

the driver’s attention to higher-priority

warnings—for example, related to the

operation of the vehicle or a potential

safety risk within the external roadway

environment, such as an alert provided

by an advanced driver assistance system

(ADAS), crash avoidance system or

automated driving system (ADS) request

to intervene. Another commenter

recommended that the existing FMVSS

No. 101 Seat Belt Unfastened Telltale be

utilized as a persistent ‘‘baseline’’

warning when there is an active seat

belt warning for any occupant, even in

the event that the display of detailed

seat belt information is prevented by a

higher priority warning.

Other commenters did not believe

there would be conflicts with other

warnings, and one manufacturer did not

believe there would be a conflict if the

audible warning is accompanied by a

visual warning.

Agency Response

NHTSA is proposing that the rear seat

belt reminder telltale must not be

overridden by other visual warnings for

the required duration. This is consistent

with the current requirements in

FMVSS No. 101 for the driver’s seat belt

warning which specify, among other

things, that the seat belt telltale must

displace any other symbol or message in

that common space while the

underlying condition for the telltale’s

activation exists.

187

We do not believe

that the seat belt warning requirements

will interfere with other warnings for

safety systems since they have

dedicated warning signals. This should

give manufacturers the flexibility to

determine the best way to implement

their warnings. For instance, warnings

for a potential safety risk can be more

aggressive than those for the seat belts.

With regard to available space, the

visual signal might be displayed as a

telltale light on the instrument panel or

on the vehicle’s information display

screen. Manufacturers will also have to

determine whether the driver and rear

passenger seat belt visual warning will

be treated the same.

D. Alternative Warning Signals

The ANPRM sought comment on

requiring or specifying as a compliance

option a rear seat belt warning that

differs from the type of audio-visual

warning that is currently required for

the driver’s seat belt. Alternatives to a

visual warning on vehicle start-up could

include an audible signal, either

electronic or mechanical, or a haptic

warning (e.g., steering wheel or seat

vibration). Similarly, an audible or

visual warning of a change in the status

of rear seat belts could be either

electronic or mechanical and could

include a haptic signal. We also sought

comment on alternative solutions that

would alert the driver when a rear seat

passenger buckles and/or unbuckles

(e.g., mirrors to see whether belts are

buckled, or the sound of the latch plate

clicking into the buckle).

Comments

Many commenters recommended

requiring the traditional audio-visual

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With respect to Blue Bird’s argument

regarding the practicability of a rear warning for

buses, see Section X.B, Applicability.

189

Mazzae, E.N., Baldwin, G.H.S., & Andrella,

A.T. (2018, October). Performance assessment of

prototype seat belt misuse detection system (Report

No. DOT HS 812 593). Washington, DC: National

Highway Traffic Safety Administration.

190

Section 8.4.5.

191

Section 8.4.5.1.

192

Section 3.4.3.1.2.

193

S5.5.6(b).

warnings currently used for the front

seats. One commenter stated that

warning specifications should be based

on effectiveness and that audio-visual

warnings would likely be highly

effective given occupants’ familiarity

with them; it did not believe that a less-

sophisticated warning, such as a

specialized system of mirrors, would be

sufficient to inform the driver about the

status of the rear seat belts. Two

commenters noted the potential for

confusion/distraction if an alternative

warning were used. A commenter stated

that the ‘‘click’’ of the belt buckle, while

certainly evidence of a buckled seat belt,

can easily be missed by the driver and

other occupants, as it could be masked

not only by the drivers’ own belt

clicking, but also by ambient noise in

the vehicle, and that, given the research

supporting the effectiveness of an audio-

visual signal, an alternative warning

system would not be acceptable. Two

commenters said that an alternate

warning is not necessary because ECE

R16’s requirements are adequate.

A commenter said that, in addition to

requiring an audio-visual warning, the

proposed rule should require a

notification on the instrument cluster if

a seat belt is unbuckled that must be

acknowledged by the driver before any

other use of the instrument panel is

permitted.

A commenter stated that rear seat belt

warnings are not practicable for buses,

but if they were used, an audible alarm

similar to that required for emergency

exits would be necessary to provide an

effective notice to the driver. The

commenter believed that the interior

mirror on buses designed to permit the

driver to view the passengers, while not

as effective in determining proper seat

belt use as an electronic monitoring

system, has been effective in aiding the

driver to observe passengers that were

obviously not properly belted. The

commenter did not support the use of

haptic signals on buses. A public

commenter suggested use of cameras.

Agency Response

We agree with the commenters who

believe that an alternative warning is

not necessary and that an audio-visual

warning would be appropriate.

188

Cameras would be unnecessary and

would add cost. The agency believes

that mirrors alone would not be as

effective as an audio-visual warning and

may pose risks, as drivers would have

to study the view to determine belt

status, assuming they could clearly see

the belts. In addition, as explained

above, the proposed rule would not

apply to school buses.

We are specifying minimum

performance requirements in order to

balance the effectiveness and

acceptability of these systems.

Manufacturers can go beyond our

requirements, such as by providing a

warning on the instrument panel that

must be acknowledged by the driver

before any other use of the instrument

panel is permitted.

E. Resistance to Intentional and

Inadvertent Defeat and Deactivation

The ANPRM sought comment on

whether NHTSA should propose

requirements to address circumvention.

We pointed to agency research on the

development of a seat belt misuse

detection system that identified a

number of ways in which a rear seat belt

warning system might be intentionally

defeated, as well as potential

countermeasures.

189

For example, a

warning system could be defeated if:

• The belt is buckled before the

occupant sits in the seat. This could be

addressed by requiring a sequential

logic system. A sequential logic system

would require that the belt be buckled

after the seat has been occupied in order

for the system to recognize the seat belt

as being buckled.

• An occupant buckles the seat belt

behind themselves. This could be

addressed by utilizing both seat belt

latch and spool-out sensors and

deactivating the warning only if the

webbing were spooled out more than a

predetermined length. However, even

these sensors could be defeated by

pulling out additional webbing and

clipping it off to prevent retraction.

• The seat belt and/or occupant

detection sensors utilized by the rear

warning system in vehicles with

removable rear seats are intentionally

disconnected.

We also noted some ways in which

the warning could be inadvertently

circumvented (for example, when the

driver uses a remote engine starter so

that the initial warning activates before

the driver is in the vehicle).

We also sought comment on whether

a feature allowing single-trip manual

deactivation would diminish the

likelihood of circumvention. The ECE

regulations allow the rear seat belt

warning system to incorporate a short-

term and/or a long-term deactivation

feature for the audible change-of-status

warning.

190

Under those regulations, a

short-term deactivation may only be

effectuated by specific controls that are

not integrated in the safety-belt buckle,

and only when the vehicle is

stationary.

191

When the ignition or

master control switch is deactivated for

more than 30 minutes and activated

again, a short-term deactivated safety-

belt reminder must reactivate. A long-

term deactivation may only be

effectuated by a sequence of operations

that are detailed only in the

manufacturer’s technical manual or

which require tools that are not

provided with the vehicle. It must not

be possible to provide either short- or

long-term deactivation of the visual

warning. Under Euro NCAP, the system

may allow the driver to acknowledge

the signal and switch it off for that

unique event, except for change-of-

status events; a new trigger of the

warning should not be prevented.

192

therefore understand there to be two

distinct but related concepts in the ECE

regulations and Euro NCAP:

acknowledgement and deactivation. The

former allows the driver to turn off the

signal once it is activated, while the

latter prevents the signal from activating

altogether. In addition, FMVSS No. 101

provides that telltales for several

functions (such as high beams), but not

including the driver’s seat belt warning,

must not be cancelable while the

underlying condition for their activation

exists.

193

Comments

Several commenters supported

addressing intentional and/or

inadvertent defeat. A commenter stated

that, given the relatively small

proportion of hard-core nonusers, the

proportion of the potential target

population seeking to intentionally

defeat the systems is relatively small.

Nonetheless, the commenter stated that,

if mitigation strategies can be built into

the systems, such an advance would

likely help address at least some portion

of ‘‘hard-core nonusers’’ as well as those

exhibiting inadvertent misuse.

Commenters believed that the cost of

the potential countermeasures would be

minimal, and they should be required to

the extent feasible. A commenter stated

that the rear warning system should

include appropriate requirements for

inadvertent defeat, but not intentional

defeat. Another commenter supported

investigating the possibility of

eliminating the ‘‘false comply’’

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DOT 2009 Seat Belt Study at 2; Transportation

Research Board Study at 8.

condition of buckling behind the back

or extracting and ‘‘pinning’’ the belt

without buckling. One potential option

is to replicate current systems used to

identify seat belt use for front seated

occupants, as occupant detection

systems can also assist with identifying

misuse. They also commented that

sensor technology that identifies belt

pullout, occupant location, and buckle

switches can add redundancy and

reduce the risk of intentional and

inadvertent defeat.

Other commenters disagreed with

hardening the system against

circumvention because it would be

burdensome and unnecessary (minimal

benefits). One commenter noted the

relatively small proportion of drivers

who circumvent the seat belt warning.

With respect to deactivation, three

commenters supported following R16,

and IEE supported following R16 and/

or Euro NCAP. Three other commenters

opposed allowing deactivation because

it would drastically weaken system

effectiveness.

We also received comments on the

interaction with a remote engine starter

and the warning. A commenter believed

that adopting the requirements of R16

should help address this issue, as

warnings must be provided when the

ignition switch (or master control

switch) is activated (i.e., capable of

being driven). The commenter also

believed that the current driver’s

warning requirements (where the

warning is provided beginning when the

vehicle ignition switch is moved to the

‘‘on’’ or the ‘‘start’’ position) address

this issue. Another commenter

recommended that NHTSA specify the

start of the drive as the moment when

the ignition is activated in the mode

where the vehicle is capable of being

driven. A commenter stated that this

potential issue can easily be avoided

with occupant detection, because the

warning cycle would only be triggered

based on the actual presence of

occupants.

Agency Response

We have tentatively decided not to

propose any system-hardening features.

In drafting this proposal, the agency

focused on extending the rear seat belt

warning technologies currently in a

relatively small proportion of vehicles

to the rest of the fleet. These existing

systems generally do not provide

mechanisms to limit circumvention. We

decided not to include requirements to

address circumvention for a variety of

reasons. Most importantly, doing so

would increase cost and complexity. For

example, since we are not proposing to

require occupant detection technology,

we are not proposing a sequential logic

system. We also believe that because the

proposed warnings are minimally

intrusive—a relatively short-duration

visual warning on start-up, and an

additional short audio-visual warning

for a seat belt that is subsequently

unbuckled—attempts to defeat the

system will be rare.

We have also tentatively decided not

to allow acknowledgement or

deactivation of the required warning

signals. While some commenters

suggested adopting the R16

requirements, they did not offer further

information on the need or use of these

options, except for one commenter that

noted it would diminish the safety value

of the system. Therefore, we believe that

proposing to allow an acknowledgment,

short-term deactivation, and or long-

term deactivation option would have a

net negative impact on the effectiveness

of the proposed warning system (the

driver would not get the full benefit of

the warning). As discussed earlier in

this proposed rule, we believe that the

proposed warnings are minimally

intrusive and have relatively short

durations (visual-only at start-up and

audio-visual for a change-of-status), and

the positive-only compliance option

would mitigate warnings for

unoccupied seats. In addition, we

believe that allowing the driver to turn

off the change-of-status warning would

not meet the need for safety. Since we

cannot justify allowing such options

from a safety perspective (allowing it

would negatively impact the

effectiveness of the systems) or

consumer acceptance perspective

(warning signals are unobtrusive and

vehicle manufacturers could opt for the

positive-only option), we have

tentatively decided not to allow either a

deactivation or acknowledgment option.

For this reason, we also propose

amending FMVSS No. 101 S5.5.6(b) by

adding the seat belt telltale to the list of

telltales that may not be cancellable

while the underlying condition for the

telltale exists. This would apply to both

the front and rear seat belt warnings.

This would mean that the seat belt

warning telltale would not be allowed to

be acknowledged (i.e., cancelled) until

the minimum warning duration had

been reached.

We seek comment on vehicle

manufacturers’ desire to provide such

options, and, if they currently offer such

options, how they have implemented

them. We also seek comment on

whether allowing such options would

affect manufacturers’ choice of

compliance option (e.g., if we allowed

acknowledging or deactivating the

warning signals, would they be more

inclined to choose the negative-only or

full-status compliance options?). We

also seek comment on our proposed

revision of FMVSS No. 101.

In vehicles with a remote engine

starter, the driver would potentially not

be present to witness the initial warning

signals if they are designed to meet our

minimum requirements. This could

potentially be addressed by

programming the system to require

input from the door sensors or occupant

sensors to verify that the driver is in the

vehicle, or by requiring the signals to

initiate when the transmission is moved

out of the park mode. We have chosen

not to propose a strategy for this

scenario, but request comments on

practicable solutions to this problem

that could be implemented in the final

rule and the potential cost impacts. New

technologies or solutions may be

available that may address these

scenarios without limiting the design

flexibility of manufacturers or

significantly increasing the cost.

F. Consumer Acceptance

In the ANPRM we explained that in

order for the proposed rear seat belt

warning to have a lasting impact on seat

belt use, it must balance effectiveness

and acceptability. For a seat belt

warning system to induce an unbelted

occupant to buckle up, the warning

must be noticeable enough to attract the

occupant’s attention, or, for a warning

directed at the driver, the driver’s

attention. However, if the warning is

overly intrusive, consumers may not

accept the technology.

194

Therefore, the

warning must be noticeable enough to

prompt occupants to buckle their seat

belts, but not so intrusive that the public

does not accept the warning system, or

that an occupant will circumvent or

disable it. Consumer acceptance of any

eventual seat belt warning requirements

is an important consideration, given the

potential safety benefits of rear seat belt

warnings, the history of seat belt

warning technologies, and the fact that

consumers have not yet had widespread

exposure to rear seat belt warnings.

NHTSA is especially aware of this

concern, given the agency’s experience

with public and Congressional backlash

in the 1970s over the ignition interlock

and continuous warning buzzer

regulations.

We also noted research by NHTSA

and others suggesting that consumers

would accept the new technology. The

2004 Transportation Research Board

Report observed that ‘‘the data available

to date provide strongly converging

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Transportation Research Board Study at 75–

76.

196

Id. at pg. 10.

197

Paul Schroeder & Melanie Wilbur, Survey of

Principal Drivers of Vehicles with a Rear Seat Belt

Reminder System. Washington, DC: National

Highway Traffic Safety Administration (2015). The

vehicles with seat belt warning systems were

Volvos and certain Cadillac and Chevrolet models.

198

Citing www.norc.org/Research/Projects/Pages/

underutilized-strategies-in-traffic-safety-results-of-

a-nationally-representative-survey.aspx (last

accessed Oct. 25, 2021).

199

Citing Highway Loss Data Inst., Ins. Inst. for

Highway Safety, Unbelted: Adults Admit They

Often Skip Belts in Rear Seat, 52 Status Rep. 1, 3

(Aug. 3, 2017), available at www.iihs.org/api/

datastoredocument/status-report/pdf/52/5 (last

accessed Oct. 25, 2021).

200

Citing David G. Kidd & Anne T. McCartt

(2014) Drivers’ Attitudes Toward Front or Rear

Child Passenger Belt Use and Seat Belt Reminders

at These Seating Positions, Traffic Injury

Prevention, 15:3, 278–286, DOI: 10.1080/

15389588.2013.810333.

201

We identified three manufacturers that

produce vehicles with visual warnings that last for

at least 60 seconds. One manufacturer provides

vehicles where the visual warning stays active until

the belt is fastened.

202

In the ANPRM it was 13% based on MY2019

vehicle data.

203

See Docket No. NHTSA–2010–0061 (GM

comment).

204

See Docket No. NHTSA–2010–0061 (Volvo

comment).

205

Kidd, McCartt, & Oesch. Attitudes Towards

Seat Belt Use and In-Vehicle Technologies for

Encouraging Belt Use. Insurance Institute for

Highway Safety. January 2013. The study over-

sampled part-time belt users and nonusers.

evidence in support of both the

potential effectiveness and consumer

acceptance of many new seat belt use

technologies[.]’’

195

As part of the

research for the report, NHTSA

conducted focus-group interviews with

part-time and hard-core nonusers. The

report noted that ‘‘many part-time users

interviewed by NHTSA—the primary

target group for the technology—were

receptive to the new systems. Nearly

two-thirds rated the reminders

‘‘acceptable,’’ and approximately 80

percent thought that they would be

‘‘effective.’’

196

The ANPRM also

pointed to a telephone survey of drivers

of vehicles with and without a rear seat

belt warning system that NHTSA

conducted in 2015.

197

The rear warning

systems in those vehicles had

characteristics that were similar to the

proposed requirements: a visual

warning on start-up and an audio-visual

change-of-status warning. The survey

found, among other things, that 81% of

drivers of vehicles with a rear seat belt

warning were ‘‘very satisfied’’ with the

system; less than 2% were dissatisfied.

Among drivers of vehicles without a

rear seat belt warning, attitudes towards

rear belt warnings were generally

positive as well: a majority (55%)

indicated that it was important to them

that their next vehicle be equipped with

a rear belt warning system.

Comments

Several commenters believed that

consumers would accept rear seat belt

warnings. Commenters said that

NHTSA’s research shows that a large

proportion of the consumer population

will accept rear seat belt warnings and

it noted that at the time of the interlock

issue in the 1970s, seat belt use rates

were much lower than today, and a

larger proportion of the population were

hard-core nonusers. A commenter stated

that its survey of 2,000 drivers showed

that 70 percent favored a law requiring

seat belt reminders that continuously

chime until the seat belt is buckled,

including rear seat passengers.

198

Another commenter noted a 2012 IIHS

survey showing that most motorists

supported enhanced belt reminders that

were ‘‘more persistent and intense’’ than

what most automakers offered at the

time.

199

The commenter also noted the

results of NHTSA’s 2015 survey.

Another commenter said that IIHS has

found that the majority of drivers in the

U.S. who transport passengers would

accept a rear seat belt reminder

system.

200

This study found that parents

believed an audible alert to be

especially useful in alerting the driver to

a child unbuckling in the back seat

during a trip. A commenter suggested

that consumers would accept R16-

conforming systems.

One commenter said that further

studies are necessary because there is

insufficient data on consumer

acceptance.

Agency Response

NHTSA has tentatively concluded

that the proposed warning system

would be acceptable to consumers in

light of the specific characteristics of the

proposed warning signals, real-world

experience with seat belt reminder

systems, and research and consumer

surveys by NHTSA and others.

We believe that the proposed

requirements are specified so that the

potential for consumer disapproval is

minimized. Our intent was to specify

minimum warning requirements that

would result in an effective yet

acceptable warning. With respect to the

warning on start-up, we propose

requiring only a visual warning, and not

a more intrusive audible alert. The 60-

second duration is comparable to the

visual rear seat belt warnings provided

by currently deployed systems. For

example, the visual rear belt warning in

some MY2022 vehicles lasts for at least

60 seconds.

201

The change-of-status

warning would involve an audio-visual

alert lasting at least 30 seconds. While

most vehicle models currently available

in the U.S. with rear seat belt warning

systems have a change-of-status warning

that meets this 30-second minimum

duration, we are aware of two available

models that exceed this duration for the

rear change-of-status warning. False

positives would also be minimized

because the positive-only compliance

option only necessitates a buckle sensor,

not occupant detection, which is more

prone to false positives.

Recent field experience also suggests

that consumers would accept the

proposed requirements. As noted

earlier, an increasing number of vehicles

sold in the United States have rear seat

belt warning systems; based on 2022

Purchasing with Safety in Mind: What

to Look For When Buying a Vehicle

information, 46.9% of the total vehicle

projected sales are equipped with rear

SBWS.

202

Moreover, in connection with

the 2010 RFC, GM commented that it

has not received any complaints about

its rear seat belt warning system in

either the United States or Europe,

203

and Volvo indicated that it had found a

high level of acceptance for its

system.

204

In addition to this, many

OEMs have implemented enhanced seat

belt warnings for the front outboard

seats over the past two decades.

Consumers’ acceptance of these

warnings also suggests that they would

accept warnings for the rear seats.

Finally, in addition to the research

noted in the ANPRM we note the

studies cited by the commenters that

support our tentative conclusion that

consumers would accept the proposed

warnings. In 2012, IIHS conducted a

national telephone survey of drivers and

passengers about seat belt use. Using

this survey data, it proceeded to

conduct several studies.

One study, cited by the commenters,

was on the attitudes towards seat belt

use and in-vehicle technologies for

encouraging seat belt use.

205

All

respondents were asked questions

regarding their belt use habits and

perceptions of different types of seat

belt interlocks. Part-time belt users and

nonusers were additionally questioned

about different types of reminders and

reminder strategies. The survey found

that enhanced reminders are more

acceptable than seat belt interlocks and

are viewed as having the potential to be

as effective as interlocks if sufficiently

persistent. A larger proportion of part-

time belt users and nonusers said they

would be more likely to buckle up in

response to auditory and haptic

reminders than visual reminders. More

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Kidd, D.G. and McCartt, A.T. 2013. Drivers’

attitudes toward front or rear child passenger belt

use and seat belt reminders at these seating

positions. Insurance Institute for Highway Safety,

January 2013.

207

For example, in NHTSA 2015 phone survey,

for drivers of vehicles without a rear belt warning,

23% found their vehicle’s seat belt warning (i.e., for

the front outboard passenger seats) annoying, and

16% would not need or want a seat belt warning

system in their vehicle.

208

See also, e.g., Highway Loss Data Inst., Ins.

Inst. for Highway Safety, Unbelted: Adults Admit

They Often Skip Belts in Rear Seat, 52 Status Rep.

1, 3 (Aug. 3, 2017) (indicating that most rear belt

nonusers are not hard-core nonusers).

209

See also Section XIV, Overview of Benefits

and Costs.

than two-thirds of part-time belt users

and at least one-third of nonusers said

they would be more likely to buckle up

in response to seat belt reminders that

become more intense or continue

indefinitely; these reminders would be

acceptable to about half of part-time belt

users and around one-fifth of nonusers.

Another study cited by the

commenters used the same survey that

also collected information about drivers’

attitudes towards passenger belt use and

belt reminders for front passengers and

children in back seats.

206

This study

used the 477 respondents (of the 1,218

total surveyed) that were drivers who

transport a front-seat passenger at least

once a week and 254 were drivers who

transport an 8- to 15-year-old child in

the back seat. The respondents were

asked about their attitudes toward seat

belt use by their front passengers or rear

child passengers and preferences for

different passenger belt reminder

features. The study found that nearly

every driver who transports children in

the back seat would encourage their belt

use, regardless of the driver’s belt use

habits. Most drivers who transport front

passengers wanted passenger seat belt

reminders to encourage passengers to

buckle up. As far as signal

characteristics, the study found that

front and rear passenger reminder

signals that last indefinitely would be

acceptable to most drivers who

transport these passengers, and that an

audible alert may be especially useful to

alert drivers to children unbuckling in

the rear seat during a trip.

We therefore tentatively conclude that

consumers would accept the proposed

warnings. NHTSA recognizes that there

is some proportion of the public that

may not desire a rear belt warning

system.

207

However, based on extensive

research by NHTSA and others, we

agree with commenters that consumers

are more accepting of seat belt warnings

now than in the 1970s.

208

We are also

mindful of Congress’s repeal of the

duration limitation on the audible

warning for the driver’s seat belt, as well

as its directive to NHTSA to initiate a

rulemaking for rear seat belt use

systems. We believe this likewise

suggests that the public would be

amenable to appropriately specified

warnings. NHTSA welcomes public

comment on this issue.

G. Technological and Economic

Feasibility

The ANPRM sought comment on the

technological and economic feasibility

of rear belt warning systems.

Comments

Several commenters stated that rear

warnings are technically feasible. Four

commenters stated that rear warning

requirements in foreign markets show

that such systems are technically

feasible and available. Two commenters

also noted that rear reminders are

already available in a number of makes

and models in the United States, with

a commenter noting that Volvo has been

offering such a system in the United

States since 2009.

A commenter said that because

technological complexity and cost will

depend on the specifics of the particular

system, NHTSA should provide OEMs

flexibility by establishing baseline

performance requirements with

compliance options that would allow

for more advanced system

characteristics.

Another commenter stated that buses

present challenges for a rear seat belt

warning system with respect to the

number of passengers and harshness of

the interior environment. The

commenter also said that it would be

difficult integrating a passenger seat

system with rear seat belt warnings that

are the same as the OEM driver and

copilot warning system, so that the

warnings may not match. The

commenter said that there are seat belt

warning systems being developed that

utilize wireless technology and such a

system would be less complex than a

wired electrical connection system. The

limitation of a wireless system is the

battery life, and more system features

such as individual passenger alerts

would reduce battery life further.

However, a battery-operated wireless

system would be much simpler for large

vehicles with many passengers, as it

would reduce the need for complex

wiring systems. Another commenter

believed that larger vehicles with many

rear designated seating positions could

present technical challenges, including

the ability of a system to differentiate

between objects that might be placed on

seats and actual passengers of various

weights and sizes.

Agency Response

NHTSA has tentatively concluded

that the proposed requirements are

technologically and economically

practicable.

209

Based on 2022

Purchasing with Safety in Mind: What

to Look For When Buying a Vehicle

information, 46.9% of the total U.S.

vehicle projected sales are equipped

with rear seat belt warning systems. For

vehicles that do not already incorporate

a rear seat belt warning system, the

positive-only compliance option would

require seat belt sensors, wiring, and

display adjustments. All of this

technology is readily available. The seat

belt latch sensors that would be needed

for all three systems are already used by

many manufacturers to comply with the

existing driver seat belt requirements.

Occupant detection might present

technological challenges but would not

be necessary for a positive-only warning

system. As we explain in more detail in

Section XIV, Overview of Costs and

Benefits, we estimate that the minimum

cost to comply with the rear seat belt

warning requirements (the positive-only

system) would be $167.8 million. This

is based on a per-vehicle cost of $19.59

for 53.1% of 16M affected new vehicles.

As explained later, our preliminary

regulatory impact analysis indicates that

the proposed requirements are cost-

beneficial across a range of discount

rates and reasonable effectiveness

estimates.

As we noted in the ANPRM,

implementing a visual warning may

require physical redesign of the

instrument panel. Such redesign would

have to take into account visibility,

interaction with existing signals and

displays, available space on the

instrument panel, and effectiveness, as

well as other factors. In some instances,

a visual signal might be displayed as a

telltale on the instrument panel or on

the vehicle’s information display screen.

Manufacturers would also have to

determine whether driver and rear

passenger seat belt warning visual

signals would be treated the same.

We also recognize that vehicles with

many rear designated seating positions

may present some challenges, but we

have tentatively concluded that they

should be subject to the proposed

requirements (with the exception of

school buses) because those vehicles

would be at least as likely, if not more

likely, to have rear occupants. In

addition, multiple rear seats may

increase the difficulty of the driver in

ascertaining rear seat belt use, so a

warning could prove especially useful

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In Section XIII.C we discuss the potential for

more than one front outboard passenger seat in

ADS-equipped vehicles.

211

See, e.g., Interpretation Letter from NHTSA to

R. Lucki, July 24, 1985 (‘‘Thus, the intent was to

require a warning system for only the driver’s

position.’’).

212

Section 8.4.1.1.

213

National Center for Statistics and Analysis.

(2021, February). Seat belt use in 2020—Overall

results (Traffic Safety Facts Research Note. Report

No. DOT HS 813 072). National Highway Traffic

Safety Administration.

214

There are some compliance options for certain

trucks and MPVs that permit passive protection in

lieu of seat belts at the front outboard seating

positions. See S4.2.3 (compliance options for trucks

and MPVs weighing between 8,500–10,000 lb);

S4.2.6 & S4.2.1.1 (compliance options for walk-in

van-type trucks and vehicles designed to be sold

exclusively to the U.S. Postal Service 8,500 lb and

less).

in these vehicles. We also recognize the

intent of the MAP–21 requirements in

improving protection for rear occupants,

and given the proven benefits of seat

belts, believe the warning should be

broadly applied. Our main motivation

for including small buses is to capture

large capacity passenger vans; these

vehicles might utilize the option of a

warning that indicates the number of

seat belts fastened. However, we do seek

comment on whether it would be

appropriate to exclude additional

vehicle types.

Overall, we believe that the proposed

compliance options would provide

manufacturers with the flexibility to

innovate and develop new technologies,

while also ensuring a minimum level of

safety. We seek comments on the

practicability of the proposed

compliance options.

XI. Warning Requirements for Front

Outboard Seats

We propose several changes and

enhancements to the seat belt warning

requirements for the front outboard

seats. There are three main changes we

are proposing.

First, we are proposing a requirement

for an audio-visual warning on vehicle

start-up for the front outboard passenger

seat. Currently, the standard requires a

short duration (4–60 seconds,

depending on the compliance option)

audio-visual seat belt warning on

vehicle start-up for the driver’s seat belt

for most vehicles with a GVWR under

10,000 lb (excluding medium-sized

buses), but not for any other front seats.

The vast majority of the vehicles being

sold today (approximately 96.6% of the

fleet, according to information

submitted by vehicle manufacturers to

NHTSA for NCAP in MY 2022) already

provide a seat belt warning for the front

outboard passenger seat. We propose to

require a seat belt warning for this seat

to ensure that all vehicles have this

important safety feature.

Second, we propose to close the

current gap for a driver’s seat belt

warning in medium-sized buses. We are

unaware of any such buses that do not

already provide a driver’s seat belt

warning; requiring this would ensure

that they continue to have a driver seat

belt warning in the future.

Third, we propose several changes to

the current requirements for the audio-

visual warning signal that currently

apply to the driver’s seat that would

also apply to the front outboard

passenger seat. The most notable of

these is that we propose to require that

the audio-visual warning on vehicle

start-up last until the belts at any

occupied front outboard seats are

fastened, and a change-of-status warning

for any front outboard seat that would

also last until the seat belt is refastened

(unless a front door is open).

These proposals are explained in

more detail below.

A. Seat Belt Warning for Front Outboard

Passenger Seat

This document proposes to require an

audio-visual seat belt warning for any

front outboard passenger seat.

210

FMVSS No. 208 currently requires an

audio-visual seat belt warning for the

driver’s seat in passenger cars and

trucks, buses, and MPVs with a GVWR

of 4,536 kg (10,000 lb) or less, except for

buses with a GVWR greater than 3,855

kg (8,500 lb) and less than or equal to

4,536 kg (10,000 lb). NHTSA’s

regulations currently do not require seat

belt warnings for any seating position

other than the driver’s seat.

211

Although

the ANPRM did not discuss extending

the seat belt warning requirements to

any front passenger seats, two

commenters recommended that NHTSA

amend FMVSS No. 208 to require a seat

belt warning for all front seats, and

another commenter recommended

adopting the ECE R16 requirements for

front outboard seating positions. ECE

R16 requires an audio-visual seat belt

warning for the front outboard

passenger seat.

212

We believe there is good reason to do

so, as the reasons for ensuring the driver

is buckled apply equally to front

outboard passenger. About 10.4% of

right-front passengers do not always

fasten the belt

213

and unbelted

occupants are overrepresented in fatal

crashes. The lack of a seat belt warning

requirement for the front outboard

passenger seat dates to the 1970s, when

seat belt use rates were much lower and

seat belt warnings were not as

acceptable to consumers as they are

today. Further, almost all (96.6%)

vehicles offered for sale in the U.S. that

participate in the NCAP information

request are already equipped with a seat

belt warning at this position, so

requiring such a warning would ensure

that all vehicles be equipped with a seat

belt warning at this position.

We are proposing an audio-visual

warning on vehicle start-up because

research by NHTSA and others suggests

that seat belt warnings that use an

audio-visual signal are more effective

than visual warnings alone. In addition,

the potential technological, consumer

acceptance, and cost issues associated

with requiring an audible warning for a

rear seat belt warning do not apply to

an audible warning for the front

outboard passenger seat because,

although the audible warning would

entail use of occupant detection

technology, most vehicles are already

equipped with both an audible seat belt

warning and occupant detection for the

front outboard passenger seat. This

proposal would not require that the

audible warning be specific to either the

driver or front outboard passenger seat;

therefore, manufacturers could utilize

the same audible warning for both seats

as is done with some of the existing

front belt warning systems.

The proposed front outboard

passenger seat requirements would

apply to all the vehicles to which the

proposed rear belt warning

requirements would apply: all front

outboard designated seating positions in

passenger cars, and all front outboard

designated seating positions certified to

a compliance option requiring seat belts

in trucks, MPVs, and buses with a

GVWR of 4,536 kg (10,000 lb) or less.

214

We have tentatively decided not to

extend the seat belt warning

requirements to front center seats

because our preliminary regulatory

impact analysis found that a system for

the front center seat without occupant

detection would provide limited benefit

due to the low occupancy of the front

center seat and the limited number of

vehicles in the fleet with a front center

seat. See Section XIII, Regulatory

Alternatives, and the PRIA for a more

detailed analysis.

Occupant Detection

Because we are proposing an audio-

visual warning, we are also proposing to

require that any front outboard

passenger seat be equipped with an

occupant detection system; an audio-

visual warning is typically only

appropriate for occupied seats because

having an audible warning activate for

an unoccupied seat could be a nuisance

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Occupant detection is utilized by the

advanced air bags to properly classify the occupant

in the seat (e.g., child, adult, small-statured adult)

so that the advanced frontal air bag systems can

determine if and with what level of power the front

air bag will inflate. We also believe that occupant

detection is voluntarily used in the front passenger

seat to avoid having an audible seat belt warning

activate for an unoccupied seat.

216

Occupant detection systems are less

challenging for the front outboard passenger seat

than for the rear seats because the front outboard

passenger seat is not typically subject to as many

of the potential complications to occupant detection

(such as large occupants spanning multiple seating

positions). There may be infrequent situations

where occupant detection sensors may incorrectly

is unoccupied (e.g., mistaking cargo for an

occupant). However, if cargo placed on the seat

causes a false occupant detection reading and

inadvertent activation of the front passenger seat

belt warning signal, the driver can readily discern

it is a false reading and can easily either place the

cargo on the floor or fasten the seat belt to disable

the signal.

217

S7.3.

218

The laboratory procedures are not part the

regulatory text. Published separately by NHTSA’s

Office of Vehicle Safety Compliance, they are

intended to provide laboratories contracted by

NHTSA with additional guidelines for obtaining

compliance test data.

219

Citing www.norc.org/Research/Projects/Pages/

underutilized-strategies-in-traffic-safety-results-of-

a-nationally-representative-survey.aspx (last

accessed Oct. 25, 2021).

220

Citing Highway Loss Data Inst., Ins. Inst. for

Highway Safety, Unbelted: Adults Admit They

Often Skip Belts in Rear Seat, 52 STATUS REP. 1,

3 (Aug. 3, 2017), available at www.iihs.org/api/

datastoredocument/status-report/pdf/52/5 (last

accessed Oct. 25, 2021).

for the occupants and might desensitize

them to the warning or lead them to

circumvent the system. Requiring

occupant detection is consistent with

Euro NCAP, which requires occupant

detection for the front passenger seat

belt warning. In the United States,

occupant detection is already widely

deployed in the front outboard

passenger seat, either as part of an

advanced air bag system, or as part of

a voluntary seat belt warning system.

215

Based on compliance and consumer

information data submitted to NHTSA

by vehicle manufacturers, NHTSA is not

aware of any vehicles to which the

proposed requirements would apply

that are not already equipped with

occupant detection for this seating

position. This demonstrates that the

technology is feasible and that an

occupant detection requirement would

not result in any additional costs.

216

would also ensure that vehicles

produced in the future would be

equipped with the technology.

We propose that the warning system

consider this seating position

‘‘occupied’’ when an occupant who

weighs at least 46.7 kg (103 lb) and is

at least 139.7 cm (55 in) tall is seated in

the seat. These values are the weight

and height criteria currently specified in

FMVSS No. 208 (S29.1(f)) for a person

who is used as an alternative for the 5th

percentile adult female test dummy for

compliance testing of advanced air bag

systems utilizing static suppression.

These criteria are consistent with the

agency’s recommendation on not

transporting children in the front seat,

as well as Euro NCAP and the ECE R16

test procedures. As described below, in

connection with the proposed test

procedures (Section XII.B, Test

Procedures), the agency would use

either a person or test dummy meeting

these criteria.

B. Driver’s Seat Belt Warning for

Medium-Sized Buses

FMVSS No. 208 currently does not

require buses with a GVWR greater than

3,855 kg (8,500 lb) and less than or

equal to 4,536 kg (10,000 lb), or with a

GVWR less than or equal to 3,855 kg

(8,500 lb) and an unloaded weight

greater than 2,495 kg (5,500 lb), to be

equipped with a driver seat belt

warning. We are proposing to amend

FMVSS No. 208 to close this loophole.

We are unaware of any such buses

that do not already have a driver seat

belt warning that meets or surpasses the

warning specified in FMVSS No. 208.

Accordingly, we believe this

requirement would have minimal, if

any, costs or benefits. Requiring a driver

seat belt warning for these buses would

ensure that they continue to have a

driver seat belt warning in the future.

We invite comments on this proposal

and these assumptions.

C. Amendments to the Current Warning

Signal Requirements

The current driver’s seat belt warning

requirements provide manufacturers

with two compliance options.

217

The

first option requires that if the key is in

the ‘‘on’’ or ‘‘start’’ position and the seat

belt is not in use, the vehicle must

provide a visual warning for at least 60

seconds, and an audible warning that

lasts 4 to 8 seconds. Under the second

option, when the key is turned to the

‘‘on’’ or ‘‘start’’ position, the vehicle

must provide a visual warning for 4 to

8 seconds (regardless of whether the

driver seat belt is fastened) and an

audible warning lasting 4 to 8 seconds

if the driver seat belt is not in use.

We propose to modify these

requirements in three main ways. First,

we propose a single compliance option

that requires a start-of-trip audio-visual

warning that lasts until the seat belt at

any occupied front outboard seat is

fastened. Second, we propose to require

an audio-visual change-of-status

warning if a buckled belt at either of

these seating positions is unfastened in

the middle of a trip. Third, we propose

some additional requirements for the

audible warning related to increasing

the duration (for example, specifying a

minimum 0.20 duty cycle for the

audible warning); however, we

generally do not propose requirements

beyond what is currently in the

standard related to other aspects of the

warning. These proposals are explained

in more detail below.

1. Increasing the Duration of the Audio-

Visual Warning on Vehicle Start-Up

The current eight-second limitation

on the duration of the audible warning

was based on a statutory restriction,

enacted in 1974, that limited the length

of the audible warning. MAP–21

repealed this limitation. In light of

MAP–21’s repeal of the 8-second

limitation, the ANPRM sought comment

on removing the corresponding

limitation in FMVSS No. 208.

Comments

Several commenters supported

removing this restriction. One

commenter said that removing it would

provide manufacturers with greater

regulatory certainty in deploying

enhanced seat belt reminders, although,

the commenter stated, there needs to be

an upper bound on the duration of the

required warning to ensure an objective

and repeatable test for the purposes of

vehicle certification. The commenter

recommended maintaining the current

4- to 8-second warning thresholds

defined in table 4 of the FMVSS No. 208

laboratory test procedures.

218

Another

commenter encouraged NHTSA to allow

enhanced seat belt reminder systems as

a compliance option, possibly in lieu of

the currently required 4 to 8 second

alarm. A commenter recommended

increasing the minimum duration for

the audible warning to at least 90

seconds because the current audible

signal duration upper limit is ineffective

for increasing seat belt use (and cited

studies to support this

recommendation). Related to this, a

commenter stated that a survey of 2,000

drivers it commissioned showed that 70

percent favored a law requiring seat belt

reminders that continuously chime until

the seat belt is buckled, including rear

seat passengers,

219

and a commenter

noted a 2012 IIHS survey showing that

most motorists supported enhanced belt

reminders that were ‘‘more persistent

and intense’’ than what most

automakers offered at the time.

220

On the other hand, a commenter

recommended that NHTSA incorporate

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What is now the second compliance option

(S7.3(a)(2)) was added to the standard in 1974, and

what is now the first compliance option (S7.3(a)(1))

was added to the standard in 1991. See 39 FR 42692

(Dec. 6, 1974); 56 FR 3222 (Jan. 29, 1991). The

second (and original) compliance option requires an

‘‘advisory’’ visual warning that is required to

activate regardless of whether the seat belt is

buckled; the purpose for this, as NHTSA explained

in 1974, was so the ‘‘reminder would remain

effective even if the belt were disabled to silence

the audible warning.’’ 39 FR 42692. (A later

rulemaking preamble also suggested that this would

serve to remind other occupants to buckle their

belts. 56 FR 3222.) The 4- to 8-second duration was

selected ‘‘because an irritating light can be easily

ignored or disabled, a visual signal can effectively

serve only a reminder function, and as such, it

should be as simple as possible. The NHTSA

concludes that a 4- to 8-second reminder is best

calculated to accomplish the advisory function.’’ 39

FR 42692. The first compliance option was added

in response to a petition for rulemaking from

General Motors to allow manufacturers to use a

safety belt warning system meeting the

requirements for automatic safety belt warning

systems as an alternative to the warning system that

was specified for manual belt systems.

222

See Section III, Regulatory and Legislative

History. Similarly, an advisory warning for other

seating positions is not necessary because if the

proposal is adopted the front outboard passenger

seat and the rear seats would have warnings

specifically for those seats.

223

See supra note 38.

224

Specifically, we received information on

driver visual warning duration for 599 models for;

driver audible warning duration for 599 models;

front outboard passenger visual warning duration

for 564 models; and front outboard passenger

audible warning duration for 558 models. The

number of models differs because some models for

which a vehicle manufacturer submitted

information did not include complete information

on the front outboard seat belt warnings and some

vehicles are not equipped with a front passenger

seat belt warning system.

225

The 300–329 second interval consists of

vehicles from just one manufacturer, all of which

have a 300-second reminder. The 90–119 second

interval includes a variety of different-make vehicle

models with different reminder durations.

the Euro NCAP enhanced seat belt

reminder requirements in the U.S.

NCAP program if the agency wants to

encourage enhanced seat belt reminders

that provide driver warnings beyond 8-

seconds.

A commenter recommended that the

front and rear requirements be

consistent with respect to the required

duration of the audible warning.

Agency Response

NHTSA has tentatively decided to

increase the required duration for the

audio-visual warning provided on

vehicle start-up to occupants of the front

outboard seats. The extremely short

duration currently required for the

driver’s seat belt warning—which

originated in the early 1970s—is

outdated.

221

It was premised on the

since-repealed eight-second statutory

limitation on the audible warning

duration, then-existing low seat belt use

rates, and consumer resistance to

enhanced warnings, and the related lack

of such warnings in most vehicles.

These circumstances no longer hold.

There are several respects in which the

current requirements are therefore not

relevant to today’s market.

First, the existing requirements are

significantly exceeded by the warnings

provided in current vehicles. Although

NHTSA did not previously have the

authority to require a seat belt warning

with an audible signal lasting more than

8 seconds, starting in at least the early

2000s, manufacturers voluntarily began

providing enhanced audio-visual

warnings exceeding the FMVSS No.

208-minimum durations.

222

In order to

get a better sense of the warning

durations in currently sold vehicles,

NHTSA analyzed data on the seat belt

warning durations for MY 2022 vehicle

models provided to the agency by

vehicle manufacturers for NCAP; this

data covers most vehicles offered for

sale in the U.S. for MY 2022 with a

GVWR of 4,536 kg (10,000 lbs.) or

less.

223

In total, we received seat belt

duration information on over 500

different vehicle models.

224

For each

vehicle model, we looked at the warning

durations for the visual and audible

warnings for the driver and front

outboard passengers seat belts, as well

as the reported projected sales for that

model as a proportion of the total

projected sales for all of the vehicle

models for which data was provided to

NHTSA. We then tabulated this data to

determine how warning durations were

distributed across the new vehicle fleet.

Specifically, we divided the range of

warning durations provided—ranging

from six seconds to indefinitely long—

into intervals. For each interval, we

summed up the projected vehicle sales

of all the vehicle models providing a

warning with a duration falling within

that interval and divided that sum by

the total projected sales of all vehicle

models. In general, we found that

roughly half of new light vehicles

provide a visual warning that lasts until

the belt is fastened and an audible

warning that lasts at least two minutes

(120 sec). In the discussion later, we

discuss this data in more detail. We also

looked at the warning durations

provided in new vehicles tabulated by

vehicle model instead of projected sales.

The results are generally the same,

although there are some differences

compared to the vehicle sales analysis

presented here. These data and results

are presented in appendix A.

With respect to the driver visual

warning, the majority of new vehicles—

over 60% as a percentage of total

projected sales volume—have a warning

that lasts until the belt is fastened

(Figure 3). The remainder of the fleet is

about equally divided between a 5-

minute (300 second) visual warning and

a visual warning lasting at least 1.5

minutes, but less than 2 minutes (90–

119 seconds).

225

Less than 2% of the

fleet has a warning lasting less than 1.5

minutes (90 sec). The results for the

front outboard passenger visual warning

are essentially the same as for the driver

seat belt visual warning. See Figure 4.

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For the driver audible warning, the 0–29

second interval consists of a number of different

vehicle makes, all of which provide either a six or

eight-second warning.

With respect to the driver audible

warning, all of the vehicles for which

NHTSA had data have an audible

warning lasting longer than the

regulatory minimum of 4 seconds. A

small number of vehicles (about 1% as

a share of total projected sales volume)

have an audible warning that last six or

eight seconds.

226

See Figure 5. Thus, a

very small proportion of the current

vehicle fleet provide the very low-

duration audible warning currently

required by FMVSS No. 208.

Instead, almost all new vehicles

provide a driver audible warning that

significantly exceeds the current

minimum. Overall, about 99% of

vehicles (by share of total projected

sales volume) provide an audible

warning that lasts at least 30 seconds,

and about 92% of vehicles provide an

audible warning that lasts at least 1.5

min (90+ sec). See Figure 6. About half

of the fleet (47%) provide an audible

warning that lasts two minutes or more

(120+ s). Of the vehicles that provide an

audible warning with a finite length, the

sales-weighted mean is 2.9 minutes (174

seconds) and the median is 1.7 minutes

(100 seconds).

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90, 96, 100, and 108 seconds are the most used

durations in that range, but there are other

durations too. 100 seconds is the most used.

228

The only warning duration provided in the

300–329 sec interval is 300 sec.

229

Specifically, these are all on vehicles from one

manufacturer, which provide an audible warning

lasting 261 s.

230

The sale-weighted mean for the front

passenger audible warning is 176.57 and the

median is 96.

231

It also might be the case that so-called ‘‘hard-

core’’ nonusers, who comprise about 11–17% of

nonusers, would use the belt if the reminder were

sufficiently annoying, although, for the purposes of

our effectiveness (and benefits) analysis, we

conservatively assume that the increase in belt use

would be due entirely to part-time nonusers.

232

DOT 2009 Belt Warning Study, p. 1

(‘‘Although improvements in seat belt use rates

appear to result from ESBRs, there is not yet good

evidence concerning what works best and why a

given system may influence occupant behavior.’’).

233

See, e.g., DOT 2009 Belt warning Study, pp.

8, 46–49. See also David G. Kidd & Jeremiah Singer,

The effects of persistent audible seat belt reminders

and a speed-limiting interlock on the seat belt use

of drivers who do not always use a seat belt.

Insurance Institute for Highway Safety (2019)

(‘‘Persistent enhanced reminders with longer-lasting

or more frequent auditory chimes have been found

to be more effective for increasing seat belt use.’’)

(citing NHTSA research).

Turning to the specific durations

provided for the driver audible seat belt

warning, about half of new vehicles

(45.5% as a share of total projected sales

volume) provide a warning that lasts

90–to–119 s (1.5 s¥1.98 s).

227

See

Figure 5. The longest-duration audible

warnings, provided by two vehicle

manufacturers, last until the belt has

been buckled (accounting for about 8%

of new vehicles sold). The longest

limited-duration audible warnings,

lasting 5 and 8 minutes (300 and 480

seconds) are provided by two

manufacturers (about 22% of new

vehicles).

228

The other duration that is

used in a non-trivial share of new

vehicles is from 4 min¥4.5 min (240

s¥269 s) (about 12% of new

vehicles).

229

The corresponding analysis

for the front outboard passenger seat

belt warning is very similar.

230

See

Figure 7 and Figure 8.

Second, we tentatively agree with

IIHS that the current audible signal

duration upper limit of eight seconds is

ineffective for increasing seat belt use.

From the vehicle survey data presented

here, it is clearly not a factor affecting

vehicle design. As discussed earlier in

this preamble, front seat belt use rates

have plateaued in recent years so that

about 10% of front-row occupants do

not always use a seat belt. Coupled with

this, we note that approximately 83–

89% of nonusers are part-time nonusers

who would be open to using a belt.

231

Although research may not yet have

firmly established which exact system

specifications are optimal,

232

research

by NHTSA and others suggests that

audio-visual warnings are more effective

than visual warnings alone and that

longer duration warnings are more

effective than shorter duration

warnings.

233

NHTSA’s earlier research

estimated that an enhanced reminder,

on average, increased seat belt use three

to four percentage points compared to

the basic reminder currently required by

FMVSS No. 208. IIHS in its comment

cited recent research it had conducted

that evaluated the effectiveness of three

different driver’s seat belt reminders.

All of the reminders had a visual

warning that persisted until the seat belt

was fastened but had audible reminders

of varying duration. The research found

that, compared to a short intermittent

audible reminder (specifically, three

intermittent 7-second audible

reminders), an audible reminder with an

indefinite duration increased seat belt

use by 34%, and an audible reminder

with a 100-second duration increased

seat belt use by 30%. However, we note

that more than 90% of MY 2022

vehicles already have audible warnings

of at least 90 seconds, but only about

8% have an indefinite reminder. For

more information on these effectiveness

estimates, see Section XIV, Costs and

Benefits.

Third, we tentatively believe that

contemporary consumers would accept

a longer warning. As we discussed

earlier in this preamble, in the early

1970s, NHTSA faced consumer backlash

when it required long-lasting seat belt

warnings. However, consumer behavior

and attitudes have changed since then—

seat belt use is more widespread, and

opposition to using a seat belt is much

less prevalent than it was in the 1970s.

This is evidenced by MAP–21’s repeal

of the eight-second audible seat belt

warning limitation, and by the fact that

almost all light vehicles sold in the U.S.

now feature relatively long duration

visual and audible warnings for the

front outboard seats. Research by

NHTSA and others suggests that

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Kidd, McCartt, & Oesch. Attitudes Towards

Seat Belt Use and In-Vehicle Technologies for

Encouraging Belt Use. Insurance Institute for

Highway Safety. January 2013, pp. 1–3. The study

over-sampled part-time belt users and nonusers. But

see p. 3 (‘‘Requiring all vehicles to have more

intense enhanced reminders is a promising way to

increase belt use among part-time belt users, but

public acceptance still is a concern because the

characteristics that make reminders more effective

also are the characteristics that make them more

annoying. It is not clear how intense a reminder

needs to be to increase belt use among the

remaining part-time belt users and non-users and

what trade-off in annoyance is acceptable.’’)

(citation omitted).

235

Kidd, D.G. and McCartt, A.T. 2013. Drivers’

attitudes toward front or rear child passenger belt

use and seat belt reminders at these seating

positions. Insurance Institute for Highway Safety,

January 2013. But see id. at p. 13 (‘‘Long-lasting,

auditory front passenger reminders might not be

acceptable to these drivers, so it is important to find

ways to reduce the potential annoyance of front

passenger reminders without compromising their

effectiveness.’’).

236

DOT 2009 Belt Warning Study, supra n.36, p.

39 (drivers); p. 45 (passengers).

237

See, e.g., DOT 2009 Seat Belt Study at 54, 58

(while research to date on front seat systems

suggests that features such as a longer-lasting

flashing visual warning might be more effective

than a basic system, some warnings that may be

more effective could also be more annoying to

occupants).

238

See DOT 2009 Seat Belt Study at 60.

239

DOT 2009 Belt Warning Study, p. 8; Schroeder

& Wilbur, supra, p. 33.

240

N. Lerner et al. 2007. Acceptability and

Potential Effectiveness of Enhanced Seat Belt

Reminder System Features. DOT HS 810 848.

Washington, DC: National Highway Traffic Safety

Administration, p. 41–42

consumers would potentially accept an

appreciably longer duration warning. As

we noted above in connection with the

rear seat belt warning (Section X.F,

Consumer Acceptance), NHTSA’s

research suggests that part-time belt

users are receptive to seat belt warning

technologies, including front seat belt

warnings. Furthermore, more recent

research by others suggests support for

more persistent reminders. IIHS’s

research has found that, while public

acceptance of intense reminders was a

concern, seat belt reminders that

become more intense or continue

indefinitely would be acceptable to

about half of part-time belt users and

around one-fifth of nonusers.

234

Another IIHS study found that, while its

data was subject to some limitations,

‘‘most drivers who transport front

passengers wanted . . . reminders that

last indefinitely until the front

passenger buckles up,’’ ‘‘suggest[ing]

that stronger front passenger reminders,

such as those meeting Euro NCAP’s

design requirements, may be acceptable

to most drivers who transport front

passengers.’’

235

We also note the studies

cited by NSC and CAS suggesting strong

support for more persistent—and even

indefinitely long—reminders. At the

same time, we do acknowledge that

while enhanced warnings are

potentially more effective, they are also

more intrusive.

236

They therefore

present potential consumer acceptance

challenges that may reduce their

effectiveness.

237

NHTSA’s earlier

research suggests that it may be

challenging to design a warning system

with effective yet acceptable

characteristics,

238

and that no clear

consensus exists about which warning

system features are most acceptable.

239

It also noted that while it appears that

a majority of the general public accepts

seat belt reminders, the data on public

acceptance is somewhat limited and

anecdotal, and that resistance by a

minority of the public could limit

overall public acceptability.

240

However, based on the best data

available to us, we tentatively believe

that consumers would accept an audio-

visual front seat belt reminder with a

significantly longer duration than the

standard currently requires, including

an indefinite duration.

Fourth, the technology necessary to

implement such an enhanced warning is

already standard equipment on almost

all light vehicles. An enhanced warning

that activates for an unoccupied seat

could be a nuisance that either

desensitizes the occupants to the

warning, or leads them to circumvent or

defeat the warning. Enhanced warnings

therefore generally need to work in

conjunction with an occupant detection

system. This makes light vehicle front

outboard seats well-suited for enhanced

warnings, because almost all front

outboard seats are already equipped

with occupant classifications systems in

order to comply with the advanced air

bag requirements. Seat belt warnings for

the front outboard seats are therefore

capable of being activated only when an

unbelted occupant is present, which

greatly diminishes the risk of false

warnings. Accordingly, increasing the

reminder duration would entail

minimal costs.

Finally, a longer-duration is

consistent with seat belt warning

durations required or encouraged in

other markets and ratings programs. ECE

R16 requires that for the front seats

there be a 30 second visual warning

when the front seat belts are not

fastened and the ignition is activated. It

also requires an audio-visual warning

that must activate for at least 30 seconds

if the seat belt remains unfastened and

specific onset criteria are met (e.g.,

distance traveled, speed, etc.). To

prevent unnecessary signals, both ECE

R16 and Euro NCAP require that the

system be capable of detecting whether

the front passenger seat is occupied. The

Euro NCAP assessment protocol

requires a visual signal that remains

active until the seat belt is fastened, and

a two-stage audible signal; the initial

audible signal must not exceed 30

seconds and the final audible signal

must be at least 90 seconds. Similar to

Euro NCAP, under the IIHS seat belt

reminder system ratings protocol, the

primary audible reminder signal for the

front outboard seats must be at least 90

seconds in total duration in order to

obtain an ‘‘acceptable’’ or ‘‘good’’ rating.

Although ECE R16 does not require an

indefinite reminder, such a reminder

would comply with that standard, as

they do not contain a maximum length.

We are therefore proposing to increase

the minimum duration of the audio-

visual warning for the front outboard

seat belts on vehicle start-up. In

developing this proposal, we considered

a range of alternative warning durations.

At the upper end of the range is an

indefinite reminder—a reminder that

remains activated until the occupant

fastens the seat belt. Short of this are

reminders that have relatively long

durations, but do not last indefinitely.

Because there is a large range of

durations that could be selected, in

order to help structure the proposal (and

aid comment) we considered the

following ‘‘buckets’’ of reminder

durations, based on the front audible

warning durations provided in MY 2022

light vehicles offered for sale in the U.S.

as well as the durations specified in ECE

R16, Euro NCAP, and the IIHS ratings

protocol:

• Less than thirty seconds (less than

required in Europe and provided in only

about 1% of new vehicles offered for

sale in the U.S. in MY 2022);

• 30 seconds up to but not including

90 seconds (1.5 minutes) (consistent

with ECE R16, and provided in about

8% of MY 2022 vehicles in the U.S.);

• 90 seconds (1.5 minutes) up to but

not including 2 minutes (consistent

with Euro NCAP, and provided in about

46% of MY 2022 vehicles in the U.S.);

• 2 minutes (120 sec) up to (and

including) 5 minutes (300 seconds) (the

approximate mid-range of the audible

warning durations provided in MY 2022

vehicles in the U.S.);

• Greater than 5 minutes (300 sec) but

not indefinite (which includes the

longest limited-duration audible

warning, 8 minutes (480 sec) (provided

in about 8% of new vehicles in the

U.S.); and

• Indefinite duration (currently

adopted by two vehicle manufacturers,

accounting for about 8% of new

vehicles in the U.S.).

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We have tentatively decided to

propose requiring an audio-visual

reminder that lasts until the belts are

fastened at any occupied front outboard

seating position, in light of the increase

in roadway fatalities and the lack of

improvement of front seat belt use rates.

We also tentatively believe this is

supported by the favorable ratio of part-

time to hard-core seat belt nonusers,

surveys indicating a significant level of

acceptance for enhanced seat belt

warnings, and the fact that a non-trivial

share of currently sold vehicles have an

indefinite-duration reminder. These

vehicles incorporating the indefinite

warning support the practicability of the

proposal. Additionally, the small

percentage of market penetration

provides the greatest opportunity for

potential benefit (see section XIII). We

also believe that other warning signal

characteristics—such as duty cycle,

frequency, volume, or timbre—can be

adjusted to balance effectiveness and

consumer acceptance; manufacturers

would have the flexibility to adjust

these or other aspects of the warning,

within certain limits, as discussed

further below. We do not agree with

Global that an upper bound on the

warning duration is necessary for

objectivity. The warning simply would

be required to remain active as long as

the belt were unfastened at an occupied

seat; NHTSA’s compliance test would

necessarily have to stop at some point,

but NHTSA could make the test time as

long as it wanted and manufacturers

would have to certify that the warning

would be indefinite.

NHTSA seeks comment on this

proposal. If opposed to an indefinite

warning, what data support limiting its

duration? If NHTSA were to instead

require an enhanced but limited-

duration warning, how long should the

warning be? We also seek comment

from manufacturers (and others) about

the basis for the warning durations

provided in current vehicles,

particularly the warnings that exceed

the Euro NCAP duration (90 sec); for

example, the basis for the 5-minute

warning, or the 8-minute warning, or

the indefinite warning. We also seek

comment on the effectiveness and

consumer acceptance of the proposed

and alternative durations. One reason a

shorter duration could be more effective

is that some seat belt nonusers might be

more likely to habitually circumvent an

indefinite-duration warning as opposed

to a limited-duration warning. However,

such an assumption presupposes there

is some limited duration for which a

nonuser would be less likely to

circumvent. What would such a

duration be, and would it have a

reduced effectiveness over a longer or

indefinite limit such that the benefit

from reduced circumvention was offset

by a lower effectiveness? We also seek

any additional data on effectiveness or

acceptance, or any relevant studies that

NHTSA has not identified in the

preamble or the PRIA.

We also seek comment on whether the

required durations for the visual and

audible components of the warning

should be identical or different (for

example, requiring an indefinitely long

visual warning and an audible warning

that is of a relatively long, but limited,

duration)? Similarly, should the

warning durations for the driver and

passenger differ or be identical? We also

recognize that duration is not the only

warning signal characteristic that might

increase effectiveness (and affect

acceptance); we seek comment on

whether NHTSA should set minimum

performance requirements for other

aspects of the warning (e.g., volume of

audible warning and frequency of visual

flashing warning and intermittent

audible warning) in lieu of or in

addition to an increase in the warning

duration, and the empirical support for

such a choice. We discuss proposed

limits and seek comment on certain

parameters related to the audible

warning below.

2. Requiring an Audio-Visual Change-of-

Status Warning

NHTSA also proposes to require an

audio-visual warning whenever the

driver or front outboard passenger seat

belt is unfastened during a trip.

Although the driver may be aware that

the front outboard passenger seat belt

has been unfastened, we believe a

change-of-status warning may encourage

or remind front outboard passengers to

refasten their seat belt. We propose an

audio-visual warning consisting of a

continuous or flashing visual warning of

icons or text visible to the driver and

any front outboard passenger and a

continuous or intermittent audible

signal lasting until the seat belt is

refastened. The warning would be

required to activate when the vehicle’s

ignition switch is in the ‘‘on’’ or ‘‘start’’

position, the vehicle’s transmission

selector is in a forward or reverse gear,

and the driver and or front outboard

passenger seat belt status changes from

in use to not in use. However, similar

to the Euro NCAP protocol

requirements, if the change-of-status

occurs and a front door on the same side

of the vehicle as the belt triggering the

warning is open, the system can

consider that the start of a new trip. The

proposed indefinite duration is longer

than the minimum 30-second duration

proposed for the rear seat belt change-

of-status warning. We tentatively

believe a longer duration for the front

seat belt warning is justified because it

does not pose the same potential for

driver distraction as it does for the rear

seat belt warning. Additionally, if the

change-of-status is finite, this would

essentially provide a method of

circumventing the indefinite startup

warning, i.e., an occupant could be

buckled at startup, but then unbuckle

during the trip and only receive a fixed

duration warning.

ECE R16 essentially requires the same

change-of-status warning requirements

for the front and rear seats (the duration

is generally about 30 seconds unless the

belt is fastened sooner), so the reader is

referred to the discussion of the change-

of-status warning in connection with the

rear seat belt warning proposal (Section

X.C.2). Euro NCAP specifies that the

change-of-status warning must

essentially meet the requirements of the

initial warning, but those requirements

are different for the front and rear seats.

Again, for the front seats, Euro NCAP

specifies that for the initial warning a

visual signal shall remain active until

the seat belt is fastened, and specifies a

two-stage audible signal; the initial

audible signal must not exceed 30

seconds and the final audible signal

must be at least 90 seconds.

We seek comment on the proposed

change-of-status warning. What types of

change-of-status warnings are vehicle

manufacturers currently using for the

front and rear seats (e.g., audio-visual,

duration, etc.)? NHTSA is also

considering, as it is for the start-of-trip

warning, a limited-duration change-of-

status warning. Would a limited-

duration change-of-status warning be

preferable? And should it be identical to

the start-of-trip warning, or is there a

reason to require different warnings

(with respect to any warning signal

characteristic, but especially duration)?

How are vehicle manufacturers

currently handling change-of-status

events that occur when the vehicle is

stopped or at low vehicle speeds,

without a door being opened? Similarly,

how are change-of-status events handled

when passengers exit the vehicle

without the vehicle being in the park

gear?

3. Audible Warning Characteristics

If the proposed indefinite audible

warning were adopted, manufacturers

would almost certainly design audible

warnings that were not continuous but

instead cycled, in order to avoid the

excessive annoyance of a fully

continuous, long-lasting audible

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241

Mark Freedman et al., Effectiveness and

Acceptance of Enhanced Seat Belt Reminder

Systems: Characteristics of Optimal Reminder

Systems Final Report. DOT HS 811 097.

242

DOT HS 810 848; Lerner, N; Singer, L; Huey,

R; Jenness, J; ‘‘Acceptability and Potential

Effectiveness of Enhanced Seat Belt Reminders

System Features,’’ (2007)

243

Kidd, D.G. (2012). Response of part-time belt

users to enhanced seat belt reminder systems of

different duty cycles and duration. Transportation

Research Part F, 15, 525–534.

warning and to fine-tune annoyance and

effectiveness. In light of this, NHTSA

believes that it is necessary to more

fully specify the audible warning

characteristics than was necessary for a

brief audible warning to ensure that the

warnings have at least a minimum level

of persistence.

We therefore propose to define a set

of terms objectively describing the

audible warning: warning cycle, chime

frequency, and duty cycle:

• A warning cycle for an intermittent

audible warning consists of period(s)

when the warning is active at the chime

frequency or continuously, and inactive

period(s). A warning cycle begins with

an active period and is 30 seconds in

duration.

• Chime frequency means the

repetition rate for an intermittent

audible warning when the warning is

active.

• Duty cycle means the total amount

of time an intermittent audible warning

is active during a warning cycle at the

chime frequency or continuously,

divided by the total warning cycle

duration (30 seconds).

When an audible warning is emitting

sound, it may do so continuously or

intermittently. We believe if the chime

frequency of the warning is too low, the

warning may become less effective. In a

2009 agency study that focused on

analyzing characteristics of optimal

reminder systems, we found that, among

the reminder systems analyzed, the one

with the highest belt use rate had the

longest average single-cycle duration

and the highest maximum sound

frequency.

241

However, the agency

wishes to provide ample design latitude

with respect to the chime frequency. In

a 2007 agency-funded study on

enhanced seat belt reminder features,

the ‘‘slow chime’’ warning evaluated

had a 0.83 Hz frequency.

242

We are

proposing a minimum frequency of 0.5

Hz. The warning will be considered

active when the audible warning is

emitting a continuous sound or a sound

at a 0.5 Hz frequency or higher. We seek

comment on the proposed specification

for minimum chime frequency.

Another important characteristic for

an indefinite warning is the duty cycle.

The duty cycle is the ratio of the total

time when the audible warning is active

divided by the total warning cycle time.

A 1.0 or 100-percent duty cycle for a 30-

second warning cycle means that the

warning is active throughout the entire

30 seconds. In order for the duty cycle

specification to be meaningful, the

warning cycle time must be specified.

We are proposing that the warning cycle

be fixed at 30 seconds. Therefore,

because we are proposing that the

audio-visual warning continue until an

unfastened seat belt at an occupied seat

is buckled, the audible warning will be

composed of a continuous series of 30-

second warning cycles that continues

until the belt is buckled.

We have tentatively decided to

require a minimum duty cycle of 0.20 or

20 percent (i.e., 6 seconds for each 30-

second warning cycle). We have

tentatively selected this because we are

aware of research data that suggests that

a 20 percent duty cycle is effective but

are not aware of data that a lower duty

cycle would be sufficiently effective. In

2012, IIHS published a study examining

the effects of duty cycle and duration on

seat belt reminder effectiveness and

annoyance.

243

The study examined four

duty cycle conditions: 100, 50, and 20

percent, and a basic reminder (as ratios

1.0, 0.5 and 0.2). The warning cycles

were consecutive 30 intervals. In the

100 percent duty cycle condition, the

flashing icon and 1 Hz frequency chime

were present for the entire 30-second

reminder cycle. In the 50 percent duty

cycle condition, the flashing icon and 1

Hz frequency chime were present for the

first 15 seconds of the reminder cycle,

and a continuously illuminated icon

was present for the final 15 seconds. In

the 20 percent duty cycle condition, the

flashing icon and 1 Hz frequency chime

were present for the first 6 seconds of

the reminder cycle followed by a

continuously illuminated icon for the

remaining 24 seconds. In the basic

reminder system condition, the flashing

icon and chime were present for the first

6 seconds of the first reminder cycle

only, and then icon was continuously

illuminated for the remainder of the

warning. In terms of effectiveness, the

20 percent duty cycle reminder was

rated no less effective than the 100

percent duty cycle reminder.

The chime frequency and duty cycle

can also be adjusted to optimize the

warning. As chime frequencies and/or

duty cycle increase, effectiveness

generally (though not necessarily)

increases, and annoyance generally

increases. Given the proposed indefinite

warning duration for the front seats,

vehicle manufacturers would almost

certainly design warnings with duty

cycles of less than 100 percent in order

to address consumer acceptance issues.

For instance, the 2012 IIHS study found

that a decrease in the duty cycle could

reduce annoyance while not appreciably

reducing effectiveness. The enhanced

reminders, however, were not equally

annoying. Forty percent of participants

in the 1.0 duty cycle reminder condition

and 40 percent of participants in the 0.5

duty cycle reminder condition agreed or

strongly agreed that the reminder

distracted them while they were

driving. However, only 25 percent of

participants in the 0.2 duty cycle

reminder condition indicated the

reminder distracted them.

Manufacturers can also balance the duty

cycle against the chime frequency.

These proposed specifications differ

somewhat from Euro NCAP and ECE

R16. Rather than directly specifying a

duty cycle, Euro NCAP specifies that for

the front seats the audible signal must

not have gaps greater than 10 seconds,

and that gaps longer than 3 seconds

would not count toward the warning’s

total duration. ECE R16 also does not

count warning gaps longer than 3

seconds toward the required minimum

warning duration requirement. We are

not specifying a limit on the maximum

duration of audible gaps for the

purposes of determining the warning’s

total duration since we are not

proposing a minimum warning duration

requirement. The 10 second limit Euro

NCAP specifies, in addition to its

specification of a 3 second gap limit

toward the calculation of the warning’s

total duration, would not be sufficient to

ensure a 0.20 duty cycle warning (that

is supported by the IIHS research). For

instance, a system with a warning cycle

that is 11 seconds long and a 10 second

gap would result in a duty cycle of 0.09

which would likely not be as effective

as a system meeting our proposed

requirements.

We seek comment on our proposed

method of specifying the audible

warning duty cycle and the limits

proposed.

4. Visual Warning Characteristics

We are retaining the existing

requirements with respect to some

aspects of the visual warning and

modifying them in other respects.

We are retaining the current

requirements that the warning be

continuous or intermittent (flashing)

and must display either the identifying

symbol or the words (‘‘Fasten Belts’’ or

‘‘Fasten Seat belts’’) specified in table 2

of FMVSS No. 101. We have tentatively

decided not to specify minimum

requirements for the duty cycle or flash

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See DOT 2009 Seat Belt Study at 67–68.

245

Section 3.7.5.5.

246

DOT 2009 Seat Belt Study at 67–68.

247

Section 3.4.1.6.

248

Section 8.4.2.4.3 (warning can cease if vehicle

is not moving forward at least 10 km/h).

rates analogous to what we are

proposing for the audible warning; we

tentatively believe that manufacturers

will design the visual warning features

in conjunction with and in a way that

complements the audible warning

characteristics. We have decided to

retain the requirement for the symbols

or text specified in FMVSS No. 101

because these visual warning have been

in place for decades and we believe that

consumers are accustomed to them.

Removing the requirement may have

unintended negative effects if drivers

and front passengers are not accustomed

to new visual warnings or do not find

the new visual warnings as effective.

This means that if a manufacturer chose

to use a pictogram format for the rear

seat belt warning, it could include the

front seat belts in this pictogram, but it

would also have to provide the

warnings specified in FMVSS No. 101,

table 2. We believe manufactures are

already doing this. We seek comment on

all of these tentative decisions.

We are also proposing requirements

with respect to telltale visibility. We

propose requiring that if there is a

driver’s designated seating position, the

visual warning for the driver’s seat belt

must be visible from the driver’s seat

and the visual warning for the front

outboard passenger seat belt must be

visible from the driver’s seat and the

front outboard passenger seat. (For the

case where there is not a driver’s

designated seating position (which is

the case with an ADS-equipped vehicle

without any manual driving controls),

see Section XII.C.). We are proposing to

require that the visual warning be

visible to both the driver and any front

outboard passenger because NHTSA’s

study on front seat belt warning systems

suggests that visual warnings for front

outboard passenger seat belts are more

effective when they are visible to the

passenger as well as the driver.

244

Euro

NCAP similarly recommends that the

visual warning be visible to the front

passenger.

245

We believe it would be

practicable for manufacturers to comply

with this requirement; for example, the

warning could be located in the center

console display (which might be a

salient place to present visual displays,

both because of its location and because

it may allow larger size icons or text).

246

Some manufacturers already provide a

passenger seat belt warning in close

proximity to the passenger air bag status

indicator, which is visible to both the

driver and front passenger.

We have tentatively decided not to

specify more detailed criteria for the

location or visibility of the telltale as,

for example, are provided in S19.2.2 for

the passenger air bag telltale. A visual

warning for the driver’s seat belt has

been required since the early 1970s and

we are not aware of any issues with the

visibility of that telltale, so we

tentatively believe this is unnecessary.

5. Other Warning Signal Features and

Criteria

We have tentatively decided not to

specify requirements or criteria for other

aspects of the front outboard seat belt

warnings.

Warning activation criteria. Global

and Honda commented that NHTSA

should consider updates to the driver

seat belt reminder requirements to

include additional trigger thresholds

beyond the vehicle ignition switch

being moved to the ‘‘on’’ or ‘‘start’’

position. The commenters believed

advances in vehicle sensor technology

enable warnings to be provided for a

range of conditions, such as when the

vehicle speed reaches a certain limit, or

when the transmission is moved from

the park position. One commenter

suggested that the front and rear

warning requirements be consistent in

this respect.

Euro NCAP and ECE R16 specify

additional trigger requirements above

and beyond the ignition being engaged

and a seat belt not fastened for some

aspects of the front seat belt warnings.

Euro NCAP specifies trigger criteria

related to factors such as speed, distance

traveled, and time elapsed for the

change-of-status warning, the audible

warning at the start of a trip, and the

final (loud and clear) warning. ECE R16

specifies, for both the start of trip

warning and the change-of-status

warning, additional activation criteria

for the second-level warning related to

vehicle speed, distance traveled, and

time elapsed.

We have tentatively decided not to

specify trigger criteria other than the

criteria proposed above. The reasons for

doing so mirror the reasons given in the

analogous discussions in the rear seat

belt warning discussion. See Section

X.C.1.b (start-of-trip warning) and

Section X.C.2 (change-of-status

warning).

Warning duration criteria. Euro NCAP

and ECE R16 also specify additional

duration criteria other than a minimum

time and the seat belt becoming

fastened. Euro NCAP specifies, for the

audible warning duration (for both the

start-of-trip and change-of-status

warnings) criteria related to vehicle

speed, door/belt status, running time,

and distance traveled.

247

ECE R16

specifies, for the second-level audio-

visual warning duration for the front

seat belts an additional criterion related

to vehicle speed.

248

We have tentatively

decided not to include more complex

criteria. The reasons for this mirror the

reasons given for the rear seat belt

change-of-status warning duration in

Section X.C.2.

Warning circumvention,

acknowledgment and deactivation. We

have tentatively decided not to propose

features to harden the system against

circumvention (such as a sequential

logic system which would evaluate

whether the belt was fastened prior to

an occupant sitting in the seat or sensors

that can determine seat belts fastened

behind an occupant’s back) because

such features would increase the cost

and complexity of the systems. Neither

ECE R16 nor Euro NCAP require such

features.

We have also tentatively decided not

to allow features which would permit

the driver to acknowledge the warning

and cancel it prior to the required

duration or to deactivate the warning for

an entire trip or for a specified time

period (thus preventing it from

activating in the first place). ECE R16

allows both short-term and long-term

deactivation of the audible warning

(with a variety of restrictions, such as

that it be more difficult to effectuate a

short-term deactivation than to buckle

the belt). Euro NCAP does not provide

any specifications for deactivation or

acknowledgement of the warnings for

the front seats; it only allows

acknowledgement of warnings for rear

seats, except for change-of-status

warnings. We seek comment on this.

Should a final rule incorporate either or

both of these features? Would this

unacceptably impact the effectiveness of

the warning and essentially negate its

indefinite duration? Or could it

facilitate acceptance and thus either not

impact effectiveness or even have a

positive impact on effectiveness, to the

extent it might make it less likely that

the occupant habitually completely

circumvents the system? Or should

cancelation or deactivation be allowed

for the passenger seat belt audible

warning but not the driver seat belt

warning, in order to mitigate the

potential for false positives (due to cargo

on the seat that the occupant detection

system classifies as a person, etc.)? We

note that, since we are not proposing

hardening requirements, the proposal

would not preclude designs that do not

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The first option requires that if the key is in

the ‘‘on’’ or ‘‘start’’ position and the seat belt is not

in use, the vehicle must provide a visual warning

for at least 60 seconds, and an audible warning that

lasts 4 to 8 seconds. Under the second option, when

the key is turned to the ‘‘on’’ or ‘‘start’’ position,

the vehicle must provide a visual warning for 4 to

8 seconds (regardless of whether the driver seat belt

is fastened) and an audible warning lasting 4 to 8

seconds if the driver seat belt is not in use.

250

For anthropomorphic test devices, this would

include the 50th percentile male, 5th percentile

female, and the 6-year-old and 10-year-old child

dummies.

251

87 FR 18560 (Mar. 30, 2022).

252

An [ADS-Equipped] Dual-Mode Vehicle is

defined as ‘‘[a] type of ADS-equipped vehicle

designed for both driverless operation and

operation by a conventional driver for complete

trips.’’ SAE J3016_201806 Taxonomy and

activate a passenger seat belt warning if

the seat belt is fastened and no one is

in the seat. Thus, such nuisance

warnings due to cargo could be

prevented by buckling the seat belt or

simply placing the cargo somewhere

else.

Should the final rule allow for

permanent or short-term deactivation of

front seat audible warnings when the

vehicle is traveling below a certain

speed? This might allow for situations

such as someone needing to drive to a

mailbox on a road located on private

property or perhaps driving in a parking

lot. Below what speed could such a

deactivation be implemented without

potential loss of benefits? Would such

an allowance cause confusion and be

counterproductive to the goal of the

proposal?

XII. Other Issues

A. Automatic Belts

This proposal applies to automatic

belts. Automatic belts are belts that

secure without any action by the

occupant. The agency is not aware of

any currently produced vehicles that

would be affected by the proposed

requirements that have automatic belts.

We propose that a seating position with

an automatic belt would have to meet

the same seat belt warning requirements

that apply to manual belts. We are not

including provisions in the proposed

test procedures specific to automatic

seat belt systems because we believe the

seat belt use definitions provide

sufficient guidance. We seek comments

on this issue.

B. Test Procedures

This NPRM includes procedures for

how the agency would test the front

outboard passenger and rear seat belt

warning systems for compliance with

the proposed requirements.

We note that ECE R16 (in Annex 18)

sets out some limited test procedures.

With respect to the front passenger belt

warning, it sets out procedures for

testing the warning when the seat belt

is unbuckled at the onset of a trip and

procedures for testing the change-of-

status warning. For the rear seat belt

warning system, it has procedures for

testing the change-of-status warning. In

Europe and other countries around the

world, compliance with safety standards

is based on type approval. Type

approval is the confirmation that

production samples of a design will

meet specified performance standards.

For type approval, manufacturers

submit product specifications to

governmental authorities, which then

require third party approval testing,

certification, and a production

conformity assessment by an

independent body. Test procedures in

FMVSS, on the other hand, are more

extensive and detailed, because an

FMVSS must be objective, so that

manufacturers can self-certify that their

vehicles are in compliance.

The proposed test procedures in this

NPRM specify that NHTSA could test

any system under any combination of

seat occupancy or seat belt use status.

The test procedures also specify how

the agency would test a seat belt

warning system with a designated

seating position that is occupied.

In order to test a seat belt warning

system with a front seating position that

is occupied, the agency would use

either any anthropomorphic test device

specified in part 572 or a person

meeting or exceeding the proposed

weight and height criteria (at least 46.7

kg and 139.7 cm, respectively,

corresponding to the 5th percentile

adult female test dummy specified in

part 572). The human beings or test

dummies used would be seated, the seat

belt use and ignition conditions would

be applied, and the required signals

must operate (that is, either activate or

not activate) accordingly. For example,

if the agency placed the appropriate test

dummies in both front outboard seating

positions and fastened both outboard

seat belts so that the seat belts were in

use, the front seat belt warning system

would not be permitted to activate the

audible or visual signals under the

current first compliance option and

could only activate the visual signal

under the current second compliance

option.

249

The test could be conducted

with the seat and adjustable belt

anchorages in any position.

For rear warning systems that utilize

occupant detection (either negative-only

or full-status systems), the agency

would use either a person or any

anthropomorphic test device specified

in part 572 that meets the proposed

weight and height criteria (at least 21 kg

and 114 cm, respectively).

250

The

agency would perform the test with the

seat in any position, the seat back in the

manufacturer’s nominal design riding

position, and any adjustable anchorages

in any position.

We seek comment on all aspects of

the test procedures. We also seek

comment on whether the R16 Annex 18

test procedures affect how the

requirements in R16 should be

interpreted, and whether any deviations

between the proposed test procedures

and the Annex 18 test procedures are

undesirable. We also seek comment on

whether the proposed procedures are

sufficiently detailed and objective.

C. Considerations for Automated

Driving Systems

The ANPRM did not address

considerations related to automated

driving systems (ADSs).

Comments

A commenter recommended avoiding

any additional references to the ‘‘driver’’

in FMVSS No. 208 to avoid introducing

further barriers to the deployment of

automated driving systems.

Agency Response

NHTSA is actively addressing how

the FMVSS might be revised to take

vehicles with different types of ADSs

into account. On March 30, 2022,

NHTSA published a final rule updating

the occupant protection standards (200-

series FMVSS) to account for ADS-

equipped vehicles, particularly those

without driving controls.

251

The final

rule amended the 200-series FMVSS to

account for future vehicles that do not

have the traditional manual controls

associated with a human driver because

they are equipped with ADSs.

One aspect of this NPRM is a

requirement specifically tailored to an

ADS-equipped vehicle without a driver

DSP. For the amendment to the driver’s

seat belt warning, we are proposing that

the front passenger warning apply to

‘‘any’’ front outboard passenger. The

addition of the term ‘‘any’’ makes it

clear that, in some vehicles, there may

be more than one front outboard

passenger seating position. This would

be the situation of an ADS-equipped

vehicle that has no manually operated

driving controls. The agency views this

as a means for maintaining the same

level of occupant protection in ADS-

equipped vehicles that exists in

conventional vehicles, i.e., both will be

required to have seat belt warnings in

both outboard seating positions. We

note that in a dual mode vehicle,

252

the

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Definitions for Terms Related to Driving

Automation Systems for On-Road Motor Vehicles.

253

The discussion in this preamble focuses on

Euro NCAP and R16. NCAP programs in other

regions are largely similar to Euro NCAP or R16, so

our analysis of these requirements will adequately

cover the requirements of the NCAP programs in

other regions.

254

H.R. 3684 (117th Congress) (2021).

255

The ANPRM sought comment on this in the

context of various aspects of the rear seat belt

warning, and this is what the comments likely

concerned, but the discussion in the agency

response below also includes the front seats.

256

Some comments specifically identified version

R16–07. As noted earlier, the ECE has subsequently

revised that regulation. The current version is

Revision 10. We assume commenters favoring

harmonization intended that we harmonize with

the most current version of R16.

left front seat is still by definition a

driver’s seat, regardless of the

operational status of the vehicle, so a

provision to just have a warning for the

driver and right outboard passenger

would be sufficient to assure that all

front seat occupants receive a warning.

We are also proposing that if there are

multiple front outboard passenger seats

in an ADS-equipped vehicle without

manual driving controls, then both front

outboard seat belt warnings and change-

of-status warnings must be visible to

both front outboard passengers. The

rationale for this is as follows. Although

an ADS-equipped vehicle without

manually operated controls by

definition does not have a driver, it is

reasonable to assume that one of the

front outboard passengers may be

performing the management role for the

duration of a trip, such as might be the

case of a parent in a vehicle with

children under their care. In such a

situation, the manager of the trip may be

seated in either front outboard seat.

Thus, to be most beneficial, the visual

warning must be seen by an occupant

choosing to sit in either front outboard

seat. Additionally, if the agency

restricted the warning visibility to just

the right outboard passenger and not

‘‘any’’ outboard passenger, in an ADS-

equipped vehicle with no driving

controls and a lone vehicle occupant in

the left front seat, that occupant would

not receive a seat belt use warning.

The 2022 ADS final rule also

addressed situations where an ADS-

equipped vehicle without manual

driving controls has one or no outboard

seats in the front row (e.g., an ADS-

equipped vehicle with only two seats in

the front row, one or both of which

would be classified as inboard

passenger seating positions under 571.3)

and requires seat belt warnings for

certain inboard seats in such vehicles.

We are proposing that these front

inboard passenger seats have the same

seat belt warnings as front outboard

seats.

The agency acknowledges that the

proposal does not address the influence

of ADS-equipped vehicles on the

visibility of the rear seat belt warning.

As proposed, the rear seat belt warning

is only required to be visible from the

driver’s seat. As previously discussed,

there may be no driver’s DSP in an ADS-

equipped vehicle. Thus, no vehicle

occupant will be required to see the rear

seat belt warning. NHTSA

acknowledges the inadequacy of this

situation and we believe there are many

potential solutions. For example, it

could be required that for a vehicle

without manually operated driving

controls, any front seat occupant receive

the rear seat belt warning. Another

approach would be to require that in

such vehicles, all seating positions be

apprised of the seat belt use in all other

DSPs in the vehicle. The agency has

determined that it is not prepared to

propose a solution for the visibility of

rear seat belt warnings for ADS-

equipped vehicles and that it is beyond

the scope of this proposed rule. As we

stated in the March 30, 2022 final rule,

the agency plans future agency work

related to telltales and indicators for

ADS-equipped vehicles.

XIII. Regulatory Alternatives

NHTSA has considered alternatives to

the proposal. In the preceding sections

of this document, we have discussed

various alternatives for different aspects

of the proposed requirements. In this

section we address five major

alternatives that we considered: ECE

R16 and Euro NCAP; occupant detection

and enhanced warning signals for the

rear seat belt warning; non-regulatory

alternatives; requiring a warning for the

front center seat; and requiring an

audio-visual seat belt warning for the

front outboard seating positions with a

duration not less than 90 seconds. For

three of these alternatives (rear-seat

occupant detection, front center seat,

and 90-second front warning), we also

quantified the costs and benefits (see

Section XIV).

A. ECE R16 and Euro NCAP

The ANPRM sought comment on the

extent to which any requirements

should be based upon or differ from

other regulatory requirements (such as

ECE requirements) or consumer

information programs such as Euro

NCAP.

253

As discussed in more detail in

the regulatory analyses section below,

Executive Order 13609 provides that

International regulatory cooperation can

reduce, eliminate, or prevent

unnecessary differences in regulatory

requirements. Similarly, § 24211 of the

Infrastructure, Investment, and Jobs

Act

254

instructs DOT to harmonize the

FMVSS with global regulations to the

maximum extent practicable (for

example, to the extent that

harmonization would be consistent with

the Safety Act).

Comments

255

Several commenters recommended

harmonizing with R16.

256

Two

commenters stated that almost all

automakers have already developed

systems to conform to the R16

requirements, and that

disharmonization would increase costs

without any benefits. Two commenters

said that harmonization would

accelerate introduction of seat belt

reminders. A commenter said that R16

represents a ‘‘sweet spot’’ between

safety benefits, consumer acceptance,

harmonization, and compliance costs.

The commenter also said that the

benefits from harmonization can be

substantial, such as flexibility to

innovate, cost minimization, and

efficiency of global research,

development, and production processes;

a non-harmonized approach could also

necessitate system redesign for the

United States market.

Some commenters recommended

harmonizing with NCAP programs in

other regions, such as Euro NCAP. For

example, a commenter supported

harmonization with Euro NCAP;

another supported harmonization with

Euro NCAP (or, if not that, then with

R16), and a third commenter suggested

using other NCAP programs as a model

when empirical data is lacking. A

commenter recommended

harmonization with Euro NCAP and

IIHS’s assessment protocol.

A few commenters, while

acknowledging that harmonization is

generally desirable, commented that the

proposed rule should not harmonize at

the expense of safety/effectiveness.

Commenters said that the requirements

should be evidence-based.

Agency Response

In developing this proposal, our

intent was to harmonize with ECE R16

and Euro NCAP as much as possible but

deviate where we believed it was

justified with respect to the Safety Act

criteria (need for safety, objectivity,

practicability). The tentative reasons for

following or deviating in any of these

respects are explained in detail in the

relevant section of the preamble. In

general, we believe that although the

proposal deviates from R16 in some

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https://www.iihs.org/media/f15e5be9-ac62-

4ea6-a88d-7511105bfff5/H3hGKQ/Ratings/

Protocols/current/Seat%20Belt%20Reminder%

20Test%20Protocol.pdf.

ways, the two are not incompatible, so

that it is possible to design a rear

reminder system that complies with the

proposed requirements and is

compatible with R16.

On December 2021, IIHS released its

Seat Belt Reminder System Test and

Rating protocol.

257

It sets out general

requirements for the seat belt reminder

visual and audible signals for front

outboard and rear seating positions. It

does not put much emphasis on the

visual warning for front-outboard

seating positions other than specifying

that a visual signal needs to be

displayed in the instrument panel,

overhead panel, or center console,

indicating an unfastened belt. On the

other hand, for the audible warning

there are requirements for when it must

begin if the seat belt is unfastened at

ignition and for change-of-status, and

when it can cease (when the seat belt is

unfastened, vehicle is no longer in

motion, or seat is no longer occupied).

It also has sound pressure level and

frequency requirements for the audible

warning.

For the rear seats, it specifies that the

visual signal must activate within 10

seconds of the ignition being turned on,

that the signal must indicate whether

the seat belt at each rear seating position

is fastened or unfastened, and that it

must last at least 60 seconds. It does not

require a visual signal if the seat belts

at all occupied rear seats are fastened or

if no rear occupants are present. It

allows the visual signal to be cancelled

by the driver. For a seat belt change-of-

status in the rear seats when the vehicle

is in motion, it requires an audible and

visual signal that lasts at least 30

seconds. It further specifies that the

audible and visual signal can stop when

seat belts at the occupied rear seats are

fastened, the vehicle is no longer in

motion, or the seats are no longer

occupied.

For the front seats, under the IIHS

ratings protocol, the primary audible

reminder signal for the front outboard

seats must be at least 90 seconds in total

duration in order to obtain an

‘‘acceptable’’ or ‘‘good’’ rating.

Unlike Euro NCAP the IIHS rating

system provides ratings instead of

points (poor, marginal, acceptable,

good). For instance, if the front-

passenger seat has an audible signal that

lasts less than 8 seconds it would be

given a ‘‘Poor’’ rating. For a ‘‘Good’’

rating’’ both the driver and front-

passenger belt reminder must have an

audible signal that lasts at least 90

seconds and meet the rest of the belt

reminder system requirements

(essentially meet the requirements for

an ‘‘Acceptable’’ rating) and meet the

requirements set forth for the rear seat

belt reminder system. Accordingly, a

vehicle cannot receive a ‘‘Good’’ rating

without having a rear seat belt reminder

system, and a rear seat belt reminder

system is not required for all the other

ratings. It does not specify occupancy

criteria. We do not believe our

requirements impede meeting the

requirements of the IIHS protocol.

B. Occupant Detection and Enhanced

Warning Signals for the Rear Seat Belt

Warning

Rear seat warning systems that

employ occupant detection have

potential advantages over systems

without it. With occupant detection, a

warning system can provide more

informative warnings. The system can

determine whether any seats are

occupied by an unbelted occupant, as

opposed to simply notifying the driver

which belts, if any, are fastened. Such

systems are also better able to provide

enhanced warnings. Enhanced warnings

refer (for the purposes of this document)

to warnings that are relatively longer-

lasting or have an audible component.

Having an audible or longer-duration

visual warning activate for an

unoccupied seat could be a nuisance for

the driver and might either desensitize

the occupants to the warning signal or

lead them to circumvent or defeat the

system. Enhanced warnings therefore

generally need to work in conjunction

with an occupant detection system.

In the ANPRM we observed, however,

that occupant detection for the rear seats

may present technical or cost

challenges. Rear seats are used in ways

that can complicate occupant detection.

Rear seats may frequently be used to

transport cargo such as groceries, pets,

and other heavy objects that could be

mistaken for an occupant. In addition,

rear seats may be less well-defined than

front seats, which could impede

accurate detection. For example, it may

be technically challenging for an

occupant detection system to recognize

a large occupant spanning multiple

seating positions as a single occupant

rather than two occupants. This could

lead to false warnings, which can lead

occupants to disregard or attempt to

circumvent the system. Occupant

detection would also be more

expensive. While approximately 46.9%

of MY 2022 projected vehicle sales in

the United Sates have rear seat belt

warning systems, only about 7% are

equipped with occupant detection.

Occupant detection is optional but

not required by both ECE R16 and Euro

NCAP. Accordingly, neither Euro NCAP

nor ECE R16 require an audible warning

on vehicle start-up for the rear seats.

Euro NCAP specifies that, if there is no

occupant detection, only a 60-second

visual signal is needed for the rear

warning in order to earn bonus points,

and R16 requires a 60-second visual

signal. For systems with occupant

detection in all rear seats, Euro NCAP

specifies that the visual signal does not

need to indicate the number of seat belts

in use or not in use, but the signal must

remain as long as the seat belts remain

unfastened on any of the occupied rear

seats. Neither R16 nor Euro NCAP

require a visual signal if the system can

determine there are no occupants in the

rear.

The ANPRM sought comment on

whether NHTSA should propose rear

seat belt warning system requirements

that would necessitate occupant

detection or enhanced warning signals.

Comments

Many commenters recommended

requiring occupant detection in the rear

seats. Other commenters argued that

occupant detection would reduce false

signals, and some argued that occupant

detection was feasible and already

available in numerous vehicle models.

A commenter stated that NHTSA had

provided no literature review of

available systems and their capabilities,

and that NCAP programs throughout the

world had concluded that these systems

are feasible and important to advancing

safety. Two commenter said that some

of the technological challenges NHTSA

identified in the ANPRM have already

been addressed in systems developed

for the right front passenger seat. A

commenter also noted that various

NCAP programs award points for

occupant detection. Another commenter

said that the residual technical

challenges appear to be mostly

associated with accommodating certain

child restraint systems. The commenter

believed that occupant detection with

the option of temporary driver override

for the duration of an individual trip is

a reasonable approach that balances

notification with recognition that seats

may be occupied by objects other than

unrestrained human occupants.

Commenters also said that occupant

detection systems are cost-efficient,

with a number of systems costing less

than $10.

On the other hand, several

commenters opposed requiring

occupant detection. Commenters

suggested harmonizing with ECE R16,

which does not require occupant

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See Section X.C.1.a, Visual Warning at Start of

Trip with Three Compliance Options.

detection. Some commenters brought up

the technological and use challenges.

For example, a commenter stated that it

is difficult to distinguish actual rear

occupants from other rear objects

because consumers tend to use rear

seats in a wider variety of conditions

(e.g., child restraints, pets, groceries,

and various types of cargo); its

experience shows that occupant

detection in rear seats leads to false

alarms and reduced consumer

acceptance. Several commenters raised

concerns about cost. One commenter

believed that the cost of such systems

would not justify any additional

benefits. Another commenter believed

that there were insufficient data

available to demonstrate that occupant

detection would actually increase

system effectiveness because without

occupant detection the driver knows

how many occupants are in the vehicle.

On the other hand, a commenter said

that costs are not prohibitive; the

commenter also stated that rear seat

occupant detection systems are

available that can take into

consideration the specific challenges of

the rear seat compared to a front seat,

including robust sensors to help avoid

false positive warnings. At the same

time, commenters requested that any

requirements not prohibit innovation

and provide manufacturers with

flexibility. One commenter opposed

requiring occupant detection on buses

because such systems would be

complicated (e.g., the number of seats

and seating configurations, challenges

with LATCH). It also stated that it is

unaware of any occupant detection

systems currently available for buses, so

all rear passenger seats currently in use

will require significant development

efforts.

As noted earlier,

258

several

commenters favored requiring an audio-

visual warning at the start of the trip. A

commenter also supported requiring the

most effective warnings.

On the other hand, commenters

argued against requiring enhanced

warnings. A commenter recommended

requiring only a visual warning on start-

up to avoid false alarms and consumer

acceptance issues because occupant

detection is currently not affordable.

Another commenter also stated that

consumer acceptance of enhanced

warning systems in the United States is

not well understood. Commenters

recommended following R16 with

respect to enhanced warnings, because

it strikes an appropriate balance of

benefits, acceptance, harmonization,

and costs. Two commenters suggested

that NHTSA instead consider updating

NCAP to include enhanced warnings. A

commenter said that the reminder

system should use existing audio/visual

warning patterns because the driving

public likely would be able to

understand those more easily.

Agency Response

We have tentatively decided not to

require occupant detection in the rear

seats because we tentatively believe that

occupant detection continues to present

technical challenges. While it can

reduce false warnings for unoccupied

seats it can also result in false warnings,

due to the limitations of the sensors and

different use scenarios in the rear seats.

We acknowledge that most of the

components necessary to meet the

proposed minimum performance

requirements for a system with

occupant detection are readily available,

and that a small portion of the total U.S.

vehicle projected sales, based on the

MY2022 NCAP data, are equipped with

rear SBWS with occupant detection.

However, these potential issues

surrounding the implementation of

occupant detection could reduce the

effectiveness and/or acceptance of these

systems and thus we tentatively decided

against requiring occupant detection.

Occupant detection would be cost-

beneficial only if rear seat belt use

increased substantially more than we

estimate that it would for a warning

system without occupant detection. Our

teardown analysis indicates that

occupant detection components cost

$39.75 per vehicle, which, added to the

$19.59 per vehicle cost of the buckle

sensor, results in a combined warning

system cost of $59.33 per vehicle

(2020 $). We estimate that the total new

fleet cost of a rear seat belt warning

system with occupant detection would

be about $758 million (2020 $). As

explained in more detail in Section XIV,

Overview of Costs and Benefits, and in

the PRIA, in order for benefits and costs

to be equal for this regulatory option,

seat belt use for rear seat occupants 11

years and older would need to increase

by approximately 9.4 percent when

discounted at 3 percent and 11.6

percent when discounted at seven

percent. A 9 to 12 percent increase in

seat belt use is about 2 to 3 times greater

than that estimated for the proposed

SBWS requirement. While we would

expect some possible increase in seat

belt use from that specific functionality,

it is doubtful that it would double or

triple the increase in seat belt use

estimated for SBWS without occupant

detection. Therefore, we do not expect

this regulatory alternative to be cost-

effective or net beneficial.

This tentative decision is based on

current information on factors such as

the needed increase in seat belt use for

this regulatory alternative to have

positive net benefits. This proposal does

not preclude manufacturers from

choosing to use occupant detection and

includes compliance options that

involve the use of occupant detection.

This harmonizes with R16 and Euro

NCAP. Vehicle manufacturers may in

the future implement rear seat occupant

detection technology for other functions

(such as advanced occupant restraint

functions or warnings for unattended

children in the rear seating positions

after the vehicle motor is turned off),

which would relieve some of the cost

burden and facilitate the integration of

occupant detection technology for rear

seat belt warning systems. Because we

are not requiring occupant detection, we

are therefore also not requiring

enhanced warnings (such as an audible

warning on vehicle start-up) for the rear

seat belt reminder. The proposal,

however, gives manufacturers the

flexibility to innovate and optimize

warning signal characteristics, including

providing enhanced warnings. We seek

comment on these issues.

C. Non-Regulatory Alternatives

The ANPRM sought comment on

whether NHTSA should consider non-

regulatory approaches. It identified two

potential non-regulatory approaches:

awarding NCAP bonus points and

voluntary guidelines.

Comments

Some commenters supported

including rear seat belt reminders in

NCAP in addition to, but not in lieu of,

a regulatory requirement in order to

accelerate adoption of advanced

systems. Two commenters also believed

that inclusion in NCAP could encourage

adoption. One commenter was opposed

to voluntary guidelines. The commenter

said that inclusion of occupant

detection in NCAP would be the most

appropriate way to incentivize such

systems and familiarize industry with

their implementation.

Agency Response

In light of the MAP–21 mandate and

our tentative conclusion that the

proposed requirements would meet the

section 30111 criteria, we have decided

to issue this proposal, and not pursue

non-regulatory alternatives. However,

we would like to note that on March 9,

2022, NHTSA published an RFC notice

announcing its current and future plans

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259

87 FR 13452 (Mar. 9, 2022).

260

See Traffic Safety Facts 2013, NHTSA, DOT

HS 812 139 (2015), Tables 87–88. Only light truck

occupant injuries are reported. The number of

passenger car occupants injured was not reported

because it was less than 500.

261

Citing Li, R., Pickrell, T.M. (2019, February).

Occupant restraint use in 2017: Results from the

NOPUS controlled intersection study (Report No.

DOT HS 812 594). Washington, DC: National

Highway Traffic Safety Administration, at: https://

crashstats.nhtsa.dot.gov/Api/Public/

ViewPublication/812594.pdf.

262

Citing Aarian Marshall, A Third of Americans

Use Ride-Hail. Uber and Lyft Need More, Wired,

Jan. 8, 2019, https://www.wired.com/story/uber-lyft-

ride-hail-stats-pew-research/ (last accessed Nov. 26,

2019).

263

Citing Jessica Jermakian & Rebecca Weast,

Passenger use of and attitudes toward rear seat

belts. J. Safety Research 66, p. 113–119, Feb. 2018,

https://doi.org/10.1016/j.jsr.2017.12.006 (last

accessed Nov. 26, 2019); Kenneth Nemire, Seat belt

use by adult rear seat passengers in private

passenger, taxi, and rideshare vehicles, Proceedings

of the Human Factors and Ergonomics Society

Annual Meeting, Oct. 20, 2017, https://doi.org/

10.1177/1541931213601896 (last accessed Nov. 26,

2019).

264

Citing Rear Seat Belt Use: Little Change in

Four Years, Much More To Do, GHSA, (Nov., 2019),

https://www.ghsa.org/resources/RearBeltReport19.

for updating NCAP.

259

The RFC notice

included a section on seat belt

interlocks that requested comment on

whether NCAP should consider credit

for enhanced seat belt reminder systems

and whether NCAP should include a

seat belt interlock assessment and, if so,

what it would consist of (e.g., interlock

types, what seats would be covered,

etc.). The notice requested data on both

topics. Our preliminary review of the

comments about whether NCAP should

consider credit for enhanced seat belt

reminders found that the majority of

commenters were in support of such an

initiative. A commenter stated that,

rather than considering credit for

enhanced seat belt reminders, NHTSA

should regulate more persistent

reminders as allowed under MAP–21.

D. Requiring a Warning System for the

Front Center Seat

The agency also considered requiring

a seat belt warning system for the front

center seating position but is not

proposing doing so for a few reasons.

First, there is low occupancy for the

front center seat. According to 2013

FARS and GES data, only 0.4 percent of

the occupants of passenger cars and

light trucks with a GVWR of 10,000 lb

or less involved in fatal or injury-only

crashes were seated in the front center

seating position. This is due to the rarity

of front center seats in the modern

vehicle fleet, not because this position

is safer. More specifically, 62 occupants

of these vehicles seated in the front

center seat were killed. Of those

fatalities, 79 percent (49 occupants)

were unrestrained. In addition, there

were 8,000 occupants of these vehicles

that were injured while seated in the

front center seat. Of those front center

seat occupants injured, approximately

8.2 percent (656 occupants) were

unrestrained.

260

Next, a system for the front center seat

without occupant detection would

likely not be effective. Without

occupant detection, a belt reminder

system for the front center seat would be

limited to providing a positive-only

visual signal (for the reasons discussed

regarding the front and rear seats and

occupant detection). We believe that

such a signal would not be likely to

result in meaningful safety benefits for

the front center seat. Because it would

be only a visible and not an audible

warning, it would likely not provide the

occupant in the front center seat much

incentive to fasten the seat belt or

provide the driver an additional

incentive to request the front center

passenger to fasten the seat belt.

Finally, a system with occupant

detection would not be cost-effective or

net-beneficial. When discounted at three

and seven percent, the cost per ELS is

approximately $88.9 million and $110.0

million, respectively and the net

benefits are negative for this regulatory

alternative. Because the cost per ELS is

higher than the comprehensive cost of a

fatality and the net benefits are negative,

this regulatory alternative is not cost-

effective or net-beneficial.

E. Requiring a 90 Second Duration Seat

Belt Warning System for the Front

Outboard Seating Positions

As explained earlier (see Section

XI.C.1), NHTSA considered a range of

alternative warning durations for the

front outboard seat belt warning.

NHTSA quantified the costs and

benefits for one of these alternate

durations (90 seconds). NHTSA selected

the 90 second duration length as an

alternative because this is the most

common audible warning duration for

the front outboard seats, based on our

NCAP data. About 92.4 percent of the

new vehicle fleet is already equipped

with an audible seat belt warning with

a duration of 90 seconds or greater.

Therefore, a requirement for a minimum

of 90 second duration audible warning

would only affect 7.6 percent of the new

vehicle fleet. The benefit and cost

analysis was conducted in a similar

manner as that for the indefinite

duration seat belt warning described in

Section XIV. Our analysis found that a

requirement for a 90-second audible

warning would save 7 equivalent lives

with no change in the estimated cost.

These benefits are significantly lower

than those for the proposed warning

that remains on until the seat belt is

buckled.

We seek comment on these issues.

XIV. Overview of Benefits and Costs

In this section, we briefly present our

estimates of the benefits and costs of the

proposed rear and front seat belt

warning requirements, as well as three

of the major regulatory alternatives we

considered. For a more detailed

discussion, please refer to the

Preliminary Regulatory Impact Analysis

(PRIA) in the docket for this rulemaking.

NHTSA seeks comment on its

methodology, data sources, and

estimates.

A. Proposed Requirements

NHTSA quantified the benefits and

costs of the proposed requirements. In

this section we present a summary of

these estimates for the rear seat belt

warning system, front outboard seat belt

warning system, and then the combined

costs and benefits for both proposals.

1. Rear Seat Belt Warning System

The ANPRM sought comment on the

potential effectiveness, benefits, and

costs of a rear seat belt warning.

Comments

NHTSA received several comments

on the potential target population. For

example, a commenter said that

approximately 900 second row

unrestrained occupants are killed and

another 19,000 are injured each year,

and a portion of this target population

would likely have injuries mitigated or

eliminated through the use of rear seat

belt warning systems. Another

commenter brought up the increasing

number of rear seat passengers,

261

including the rise of rideshare

vehicles.

262

Two

263

commenters

264

also

stated that studies have found rear seat

passengers in rideshare or taxis (for hire

vehicles) are less likely to buckle up

than those in privately owned (not for

hire) vehicles, and one of the

commenters noted that children usually

sit in the back row, and they may

unfasten their seat belt out of boredom

during a trip. A commenter also said

that restraint non-use exceeds the

national average (47%) in the

population of occupants starting at age

8–12, and the unrestrained percentage

for younger occupants is 36% for 4–7

year olds and 22% for occupants less

than 4 years old.

Several commenters noted a relative

lack of data regarding the effectiveness

of rear seat belt warnings. A commenter

stated that the first vehicles with an

advanced rear seat belt reminder system

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M. Akamatsu, H. Hashimoto and S. Shimaoka,

‘‘Assessment Method of Effectiveness of Passenger

Seat Belt Warning,’’ in SAE International 2012–01–

0050, 2012. This study is discussed in the PRIA

(Section 2.3).

266

Citing Highway Loss Data Inst., Ins. Inst. for

Highway Safety, Unbelted: Adults Admit They

Often Skip Belts in Rear Seat, 52 Status Rep. 1, 3

(Aug. 3, 2017), available at https://www.iihs.org/

api/datastoredocument/status-report/pdf/52/5 (last

accessed Nov. 26, 2019).

267

See PRIA, Appendix D.

268

See PRIA, Table 29.

269

Motoyuki Akamatsu et al., Assessment

Method of Effectiveness of Passenger Seat Belt

Reminder. 2012–01–0050, SAE International (2012).

270

Survey of Principal Drivers of Vehicles with

a Rear Seat Belt Reminder System at 47.

only entered the Japanese and EU

markets in recent years, and there are

not yet any field data available on

effectiveness.

However, a few commenters did

provide rough effectiveness estimates.

One commenter estimated that it was

likely similar to front seat effectiveness

(3–4%). Two other commenters pointed

to a 2012 SAE paper that compared the

effect of various visual and audible

warnings on rear belt use based on a

series of experiments.

265

One of the

commenters said that its research has

found that seat belt warning systems

with persistent audible tones lasting at

least 90 seconds increase the seat belt

use of drivers who do not routinely use

a seat belt by 34%. The commenter also

referenced a Volvo survey of Volvo

owners in Sweden and Italy in 2005

showing that a rear belt warning system

had an effectiveness of approximately

50%.

Several commenters commented

generally that a rear belt reminder

would be effective while not providing

specific effectiveness estimates. A

commenter agreed with NHTSA that the

proportion of occupants who actively

seek to avoid restraint use is small

compared to the proportion of part-time

nonusers who would likely be amenable

to warnings. Another commenter

similarly stated that many consumers do

not prioritize rear belt use but rather

consider it unnecessary (for short trips

in particular), forget to buckle up, or

perceive no deterrent threat from traffic

enforcement, and enforcement of seat

belt laws is more challenging for the

back seat due to more difficult visibility.

A commenter said that there is

extensive evidence of the effectiveness

of front seat belt reminders and there is

no reason to believe that rear seat belt

reminder effectiveness would

significantly differ. Commenters noted

the NHTSA research on seat belt

warnings discussed in Section V,

showing a generally positive increase in

use rates. Commenters referred to an

IIHS survey showing that, of 1,172

respondents who had ridden in the back

seat during the preceding six months,

75% said they would be more likely to

wear the rear seat belt if someone in the

car reminded them, 62% would if there

was an audible belt reminder, and 50%

would if there was a visual belt

reminder.

266

With respect to costs, a commenter

said that seat belt reminder systems

require a relatively small investment,

and low-cost 2–D or digital cameras

(which are cheaper than seat sensors)

could be used to detect a rear seat

passenger. Two commenters said that

the cost will decrease further if rear seat

belt reminder systems are required in all

vehicles. A commenter said that for

passenger cars already equipped with

rear seat buckle monitoring (13% in US

for MY 2019; almost 100% of new

vehicle models in the EU market, legally

required in EU for new types from

September 2019 onwards), the

additional costs for the occupant

detection technology to cover the

second row seating positions are in the

low two-digit range. The commenter

also stated that among vehicles available

in the EU with advanced rear seat SBR

systems, a couple are vehicle models

that belong to the high-volume, cost-

sensitive vehicle segments (small/

compact cars), showing that the

additional costs for the rear seat

occupant detection are not prohibitive.

The commenter said that the occupant

detection sensors for a seat belt warning

system are available at lower costs than

occupant classification (e.g., for front air

bags) sensors.

Agency Response

Based on FARS and NASS–CDS data

from 2011 to 2015, on average 1,002

unrestrained rear seat occupants were

killed in crashes and 7,820 were

injured.

267

After adjusting these to

account for future decreases in fatalities

and injuries projected to occur in the

absence of the proposed requirements

due to the introduction of other

mandatory safety technologies (e.g.,

electronic stability control), there were,

on average, 475 fatalities and 7,036

injuries to unrestrained rear seat

occupants each year. This is the overall

target population—the annual deaths

and injuries that the proposed

requirements are aimed at reducing.

We estimated the benefits we expect

to result from the proposed rear seat belt

warning requirements. The benefits are

the fatalities and injuries that we

estimate would be prevented by the

proposed requirements. The benefits

depend, principally, on the

effectiveness of seat belts in preventing

deaths and injuries and the expected

increase in seat belt use due to the

proposed rear seat belt warning system

requirements. Seat belt effectiveness for

rear seat occupants is 55 percent for

passenger cars and 74 percent for light

trucks and vans.

268

NHTSA believes that the proposed

minimum required warning signal

characteristics would be effective at

informing the driver of the use status of

the rear seat belts and facilitating the

driver to request that a rear passenger

fasten an unfastened belt. A seat belt

warning system can increase rear seat

belt use in two ways: it can remind an

occupant to fasten their belt, and it can

inform the driver that a passenger is

unbuckled, so that the driver can

request the occupant to fasten their

belt.

269

Without a rear seat belt warning,

the driver must turn around to ascertain

whether a rear seat occupant is using a

seat belt (or ask the occupant); in some

vehicles, belt use may not be evident to

the driver, even if he or she turned

around, due to line-of-sight limitations.

As noted above, in NHTSA’s 2015

survey, 65% of drivers of vehicles

equipped with rear seat belt reminders

reported that the rear seat belt reminder

made it easier to encourage the rear seat

passengers to buckle up.

270

Also, as

noted earlier, part-time users—the

predominant nonuser group—are

amenable to seat belt warnings. In

addition, children, who might be

particularly compliant to driver

requests, are proportionally much more

likely to be rear seat passengers than are

adults.

271

We believe that any of the three

compliance options would be effective

at doing this. While some provide more

information than others, and some

would require the driver to fill in some

informational gaps, even the most basic

system (positive-only) would inform the

driver about which belts are fastened;

the driver would readily be able to

determine whether there were any

unbelted occupants. We also believe

that the 60-second visual warning

would be effective. NHTSA could have

proposed a more intrusive warning

signal, such as an audible warning and/

or a longer-duration visual warning.

However, because such warnings

necessitate occupant detection and we

have tentatively decided not to require

occupant detection, we have also

tentatively decided not to propose more

aggressive warnings.

NHTSA estimated the effectiveness of

the proposed rear seat belt warnings.

Available research regarding seat belt

use indicates that seat belt warning

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See PRIA, Table 33.

273

See PRIA, Table 33.

274

See PRIA, Table 47.

275

The Abbreviated Injury Scale (AIS) is a

classification system for assessing impact injury

severity developed and published by the

Association for the Advancement of Automotive

Medicine and is used for coding single injuries,

assessing multiple injuries, or for assessing

cumulative effects of more than one injury. MAIS

represents the maximum injury severity of an

occupant at an AIS level, i.e., the highest single AIS

for a person with one or more injuries. MAIS 1 &

2 injuries are considered minor injuries and MAIS

3–5 are considered serious injuries.

276

See PRIA, Table 72.

277

See PRIA, Table 79.

systems are effective at increasing seat

belt use; however, estimates of the

amount of increased belt usage that can

be attributed to warning systems vary.

In arriving at our estimates of increased

seat belt usage, we examined research

conducted by NHTSA and others, as

well as information submitted in

response to the request for comments.

For rear seat passengers eleven years old

and older, we used a ‘‘low’’ estimate of

3.4 percentage points, and a ‘‘high’’

estimate of 5.1 percentage points.

272

For

rear seat passengers from six to eleven

years old, we used a low estimate of

0.27 percentage points and a high

estimate of 0.41 percentage points.

273

(The estimated increases for younger

passengers are much lower because they

already have high rates of seat belt use).

For simplicity, we refer to these

scenarios as ‘‘Low’’ and ‘‘High,’’ or

‘‘3%’’ and ‘‘5%.’’

Based on these belt and warning

system effectiveness estimates, we

estimate that the proposed rear seat belt

warning requirements would prevent 22

fatalities and 75 injuries annually under

the ‘‘Low’’ scenario. Under the ‘‘High’’

scenario, we estimate that 34 fatalities

and 112 injuries would be prevented

annually.

274

See table 9. Another way to

measure benefits is by calculating

equivalent lives saved. Equivalent lives

saved are the number of prevented

fatalities added to the number of

prevented injuries, with the prevented

injuries expressed in terms of fatalities

(that is, with an injury expressed as a

fraction of a fatality, so that the more

serious the injury, the higher the

fraction). The estimated equivalent lives

saved are presented in table 10.

ABLE

9—E

STIMATED

NNUAL

ENEFITS

—L

IVES

AVED AND

NJURIES

REVENTED FOR

OSITIVE

-O

NLY

SBWS (R

EAR

EATS

), W

ITH

STIMATED

3 & 5 P

ERCENTAGE

OINT

NCREASE IN

ELT

Injury level 3% (low) 5% (high)

MAIS 1

275

................................................................................................................................................................ 23.2 34.3

MAIS 2 ..................................................................................................................................................................... 40.2 60.3

MAIS 3 ..................................................................................................................................................................... 5.6 8.4

MAIS 4 ..................................................................................................................................................................... 5.5 8.2

MAIS 5 ..................................................................................................................................................................... 0.2 0.3

Total Injuries ..................................................................................................................................................... 74.7 111.5

Fatal ......................................................................................................................................................................... 22.3 33.6

ABLE

10—E

STIMATED

NNUAL

ENEFITS

—E

QUIVALENT

IVES

AVED

—P

OSITIVE

-O

NLY

SBWS (R

EAR

EATS

)

276

Belt use increase

3% Discount

rate

7% Discount

rate

3% increase ............................................................................................................................................................. 21.9 17.7

5% increase ............................................................................................................................................................. 32.9 26.7

We also estimated the costs of the

proposed requirements. To comply with

the minimum proposed requirements

(the positive-only compliance option),

the system would need to have seat belt

buckle sensors (to determine if the belt

is fastened) and wiring and wire

conduits to provide information on the

belt buckle status from the rear seats to

the computer processor controlling the

warning system. Based on the results of

NHTSA’s teardown analysis, we

estimate a cost of $6.28 per seat. Given

an average of 3.12 rear seats per vehicle,

this yields a final cost of $19.59 per

vehicle. Based on this, the cost to the

fleet to comply with the proposed

minimum requirements (the positive-

only system) is $167.8 million (M).

Based on the forgoing, we performed

benefit-cost and cost-effectiveness

analyses. A benefit-cost analysis

calculates net benefits, which is the

difference between the benefits flowing

from injury and fatality reductions and

the cost of the rule. Our net benefit

estimates are presented in table 11. The

cost-effectiveness analysis derives the

cost per equivalent life saved, which is

equal to the total cost of the rule divided

by the total fatal equivalents that it

prevents. These estimates are presented

in table 12.

ABLE

11—N

ENEFITS

—P

OSITIVE

-O

NLY

SBWS (R

EAR

EATS

)

277

[2020 Dollars, in millions]

Seat position and belt use increase

3% Discount

rate

7% Discount

rate

3% increase ............................................................................................................................................................. $95.6 $46.2

5% increase ............................................................................................................................................................. 228.3 153.9

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278

See PRIA, Table 73.

279

National Center for Statistics and Analysis.

(2021, December). Seat belt use in 2021—Overall

results (Traffic Safety Facts Research Note. Report

No. DOT HS 813 241). National Highway Traffic

Safety Administration.

280

May Chu, ‘‘Statistical brief #62: Characteristics

of Persons Who Seldom or Never Wear Seat Belts

2002.’’ https://meps.ahrq.gov/data_files/

publications/st62/stat62.pdf.

281

Spado, D., Schaad, A., & Block, A. (2019,

December). 2016 motor vehicle occupant safety

survey; Volume 2: Seat belt report (Report No. DOT

HS 812 727). National Highway Traffic Safety

Administration.

282

Compared to the 2016 MVOSS, which had,

depending on the question, sample sizes of

approximately 5,000 to 10,000.

283

For example, the 2016 MVOSS found that

about 6% of drivers reported using their belt

sometimes (most of the time or some of the time.

See pg. 7 (Fig. 5) in the MVOSS.

284

‘‘The effects of persistent audible seat belt

reminders and a speed-limiting interlock on the seat

belt use of drivers who do not always use a seat

belt,’’ April 2019, David G. Kidd Insurance Institute

for Highway Safety, Jeremiah Singer Westat, Inc.

ABLE

12—C

OST

-E

FFECTIVENESS

NALYSIS

OST PER

QUIVALENT

IFE

AVED

)—P

ROPOSED

OSITIVE

-O

NLY

YSTEM

278

[2020 Dollars, in millions]

Seat position and belt use increase ELS Cost Cost/ELS

3% Discount Rate

3% increase ................................................................................................................................. 21.9 $166.4 $7.6

5% increase ................................................................................................................................. 32.9 166.4 5.0

7% Discount Rate

3% increase ................................................................................................................................. 17.7 $166.4 $9.4

5% increase ................................................................................................................................. 26.7 166.4 6.2

2. Front Seat Belt Warning System

Based on FARS and NASS–GES data

from 2011 to 2015, on average 7,503

unrestrained drivers and 1,453

unrestrained front outboard passengers

of passenger cars and light trucks were

killed annually in traffic crashes.

Additionally, 53,113 unrestrained

drivers and 10,324 unrestrained front

outboard passengers were, on average,

injured annually. After adjusting these

to account for future decreases in

fatalities and injuries projected to occur

in the absence of the proposed

requirements due to the introduction of

other mandatory safety technologies

(e.g., electronic stability control), there

were, on average, 6,733 fatalities and

47,952 injuries to unrestrained front seat

occupants each year. This is the overall

target population—the annual deaths

and injuries that the proposed

requirements are aimed at reducing.

According to the NOPUS, 90.6% of

the drivers used the seat belt in 2021,

which is slightly higher when compared

to passengers in the right-front seating

position with an observed belt use rate

of 89.4%.

279

In order to estimate the

percentage of drivers and front

passengers who do not always use a seat

belt, we used the results from a 2004

analysis using data from the Household

Component of the 2002 Medical

Expenditure Panel Survey (MEPS–

HC)

280

that found that among persons

16–64 years of age, 87.7 percent

reported always or nearly always using

seat belts when driving or riding in a

car. Another 6.9 percent reported

sometimes using seat belts, while 5.4

percent reported seldom or never using

seat belts when driving or riding in a

car. These results are summarized in

table 13. This means, when an

observation is made about the

percentage of drivers who use the seat

belts, the observed belt use rate is higher

than 87.7% since the other groups

would contribute to the observed belt

use rate although they are not always

using the seat belts. NHTSA recognizes

that driving habits may or may not have

changed since 2002 as seat belt use rates

have increased and as new generations

of drivers and passengers are on the

road. NHTSA considered, but

tentatively decided not to use, the

results of more recent studies, such as

the (2016) Motor Vehicle Occupant

Safety Survey

281

to estimate the

percentage of drivers and front

passengers who do not always use a seat

belt. While the 2016 MVOSS is more

recent, we decided to use the 2004

study because we tentatively concluded

that the data provided by the 2004 study

best suited the needs of our analysis.

Given that most data on seat belt use is

self-reported, the 2004 study has a high

sample size (approximately 25,000)

282

and provides robust categorizations of

seat belt use that fits the needs of our

analysis. Furthermore, when comparing

this data to the findings of the 2016

MVOSS, we did not find evidence that

these trends have significantly changed

over time.

283

NHTSA seeks comment on

instead using the results of more recent

studies, such as the 2016 MVOSS, or

other data sources commenters are able

to identify.

ABLE

13—S

EAT

ELT

HARACTERISTICS

Belt user and related items

Rate

(%)

A reported ‘‘sometimes using

seat belts’’ ......................... 6.9

A reported ‘‘seldom or never

using seat belts when driv-

ing or riding in a car’’ ........ 5.4

Percentage of drivers who

always use seat belts, cal-

culated ............................... 87.7

Total ............................... 100.0

As we did for the rear seats, NHTSA

estimated the effectiveness and benefits

associated with requiring a seat belt

warning system that remains activated

until the seat belts are buckled for the

driver and front outboard passenger

seats. In developing this estimate,

NHTSA used the results of a study

conducted by the Insurance Institute for

Highway Safety (IIHS) by Kidd et al.

(2019)

284

In the Kidd et al. (2019) study,

part-time belt users (who had a recent

seat belt citation and reported not

always using a seat belt) drove two

vehicles for a certain period of time, a

Chevrolet with three intermittent 7-

second audible warnings followed by

either a BMW with a 100-second

audible warning (n=17) or a Subaru

with an audible warning that continues

until the seat belt is buckled (n=16). (All

of the vehicles provided a visual

warning that lasted until the seat belt

was buckled.) Kidd et al. found that,

relative to the intermittent reminder

(i.e., 7-second audible reminder), the

BMW warning with the 100-second

audible reminder increased seat belt use

by 30% and the Subaru warning with

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285

There were several limitations in this study,

the main one being that the number of study

participants was small, and, consequently, there

was limited statistical power when comparing the

change in rate of belt use between the different

vehicle technology conditions. The study further

discusses this and other limitations, such as how

the demographics of the study sample differs from

part-time belt users nationwide.

286

See PRIA, Table 30.

287

See PRIA, Table 30.

the indefinite audible warning increased

belt use by 34%.

285

NHTSA estimates, based on the

NOPUS, Chu, and IIHS studies, that a

requirement for an indefinite duration

audible seat belt warning would

increase the overall observed seat belt

use rate by 2.8 percentage points for the

driver and 2.4 percentage points for the

front outboard passenger from current

observed seat belt use levels.

NHTSA also reviewed manufacturer

data for model year 2020 vehicles to

determine market penetration of

indefinite duration seat belt warning

systems in the front outboard seats and

that of a 90-second or greater duration

warning and obtained the estimates in

table 14.

ABLE

14—M

ARKET

ENETRATION OF

IFFERENT

URATION

EAT

ELT

UDIBLE

ARNING

YSTEMS

SBWS system

Percentage

of sales

<90 second warning ............. 7.6

90 second and 90+ but not

indefinite ............................ 85.2

Enhanced—Warning until

seat belt is buckled ........... 7.2

For front seat occupants, seat belts

reduce the risk of fatality by 44% (for

passenger cars) and 73% (for light

trucks and vans).

286

Seat belts reduce

the risk of moderate to greater severity

injuries by up to 50%.

287

Based on the estimated seat belt

warning system effectiveness in

increasing seat belt use, the market

penetration of different duration seat

belt audible warning systems, and the

effectiveness of seat belts in mitigating

fatalities and injuries, NHTSA estimates

that requiring an audio-visual seat belt

warning that remains activated until the

seat belt is buckled (indefinite duration)

would prevent 65 driver fatalities, 11

front outboard passenger fatalities, and

a total of 211 injuries annually, as

shown in table 15. This results in 92

equivalent lives saved (Table 16).

ABLE

15—E

STIMATED

NNUAL

ENEFITS

—L

IVES

AVED AND

NJURIES

REVENTED

—I

NDEFINITE

SBWS (F

RONT

UTBOARD

EATS

)

Injury level Driver

Front

passenger

Total

MAIS 1 ......................................................................................................................................... 20.7 3.7 24.4

MAIS 2 ......................................................................................................................................... 120.0 20.5 140.5

MAIS 3 ......................................................................................................................................... 21.6 3.9 25.5

MAIS 4 ......................................................................................................................................... 17.4 3.1 20.5

MAIS 5 ......................................................................................................................................... 0.5 0.1 0.6

Total Injuries ......................................................................................................................... 180.2 31.2 211.4

Fatal ............................................................................................................................................. 65.9 11.4 77.3

The estimated annual benefits in

terms of equivalent lives saved is shown

in Table 17.

ABLE

16—E

STIMATED

NNUAL

ENEFITS

—E

QUIVALENT

IVES

AVED

—I

NDEFINITE

SBWS

[Front Outboard Seats]

Undiscounted

3% Discount

rate

7% Discount

rate

Driver ........................................................................................................................................... 78.7 65.2 52.8

Front Passenger .......................................................................................................................... 13.6 11.3 9.2

Total ...................................................................................................................................... 92.3 76.5 62.0

We also estimated the costs of the

proposed requirements. Since all driver

seats are required to have at least the

basic warning system, the incremental

cost of enhanced seat belt warning for

the driver seat is zero. We assume there

would be some labor costs associated

with software updates needed to extend

the warning. However, as this is a

simple programming change, this cost

would be amortized over each vehicle’s

production and is therefore considered

de minimis. Though there are no

requirements for a seat belt warning

system for the front outboard passenger

seat, NHTSA estimates that 96 percent

of vehicles have seat belt warning

systems on the front outboard passenger

seat. NHTSA estimated the cost of

equipping a seat belt warning system in

the front outboard passenger seat to be

$2.13 per seat. Therefore, the cost of

equipping the remaining 4 percent of

the 16 million new vehicle fleet is $1.36

million (= 16 million × 4 percent ×

$2.13).

Based on the foregoing, we performed

benefit-cost and cost-effectiveness

analyses. The estimated net benefits are

presented in table 17 and the cost-

effectiveness estimates are presented in

Table 18.

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ABLE

17—A

NNUAL

ONETIZED

ENEFITS

, C

OSTS AND

ENEFITS

—I

NDEFINITE

SBWS (F

RONT

UTBOARD

EATS

)

[2020 dollars, in millions]

Driver Front passenger Driver and Front Passenger

Undiscounted 3% 7% Undiscounted 3% 7% % % %

Passenger Car Benefits .................................... $422.5 $353.0 $288.0 $79.9 $66.7 $54.4 $502.4 $419.7 $342.4

Light Truck & Van Benefits ............................... 520.4 427.6 344.8 83.4 68.5 55.2 603.8 496.1 400

Total Benefits ............................................. 942.9 780.5 632.8 163.3 135.2 109.7 1,106.2 915.8 742.5

Total Costs ................................................. 0 0 0 1.36 1.36 1.36 1.36 1.36 1.36

Net Benefits ....................................................... 942.9 780.5 632.8 161.9 133.9 108.3 1,104.8 914.4 741.1

ABLE

18—C

OST

-E

FFECTIVENESS

NALYSIS

OST PER

QUIVALENT

IFE

AVED

)—I

NDEFINITE

SBWS (F

RONT

UTBOARD

EATS

)

[2020 dollars, in millions]

Discount rate ELS Cost Cost/ELS

3% ................................................................................................................................................ 76.5 $1.36 $0.018

7% ................................................................................................................................................ 62.0 1.36 0.022

3. Overall Benefits and Costs of Proposal

In Table 19, we combine the benefits

and costs for the proposed rear and front

seat belt warning requirements. We

estimate positive net benefits under all

discount rates and effectiveness

estimates.

ABLE

19—N

ENEFITS

ROM THE

ROPOSAL

(SBWS

FOR

EAR

EATING

OSITIONS AND

NDEFINITE

SBWS

FOR

RONT

UTBOARD

EATING

OSITIONS

)

[2020 dollars, in millions]

3% Discount

rate

7% Discount

rate

Front Outboard Seats .............................................................................................................................................. $914.4 $741.1

Rear Seats (3% increase in rear seat belt use) ...................................................................................................... 95.6 46.2

Rear Seats (5% increase in rear seat belt use) ...................................................................................................... 228.3 153.9

Total Net Benefits (3% increase in rear belt use) ................................................................................................... 1,010.0 787.4

Total Net Benefits (5% increase in rear belt use) ................................................................................................... 1,142.7 895.0

In Table 20, we combine the

equivalent lives saved and cost for the

proposed rear and front seat belt

warning requirements to determine the

cost per equivalent life saved.

ABLE

20—C

OST PER

QUIVALENT

IVES

AVED

ROM THE

ROPOSAL

(SBWS

FOR

EAR

EATING

OSITIONS AND

NDEFINITE

SBWS

FOR

RONT

UTBOARD

EATING

OSITIONS

)

[2020 dollars, in millions]

Category %

3% Discount rate 7% Discount rate

Equivalent

lives saved

Cost

Cost per

equivalent

lives saved

Equivalent

lives saved

Cost

Cost per

equivalent

lives saved

Rear Seat Occupants ................ 3 21.9 $166.4 $7.61 17.7 $166.4 $9.38

5 32.9 5.05 26.7 6.23

Front Seat Occupants ................ 76.5 1.4 0.018 62.0 1.4 0.022

Total .................................... 3 98.4 167.8 1.71 79.7 167.8 2.11

5 109.4 1.53 88.7 1.89

B. Regulatory Alternatives

In the preceding sections of this

document, we discussed various

alternatives for different aspects of the

proposed requirements. In Section XIII,

Regulatory Alternatives, we identified

five major alternatives that we

considered. We quantified the costs and

benefits of three of these alternatives

(rear-seat occupant detection, a 90-

second front outboard seat belt warning,

and front center seat belt warning).

Below, we briefly summarize our

results. For a more detailed discussion,

the reader is referred to the Preliminary

Regulatory Impact Analysis in the

docket for this rulemaking.

1. Occupant Detection in Rear Seats

For the rear seat belt reminder,

NHTSA is proposing to specify three

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different compliance options. One of

these (the positive-only system) would

not necessitate occupant detection,

while the other two (the negative-only

and full-status) would necessitate

occupant detection. NHTSA estimated

the costs and benefits of requiring a

system with occupant detection.

NHTSA’s teardown analysis indicates

that occupant detection components

cost $39.75 per vehicle, which, added to

the $19.59 per vehicle cost of the buckle

sensor, results in a combined warning

system cost of $59.33 per vehicle (2020

$). NHTSA estimates that about 47

percent of new vehicles have a SBWS

for the rear seating positions and 7

percent of new vehicles have occupant

detection in rear seats. If NHTSA

selected the regulatory alternative where

occupant detection is required, this

would result in a total cost of $757.7M.

This cost estimate is based on the

assumption that 53 percent of new

vehicles would need to install a seat belt

sensor in the rear seats and 93 percent

would need to also install occupant

detection in the rear seats to comply

with the regulatory requirement.

Because there is uncertainty in how

much more effective a SBWS with

occupant detection would be in

increasing seat belt use compared to the

already estimated increase in seat belt

use with the proposed SBWS without

occupant detection, NHTSA did not

conduct a cost-effectiveness and net

benefits analysis. Instead, NHTSA

estimated the minimum increase in seat

belt use for this regulatory alternative

that would result in overall benefits

equal to the overall costs (zero net

benefits). The agency estimated that seat

belt use for rear seat occupants 11 years

and older would need to increase by

approximately 9.4 percent when

discounted at 3 percent and 11.6

percent when discounted at 7 percent

for this regulatory alternative to result in

zero net benefits. Therefore, increase in

seat belt use from this regulatory

alternative would need to be greater

than 9.4 percent at 3 percent discount

rate and greater than 11.6 percent at 7

percent discount rate for positive net

benefits. A 9 to 12 percent increase in

seat belt use is about 2 to 3 times greater

than that estimated for the proposed

SBWS requirement. The SBWS

considered under this regulatory

alternative are capable of letting the

driver know, for occupied rear seats,

either which occupants are not using

their seat belts or how many of the rear

seat occupants are not using their seat

belts. While we would expect some

possible increase in seat belt use from

that specific functionality, it is doubtful

that it would double or triple the

increase in seat belt use estimated for

SBWS without occupant detection.

Therefore, we do not expect this

regulatory alternative to be cost-effective

or net beneficial.

2. 90-Second Front Outboard Seat Belt

Warning

NHTSA also estimated the costs and

benefits if it were to require a 90-second

audio-visual warning for the front

outboard seats instead of the proposed

requirement for a warning that lasts

until the belt and any occupied seat is

buckled. NHTSA estimated the benefits

in a similar manner as that for the

proposed seat belt warning for front seat

occupants where the warning remains

on until the seat belt is buckled. One

difference is that, for the 90-second

duration alternative, we assumed that

the drivers and passengers who identify

as never using a seat belt would likely

not use the seat belt with a 90-second

duration warning. Another difference is

that this alternative only affects 7.6

percent of the vehicle fleet with front

seat occupant seat belt warning with

duration less than 90 seconds.

The benefits of this alternative are

presented in Table 21.

ABLE

21—I

NJURIES

REVENTED

, L

IVES

AVED

AND

QUIVALENT

IVES

AVED IN

RONT

UTBOARD

EATS BY A

90-

ECOND

URATION

SBWS

Injury level

Injuries and fatalities prevented Equivalent lives saved

Driver

Front

passenger

Driver

Front

passenger

MAIS 1 ............................................................................................................. 1.84 0.22 0.01 0.00

MAIS 2 ............................................................................................................. 9.85 1.18 0.46 0.05

MAIS 3 ............................................................................................................. 1.77 0.22 0.19 0.02

MAIS 4 ............................................................................................................. 1.43 0.18 0.38 0.05

MAIS 5 ............................................................................................................. 0.04 0.00 0.02 0.00

Fatal ................................................................................................................. 5.29 0.65 5.29 0.65

Total .......................................................................................................... ........................ ........................ 6.34 0.77

About 7 equivalent lives are saved by

this alternative, which is significantly

lower than the 86 equivalent lives saved

by a warning that remains on until the

seat belt is buckled. The cost of this

alternative is the same as that for the

proposed warning. The only cost is that

for the 4 percent of vehicles without a

seat belt warning system in the front

outboard passenger seat (cost = $1.36

million). The annual monetized

benefits, costs, and net benefits of this

alternative are shown in Table 22.

ABLE

22—A

NNUAL

ONETIZED

ENEFITS

, C

OSTS AND

ENEFITS FOR A

90-S

ECOND

URATION

SBWS

RONT

UTBOARD

EATS

288

[2020 dollars, in millions]

Vehicle type

Driver Front passenger Driver and front passenger

Undiscounted 3% 7% Undiscounted 3% 7% Undiscounted 3% 7%

PC .............................. $35.3 $29.5 $25.4 $4.7 $3.9 $3.2 $40.0 $33.4 $27.2

LTV ............................. 40.7 33.4 26.9 4.6 3.8 3.1 45.2 37.2 30.0

Total Benefits ...... 75.9 62.9 51.0 9.3 7.7 6.2 85.2 70.6 57.2

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See PRIA, Table 92.

ABLE

22—A

NNUAL

ONETIZED

ENEFITS

, C

OSTS AND

ENEFITS FOR A

90-S

ECOND

URATION

SBWS

RONT

UTBOARD

EATS

288

—Continued

[2020 dollars, in millions]

Vehicle type

Driver Front passenger Driver and front passenger

Undiscounted 3% 7% Undiscounted 3% 7% Undiscounted 3% 7%

Costs .......................... 0 0 0 1.36 1.36 1.36 1.36 1.36 1.36

Net Benefits ............... 75.9 62.9 51.0 7.9 6.3 4.9 83.8 69.2 55.9

While this regulatory alternative is

cost effective, the benefits are

significantly lower than that of the

proposed warning.

3. Seat Belt Warning for Front Center

Seat

The agency also considered requiring

a seat belt warning system for the front

center seating position. To estimate

incremental benefits, NHTSA used the

2011–2015 FARS data, the adjustment

factors to account for safety impacts of

new required safety technologies, and

the injury-to-fatality ratios by injury

severity to establish the target

population addressed by this regulatory

alterative (Table 23).

ABLE

23—A

NNUAL

DJUSTED

ATALITIES AND

-F

ATAL

NJURIES TO

RONT

ENTER

EAT

ASSENGERS

Vehicle type Injury severity Restrained Unrestrained Total

PC .................................................... MAIS 1 .......................................................................... 11 15 26

MAIS 2 .......................................................................... 5 7 11

MAIS 3 .......................................................................... 1 2 3

MAIS 4 .......................................................................... 1 1 2

MAIS 5 .......................................................................... 0 0 0

Total Injuries (MAIS 1–5) .............................................. 18 25 43

Fatal .............................................................................. 2 3 6

LTV ................................................... MAIS 1 .......................................................................... 23 112 135

MAIS 2 .......................................................................... 8 38 46

MAIS 3 .......................................................................... 0 0 0

MAIS 4 .......................................................................... 0 2 2

MAIS 5 .......................................................................... 0 0 0

Total Injuries (MAIS 1–5) .............................................. 31 152 183

Fatal .............................................................................. 5 23 28

Due to a lack of data, NHTSA is

unable to establish the seat belt use rate

for front center passengers under the

baseline. Also, due to this limitation,

the agency cannot estimate the increase

in seat belt use rates under this

regulatory alternative. Since front center

seat passengers are most similar to right

front seat passengers, NHTSA used the

effectiveness rates calculated for

indefinite duration seat belt warning

system for the front outboard passenger

seat to estimate incremental benefits as

shown in Table 24.

ABLE

24—I

NCREMENTAL

ENEFITS FOR

NDEFINITE

URATION

SBWS

RONT

ENTER

EATING

OSITION

Injury severity Observed injuries

Calculated

effectiveness of

indefinite duration

SBWS for front

outboard

passenger seats

(%)

Incremental

benefits

Passenger Cars

MAIS 1 ....................................................................................................................... 26 0.03 0.0078

MAIS 2 ....................................................................................................................... 11 0.41 0.0466

MAIS 3 ....................................................................................................................... 3 0.41 0.0129

MAIS 4 ....................................................................................................................... 2 0.41 0.0093

MAIS 5 ....................................................................................................................... 0 0.41 0.0002

Fatal ........................................................................................................................... 6 0.43 0.0241

LTVs

MAIS 1 ....................................................................................................................... 135 0.03 0.0405

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ABLE

24—I

NCREMENTAL

ENEFITS FOR

NDEFINITE

URATION

SBWS

RONT

ENTER

EATING

OSITION

—Continued

Injury severity Observed injuries

Calculated

effectiveness of

indefinite duration

SBWS for front

outboard

passenger seats

(%)

Incremental

benefits

MAIS 2 ....................................................................................................................... 46 0.41 0.1878

MAIS 3 ....................................................................................................................... 0 0.41 0.0012

MAIS 4 ....................................................................................................................... 2 0.41 0.0088

MAIS 5 ....................................................................................................................... 0 0.41 0.0006

Fatal ........................................................................................................................... 28 0.43 0.1203

The cost for front center passenger

seats would include the cost for a

buckle sensor and occupant detection.

Therefore, the cost per vehicle for this

regulatory alternative is $14.86 in 2020

dollars. This cost estimate reflects a cost

of $2.13 to add a buckle sensor and the

cost to add occupant detection for

$12.73.

In assessing the number of vehicles

that would be impacted by this

regulatory alternative, we consider that

the front center seat is not a common

feature in new light vehicles. Based on

our engineering judgement, we expect

that 800,000 vehicles or five percent of

the new vehicle fleet include a center

seating position. Table 25 presents the

total cost to meet the requirements

under this regulatory alternative for an

indefinite duration SBWS for front

center passenger seats.

ABLE

25—T

OTAL

OST OF

NDEFINITE

URATION

SBWS

FOR

RONT

ENTER

ASSENGER

EATS

Number of vehicles impacted

Per vehicle

cost

Total cost

800,000 .................................................................................................................................................................... $14.86 $11,888,000

Table 26 presents the of the cost-

effectiveness analysis and Table 27

presents the benefit-cost analysis for

this regulatory alternative. When

discounted at three and seven percent,

the cost per ELS is approximately $88.9

million and $110.0 million, respectively

and the net benefits are negative for this

regulatory alternative. Because the cost

per ELS is higher than the

comprehensive cost of a fatality and the

net benefits are negative, this regulatory

alternative is not cost-effective.

ABLE

26—C

OST

-E

FFECTIVENESS

NALYSIS FOR

SBWS F

RONT

ENTER

EAT

ASSENGERS

[Millions]