[Federal Register Volume 88, Number 172 (Thursday, September 7, 2023)]
[Proposed Rules]
[Pages 61674-61743]
[FR Doc No: 2023-18413]

Vol. 88

Thursday,

No. 172

September 7, 2023

Part II

Department of Transportation

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National Highway Traffic Safety Administration

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49 CFR Part 571

Federal Motor Vehicle Safety Standards; Occupant Crash Protection, Seat
Belt Reminder Systems; Proposed Rule

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

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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).

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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<PHONE_NUMBER> before coming.
     Fax:<PHONE_NUMBER>.
    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:<PHONE_NUMBER>.
    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:<PHONE_NUMBER>. For
legal issues, you may contact Mr. John Piazza, Office of Chief Counsel,
Telephone:<PHONE_NUMBER>; 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

    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.\1\ This was 2,652 more fatalities than in 2019 (when
there were 36,355 fatalities).\2\ In 2021, motor vehicle traffic
fatalities increased again to 42,939.\3\ The traffic fatality count in
2021 is the highest since 2005 (43,510) and represents the second year-
to-year increase since 2019.\4\ The 10-percent fatality increase from
2020 to 2021 is the highest year-to-year percentage increase since FARS
started data collection in 1975.\5\ NHTSA has preliminarily estimated
42,795 fatalities in 2022, representing a small decrease of about 0.3%
from 2021.\6\ 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.
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    \1\ 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.
    \2\ Id. at pg. 2.
    \3\ Id. at pg. 5.
    \4\ Id.
    \5\ Id. The 2021 fatality estimates are not entirely final, and
may change somewhat as NHTSA receives further updates or
corrections.
    \6\ 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.
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    Consistent with MAP-21 and the National Roadway Safety Strategy,
this NPRM proposes to require a seat belt use warning system \7\ 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.
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    \7\ 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).
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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%).\8\ 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).
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    \8\ 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.
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    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.\9\ 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.
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    \9\ 2016 MVOSS, p.7 (calculated from Fig. 5).
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    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.\10\
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    \10\ 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.
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    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,

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

(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.\11\ We
propose to require a seat belt warning for the front outboard passenger
seat.
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    \11\ 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.
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     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.\12\ For simplicity, NHTSA refers to
these scenarios as ``Low'' and ``High,'' or ``3%'' and ``5%.'' The
estimated annual benefits are presented in table 1.\13\
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    \12\ 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.
    \13\ 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.
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    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.

 Table 1--Estimated Annual Benefits--Potential Lives Saved and Injuries
  Prevented for Positive-Only SBWS (Rear Seats), With Estimated 3% & 5%
                          Increase in Belt Use
------------------------------------------------------------------------
              Injury level                   3% (Low)        5% (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
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Fatal...................................            22.3            33.6
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  Table 2--Estimated Annual Benefits--Equivalent Lives Saved--Positive-
                         Only SBWS (Rear Seats)
------------------------------------------------------------------------
                                            3% Discount     7% Discount
            Belt use increase                  rate            rate
------------------------------------------------------------------------
3% increase (Low).......................            21.9            17.7
5% increase (High)......................            32.9            26.7
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    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.

                             Table 3--Net Benefits--Proposed Positive-Only Rear SBWS
                                           [2020 Dollars, in millions]
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                                                                                Net benefits    Net benefits
    Seat position & belt use        Benefits 3%     Benefits 7%        Cost         3% discount     7% discount
            increase                 discount        discount                          rate            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
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   Table 4--Cost-Effectiveness Analysis (Cost per Equivalent Life Saved)--Proposed Positive-Only System (Rear
                                                     Seats)
                                           [2020 Dollars, in millions]
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    Seat position & belt use          ELS 3%          ELS 7%                        Cost/ELS 3%     Cost/ELS 7%
            increase                 discount        discount          Cost          discount        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.

Table 5--Estimated Annual Benefits--Lives Saved and Injuries Prevented--Indefinite Duration SBWS (Front Outboard
                                                     Seats)
----------------------------------------------------------------------------------------------------------------
                                                                                Front
                          Injury level                                Driver         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
----------------------------------------------------------------------------------------------------------------

       Table 6--Estimated Annual Benefits--Equivalent Lives Saved--Indefinite SBWS (Front Outboard Seats)
----------------------------------------------------------------------------------------------------------------
                                                                                3% Discount     7% Discount
                                                                   Undiscounted        rate            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.\14\ 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 x 0.04 x 16 million).
---------------------------------------------------------------------------

    \14\ 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.
---------------------------------------------------------------------------

    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.

                           Table 7--Annual Monetized Benefits, Costs and Net Benefits--Indefinite SBWS (Front Outboard Seats)
                                                               [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.

Table 8--Net Benefits From the Proposal (SBWS for Rear Seating Positions
        and Indefinite SBWS for Front Outboard Seating Positions)
                       [2020 Dollars, in millions]
------------------------------------------------------------------------
                                            3% Discount     7% Discount
                                               rate            rate
------------------------------------------------------------------------
Front Outboard Seats....................          $914.4          $741.1
Rear Seats (3% increase in rear seat                95.6            46.2
 belt use)..............................
Rear Seats (5% increase in rear seat               228.3           153.9
 belt use)..............................
                                         -------------------------------
    Total Net Benefits (3% increase in           1,010.0           787.4
     rear belt use).....................
    Total Net Benefits (5% increase in           1,142.7           895.0
     rear belt use).....................
------------------------------------------------------------------------

II. Background

    In 2020, there were 39,007 motor vehicle traffic fatalities in the
United States.\15\ This was 2,652 more fatalities than in 2019.\16\ In
2021, motor vehicle traffic fatalities increased again to 42,939.\17\
The traffic fatality count in 2021 is the highest since 2005 (43,510)
and represents the second year-to-year increase since 2019.\18\ The 10-
percent fatality increase from 2020 to 2021 is the highest year-to-year
percentage increase since FARS started data collection in 1975.\19\
NHTSA has preliminary estimated 42,795 fatalities in 2022, representing
a small decrease of about 0.3% from 2021.\20\ The Department of
Transportation has released a comprehensive National Roadway Safety
Strategy to address this rise in roadway fatalities and injuries.\21\
Part of that strategy is making vehicles safer.
---------------------------------------------------------------------------

    \15\ 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.
    \16\ Id. at pg. 2.
    \17\ Id. at pg. 5.
    \18\ Id.
    \19\ Id. The 2021 and 2022 fatality estimates are not entirely
final, and may change somewhat as NHTSA receives further updates or
corrections.
    \20\ 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.
    \21\ https://www.transportation.gov/sites/dot.gov/files/2022-02/USDOT-National-Roadway-Safety-Strategy.pdf.
---------------------------------------------------------------------------

    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.\22\
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.\23\ 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%.\24\ 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.
---------------------------------------------------------------------------

    \22\ 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''].
    \23\ 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''].
    \24\ See the Preliminary Regulatory Impact Analysis (PRIA) (in
the docket for this rulemaking) for these effectiveness estimates.
---------------------------------------------------------------------------

    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%).\25\ 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.\26\ See Figure 1.
---------------------------------------------------------------------------

    \25\ 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.
    \26\ Id.
    [GRAPHIC] [TIFF OMITTED] TP07SE23.000

    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.\27\ 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.\28\ Hard-core nonusers are those who ``generally do
not acknowledge the benefits of seat belts and are opposed to their
use.'' \29\ 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.\30\ 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.\31\
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.\32\ 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.\33\
---------------------------------------------------------------------------

    \27\ See, e.g., Transportation Research Board Study at 3.
    \28\ 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.
    \29\ Transportation Research Board Study at 40.
    \30\ 2016 MVOSS, p.7 (calculated from Fig. 5).
    \31\ Id. at p. 12 (calculated from Fig. 10).
    \32\ Id. at p. 13 (calculated from Fig. 11).
    \33\ 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 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.\34\ 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.
---------------------------------------------------------------------------

    \34\ 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.
---------------------------------------------------------------------------

    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.\35\ 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.\36\ 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.)
---------------------------------------------------------------------------

    \35\ 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.
    \36\ 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'').
---------------------------------------------------------------------------

    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.\37\ 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.
---------------------------------------------------------------------------

    \37\ See Section XI.C.1, Increasing the duration of the audio-
visual warning on vehicle start-up.
---------------------------------------------------------------------------

    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

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.\38\
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.
---------------------------------------------------------------------------

    \38\ 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.
---------------------------------------------------------------------------

    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.'' \39\ 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).'' \40\
Moreover, children are proportionally much more likely to be rear seat
passengers than adults,\41\ and the increased prevalence of ridesharing
services has likely increased the prevalence of rear-seat passengers.
---------------------------------------------------------------------------

    \39\ 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).
    \40\ 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).
    \41\ Trowbridge & Kent at 322.
---------------------------------------------------------------------------

    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.\42\
---------------------------------------------------------------------------

    \42\ 32 FR 2408, 2415 (Feb. 3, 1967).
---------------------------------------------------------------------------

    The standard currently requires a seat belt warning for the
driver's seat belt on passenger cars; \43\ 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); \44\ 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).\45\ The regulations do not require seat belt
warnings for any seating position other than the driver's seat.\46\
---------------------------------------------------------------------------

    \43\ S<IP_ADDRESS>(a)(3); S7.3.
    \44\ S4.2.6; S7.3.
    \45\ S4.2.6 (with the exception of some compliance options).
    \46\ 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.
---------------------------------------------------------------------------

    Manufacturers have two compliance options for the driver's
warning.\47\ 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.\48\
---------------------------------------------------------------------------

    \47\ 49 CFR 571.208, S7.3.
    \48\ 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.
---------------------------------------------------------------------------

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.\49\ A 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.\50\ 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.\51\ 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.
---------------------------------------------------------------------------

    \49\ ``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).
    \50\ 36 FR 4600 (May 10, 1971).
    \51\ 37 FR 3911 (Feb. 24, 1972).
---------------------------------------------------------------------------

    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.\52\ In response, NHTSA amended FMVSS No. 208 in 1974 to
require that only the driver seating

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.\53\ 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.
---------------------------------------------------------------------------

    \52\ 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.
    \53\ 39 FR 42692 (Dec. 6, 1974).
---------------------------------------------------------------------------

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.\54\ 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.\55\ 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.
---------------------------------------------------------------------------

    \54\ House Report 107-108, June 22, 2001.
    \55\ Transportation Research Board Study at 9.
---------------------------------------------------------------------------

    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.\56\ 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).\57\ (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.
---------------------------------------------------------------------------

    \56\ See Docket No. NHTSA-2002-13226.
    \57\ See Docket Nos. NHTSA-2001-9899, NHTSA-2002-13379, NHTSA-
2003-14742, NHTSA-2003-15006, and NHTSA-2003-15156.
---------------------------------------------------------------------------

    In 2005, Congress passed legislation--the Safe, Accountable,
Flexible, and Efficient Transportation Equity Act--a Legacy for Users
(SAFETEA-LU) \58\--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).
---------------------------------------------------------------------------

    \58\ Public Law 109-59, 10306 (2005).
---------------------------------------------------------------------------

    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.\59\ 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,\60\ NHTSA granted the petition.
---------------------------------------------------------------------------

    \59\ Docket No. NHTSA-2010-0061-0002.
    \60\ 84 FR 51076 (Sept. 27, 2019).
---------------------------------------------------------------------------

    On June 29, 2010, the agency published a Request for Comments
document (RFC) on the petition.\61\ The RFC discussed the agency's
research and findings regarding requiring rear seat belt warnings and
solicited comments.
---------------------------------------------------------------------------

    \61\ 75 FR 37343 (June 29, 2010) (Docket No. NHTSA-2010-0061).
---------------------------------------------------------------------------

    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,\62\ 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.
---------------------------------------------------------------------------

    \62\ 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.
---------------------------------------------------------------------------

    In 2012, Congress passed the Moving Ahead for Progress in the 21st
Century Act (MAP-21).\63\ 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.\64\
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.\65\ 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,\66\ to submit a
report to Congress describing the reasons for not prescribing such a
standard.
---------------------------------------------------------------------------

    \63\ Public Law 112-141 (2012).
    \64\ Id. at section 31202(a)(2) (repealing portion of 49 U.S.C.
30124).
    \65\ Id. at section 31503. Authority has been delegated to
NHTSA. 49 CFR 1.95.
    \66\ 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.
---------------------------------------------------------------------------

    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.\67\ (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

seat belt warning.\68\ The Court subsequently denied the petition
without prejudice to renewal in the event of significant additional
agency delay.\69\ 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.
---------------------------------------------------------------------------

    \67\ 78 FR 5865 (Jan. 28, 2013).
    \68\ In re Kids and Cars, Inc., No. 17-1229, Doc. 1702061 (D.C.
Cir. filed Oct. 30, 2017).
    \69\ In re Kids and Cars, Inc., No. 17-1229 (D.C. Cir. June 5,
2018).
---------------------------------------------------------------------------

IV. ECE Requirements and Euro NCAP

ECE Requirements

    The European Union has issued an updated version of Regulation No.
16 \70\ 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.\71\ 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.
---------------------------------------------------------------------------

    \70\ ECE Regulation No. 16, Revision 10.
    \71\ 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.
---------------------------------------------------------------------------

    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.\72\
---------------------------------------------------------------------------

    \72\ European New Car Assessment Programme Assessment Protocol--
Safety Assist, Version 9.1, November 2021.
---------------------------------------------------------------------------

    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.\73\ 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.
---------------------------------------------------------------------------

    \73\ 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.
---------------------------------------------------------------------------

    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 \74\ 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.
---------------------------------------------------------------------------

    \74\ Sction <IP_ADDRESS>.
---------------------------------------------------------------------------

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.\75\ 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.'' \76\ 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.
---------------------------------------------------------------------------

    \75\ See 68 FR 46262 (Aug. 5, 2003).
    \76\ 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).
---------------------------------------------------------------------------

    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.\77\ 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

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.\78\ The third report summarized
and extended the analyses from the previous two reports.\79\ 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.
---------------------------------------------------------------------------

    \77\ 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.
    \78\ 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].
    \79\ DOT 2009 Belt Warning Study, supra note 36.
---------------------------------------------------------------------------

    In 2015 the agency completed an additional report on a study of the
effectiveness and consumer acceptance of rear seat belt warnings.\80\
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.
---------------------------------------------------------------------------

    \80\ 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.
---------------------------------------------------------------------------

    In 2021, NHTSA published an update of the 2009 Belt Warning
Study.\81\ 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.''
---------------------------------------------------------------------------

    \81\ 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.
---------------------------------------------------------------------------

    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) \82\ and the National Automotive Sampling System (NASS)
Crashworthiness Data System (CDS) \83\ from 2011 to 2015. Because seat
belts are effective at preventing deaths and injuries in all types of
motor vehicle crashes,\84\ 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).
---------------------------------------------------------------------------

    \82\ 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.
    \83\ 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.
    \84\ 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.
---------------------------------------------------------------------------

    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.\85\ 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.
---------------------------------------------------------------------------

    \85\ See PRIA, Appendix D.
---------------------------------------------------------------------------

    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.\86\ 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.
---------------------------------------------------------------------------

    \86\ See PRIA, Appendix D.
---------------------------------------------------------------------------

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.\87\ The ANPRM sought

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.
---------------------------------------------------------------------------

    \87\ 84 FR 51076 (Sept. 27, 2019).
---------------------------------------------------------------------------

    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.\88\ ``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.'' \89\ ``Motor vehicle safety standard'' means a minimum
performance standard for motor vehicles or motor vehicle equipment.\90\
When prescribing such standards, the Secretary must consider all
relevant, available motor vehicle safety information.\91\ 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.\92\ The responsibility for
promulgation of Federal motor vehicle safety standards is delegated to
NHTSA.\93\ 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).
---------------------------------------------------------------------------

    \88\ 49 U.S.C. 30111(a).
    \89\ 49 U.S.C. 30102(a)(9).
    \90\ Section 30102(a)(10).
    \91\ Section 30111(b)(1).
    \92\ Section 30111(b)(3)-(4).
    \93\ See 49 CFR 1.95.
---------------------------------------------------------------------------

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.

     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 94
---------------------------------------------------------------------------

    \94\ 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.
---------------------------------------------------------------------------

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.\95\ We also
noted that school buses utilize compartmentalization to reduce the risk
of crash injury, even to the unbelted.
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    \95\ 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).
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    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.\96\
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    \96\ Sec.  <IP_ADDRESS>.

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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.\97\ 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.
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    \97\ 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. S<IP_ADDRESS>. 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.
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    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.\98\ A commenter stated that rear seat
belt warnings should not be required in motorcoaches; \99\ 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).
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    \98\ 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.
    \99\ We assume that this refers to traditional motorcoaches
which are over 10,000 lb.
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    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

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\
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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, S<IP_ADDRESS>. We propose to close this
loophole. See Section XI.B.
    \101\ S<IP_ADDRESS>.
    \102\ S<IP_ADDRESS>; S<IP_ADDRESS>.
    \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'').
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    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.
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    \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).
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    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.
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    \105\ More discussion of occupant detection systems is provided
in Section XIV.B.
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    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

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