61674 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

DEPARTMENT OF TRANSPORTATION 

National Highway Traffic Safety 

Administration 

49 CFR Part 571 

[Docket No. NHTSA–2023–0032] 

RIN 2127–AL37 

Federal Motor Vehicle Safety 

Standards; Occupant Crash 

Protection, Seat Belt Reminder 

Systems 

AGENCY: National Highway Traffic 

Safety Administration (NHTSA), 

Department of Transportation (DOT). 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: The Moving Ahead for 

Progress in the 21st Century Act of 2012 

(MAP–21) directs NHTSA to initiate a 

rulemaking proceeding to amend 

Federal Motor Vehicle Safety Standard 

(FMVSS) No. 208, ‘‘Occupant crash 

protection,’’ to require a seat belt use 

warning system for rear seats. Pursuant 

to this mandate and following on an 

earlier Advance Notice of Proposed 

Rulemaking, NHTSA is proposing to 

require a seat belt warning system for 

the rear seats of passenger cars, trucks, 

most buses, and multipurpose passenger 

vehicles with a gross vehicle weight 

rating of 4,536 kilograms (10,000 

pounds) or less. This document also 

proposes to enhance the existing front 

seat belt warning requirements, 

including requiring a seat belt warning 

for the front outboard passenger seat 

and increasing the duration of the 

warning. 

DATES: You should submit your 

comments early enough to be received 

not later than November 6, 2023. In 

compliance with the Paperwork 

Reduction Act, NHTSA is also seeking 

comment on a revision to an existing 

information collection. For additional 

information, see the Paperwork 

Reduction Act section under the 

Regulatory Notices and Analyses section 

below. All comments relating to the 

information collection requirements 

should be submitted to NHTSA and to 

the Office of Management and Budget 

(OMB) at the address listed in the 

ADDRESSES section on or before 

November 6, 2023. 

DATES: Proposed effective date: The first 

September 1 that is one year after the 

publication of the final rule for the front 

seat belt warning system requirements 

and the first September 1 that is two 

years after the publication of the final 

rule for the rear seat belt warning 

system requirements, with optional 

early compliance permitted. Multi-stage 

manufacturers and alterers would have 

an additional year to comply. 

ADDRESSES: You may submit comments 

electronically to the docket identified in 

the heading of this document by visiting 

the Federal eRulemaking Portal at 

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

online instructions for submitting 

comments. 

Alternatively, you can file comments 

using the following methods: 

• Mail: Docket Management Facility: 

U.S. Department of Transportation, 1200 

New Jersey Avenue SE, West Building 

Ground Floor, Room W12–140, 

Washington, DC 20590–0001. 

• Hand Delivery or Courier: West 

Building Ground Floor, Room W12–140, 

1200 New Jersey Avenue SE, between 9 

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

Friday, except Federal holidays. To be 

sure someone is there to help you, 

please call (202) 366–9826 before 

coming. 

• Fax: (202) 493–2251. 

Regardless of how you submit your 

comments, you should mention the 

docket number identified in the heading 

of this document. 

Comments on the proposed 

information collection requirements 

should be submitted to: Office of 

Management and Budget at 

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

To find this particular information 

collection, select ‘‘Currently under 

Review—Open for Public Comment’’ or 

use the search function. It is requested 

that comments sent to the OMB also be 

sent to the NHTSA rulemaking docket 

identified in the heading of this 

document. 

Instructions: All submissions must 

include the agency name and docket 

number or Regulatory Information 

Number (RIN) for this rulemaking. For 

detailed instructions on submitting 

comments and additional information 

on the rulemaking process, see the 

Public Participation heading of the 

Supplementary Information section of 

this document. Note that all comments 

received will be posted without change 

to https://www.regulations.gov, 

including any personal information 

provided. Please see the Privacy Act 

heading below. 

Docket: For access to the docket to 

read background documents or 

comments received, go to https://

www.regulations.gov. You may also 

access the docket at 1200 New Jersey 

Avenue SE, West Building, Room W12– 

140, Washington, DC 20590, between 9 

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

Friday, except Federal Holidays. 

Telephone: 202–366–9826. 

Confidential Business Information: If 

you claim that any of the information in 

your comment (including any additional 

documents or attachments) constitutes 

confidential business information 

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

or is protected from disclosure pursuant 

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

detailed instructions given under the 

Public Participation heading of the 

SUPPLEMENTARY INFORMATION section of 

this document. 

Privacy Act: Please see the Privacy 

Act heading under the Regulatory 

Analyses section of this document. 

FOR FURTHER INFORMATION CONTACT: For 

non-legal issues, you may contact Ms. 

Carla Rush, Office of Crashworthiness 

Standards, Telephone: (202) 366–4583; 

Email: carla.rush@dot.gov; Facsimile: 

(202) 493–2739. For legal issues, you 

may contact Mr. John Piazza, Office of 

Chief Counsel, Telephone: (202) 366– 

2992; Email: John.Piazza@dot.gov; 

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 MediumSized Buses 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61675 

1Stewart, 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. 

6See https://www.transportation.gov/briefingroom/nhtsa-estimates-2022-show-roadwayfatalities-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. 7Seat 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). 8Boyle, 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. 

9 2016 MVOSS, p.7 (calculated from Fig. 5). 

10This research is identified and discussed in 

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

Preliminary Regulatory Impact Analysis docketed 

with this NPRM. 

C. Amendments to the Current Warning 

Signal Requirements 

1. Increasing the Duration of the AudioVisual Warning on Vehicle Start-Up 

2. Requiring an Audio-Visual Change-ofStatus 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. 

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. 

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 nonfatal 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). 

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. Hardcore 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. 

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

Federal Motor Vehicle Safety 

Standard (FMVSS) No. 208, ‘‘Occupant 

crash protection,’’ requires a shortduration 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, 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61676 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

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 audiovisual 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 audiovisual 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 ‘‘fullstatus’’ 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 fullstatus 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 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61677 

11Based 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. 

12Children 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. 

13The Abbreviated Injury Scale (AIS) is a 

classification system for assessing impact injury 

severity developed and published by the 

Association for the Advancement of Automotive 

Medicine and is used for coding single injuries, 

assessing multiple injuries, or for assessing 

cumulative effects of more than one injury. MAIS 

represents the maximum injury severity of an 

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

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

2 injuries are considered minor injuries and MAIS 

3–5 are considered serious injuries. 

(which includes information provided 

by the vehicle manufacturer to the 

consumer, whether in digital or printed 

form) describe the warning system’s 

features, including the location and 

format of the visual warnings. We also 

propose that the owner’s manual 

include instructions on how to make 

any manual electrical connections for 

readily removable seats. 

2. Front Outboard Seat Belt Warning 

Requirements 

We propose several changes and 

enhancements to the seat belt warning 

requirements for the front outboard 

seats. There are three main changes we 

are proposing. 

• Audio-visual warning on vehicle 

start-up for front outboard passenger 

seat. Currently, only the driver’s seat is 

required to have a seat belt warning, 

although almost all vehicles now 

provide a seat belt warning for the front 

outboard passenger seat as well.11 We 

propose to require a seat belt warning 

for the front outboard passenger seat. 

• Increasing the duration of the 

audio-visual warning on vehicle startup. 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 standalone 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

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. 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61678 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

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 

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

TABLE 2—ESTIMATED ANNUAL BENEFITS—EQUIVALENT LIVES SAVED—POSITIVE-ONLY SBWS (REAR SEATS) 

Belt use increase 3% Discount 

rate 

7% Discount 

rate 

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

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

NHTSA also estimates the costs of the 

proposed requirements for rear seat belt 

warnings. NHTSA estimates that the 

minimum cost to comply with the rear 

seat belt warning requirements (the 

positive-only system) is $166.44 million 

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

of $19.59 for 53.1% of 16M affected new 

vehicles. 

Based on the forgoing, NHTSA 

performed benefit-cost and costeffectiveness 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] 

Seat position & belt use increase Benefits 

3% discount 

Benefits 

7% discount Cost 

Net benefits 

3% discount 

rate 

Net benefits 

7% discount 

rate 

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

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

TABLE 4—COST-EFFECTIVENESS ANALYSIS (COST PER EQUIVALENT LIFE SAVED)—PROPOSED POSITIVE-ONLY SYSTEM

(REAR SEATS) 

[2020 Dollars, in millions] 

Seat position & belt use increase ELS 

3% discount 

ELS 

7% discount Cost Cost/ELS 3% discount 

Cost/ELS 

7% discount 

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

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

NHTSA is also proposing enhancing 

the driver seat belt warning 

requirements by requiring an audiovisual 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) 

Injury level Driver Front 

passenger Total 

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

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

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


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61679 

14Based 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. 

TABLE 5—ESTIMATED ANNUAL BENEFITS—LIVES SAVED AND INJURIES PREVENTED—INDEFINITE DURATION SBWS 

(FRONT OUTBOARD SEATS)—Continued 

Injury level Driver Front 

passenger Total 

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

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

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

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

TABLE 6—ESTIMATED ANNUAL BENEFITS—EQUIVALENT LIVES SAVED—INDEFINITE SBWS (FRONT OUTBOARD SEATS) 

Undiscounted 3% Discount 

rate 

7% Discount 

rate 

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

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

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

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 × 0.04 × 16 million). 

The total monetized benefits, costs, 

and net benefits (total monetized 

benefits—total cost) of the enhanced 

seat belt warning system for the driver 

and front passenger is shown in table 7. 

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 

rate 

7% Discount 

rate 

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

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

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

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

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


ddrumheller on DSK120RN23PROD with PROPOSALS2
61680 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

15Stewart, 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. 

20See https://www.transportation.gov/briefingroom/nhtsa-estimates-2022-show-roadwayfatalities-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. 

21https://www.transportation.gov/sites/dot.gov/ 

files/2022-02/USDOT-National-Roadway-SafetyStrategy.pdf. 

22See, 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’’]. 

23Charles 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’’]. 

24See the Preliminary Regulatory Impact 

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

for these effectiveness estimates. 

25Boyle, 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. 

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. 

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. 

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. 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP07SE23.000</GPH>
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61681 

27See, e.g., Transportation Research Board Study 

at 3. 28See, 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. 

29Transportation 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. 

34NHTSA 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. 

35Akamatsu, 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. 

36See, 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’’). 

37See Section XI.C.1, Increasing the duration of 

the audio-visual warning on vehicle start-up. 

Consumer survey research by NHTSA 

and others (such as the Insurance 

Institute for Highway Safety and 

academic researchers) suggests that 

many unbelted occupants are likely 

amenable to using a seat belt. Seat belt 

nonusers can be categorized as either 

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

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. 

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.) 

Federal Motor Vehicle Safety 

Standard (FMVSS) No. 208, ‘‘Occupant 

crash protection,’’ requires a shortduration 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 audiovisual 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. 

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 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61682 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

38Through 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. 

39Transportation 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). 

40Matthew J. Trowbridge & Richard Kent, RearSeat 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). 

41Trowbridge & Kent at 322. 

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

43S4.1.5.1(a)(3); S7.3. 

44S4.2.6; S7.3. 

45S4.2.6 (with the exception of some compliance 

options). 

46See, 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. 

47 49 CFR 571.208, S7.3. 

48The 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. 

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). 

52These amendments were codified at 49 U.S.C. 

30124. As explained below, the provisions were 

amended in 2012 by the Moving Ahead for Progress 

in the 21st Century Act. 

from the agency’s New Car Assessment 

Program (NCAP) Purchasing with Safety 

in Mind: What to Look For When Buying 

a Vehicle program, about 46.9 percent 

are equipped with a rear seat belt 

warning system.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. 

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. 

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

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

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

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. 

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 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61683 

53 39 FR 42692 (Dec. 6, 1974). 54House Report 107–108, June 22, 2001. 55Transportation Research Board Study at 9. 56See Docket No. NHTSA–2002–13226. 57See Docket Nos. NHTSA–2001–9899, NHTSA– 

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

15006, and NHTSA–2003–15156. 

58Public Law 109–59, 10306 (2005). 

59 Docket No. NHTSA–2010–0061–0002. 

60 84 FR 51076 (Sept. 27, 2019). 

61 75 FR 37343 (June 29, 2010) (Docket No. 

NHTSA–2010–0061). 

62The 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. 

63Public 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. 

66Section 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. 

67 78 FR 5865 (Jan. 28, 2013). 

position be equipped with a seat belt 

warning system providing a visual and 

audible warning, with the audible 

warning not lasting longer than eight 

seconds.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. 

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. 

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. 

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). 

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. 

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. 

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. 

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. 

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 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61684 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

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). 

70ECE Regulation No. 16, Revision 10. 

71The 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. 

72European New Car Assessment Programme 

Assessment Protocol—Safety Assist, Version 9.1, 

November 2021. 

73For 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. 

74Sction 3.4.2.1. 

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

76U.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). 

77Mark Freedman et al. The Effectiveness of 

Enhanced Seat Belt Reminder Systems Draft Report: 

Observational Field Data Collection Methodology 

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

DC: National Highway Traffic Safety 

Administration. 

seat belt warning.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. 

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. 

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

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. 

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. 

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. 

In response to the 2005 SAFETEA–LU 

mandate, NHTSA undertook a multiphase 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 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61685 

78N. 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. 

80Paul Schroeder & Melanie Wilbur. 2015. 

Survey of Principal Drivers of Vehicles with a Rear 

Seat Belt Reminder System. Washington, DC: 

National Highway Traffic Safety Administration. 

81Polson, 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. 

82See 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. 

83The CDS target population is defined as policereported 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. 

85See PRIA, Appendix D. 

86See PRIA, Appendix D. 

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

systems. These included warning 

systems that had only the minimum 

features required by FMVSS No. 208, as 

well as twenty different enhanced 

warning systems. Because of the detail 

of the data gathered (e.g., occupant 

demographic and vehicle-specific 

information), the analysis was able to 

control for confounding factors. The 

second study uses an experimental or 

focus-group-based approach to study 

consumer acceptance as well as 

effectiveness.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. 

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. 

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.’’ 

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). 

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. 

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. 

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 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61686 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

88 49 U.S.C. 30111(a). 

89 49 U.S.C. 30102(a)(9). 

90Section 30102(a)(10). 

91Section 30111(b)(1). 

92Section 30111(b)(3)–(4). 

93See 49 CFR 1.95. 

comment on a variety of issues related 

to a requirement for a rear seat belt 

warning system, including potential 

requirements for such systems, the 

vehicles to which they should apply, 

their effectiveness, the likely consumer 

acceptance, and the associated costs and 

benefits. It also sought comment on 

removing the 8-second maximum 

duration for the driver’s seat belt 

warning specified in FMVSS No. 208 

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

statutory limitation that was the basis 

for this provision. 

The comment period closed on 

November 26, 2019. NHTSA received 45 

comments: five comments from vehicle 

manufacturers; two from school 

transportation associations; two from 

vehicle manufacturer associations; 

seven from safety advocacy groups; 

seven from automotive industry 

suppliers and trade associations; one 

comment each from a foreign country, 

insurance institute, consumer program, 

and bus manufacturer; and eighteen 

comments from individual members of 

the public. 

Most commenters, including safety 

advocates, vehicle manufacturers and 

suppliers, and individual members of 

the public, supported a rear seat belt 

warning requirement. Some commenters 

(including a bus manufacturer, a bus 

supplier, an association of school bus 

operators, and some individual 

commenters) recommended that the 

requirements not apply to heavy 

vehicles such as buses or school buses, 

citing concerns with installation, costs, 

the driver’s role, and maintenance. 

Vehicle manufacturers and suppliers 

commented that the requirements 

should harmonize with ECE R16, while 

some other commenters (predominantly 

safety advocacy groups) supported 

departures from the ECE R16 

requirements, arguing that 

harmonization should not come at the 

expense of safety. Thus, while most 

commenters supported requiring a 

visual warning on vehicle start-up and 

an audio-visual change-of-status 

warning for a belt that is unfastened 

when the vehicle is moving, some 

commenters favored requiring enhanced 

features such as an audio-visual 

warning on vehicle start-up and 

occupant detection. 

A few commenters (Advocates, Kids 

and Cars, Center for Auto Safety) 

pointed out the delays with this 

rulemaking and the urgency for a final 

rule. Most vehicle manufacturers 

supported removing the upper limit on 

the duration of the audible warning for 

the driver’s seat belt. 

VIII. NHTSA’s Statutory Authority 

NHTSA is proposing this’s NPRM 

pursuant to its authority under the 

National Traffic and Motor Vehicle 

Safety Act. 

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

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

the Secretary of Transportation is 

responsible for prescribing motor 

vehicle safety standards that are 

practicable, meet the need for motor 

vehicle safety, and are stated in 

objective terms.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). 

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 moreinformative 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. 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61687 

94Comments 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. 

95See 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). 

96 § 8.4.1.2. 

• Requirements related to electrical 

connections. Readily removable rear 

seats would be required to either 

automatically connect the electrical 

connections when the seat is put in 

place, or, if a manual connection is 

required, the connectors must be 

readily-accessible. Further, vehicles 

utilizing the negative-only compliance 

option would be required to provide a 

visual warning to the driver if a proper 

electrical connection has not been 

established for a readily removable rear 

seat. 

• Owner’s manual requirements. We 

propose that the vehicle owner’s manual 

(which includes information provided 

by the vehicle manufacturer to the 

consumer, whether in digital or printed 

form) describe the warning system’s 

features, including the location and 

format of the visual warnings. We also 

propose that the owner’s manual (which 

includes information provided by the 

vehicle manufacturer to the consumer, 

whether in digital or printed form) 

include instructions on how to make 

any manual electrical connections for 

readily removable seats. 

Front Outboard Seat Belt Warning 

Requirements 

We propose several changes and 

enhancements to the seat belt warning 

requirements for the front outboard 

seats: 

• Audio-visual warning on vehicle 

start-up for front outboard passenger 

seat. Currently, only the driver’s seat is 

required to have a seat belt warning, 

although almost all vehicles now 

provide a seat belt warning for the front 

outboard passenger seat as well. 

Accordingly, we propose to require a 

seat belt warning for the front outboard 

passenger seat. In addition, for an ADSequipped vehicle that has no manuallyoperated 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 startup. 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

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, perimeterseating, 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. 

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


ddrumheller on DSK120RN23PROD with PROPOSALS2
61688 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

97A Type 1 seat belt assembly is a lap belt for 

pelvic restraint, and a Type 2 seat belt assembly is 

a combination of pelvic and upper torso restraints 

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

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

are also required for most rear seats on buses 

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

required on most rear seats in trucks and MPVs less 

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

are not required on side-facing seats. 

98Blue 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. 

99We assume that this refers to traditional 

motorcoaches which are over 10,000 lb. 

Comments 

Advocates commented that the 

requirements should apply, at a 

minimum, to all passenger vehicles, and 

should apply in all vehicles in which 

data indicates belt non-use is occurring. 

Freedman Seating Company (a 

manufacturer of seating for the 

transportation industry) favored a 

requirement for all vehicles (and, 

presumably, seating positions) requiring 

Type 2 seat belts.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. 

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). 

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 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61689 

100Buses with GVWRs greater than 8,500 lb and 

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

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

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

loophole. See Section XI.B. 

101S4.2.7.1. 

102S4.4.3.3; S4.4.5.1. 

103See 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’’). 

104Fifteen-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). 

105More discussion of occupant detection 

systems is provided in Section XIV.B. 

would present the operator the issue of 

whether to continue operating the bus 

or not. 

Agency Response 

This proposal applies to all rear 

designated seating positions in 

passenger cars and all rear designated 

seating positions certified to a 

compliance option requiring a seat belt 

in trucks, buses, and MPVs with a 

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

except for school buses and law 

enforcement vehicles. We propose to 

apply the proposed requirements to 

these categories of vehicles because 

these vehicles are required to have seat 

belts at all rear designated seating 

positions and (except for some buses) a 

seat belt warning for the driver’s seat.100

We note that some types of trucks and 

MPVs (motor homes, walk-in van-type 

trucks, vehicles designed to be sold 

exclusively to the U.S. Postal Service, or 

vehicles between 8,500–10,000 lbs 

carrying a chassis-mount camper) 101

and over-the-road buses that are also 

prison buses 102 are not required to have 

rear seat belts. The proposed 

applicability is largely consistent with 

ECE R16, except that we are not 

proposing to exempt special-purpose 

vehicle types such as ambulances 

because they are typically customized 

after first sale.103

We believe it is particularly important 

to include vehicles with a GVWR greater 

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

or equal to 4,536 kg (10,000 lb)— 

including buses other than school 

buses—because this includes high 

occupancy vehicles (e.g., large capacity 

passenger vans and large sport utility 

vehicles [SUVs]).104 We also believe an 

increasing number of large trucks and 

vans are used as personal vehicles and 

are not solely used for work-related 

purposes. In addition, multiple rear 

seats or rows make it more difficult for 

the driver to ascertain rear seat belt use, 

so a warning could prove especially 

useful in these vehicles. We also 

recognize that the intent of the MAP–21 

mandate is to improve protection for 

rear occupants; given the proven 

benefits of seat belts, we tentatively 

believe the warning should be broadly 

applied. We acknowledge that vehicles 

with a larger number of rear seats may 

encounter visual signal complexities. 

Accordingly, our intent is to propose 

performance requirements that provide 

manufacturers with the flexibility to 

design a warning system that is 

appropriate for each vehicle type. We 

chose to limit the application of the 

passenger seating requirements to lightduty vehicles (less than or equal to 

10,000 lb). Several commenters were all 

in agreement with excluding vehicles 

over 10,000 lb; it is consistent with the 

petition and with the applicability of 

the current seat belt warning system 

requirements. 

We have tentatively decided to 

exclude all school buses (including 

those weighing under 10,000 lb [small 

school buses]) because of practicability 

issues. First, the agency is concerned 

about the costs to school systems, which 

could lead to reductions in school bus 

service, resulting in greater risk to 

students. Second, we are concerned 

about the burdens such systems might 

place on the driver. For example, with 

a rear seat belt warning system without 

occupant detection (the minimum 

compliance option that we are 

proposing in this NPRM), the school bus 

driver would have to verify that all the 

passengers are using their seat belts 

based on the system’s visual signal that 

identifies how many or which rear seat 

passengers are belted. We tentatively 

agree with the commenters who argued 

that is not practicable. This concern 

might be mitigated, in part, by a more 

robust system utilizing occupant 

detection, but we do not believe that 

would be practicable at this time.105

Third, school buses of all sizes offer 

passengers compartmentalization 

protection to reduce the risk of crash 

injury, even to the unbelted. Such 

protection is not offered in other 

vehicles. Finally, we note various other 

concerns raised by the commenters and 

summarized above, including the 

possibility of school buses being out of 

service due to malfunctioning reminder 

systems, and potential liability issues 

for school districts. 

Law enforcement vehicles would also 

be exempt from the proposed 

requirements because of concerns with 

practicability: the rear seats are mainly 

used to transport passengers that are 

under arrest and normally handcuffed, 

so if the policy of the police agency is 

that prisoners be transported with their 

seat belts fastened then the officer 

would be responsible for fastening the 

seat belt around the prisoner(s) and thus 

would already be aware of the belt 

status of the rear seat occupants. The 

term ‘‘law enforcement vehicle’’ is 

already defined in FMVSS No. 208 to 

mean ‘‘any vehicle manufactured 

primarily for use by the United States or 

by a State or local government for police 

or other law enforcement purposes.’’ 

We seek comment on our proposed 

applicability requirements. 

C. Requirements 

This NPRM proposes a visual warning 

on vehicle start-up and an audio-visual 

change-of-status warning if a belt is 

unbuckled during a trip. We also 

propose a variety of requirements with 

respect to the warning triggering 

conditions, duration, telltale, and 

electrical connections, among other 

things. 

1. Visual Warning on Vehicle Start-Up 

This NPRM proposes a visual warning 

to alert and inform the driver, upon 

vehicle start-up, to the status of the rear 

seat belts. We also propose minimum 

performance requirements for several 

aspects of this warning. 

a. Compliance Options for the Type of 

Information Conveyed 

The ANPRM sought comment on 

whether NHTSA should require a 

warning at the start of the trip, whether 

such a warning should be visual-only or 

audio-visual, and what type of 

information the visual warning should 

convey. NHTSA identified three 

potential types of warnings. One would 

require the system to indicate how 

many or which rear seat belts are in use 

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

would require the system to indicate, for 

the occupied rear seats, how many or 

which rear seat belts are not in use 

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

system to indicate, for the occupied rear 

seats, how many or which rear seat belts 

are in use and how many or which rear 

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

The second and third types of warnings 

identified would require that the system 

be capable of determining which rear 

seating positions are occupied (i.e., 

would require an occupant detection 

system). NHTSA also sought comment 

on whether some or all of the 

compliance options should require 

occupant detection. 

ECE R16 requires a visual warning at 

the start of a trip, but not an audible 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61690 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

106Section 8.4.4.1; Section 8.4.2.3.1. 107Section 8.4.2.3.1; § 8.4.2.3.2. 108Section 8.4.4.2. 109Section 8.4.4.2. 110Section 8.4.4.3. 111Section 3.4.3.1.4. 112Section 3.4.3.1.3. 113Section 3.4.3.1.1. 114Section 3.4.3.2.3. The thresholds are (at the 

choice of the OEM) either a forward speed of 25 

km/h or forward motion for 500 m. 115Section 3.4.3.2.3. For front seat belts, the 

assessment protocol requires both a visual and an 

audible warning signal (see Section 3.4.2). The 

visual signal must remain active until the seat belt 

is fastened. The audible signal has two stages, an 

initial and final audible signal, which have different 

onset criteria. The initial audible signal must not 

exceed 30 seconds and the final audible signal must 

be at least 90 seconds. To prevent unnecessary 

signals, the system must also be capable of 

detecting whether the front passenger seats are 

occupied. 

signal.106 The visual warning must 

remain active until none of the belts that 

triggered the warning are unfastened, 

the seat(s) which triggered the warning 

are no longer occupied, or 60 seconds 

has elapsed.107 The visual warning must 

‘‘indicate at least all rear seating 

positions to allow the driver to identify, 

while facing forward as seated on the 

driver seat, any seating position in 

which the safety-belt is unfastened.’’ 108

Occupant detection is not required, but 

in vehicles that do have occupant 

detection the warning does not need to 

indicate unfastened belts for 

unoccupied seating positions.109 This 

warning may be canceled by the 

driver.110

Euro NCAP’s rating protocol also 

requires a visual warning at the start of 

a trip. The requirements are similar to 

ECE R16. Euro NCAP’s rating protocol 

does not require occupant detection but 

incentivizes systems that use occupant 

detection by awarding additional points 

for this feature. For systems without 

occupant detection, the visual signal 

must show belts in use and not in 

use.111 For systems with occupant 

detection, the visual signal does not 

need to indicate the number of seat belts 

in use or not in use, but the signal must 

remain active as long as the seat belts 

remain unfastened on any of the 

occupied seats in the rear; 112 no visual 

signal is required if no rear occupants 

are detected.113 Systems with occupant 

detection must also provide a 30-second 

audible signal at the start of the trip 

before specified speed or distance 

thresholds have been crossed.114

Alternatively, if occupant detection is 

provided the manufacturer may use the 

same warning strategy as specified for 

the front seats.115

Comments 

Most commenters explicitly endorsed 

a warning on start-up, and none 

opposed it, although the comments 

differed on whether it should have an 

audible component. Two comments 

recommended harmonizing with the 

ECE R16 requirement for a visual-only 

warning on start-up. A commenter 

stated that NHTSA should provide 

flexibility in terms of the type of 

information that is required to be 

communicated by the reminder system, 

including positive-only, negative-only, 

and full-status systems, with 

consideration for both occupantdetection and non-occupant-detection 

centric approaches. Based on the 

definitions provided within the 

ANPRM, the baseline standard for R16 

could be met through a non-occupant 

detection, positive-only system, but 

would not prohibit additional 

technology features to provide 

additional functionality. Another 

commenter agreed that positive-only, 

negative-only, and full-status systems 

each could have strengths and 

limitations; the priority should be that 

all of these variations effectively allow 

the driver to identify which seats are 

unfastened (in the case without 

occupant detection), or if any occupied 

seats are unfastened (with occupant 

detection). The commenter noted that 

R16 does not establish such definitions 

of systems, but rather specifies the base 

requirement that the driver should be 

able to identify which seats are 

unfastened. The comment stated that 

NHTSA should not set criteria too 

broadly, which could restrict 

manufacturers to implementing a fullvehicle display, even if occupant 

detection is applied, in which case a 

single seat belt telltale indicator is 

sufficient. 

Three commenters recommended a 

visual-only warning. A commenter 

stated that a visual warning, such as a 

telltale, should exist as an initial 

warning, and a combination of audible 

and visual warnings could exist as a 

‘‘second-level’’ warning. Another 

commenter stated that visual displays 

are efficient at conveying information 

that is complex, that deals with 

locations in space, or that does not 

require immediate action. The comment 

stated that, while audio-visual warnings 

are more effective than visual-only 

warnings, visual displays are less 

intrusive and perceived as less annoying 

than audible warnings, so that a visualonly warning would minimize the 

impact of false warnings that could 

negatively impact consumer acceptance. 

The commenter also stated that, while 

visual displays alone have not been 

found to be effective for motivating 

occupants to use a seat belt, the driver 

may use this information to encourage 

unbuckled rear occupants to use a seat 

belt. 

Several commenters favored requiring 

an audio-visual warning at the start of 

the trip. Four commenters supported the 

specification of the most effective 

warnings and noted that audio-visual 

warnings are more effective than visible 

warnings alone. Two commenters stated 

that a visual-only warning would be 

easily missed by a driver who is focused 

on driving safely. 

Three commenters recommended 

requiring a ‘‘negative’’ warning with 

occupant detection. A commenter said 

that such systems would reduce false 

signals and annoyance. Another 

commenter similarly supported a 

warning on startup and commented that 

while a positive-only warning icon at 

the start of a ride would be helpful, it 

would not be as valuable as a warning 

triggered by negative-only status as a 

way to change the behavior of those 

occupants who are lax or reluctant to 

buckle up. 

Agency Response 

This rule proposes to require a visual 

warning (without an audible 

component) upon vehicle start-up. 

NHTSA decided to propose the three 

compliance options identified in the 

ANPRM for the type of information the 

warning must convey. Each proposed 

system has strengths and limitations. 

The positive-only system would be the 

least technically complex of the three 

proposed options. Since it would only 

need to detect whether a seat belt is in 

use, it would only require a seat belt 

latch sensor. With a positive-only 

system, the driver would need to 

determine how many rear seat 

occupants there are and then determine 

if that number equals the number of seat 

belts that are reported by the warning 

system as buckled. This compliance 

option would not necessitate occupant 

detection; we tentatively believe that 

there are still design and technological 

challenges associated with 

implementing occupant detection 

technology in rear seats (this is 

discussed in more detail in Section XIII, 

Regulatory Alternatives). 

The negative-only and full-status 

systems would provide the driver with 

more information, and thus might be 

more effective than the positive-only 

system for at least two reasons. First, 

they would directly inform the driver 

whether any rear seat occupants were 

unbuckled, without the driver having to 

compare the number or location of 

occupants and fastened belts. Second, as 

discussed in more detail below, warning 

systems equipped with occupant 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61691 

116Approximately 70% of Euro NCAP-tested 

vehicles had occupant detection in the rear seats. 

117Section 3.4.3.1.3. 

118See Euro NCAP section 3.4.3.1.4. 

detection are more amenable to audible 

warnings and enhanced warning 

features. However, we tentatively 

believe that systems such as these that 

provide a negative warning—that is, a 

warning for an unfastened belt—are 

only appropriate for systems utilizing 

occupant detection. This is because we 

tentatively believe that it is not 

appropriate to provide a warning for an 

unfastened seat belt at an unoccupied 

seat because such ‘‘false positives’’ 

could be a nuisance for the driver and 

might either desensitize the driver to the 

warning signal or lead them to 

circumvent or defeat the system— 

especially since the majority of trips do 

not have rear seat occupants. The 

proposal would therefore permit a 

warning for an unfastened belt only if 

the seating position were equipped with 

occupant detection. Accordingly, it 

would not, for example, permit a system 

without occupant detection that 

displayed the status of all the rear seat 

belts to be certified as a positive-only 

system coupled with a voluntary 

warning for unfastened seat belts. 

With respect to comments in favor of 

requiring audio-visual warnings, we 

agree that warnings with an audible 

component are generally more effective. 

However, requiring an audio-visual 

warning would necessitate requiring 

occupant detection because the 

resulting ‘‘false positives’’—having an 

audible warning activate for an 

unfastened belt at an unoccupied seat— 

would annoy the driver and could 

decrease the effectiveness of the 

warning. Thus, this NPRM does not 

require an audible warning on startup. 

However, manufacturers would be free 

to provide an audible warning on 

startup if they so choose, especially if 

the vehicle is equipped with occupant 

detection in the rear. This approach 

harmonizes with R16 and Euro NCAP. 

We acknowledge that there are 

systems currently deployed in both the 

United States and Europe that would 

not comply with the proposed 

compliance options. In particular, 

manufacturers appear to be deploying 

systems without occupant detection that 

provide a warning for an unfastened 

belt. When the ANPRM was published, 

the rear seat belt warning systems in 

vehicles sold in the United States used 

what would be classified in this 

proposal as a positive-only warning 

system. Our current, preliminary 

review, however, indicates that 

manufacturers are now providing visual 

warnings that indicate unfastened seat 

belts, and not necessarily with occupant 

detection. For example, the visual 

warning displays on some MY2022 

Honda and Porsche vehicles appear to 

indicate the status of all the rear seat 

belts, but the owner’s manual does not 

indicate that the vehicle is equipped 

with occupant detection in the rear 

seats. This information is consistent 

with Honda’s comment that the 

compliance options should allow the 

driver to identify which seats are 

unfastened (in the case without 

occupant detection). 

Similarly, it appears that, as suggested 

in the comments, European vehicle 

manufacturers are deploying systems 

that indicate seat belts that are fastened, 

seat belts that are not fastened, or the 

status of all rear seat belts, both with 

and—importantly—without occupant 

detection.116 For example, the MY 2021 

Peugeot 3008 appears to have a system 

that indicates the status of all the rear 

seat belts but does not indicate in its 

owner’s manual that it has occupant 

detection in the rear seats. Both ECE 

R16 and Euro NCAP appear to permit a 

broad range of systems, including those 

providing warnings for unfastened belts 

at unoccupied seats. R16 requires that 

the visual warning ‘‘indicate at least all 

rear seating positions to allow the driver 

to identify, while facing forward as 

seated on the driver seat, any seating 

position in which the safety-belt is 

unfastened.’’ Euro NCAP similarly 

requires systems without occupant 

detection to provide a visual warning 

showing both the belts in use and not 

in use. Nevertheless, we tentatively 

believe that the proposed deviation from 

R16 and some current United States and 

European systems is warranted because 

we tentatively believe it is not 

appropriate to provide a warning for an 

unfastened belt at an unoccupied seat. 

Although the three proposed 

compliance options are not identical to 

the R16 and Euro NCAP requirements, 

we believe that a system that complies 

with the proposed requirements could 

also comply with R16 and Euro NCAP. 

With respect to R16, each of the three 

proposed compliance options would 

‘‘allow the driver to identify, while 

facing forward as seated on the driver 

seat, any seating position in which the 

safety-belt is unfastened.’’ While the 

reference to an ‘‘unfastened’’ belt might 

be read to preclude a positive-only 

system—that is, it might be read to 

mean that the system must explicitly 

inform the driver of an unfastened belt, 

such as would be the case in the 

systems we are calling ‘‘negative-only’’ 

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

types of systems available in the 

European market we believe this is not 

the case. Similarly, the negative-only 

and full-status compliance options 

appear consistent with Euro NCAP 

because they would provide a warning 

for an unfastened seat belt at an 

occupied seat.117 However, the positiveonly compliance option does not appear 

to be consistent with Euro NCAP 

because Euro NCAP requires that 

systems without occupant detection 

show the rear seat belts in use and not 

in use, and the positive-only 

compliance option would not permit a 

visual signal for an unfastened seat 

belt.118

NHTSA seeks comment on all of these 

issues. While we have tentatively 

concluded that the proposed 

compliance options would help mitigate 

false warnings and the possibly 

attendant consumer acceptance issues, 

we are considering altering the 

proposed compliance options to 

accommodate systems that are currently 

being deployed, or that manufacturers 

may wish to deploy in the future. For 

example, we are considering allowing 

visual warnings that indicate which seat 

belts are unfastened without occupant 

detection. We therefore seek comment 

on what visual warnings vehicle 

manufacturers are using in the United 

States and Europe and whether they 

employ occupant detection. We also 

seek comment on why vehicle 

manufacturers have decided to use 

visual warnings that indicate unfastened 

seat belts without the use of occupant 

detection and whether they have 

received complaints from consumers 

about false warnings, or requests to 

deactivate the system. Is there any 

consumer acceptance data to support or 

oppose allowing visual warnings that 

indicate unfastened seat belts without 

the use of occupant detection in the rear 

seats? We also seek comment on 

whether there are any other aspects of 

the proposed compliance options with 

which current or anticipated future 

systems would not comply. Is there a 

preferable set of options that is 

sufficiently objective to satisfy the 

Safety Act? NHTSA also seeks comment 

on how manufacturers interpret the R16 

requirements, to the extent that the 

agency’s characterization of them is 

contrary to industry understanding or 

practice. NHTSA also seeks comment on 

whether the proposed regulatory text is 

sufficiently objective and unambiguous. 

b. Triggering Conditions 

In the ANPRM we indicated that 

requiring the warning at the beginning 

of each journey or trip the vehicle 

makes is intuitively appealing because it 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61692 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

119Section 8.4.2.3.1. 

120Section 3.4.1; Section 3.4.3.1.1. 

121Section 3.4.1. 

122Section 8.4.4.2 (R16; section 3.4.3.1.1 (Euro 

NCAP). 123See DOT 2009 Seat Belt Study at 65. 

would help assure that occupants are 

safely restrained prior to any potential 

vehicle crash. However, we sought 

comment on the possible advantages of 

delaying the warning to a time when the 

driver or occupants are less distracted 

and therefore might pay more attention 

to the warning. 

R16 requires that the visual warning 

activate when a belt is not fastened and 

the ignition or master control switch 

activated.119 Euro NCAP similarly 

requires that the warning start at the 

commencement of a journey when the 

ignition switch is engaged (whether or 

not the engine is running) and any of 

the rear belts are not fastened.120

However, Euro NCAP allows for short 

breaks in the journey (up to 30 seconds) 

to account for events such as engine 

stalling where the reminder is not 

required to start again.121 For both R16 

and Euro NCAP, for vehicles that have 

occupant detection in the rear seats, the 

visual warning does not need to indicate 

unfastened seat belts for unoccupied 

seating positions.122

Comments 

Many ANPRM commenters either 

specifically recommended harmonizing 

with R16 or recommended triggers that 

harmonized with R16. Three 

commenters specifically recommended 

harmonizing with R16. Many other 

commenters recommended that the 

trigger be based on the ignition switch. 

One commenter explained that this 

would provide flexibility for novel 

approaches for classifying vehicle 

motion. A few commenters stated that it 

was necessary for the warning to 

activate before the vehicle was in 

motion; for example, it was noted that 

vehicle crashes can happen quickly 

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

vehicle occupants should be buckled up 

anytime the vehicle is in motion. A 

commenter also stated that delaying the 

warning until the vehicle is in drive 

mode could leave drivers unable to 

ensure all passenger belts are fastened. 

Delaying the warning might warrant 

additional study, but if the study 

suggests changing the warning timing, it 

should do so for all vehicle occupants. 

A commenter stated that any triggering 

condition other than initiation at the 

beginning of a trip when the ignition 

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

position would necessitate occupant 

detection. 

However, a few commenters 

suggested alternative approaches. One 

commenter recommended against 

requiring a warning before a driver 

shifts a vehicle into drive because a 

transmission-less electric vehicle can 

quickly shift to drive. Requiring the 

warning before the vehicle is shifted to 

drive would potentially amount to a seat 

belt drive interlock and potentially 

delay shifting into drive. The 

commenter believed this is unnecessary, 

could result in driver frustrations that 

diminish acceptance, and lead to hasty 

detection that increases the potential for 

error. Another commenter stated that 

the warning would be most effective if 

it were triggered when the seat is 

occupied, the belt is unfastened, and the 

vehicle’s power is on. Yet another 

commenter stated that the triggering 

condition should be vehicle unlocking 

and for a period following relocking. 

Finally a commenter stated that the 

warning should be deactivated or 

disallowed if all occupants are properly 

buckled. 

Agency Response 

NHTSA proposes that the warning 

begin when the vehicle’s ignition switch 

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

This same condition appears in the 

existing driver seat belt warning 

requirements and is similar to ECE R16 

and Euro NCAP. We are not proposing 

to follow R16 and refer to a ‘‘master 

control switch’’ because we do not 

believe it is necessary to introduce this 

new term into FMVSS No. 208 for the 

proposed amendments to the standard. 

Also similar to those protocols, if the 

system has occupant detection, no 

warning is required for unoccupied 

seats under the full-status and negativeonly compliance options. As a 

commenter suggests, this would likely 

lead to more effective warnings because 

it mitigates false warnings and eases the 

burden on the driver to reconcile what 

the warning depicts with the actual 

status of the rear seat passengers. We 

believe basing the trigger on the ignition 

switch is preferable to delaying the 

warning until the vehicle is placed in 

gear because the proposed requirement 

would make it more likely that the 

occupants fasten their belts before the 

vehicle is in motion.123

With respect to the commenter on 

transmission-less electric vehicles 

quickly shifting to drive, the warning is 

triggered by the ignition, not the 

transmission gear position and would 

not impede the driver from shifting to 

drive. NHTSA also disagrees with the 

commenter that the system would be 

triggered by the vehicle being unlocked. 

This could require a warning before any 

occupants had entered the vehicle, and 

thus would likely not serve its purpose 

of warning the driver and occupants 

given the limited duration of the 

warning. Such a requirement would also 

not harmonize with the existing driver 

belt warning system and the ECE R16 

and Euro NCAP requirements. 

For the negative-only system, we 

propose to require a visual warning 

indicating which occupied seats have an 

unfastened seat belt for the required 

duration or until the belts at all 

occupied rear seating positions are in 

use. Therefore, like the R16 

requirement, if all occupied seats have 

fastened seat belts no visual warning 

would be required. 

c. Seat Occupancy Criteria and 

Interaction With Child Restraint 

Systems 

The negative-only and full-status 

compliance options would require the 

warning system to determine whether a 

seat position is occupied. Because the 

existing seat belt warning requirements 

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

the driver seat, they do not contemplate 

an occupant detection system (because 

driver seat occupancy could 

traditionally be assumed). 

There are three main detection 

scenarios an occupant detection system 

would be exposed to in the rear seats: 

adults, teenagers, and older children of 

various heights and weights; children 

seated in a child restraint system (CRS); 

and objects such as packages, pets, or 

unoccupied CRSs. This section will 

discuss how the occupant detection 

capability for negative-only and fullstatus systems should perform for these 

different scenarios and our proposed 

weight and height criteria for 

compliance testing of rear seat belt 

warning systems certified to either the 

negative-only or full-status compliance 

options. 

The ANPRM identified a need to 

objectively specify when a seat is 

occupied for the purposes of testing 

negative-only and full-status rear seat 

belt warning systems for compliance. 

The ANPRM requested comment on 

several options for seat occupancy 

criteria based on those specified in 

FMVSS No. 208 for compliance testing 

of low-risk deployment and suppression 

air bag systems in the presence of 

children or small-stature adults. These 

fall into three main categories. First, 

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

year-old child anthropomorphic test 

devices (test dummies) (weighing, 

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

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


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61693 

124FMVSS No. 208 S29.1(e). 

125Annex 18. 

126Section 3.4.1.3. 

127Safe Ride News also appeared to suggest that 

in conjunction or in the alternative, the system 

should be able to be deactivated or allow the driver 

to dismiss (acknowledge) the warning. NHTSA’s 

tentative conclusion to not adopt these approaches 

is explained in Section X.E, Resistance to 

intentional and inadvertent defeat and deactivation. 

specifies a 5th percentile female test 

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

it specifies height and weight 

requirements for a child used as an 

alternative for the 6-year-old child test 

dummy for compliance testing of 

advanced air bag systems utilizing static 

suppression (weighing between 46.5 lb 

and 56.5 lb [21 kg and 25.6 kg] and 

between 45 in and 49 in [114 cm and 

124.5 cm] tall).124

ECE R16 specifies three alternative 

methods for testing rear seats with 

occupant detection: placing a load of 40 

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

or human representing a 5th percentile 

adult female (the HIII–5F specified in 49 

CFR part 572, as adjusted for the ECE 

test); or an alternative method specified 

by the vehicle manufacturer.125 Euro 

NCAP defines occupancy as the use by 

an occupant larger, taller, or heavier 

than a 5th percentile female.126

The ANPRM also sought comment on 

whether a rear seat belt warning would 

reliably detect a child restraint system 

attached by a child restraint anchorage 

system, or LATCH. The intent of this 

question was to determine whether a 

seat belt warning system might register 

a false alarm for a LATCH-installed 

CRS. Neither R16 nor Euro NCAP have 

requirements with respect to the 

system’s interaction with LATCHinstalled CRSs. 

Comments 

We received a number of comments 

related to seat occupancy criteria and 

the detection capabilities the system 

should have. 

With respect to seat occupancy 

criteria, several commenters supported 

harmonizing with ECE R16 and/or 

basing the criteria on a 5th female 

dummy (88 lb–105 lb). Several 

commenters suggested harmonizing 

with the ECE R16 criteria. A commenter 

stated that the occupant size that the 

system is required to detect should not 

be less than the occupant size that 

would use the seat belt as the only 

restraint. Another commenter stated that 

for children seated in booster seats or 

high-back boosters (with belt 

positioning guides), the CRS often 

directly utilizes the belt provided in the 

vehicle. In these cases, a rear belt 

reminder system may be useful for 

reminding the driver to ensure the child 

seated in that seating position is either 

restrained or providing an alert that the 

restraint status has changed during a 

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

commenter recommended specifying 

the 5th percent female detection criteria 

for several reasons: starting with the 5th 

female would cover a large share of the 

target population; belt usage is high for 

children as long as they are in a CRS (so 

a warning system appears less needed); 

the 5th percent female includes a large 

share of the teenage population; it 

would harmonize with FMVSS No. 208 

and international NCAP programs; and 

it would result in more robust systems 

with respect to false positives. 

On the other hand, various 

commenters recommended that the 

occupancy criteria be based on children 

that might reasonably be expected to use 

seat belts. Two commenters suggested 

that the occupancy criteria be based on 

the smallest weight of a child that can 

reasonably be expected to be restrained 

by a seat belt rather than a CRS. One of 

the commenters stated that a weight of 

20 lb (9 kg) is consistent with all state 

laws for CRS use. Another commenter 

stated that the criteria should reflect a 

minimum weight equal to that of a 

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

However, as noted below, commenters 

believed that using weight alone was 

not enough. A commenter did not agree 

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

instead suggested the HIII 3-year-old 

dummy (36 pounds, or 16 kg) as the 

minimum weight threshold, stating that 

this dummy’s weight roughly represents 

the 95th percentile 2-year-old and the 

5th percentile 5-year-old. The 

commenter stated a 6-year-old was not 

appropriate as nearly 60% of 4- and 5- 

year-old children do not ride in a CRS 

with a harness, so many of the most 

vulnerable seat belt users (very young 

children using the belt alone or in 

conjunction with a booster) would fail 

to trigger the alarm if unbuckled. A 

commenter stated that the specifications 

should represent the occupant 

population at risk from non-use of rear 

seat belts, and stated that NHTSA’s 2017 

passenger vehicle fatality data indicates 

that restraint non-use exceeds the 

national average (47%) in the 

population of occupants starting at age 

8–12; the unrestrained percentage for 

younger occupants is 36% for 4–7-yearolds and 22% for occupants less than 4 

years old. A commenter suggested that 

the criteria should register children that 

would presumably be placed in a child 

restraint system (i.e., children as young 

as 4 years old). Another commenter 

recommended that NHTSA’s testing 

reflect the full range of body types as 

well as child restraint systems that 

could be present in rear seats. 

We also received a variety of 

comments about the detection 

capabilities the system should have. 

Several commenters argued that the 

system should be required to detect 

CRSs. Three commenters supported 

requiring LATCH detection. Two of 

those commenters stated that the 

reminder system should be able to 

recognize when a car safety seat is 

installed with LATCH instead of the 

seat belt and should not activate under 

those conditions in order to avoid 

nuisance (false) warnings. A commenter 

said that when a CRS is installed using 

the lower anchors of the LATCH system, 

the seat belt is typically not in use, so 

a non-discerning sensor would conclude 

that an unbuckled occupant is present 

(because a CRS is heavy enough to be 

classified as an occupant by an 

occupant detection system).127 A 

commenter recommended that the 

occupant detection system provide a 

warning if the CRS is improperly 

latched. 

On the other hand, several 

commenters believed that the system 

should not be required to detect a CRS. 

Three commenters stated that the 

system should not be required to detect 

a CRS, with two of the commenters 

noting variation in CRS designs and the 

fact that neither ECE R16 nor Euro 

NCAP require CRS detection 

capabilities. These three commenters 

opposed requiring LATCH detection 

because it would provide little benefit 

with significant added costs. One of the 

commenters added that LATCH systems 

are not typically latched/unlatched 

frequently, so it is far more uncommon 

to be in the unlatched state. 

Additionally, as only the latch could 

potentially be detected, and yet the 

remaining parts of the child restraint are 

unmonitored, it may give a false 

assurance to the user that the child is 

fully restrained. Two of the commenters 

said that if this were required, the 

system would need to distinguish 

different types of CRS available in the 

market, which would be difficult to 

implement. A commenter that opposed 

requiring occupant detection on buses, 

commented that buses with LATCH 

seats would require a detection system 

capable of differentiating whether an 

occupant is unbuckled or secured using 

the LATCH attachments; whether an 

occupant is unbuckled or secured using 

the securement harness provided with 

the seat; and between removed seats and 

those with incorrect electrical 

connections. Another commenter stated 

that CRSs pose a challenge to occupant 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61694 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

128All 50 states, the District of Columbia, and all 

United States territories have laws requiring 

children to be secured in the appropriate car seats 

or booster seats for their ages and sizes while riding 

in vehicles. Most states now require children to ride 

in appropriate car seats or booster seats until as old 

as age eight (Alaska covers children up to 15 years 

old as long as they fall within their specified height 

and weight criteria). 

129Within these types are CRS designs that can 

be used for multiple purposes, such as convertible 

CRSs that can be used as a rear-facing and forwardfacing CRS and combination CRSs that can be used 

as a forward-facing CRS and booster seat. 

130Many in the child passenger safety community 

refer to the child restraint anchorage system as the 

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

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

term was developed by a group of manufacturers 

and retailers for use in educating consumers on the 

availability and use of the anchorage system and for 

marketing purposes. 

131Some boosters can also be secured to the seat 

with LATCH so that it stays in place when in use 

and not in use. 

132For the NHTSA recommendations discussed 

here, see https://www.nhtsa.gov/equipment/carseats-and-booster-seats (last accessed Apr. 7, 2022). 

133See https://www.healthychildren.org/English/ 

safety-prevention/on-the-go/Pages/Car-Safety-SeatsProduct-Listing.aspx. 

134About 16.6 percent of children 4 to 7 years old 

were prematurely transitioned to seat belts in the 

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

(DOT HS 813 033). 

135For anthropomorphic test devices, this would 

include the 50th percentile male, 5th percentile 

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

dummies. 

detection systems, which would need to 

account for all of the different uses of 

the rear seat; a false-positive warning on 

a child properly restrained using the 

LATCH system (who would not be 

buckled in with the seat belt) could 

discourage the consumer from using 

LATCH. 

Finally, some commenters advocated 

requiring more sophisticated detection 

capabilities in order to limit false 

positives. Two of these commenters 

suggested that the system should be able 

to discern the difference between an 

occupant and objects such as packages. 

Another commenter said that NHTSA 

should also limit false activations when 

seats are occupied by child seats or 

other items. A commenter stated that 

NHTSA should allow for a child seat 

mode that suppresses the warning. 

Agency Response 

As an initial matter, it is important to 

understand the different types of CRSs, 

how seat belts are used with them, and 

the size/age of the children for which 

each type of CRS is typically 

appropriate.128

There are essentially three types of 

CRSs: rear-facing CRSs, forward-facing 

CRSs, and booster seats.129 Rear-facing 

and forward-facing CRSs are child seats 

that are installed using either LATCH 130

or a seat belt to secure it in place.131

Booster seats raise and position a child 

so the vehicle’s lap-and-shoulder belt 

fits properly. 

NHTSA recommends that children 

remain in a rear-facing CRS until they 

reach the top height or weight limit 

allowed by the CRS manufacturer.132

NHTSA also recommends that children 

remain in a forward-facing car seat with 

a harness and tether until they reach the 

top height or weight limit allowed by 

the car seat’s manufacturer. Most 

forward-facing CRS are rated for 

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

(29 kg).133 Once a child outgrows the 

forward-facing car seat with a harness, 

the child can travel in a booster seat and 

use a seat belt. NHTSA identifies an age 

range of 4–7 years old for when this 

transition to a booster typically occurs, 

depending on the height and weight of 

the child and the respective limits of 

their forward-facing car seat. Once a 

child outgrows the booster seat they can 

sit directly in the seat and use the seat 

belt alone; NHTSA identifies an age 

range of eight to thirteen and older for 

when this typically occurs. 

In the remainder of this section we 

discuss, first, the proposed weight and 

height criteria NHTSA proposes to use 

in compliance testing of rear seat belt 

warning systems certified to the 

negative-only or full-status compliance 

options and, second, what ability (if 

any) such systems should have to detect 

a CRS. 

Weight and Height Criteria 

NHTSA believes the rear seat belt 

warning system should be able to detect 

an occupant that should be restrained 

with a seat belt alone and provide seat 

belt use information to the driver that is 

appropriate for that type of system. This 

target population is comprised of adults, 

teenagers, and children in booster seats. 

Children in booster seats are part of the 

target population because they should 

be restrained with the seat belt and so 

would benefit from a seat belt reminder. 

As mentioned above, the transition to a 

booster seat typically occurs from ages 

4–7 years. Children in rear-facing and 

forward-facing CRSs are not part of the 

target population because these children 

are restrained by the CRS harness, not 

the seat belt. The intent of the reminder 

is not to warn of CRS misuse, but to 

warn of occupants not restrained by a 

belt alone. 

Accordingly, we are proposing that a 

rear designated seating position would 

be considered ‘‘occupied’’ when an 

occupant who weighs at least 46.5 lb (21 

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

is seated there. These criteria are 

proxies for a six-year-old child, which 

roughly corresponds to a typical age at 

which a child would transition from a 

forward-facing CRS to a booster seat. We 

have taken these criteria from FMVSS 

No. 208, which uses them to specify the 

smallest child that may be used as an 

alternative to the 6-year-old dummy in 

static suppression tests under FMVSS 

No. 208. The proposed test does not 

specify the use of a booster seat because 

we are aware that children can be 

prematurely transitioned to a seat belt 

without the use of a booster,134 and we 

believe it is desirable to test the lower 

end of the possible weight range that 

encompasses children that could 

conceivably be restrained with a seat 

belt alone. As we explain below in 

Section XII.B, Test Procedures, the 

agency proposes using either a person or 

any anthropomorphic test device 

specified in part 572 that meets these 

proposed weight and height criteria.135

These criteria specify a smaller 

occupant than does R16. We tentatively 

believe that harmonizing with R16 and 

using a heavier dummy would not 

capture the child segment of the 

population that is in booster seats; that 

is, seat belt use may occur for occupants 

smaller than the criteria specified by 

R16. We also do not believe it is 

necessary to use a larger-size occupant 

because a system capable of recognizing 

a six-year-old should also be capable of 

recognizing larger occupants. 

At the same time, we tentatively 

believe that the proposed criteria are 

preferable to criteria reflecting a 

younger occupant (lower weight). The 

smallest dummy that would meet the 

proposed weight and height criteria is 

the 6-year-old dummy specified in part 

572. The next smallest dummy 

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

Hybrid III three-year-old), but we 

believe it would not be appropriate to 

specify the use of the 3-year-old because 

a child represented by this ATD should 

be seated in a forward- or rear-facing 

CRS, not a booster seat. 

Ability of the System To Detect a CRS 

NHTSA also does not propose to 

require any sort of CRS detection 

capabilities at this time. 

We tentatively believe that a forwardor rear-facing CRS installed with the 

seat belt would not cause problematic 

false warnings; rather it would just 

register the CRS as a buckled passenger. 

Similarly, we believe that a forwardor rear-facing CRS installed with 

LATCH would not pose issues 

necessitating any specific requirements 

related to the LATCH system, such as 

LATCH sensors. There are a few reasons 

for this. First, we do not believe 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61695 

136https://www.nhtsa.gov/road-safety/childsafety. 137 DOT 2009 Belt Warning Study, supra n. 36. 

138 Global suggested not adopting the Euro NCAP 

duration requirement (90 seconds) because the 

warning must balance effectiveness and consumer 

acceptance, but NHTSA understands the Euro 

NCAP minimum duration to be 60 seconds. 

139NSC cited an IIHS study finding that an 

indefinite reminder and a 100 second constant 

reminder increased seat belt use by 30–34 percent 

over an intermittent reminder. 

140We are also proposing that these visual 

displays should not be overridden by other visual 

warnings for the required duration. 

LATCH-installed CRSs would lead to 

false warnings or driver confusion about 

the belt status of any rear occupants, 

because NHTSA recommends buckling 

unused seat belts that are within reach 

of children to prevent seat belt 

entanglement and/or strangulation.136

This includes, for forward- or rearfacing CRSs installed with LATCH, 

buckling the unused belt behind the 

CRS. (Fastening the unused seat belt 

behind the CRS when installing a CRS 

with LATCH should not be mistaken for 

installing a CRS with both the seat belt 

and LATCH; a CRS installed with 

LATCH is not also installed with the 

seat belt unless it is approved by both 

the car seat and vehicle manufacturers.) 

If users follow NHTSA’s 

recommendation and buckle the belt 

behind the CRS, the positive-only 

system would simply consider those 

belts to be fastened, and the negativeand full-status systems would not 

register a false warning. If the belt is not 

buckled as NHTSA recommends, with a 

positive-only system, the driver would 

simply see that there were no buckled 

belts, so there would be no false 

warnings. For the negative-only and 

full-status systems (which utilize 

occupant detection), the system could 

register the child in the CRS as an 

occupant depending on the weight of 

the child and CRS. We are aware of at 

least one vehicle manufacturer that uses 

occupant detection for its rear seat belt 

warnings and it recommends fastening 

the unused seat belt if the CRS is 

installed with LATCH to avoid such a 

false warning. (In the owner’s manual 

section of this preamble we seek 

comment on including such guidance in 

the owner’s manual, which includes 

information provided by the vehicle 

manufacturer to the consumer, whether 

in digital or printed form.) Again, if the 

belt is not buckled as NHTSA 

recommends, the driver would need to 

take these facts into account when 

comparing the number of rear seat 

occupants against how many or which 

rear seat belts are reported to be in use 

by the warning system. Second, we are 

not proposing to require a warning for 

CRSs improperly attached to the LATCH 

because the focus of this rulemaking is 

on providing a seat belt warning, not on 

providing warnings for improperly 

installed LATCH child seats. Third, this 

approach is consistent with ECE R16 

and Euro NCAP, neither of which have 

provisions for addressing LATCHinstalled child restraints. Finally, 

requiring LATCH sensors would add 

extra complexity and cost. 

We also do not believe a booster seat 

would present any special challenges to 

a seat belt warning system. If an 

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

system would register the belt as not 

(un)fastened and (if equipped with 

occupant detection) that the seat was 

occupied. This would not necessitate 

the system to specifically detect the 

booster seat because the performance 

criteria are weight-based. In addition, 

we would not expect an occupant 

detection system to provide a false 

warning for an unoccupied booster seat 

because the proposed seat occupancy 

criteria (roughly equivalent to a 6-yearold) is heavier than an unoccupied 

booster seat. 

We are also not proposing to require 

more sophisticated features to test how 

well the system avoids false positives— 

e.g., the ability of the system to 

distinguish packages or pets from 

occupants or a child seat mode. A 

detection system that can differentiate 

between cargo and occupants would 

require additional sensor technology in 

comparison to a weight-based sensor 

and would be more costly. This issue 

can be mitigated by moving the cargo to 

the floor or trunk of the vehicle or by 

buckling the unused belt and would not 

be an issue for the positive-only 

compliance option. Tesla’s ‘‘child seat 

mode’’ allows the driver to acknowledge 

the warning triggered by a CRS installed 

with LATCH for that trip. With respect 

to Tesla’s comment regarding a child 

seat mode, neither ECE R16 nor Euro 

NCAP contemplate this and we are not 

aware of other manufacturers that have 

employed this feature. Given that a 

child seat mode feature could be used 

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

use warning could be prevented or 

dismissed by use of the child seat 

mode), and the limited information 

NHTSA has on it, we have tentatively 

decided not to permit this feature. 

We seek comment on all these issues. 

d. Minimum Duration 

The ANPRM also sought comment on 

the minimum duration of the warning. 

NHTSA’s front seat belt warning 

research suggests that longer-duration 

warnings are more effective, but also 

more annoying.137 The current driver’s 

seat belt visual warning in FMVSS No. 

208 is required to last at least 60 

seconds under the second compliance 

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

Both R16 and Euro NCAP specify a 60- 

second visual warning (which may end 

sooner if the belt is fastened or the seat 

becomes unoccupied). 

Comments 

Many commenters recommended 

harmonizing with R16 and adopting 60 

seconds.138

A few commenters advocated a longer 

warning. Two commenters 

recommended the warning should last 

until all occupants are buckled. One 

commenter said that systems with long 

single-cycle durations and those that 

cycle audible/visual reminders 

throughout the entirety of the drive are 

more effective than systems that cycle 

for a limited number of times.139

Another commenter said that the 

visual warning duration should be 

based on evidence of effectiveness while 

maintaining a balance with annoyance. 

Agency Response 

NHTSA is proposing that the warning 

last for at least 60 seconds. We believe 

that 60 seconds is sufficient to capture 

the driver’s attention, and that a longer 

warning would have the potential to 

become distracting or a nuisance.140

This would be a shorter warning than 

we are proposing for the front outboard 

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

couple of reasons for our tentative 

decision that a shorter warning is 

warranted for the rear seats. First, we 

are not proposing to require occupant 

detection for the rear seat belt warning 

system; the positive-only compliance 

option would require that the driver be 

informed of which rear seat belts are 

fastened. This type of ‘‘warning’’ 

functions more to provide information 

to the driver, rather than a true warning 

(because it will be providing 

information to the driver even if all rear 

occupants have fastened their seat 

belts), so we tentatively think that it is 

not necessary to require that this be 

particularly long-lasting. Second, and 

related, even for the compliance options 

that would entail occupant detection, 

the complexities of occupant detection 

in the rear seats and the possibilities for 

false positives provide another reason 

for not requiring an extremely longlasting warning. Manufacturers would 

be free to provide a longer warning if 

they wished. The proposed compliance 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61696 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

141 Defined as forward motion at a speed greater 

than 10 km/h. § 2.47. 

142Section 8.4.4.5. 

143These summaries simplify the requirements 

somewhat. They will be discussed in greater detail 

later in the preamble where relevant. 

144Section 3.4.1.5. 

145Section 3.4.1.5. 

146Section 3.4.1.5. 

147Section 3.4.3.1.1. 

148Section 3.4.1.6. 

149Section 3.4.3.2. 

150Section 3.4.1.6. The audio signal must resume 

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

have been opened and the seat belt(s) remain 

unbuckled. In addition, the audible signal may 

instead meet the requirements for the front seating 

positions, if the vehicle is equipped with occupant 

detection. 

151Section 8.4.2.2.1. 152 In the proposed regulatory text, we use the 

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

consistent with the current usage in FMVSS Nos. 

101 and 208. 

options requiring occupant detection 

would not require a warning for 

occupants with fastened belts. 

This is consistent with ECE R16 and 

Euro NCAP and with systems currently 

deployed in the United States. Our 

preliminary analysis found that, of the 

15 manufacturers that provide vehicle 

models with a rear seat belt warning 

system in the United States, 8 appear to 

provide systems with initial visual 

warnings that are active for at least 60 

seconds. An additional three 

manufacturers appear to provide visual 

warnings until the seat belt is fastened. 

2. Audio-Visual Change-of-Status 

Warning 

The ANPRM sought comment on 

requiring a change-of-status warning for 

when a fastened seat belt is unfastened, 

including an audio-visual change-ofstatus warning. We also sought 

comment with respect to potential 

requirements for an audible warning, 

including the duration of the warning 

and whether NHTSA should specify 

additional warning characteristics (such 

as sound level). 

R16 specifies an audio-visual changeof-status warning for the rear seats. If a 

fastened rear belt becomes unfastened 

when the vehicle is in ‘‘normal 

operation,’’ 141 R16 specifies an audiovisual warning (second level) when 

certain distance, time and/or speed 

threshold(s) (at the choice of the 

manufacturer) are exceeded.142 The 

additional thresholds are distance 

traveled (not to exceed 500 meters), 

vehicle speed (not to exceed 25 km/h, 

and/or travel time (not to exceed 60 

sec). This warning must last for at least 

30 seconds unless the unfastened belt 

becomes fastened, the seat associated 

with the unfastened belt is no longer 

occupied, or the vehicle is no longer in 

normal operation.143 This warning may 

not be canceled by the driver. 

Euro NCAP also requires (in order to 

earn bonus points) an audio-visual 

change-of-status warning at vehicle 

speeds of 25 km/h and above.144 If the 

change-of-status occurs below 25 km/h 

and no doors are opened, the signal may 

be delayed until the vehicle has been in 

forward motion for 500 meters or has 

reached a forward speed of 25 km/h.145

A warning is not required if the system 

has occupant detection as long as all 

doors remain closed and the number of 

buckled positions remains the same, in 

order to minimize the number of false 

positives (e.g., children remaining in the 

vehicle but swapping seats in the rear 

while at a traffic light).146 The warning 

duration differs for the visual and 

audible warnings. With respect to the 

visual warning, if the system does not 

have occupant detection, the warning 

must last until the seat belt is fastened 

or 60 seconds have elapsed.147 If the 

system does have occupant detection, 

the signal must remain on until the belt 

is fastened. The audible warning must 

last until the belt is fastened,148 30 

seconds have elapsed,149 or the vehicle 

speed falls below 10 km/h.150

Comments 

Many commenters specifically 

supported requiring an audio-visual 

change-of-status warning. One 

commenter cited a survey of adult 

passengers who do not routinely use a 

seat belt in the rear in which 62% of 

respondents said they would be more 

likely to use a seat belt if there was an 

audible warning compared with only 

50% who said the same about a visual 

warning. 

With respect to the triggers for the 

warning, two commenters stated that a 

change-of-status warning should 

activate regardless of the speed. 

Several comments also discussed the 

duration of an audible alert. Several 

commenters recommended harmonizing 

with the 30 seconds required by R16. 

Other commenters argued for a longer 

audible warning, including: 60 seconds, 

90 seconds, and until all occupants are 

buckled. One comment noted that 

audio-visual warnings that continue to 

cycle throughout the drive are more 

effective than limited-duration 

warnings. Another commenter 

recommended consistency with existing 

FMVSS No. 208 audible warning 

systems for front occupants. 

Commenters stated that the duration 

should be based on evidence of 

effectiveness while maintaining a 

balance with annoyance. A commenter 

stated that, while information about the 

effect of an audio-visual rear seat belt 

warning on rear seat belt use is sparse, 

research on front seat belt warning 

systems suggests that an audio-visual 

warning lasting longer than 8 seconds 

would be expected to motivate an 

unbelted rear occupant to refasten the 

seat belt. 

With respect to other warning 

characteristics, three commenters 

recommended that the audible warning 

be heard throughout the vehicle. A 

commenter suggested following R16’s 

requirement that the warning ‘‘consist of 

a continuous or an intermittent (pauses 

shall not exceed 1 second) sound signal 

or of continuous vocal information.’’ 151

Two commenters said that specifying 

additional audible warning 

characteristics would be burdensome 

and unnecessary. A commenter said that 

there should be a balance of the sound 

level so that consumers would accept 

and react positively to the warning, and 

suggested it be the same as that for the 

driver. Another commenter 

recommended that the audible warning 

specification be based on evidence of 

effectiveness and suggested that 

maintaining consistency with other seat 

belt warning signals would be desirable. 

A commenter recommended 

consistency with existing FMVSS No. 

208 audible warning systems for front 

occupants. And yet another commenter 

recommended a warning that is 

enhanced but does not rattle the driver. 

Agency Response 

The agency proposes to require an 

audio-visual warning when a rear seat 

belt is unbuckled during a trip. We 

propose that when the vehicle’s ignition 

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

the vehicle’s transmission selector is in 

a forward or reverse gear, and a rear seat 

belt in use changes to not being in use, 

the vehicle must activate a continuous 

or flashing visual warning consisting of 

icons 152 or text visible to the driver, as 

well as a continuous or intermittent 

audible signal for a period of not less 

than 30 seconds, beginning when a seat 

belt in use changes to not being in use. 

The warnings could cut off sooner if the 

belt is refastened before the minimum 

time limit has been reached. Comments 

from vehicle manufacturers were largely 

in support of harmonizing with the ECE 

R16 requirements, and the proposed 

requirements are comparable to the 

change-of-status warnings on vehicles 

currently equipped with rear seat belt 

warnings. For example, Volvo vehicles 

provide an audio-visual warning lasting 

until the belt is refastened. 

We believe this warning will be an 

effective way to reduce the risk of injury 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61697 

153Paul Schroeder & Melanie Wilbur. 2015. 

Survey of Principal Drivers of Vehicles with a Rear 

Seat Belt Reminder System. Washington, DC: 

National Highway Traffic Safety Administration, 

[Found in the docket for this ANPRM.] 

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

small number (15) of drivers who reported that their 

children do not always use seat belts. 

155Features of the change-of-status warning that 

are common with the start of trip warning—for 

example, the telltale characteristics—are discussed 

later in the preamble. 

156Section 8.4.2.4.1. 

157Section 3.4.3.2.3. 

to rear seat occupants by alerting the 

driver when a passenger unbuckles 

during a trip. NHTSA’s 2015 consumer 

survey found that a change-of-status 

warning is effective in getting 

passengers to refasten their seat belt.153

This may be an especially beneficial 

feature for drivers transporting children 

in the back seat. Such a warning may 

reduce the risk of injury to children by 

alerting the driver that a child has 

unbuckled his or her seat belt, providing 

the driver an opportunity to direct the 

child to re-buckle the belt. Fifty-five 

percent of the drivers surveyed by 

NHTSA who transport children in the 

rear seat and who said their children do 

not always use seat belts, have had the 

experience of their child unbuckling 

during a trip.154

The proposed requirements follow 

ECE R16 and Euro NCAP in that both of 

those protocols include an audio-visual 

rear belt change-of-status warning with 

specified trigger criteria.155 We 

tentatively agree with a commenter that 

a duration longer than 8 seconds is 

warranted because it will be more 

effective and believe that a 30-second 

minimum duration appropriately 

balances effectiveness and acceptance. 

We note that this is shorter than the 

duration we are proposing for the 

change-of-status warning for the front 

outboard seats (until the belt is refastened—see Section XI.C.2) because 

we tentatively believe that a longer 

warning for the rear seats is more likely 

to lead to driver distraction, especially 

with children in the rear seats. 

The proposal differs from R16 and 

Euro NCAP in a few ways: 

• Triggers. The warning would be 

required as long as the ignition is on 

and the transmission selector is in the 

drive or reverse position, with no 

additional thresholds or triggers, such as 

the vehicle having to reach a forward 

speed of 25 km/h. We tentatively 

believe this departure from R16 and 

Euro NCAP is justified. Seat belts 

provide a safety benefit even at lower 

speeds, and regardless of the direction 

of motion. We also believe a warning 

would be beneficial even if the vehicle 

is not moving. A driver may want to 

know if any rear seat occupants— 

especially children—have been 

unbuckled while the vehicle is 

temporarily stopped (e.g., at a traffic 

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

because the vehicle could soon be 

resuming travel. In addition, providing 

a warning when the vehicle is stationary 

would allow the driver to attend to the 

unbuckled passengers before having to 

focus attention on the driving task. We 

similarly believe that a warning would 

be useful before the vehicle has reached 

any distance or trip time threshold. We 

do not adopt the Euro NCAP allowance 

for not requiring a change-of-status 

warning when all doors remain closed 

and the number of buckled positions 

remains the same because this would 

require a delay in the activation of the 

change-of-status warning; also, these 

types of events are likely limited and 

require very little time so exposure to 

the warning would be very limited. We 

do, however, adopt the Euro NCAP 

requirement that if a change-of-status 

occurs and a door is open, the system 

should consider that as the start of a 

new trip. This would allow for 

passengers to exit the vehicle when the 

driver does not shift into the park gear 

without activating the change-of-status 

warning for the full duration 

requirement. 

• Duration. The proposed 30-second 

duration harmonizes with ECE R16 

(though it is shorter than the 60-second 

duration for the visual signal specified 

in Euro NCAP, but consistent with the 

30-second duration for the audible 

signal). We propose that the audible 

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

continuous), which mirrors the 

longstanding requirements for the 

driver’s seat belt warning. ECE R16 156

and Euro NCAP 157 do not count periods 

in which the warning stops for longer 

than 3 seconds as part of the overall 

duration, and we have tentatively 

decided to propose a similar 

requirement for the rear audible changeof-status warning. (In contrast, we are 

specifying additional signal 

characteristics for the front seat belt 

change-of-status warning because we are 

proposing to require a longer duration 

for that warning. This is discussed in 

Section XI.C.2) 

• Audible warning characteristics. 

ECE R16 specifies that for intermittent 

audible warnings, the pauses shall not 

exceed 1 second, and that gaps longer 

than 3 seconds would not count toward 

the required 30 second duration. Euro 

NCAP specifies that there must be no 

gaps greater than 10 seconds, and that 

gaps longer than 3 seconds would also 

not count toward their required 

duration. We have tentatively decided 

to propose a requirement that specifies 

that periods of time when the audible 

warning is not active for longer than 3 

seconds would not count toward the 

required 30 second duration. Given the 

very limited duration of the rear seat 

change-of-status audible warning for the 

rear seats we believe this is a sufficient 

constraint for achieving an adequate 

warning. We have not further specified 

audible warning characteristics, such as 

volume or tone, in order to provide 

manufacturers design flexibility. The 

standard has required an audible 

driver’s seat belt warning with no 

additional audible warning 

requirements since the early 1970s, so 

we believe manufacturers are familiar 

with designing and implementing 

optimal audible seat belt warnings. As 

mentioned above, we are specifying 

additional signal characteristics for the 

front seat belt change-of-status warning 

because we are proposing to require an 

indefinite duration for that warning, 

which requires more thought about the 

warning characteristics to mitigate the 

use of ineffective audible warnings (See 

Section XI.C.2). 

We seek comment on all aspects of 

the proposed change-of-status warning. 

Are there situations when the warning 

at a low speed would result in an 

unnecessary or unwanted warning, and 

how frequently would such situations 

occur? Are any of the deviations from 

R16 and/or Euro NCAP unwarranted, 

and what is the basis for such a 

conclusion? We acknowledge that the 

proposed requirements may still trigger 

the change-of-status warning for a short 

period of time until a door is opened 

when a passenger exits the vehicle and 

the vehicle is not in the park gear; 

however, we believe exposure to a very 

limited warning in these scenarios is 

necessary in order to capture other 

change-of-status events that occur when 

a vehicle is stopped but not in the park 

gear. We seek comment on how vehicle 

manufacturers are currently handling 

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

provided) rear seat change-of-status 

events that occur when the vehicle is 

stopped, but not in the park gear, or at 

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

if any, is provided when passengers exit 

the vehicle without the vehicle being in 

the park gear)? As will be discussed 

later, we are proposing that the changeof-status warning for the front outboard 

seats be active until the seat belt that 

triggered the warning is refastened, so 

we seek comment on whether the 

proposed limited duration change-ofstatus warning for the rear seats should 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61698 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

158 DOT 2007 Acceptability Study, supra n.78. 

159Section 8.4.2.1.1. 

160Section 3.4.1.1. 

161FMVSS No. 208 S7.3(a) and FMVSS No. 101, 

table 2. 

162FMVSS No. 208 S7.3; FMVSS No. 101 S5.1.2. 

163FMVSS No. 101, S5.3.3(a). 

164See Table 2. 

165S5.5.2. These are: air bag malfunction, low tire 

pressure, electronic stability control malfunction, 

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

any brake system malfunction required by table 1 

to be red. 

166See FMVSS No. 101 S4 (‘‘Common space’’ is 

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

identifier, or other message may be displayed, but 

not simultaneously’’). 

167FMVSS No. 101, S5.5.5. 

168FMVSS No. 101, S5.2.3. 

169Section 8.4.2.1.2. 

170Section 8.4.2.1.1. 

171Section 8.4.4.3. 

172Section 8.4.4.3. A common telltale may be 

used for both the front and rear seat belt reminders. 

Section 8.4.4.4. The front reminder is required to 

utilize the symbol specified in Regulation 121, 

which is the same symbol specified in FMVSS No. 

101 and depicted in Figure 2. 

173Section 8.4.4.2 (‘‘The visual warning shall 

indicate at least al rear seating positions to allow 

the driver to identify, while facing forward as 

seated on the driver seat, any seating position in 

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

174Section 3.4.1.1. 

also be required to last indefinitely until 

the rear seat belt is refastened. 

3. Telltale Location 

A seat belt warning can function by 

alerting the driver that a rear seat belt 

is unbuckled, leaving it to the driver to 

request the rear passenger to buckle up. 

However, many other strategies are 

possible. For example, in addition to 

warning the driver, the front seat 

passenger could also be warned on the 

premise that, if the driver was occupied 

by other matters, the front seat 

passenger could direct the rear seat 

passengers to buckle up. Another 

strategy could be to warn the rear 

passenger(s) directly that their belt is 

unbuckled. Finally, in addition to 

warning the rear passenger(s), the driver 

and/or the front passenger could be 

warned. Some research suggests that 

having the warning visible to the 

unbelted occupant may increase 

effectiveness.158

ECE R16 requires that the visual 

warning be visible to the driver when 

they are facing forward,159 and Euro 

NCAP similarly requires that the visual 

signal be clearly visible to the driver 

without the need for the head to be 

moved from the normal driving 

position.160

Comments 

Most commenters recommended that 

the signal be visible to the driver, while 

one suggested the signal be visible to the 

rear seat passengers to avoid relying on 

the driver to enforce belt use, especially 

as rear-seat occupancy increases due to 

the increased use of for-hire vehicles 

(and, possibly at some time in the 

future, autonomous vehicles). 

Another commenter stated that it is 

impractical to provide a warning to rear 

passengers on buses due to wiring costs, 

customization, and FMVSS No. 222 

requirements for head impact 

performance (for school buses). 

Agency Response 

We agree with the majority of 

commenters and propose that the 

warning signal be visible to the driver. 

Although some research may suggest 

that having the warning visible to the 

unbelted occupant may increase 

effectiveness, we tentatively believe that 

the increased cost, complexity, and redesign such a requirement would entail 

would not be justified. However, 

manufacturers would have the 

flexibility to place the visual warning 

where it would be seen by some or all 

rear seat occupants. In Section XII.C we 

discuss the implications of the telltale 

location as it relates to automated 

vehicles. 

4. Telltale Characteristics 

The ANPRM sought comment on 

whether we should propose 

requirements for telltale characteristics 

such as color and required text. 

For the current driver’s seat belt 

warning, FMVSS No. 208 requires a 

continuous or flashing warning light 

displaying (at the choice of the 

manufacturer) either the telltale 

specified in FMVSS No. 101 (see Figure 

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

‘‘Fasten Belts.’’ 161 The telltale must be 

visible to the driver 162 in both daytime 

and nighttime.163 There are no color or 

illumination requirements for the 

telltale.164 The seat belt telltale may 

share a common space with other 

telltales except several specific telltales 

identified in FMVSS No. 101.165

Telltales in the same common space, 

however, may not be displayed 

simultaneously.166 The seat belt telltale 

must displace any other symbol or 

message in that common space while 

the underlying condition for the 

telltale’s activation exists.167

Supplementary symbols or words may 

be used in conjunction with the 

required telltale or words.168

Figure 2—Seat Belt Telltale From 

FMVSS No. 101 

The rear reminder requirements in 

ECE R16 mirror the FMVSS driver’s 

warning requirements in several 

respects: the telltale may be flashing or 

steady; 169 it must be recognizable in the 

daylight and at nighttime and 

distinguishable from other alerts; 170 and 

there are no color requirements.171

However, R16 differs from the FMVSS 

requirements in that there is no required 

telltale symbol.172 R16 also appears to 

require a visual warning that depicts all 

the rear seating positions.173

Euro NCAP specifies that as soon as 

the audible part of the seat belt 

reminder signal starts, the visual signal 

needs to flash and be synchronized with 

the audible part.174

Comments 

Several commenters favored 

standardized warnings. Two 

commenters stated that standardized 

telltales would help drivers recognize 

the icons when driving different/ 

multiple vehicles (rentals, etc.). 

In contrast, other commenters urged 

NHTSA to provide manufacturers with 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP07SE23.001</GPH>
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61699 

175Honda’s comment seems ambiguous. It urges 

harmonization with R16, which does not require a 

specific telltale, but also states that the existing seat 

belt telltale in FMVSS No. 101 is a universallyrecognized warning that can be used to provide a 

consistent link to additional seat belt information, 

and advocates using the FMVSS No. 101 telltale as 

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

belt warning continues to be provided if an 

additional seat belt warning visual display needs to 

give priority to a more important safety warning. 

176https://public.servicebox.peugeot.com/APddb/ 

modeles/3008/eGuide_ed02-16/pdfs/ 

9999_9999_091_en-GB.pdf, pg. 144. 

177https://www.cupraofficial.com/content/dam/ 

public/cupra-website/owners/cupra-car-modelmanuals/brochures/ 

CUPRA_FORMENTOR_06_21_EN.pdf, pg. 17. 

flexibility and not require a specific 

telltale. Two commenters specifically 

suggested harmonizing with ECE R16, in 

addition to the many commenters who 

generally urged harmonization with 

R16. A commenter requested flexibility 

to choose the indication method for 

each seating position, such as a telltale 

or a graphic or rendering of the vehicle 

seating positions in a more advanced 

display screen.175 Another commenter 

urged NHTSA to defer regulatory action 

on the establishment of a specific 

symbol and simply require that any 

telltale provided be communicated in 

the owner’s manual because additional 

research is needed to determine which 

approaches may be most effective in 

communicating reminder status for a 

particular row or specific designated 

seating position, and emphasized its 

belief that NHTSA should not mandate 

specific indicators or display 

characteristics in order to provide OEMs 

with flexibility. Two commenters 

similarly suggested allowing the 

telltales for the rear seat belt reminder 

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

from those currently used for the front. 

On the other hand, some commenters 

did not oppose requiring use of the 

current driver’s seat belt telltale. A 

commenter said that a typical approach 

for rear seat belt warnings is to include 

a separate area on the instrument panel 

for separate telltale(s) for the rear 

seating position. These telltales could be 

specific to the actual seating position to 

inform the driver of the actual position 

that is buckled or unbuckled. 

A commenter said that the rear seat 

warning system should be coordinated 

with the driver warning, and that an 

ideal approach would be to provide a 

pictogram of the vehicle that has icons 

showing the seat belt status for each 

seating position. The commenter 

suggested this dashboard image could 

be combined with the door-ajar image, 

and it could even be enhanced to 

indicate whether a door’s child safety 

lock feature is engaged. Similarly, a 

commenter stated that the warning 

should convey the location of each 

unbuckled occupant (negative-only 

system for which occupant detection 

would be necessary). 

Agency Response 

We are proposing that the visual 

warning be continuous or flashing and 

consist of icons or text and indicate how 

many or which rear seat belts are in use 

or not in use depending on the type of 

warning system. If icons are used to 

indicate how many or which rear belts 

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

be green; if icons are used to indicate to 

the driver how many or which belts are 

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

be red. If text is used to indicate to the 

driver how many or which rear seat 

belts are in use or not in use, we 

propose that the text contain the words 

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

in use.’’ We also propose to amend table 

2 in FMVSS No. 101, Controls and 

displays, to clarify that the ‘‘Seat Belt 

Unfastened Telltale’’ depicted there 

does not apply to the rear seat belt 

reminder. We also propose to amend 

able 1 in FMVSS No. 101 by adding in 

a row for the proposed rear seat belt 

warning. We agree with the merits of 

standardized warnings, but also seek to 

provide manufacturers flexibility to 

address their vehicle designs. 

The requirement that the visual 

warning be continuous or flashing 

mirrors the current driver’s seat belt 

visual warning requirement and is also 

consistent with R16. However, we 

propose to depart from the current 

driver’s warning and from R16 and 

standardize the color of the icons and 

text for the warnings to increase the 

likelihood that consumers would notice, 

recognize, and respond to the warnings. 

We believe that standardized colors and 

text will facilitate the interpretation of 

the signal. We are departing from the 

current driver’s warning requirements 

and following R16 by not requiring 

specific icons because we believe the 

choice of icons would largely depend on 

whether the system displayed the 

number of seat belts in use or which 

seat belts are in use; this NPRM 

provides manufacturers flexibility in 

choosing which icons to use. 

Another difference between the 

proposal and R16 is that R16 requires 

that the visual warning ‘‘indicate at least 

all rear seating positions.’’ We 

understand this to mean that the visual 

warning must depict all the rear seating 

positions. For instance, on some 

vehicles, Peugeot employs a visual 

warning that uses a schematic of the 

whole vehicle to indicate seat belt nonuse or change-of-status for each seating 

position.176 Another manufacturer, 

Cupra, uses a visual warning, on some 

of its European vehicles, which depicts 

the status of all the seat belts in the rear 

seats without using a schematic of the 

whole vehicle.177

In order to give manufacturers design 

flexibility, we do not propose to require 

that the warning depict all rear seating 

positions. Our proposed requirements 

would allow the visual warning to 

consist of text or icons indicating how 

many or which rear seats are fastened or 

unfastened. For example, the warning 

text might consist of ‘‘Middle and Right 

rear seat belts fastened.’’ Another visual 

warning option would be the seat belt 

icon with an adjacent numeral 

indicating the number of rear seat belts 

fastened. Accordingly, the proposal 

would allow, but not require, use of a 

pictogram as recommended by Safe Ride 

News. We are not requiring this because 

we believe it would be difficult to 

implement on vehicles such as 

passenger vans with many rear seats. 

(We also note that R16, which requires 

the visual warning to indicate all rear 

seats, does not apply to vehicles that 

transport more than eight passengers.) 

We acknowledge that vehicles with a 

larger number of rear seats, such as 

passenger vans/buses, may encounter 

visual signal complexities; however, we 

are not dictating specific types of signals 

in the proposed requirements in order to 

ensure manufacturers have adequate 

flexibility to address these types of 

issues. We think these vehicles, in 

particular, would benefit from the 

option to indicate how many rear seats 

are fastened. 

We seek comment on all of these 

issues, including the type of visual 

warnings that rear seat belt reminder 

systems employ currently or may 

employ in the future. We also seek 

comment on whether we should 

consider further aligning with R16 by 

requiring the visual warning to indicate 

all rear seating positions, which features 

of a visual warning would be 

appropriate for buses, and whether any 

further amendments to FMVSS No. 101 

are necessary (e.g., the common space 

requirements in S5.5). 

5. Belt Use Criteria 

The ANPRM sought comment on 

whether NHTSA should retain, for a 

rear seat belt warning, the criteria used 

for the current driver’s seat belt warning 

to determine if the occupant is belted. 

The current driver’s belt warning 

requirements specify that a belt is ‘‘not 

in use’’ when, at the option of the 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61700 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

178S7.3(c). These are the definitions for manual 

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

179Section 2.46. 

180See Docket No. NHTSA–2010–0061 

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

Manufacturers, Association of Global Automakers, 

and Automotive Safety Council). 

181We consider readily removable seats to be 

seats designed to be easily removed and replaced 

by means installed by the manufacturer for that 

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

not require any special tools for their removal. 182See Sections 8.4.1.3 and 15.4.2. 

manufacturer, either the seat belt latch 

mechanism is not fastened or the belt is 

not extended at least 10.16 centimeters 

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

position.178

ECE R16 defines an ‘‘unfastened’’ belt 

to mean ‘‘either the safety-belt buckle of 

any occupant is not engaged or the 

length of the pulled out webbing is less 

than the length of the webbing which is 

needed to buckle an un-occupied seat in 

the rear most seating position.’’ 179 Euro 

NCAP does not specify a webbing spoolout criteria, and only refers to the status 

of the belt buckle. 

Comments 

Three commenters supported using 

the existing FMVSS No. 208 criteria. 

A commenter suggested harmonizing 

with ECE R16, regardless of the type of 

system, in order to provide flexibility 

for vehicles that may have different 

characteristics with respect to rear row 

seating positions; for example, for rear 

seats that can be removed from a 

vehicle, providing an option whereby 

belt spooling can be used as an 

alternative to buckle latching may 

reduce challenges associated with any 

electrical connections that might be 

otherwise needed to provide 

functionality. 

Other commenters suggested using 

different belt use criteria considering 

the wide range of possible occupants, 

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

rear seats, but did not offer possible 

solutions. One commenter stated that 

any seat belt use criteria should take 

into account whether a bypass system 

for CRS installation would be employed 

to prevent false warnings caused by 

using the lower anchors. Another 

commenter stated that the prolific use of 

LATCH seats and integrated child seats 

on buses will necessitate an alternate 

means of seat belt use detection. 

Agency Response 

The current FMVSS No. 208 belt use 

criteria for the driver’s seat belt warning 

requirements have been in place since 

1974 and allow for the use of a belt latch 

or spool-out sensor. While these criteria 

would be effective for determining belt 

use for the initial seat belt warning, we 

believe the use of a spool-out sensor 

would not allow for an objective or 

reliable criterion for the proposed 

change-of-status warning. There may be 

instances where the webbing may not 

readily spool back in when the seat belt 

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

shoulder belt routing features or the use 

of a belt positioning booster seat), and 

thus would not reliably trigger the 

change-of-status warning. Therefore, we 

are proposing amending the belt use 

criteria in FMVSS No. 208, for the seat 

belt warning requirements, to rely on 

the use of a belt latch sensor, and not 

provide requirements that would 

accommodate the use of a spool-out 

sensor. We believe this is consistent 

with Euro NCAP. We invite comment on 

this tentative decision to not 

accommodate the use of spool-out 

sensors for the belt use criterion and 

request any data on the prevalence of 

the use of spool-out sensors in the fleet. 

Concerns about false alarms triggered 

by LATCH use for the installation of 

child restraints are already addressed by 

the simple approach, in line with 

NHTSA’s recommendations, that 

parents and caregivers fasten and lock 

the unused seat belts for the seat where 

the child restraint is being installed. 

This is an already existing agency 

recommendation to prevent seat belt 

entanglement and would prevent false 

warnings related to LATCH use. 

6. Electrical Connections 

In the ANPRM, we explained that a 

rear seat belt warning system might 

require an electrical connection between 

the seat and the vehicle to relay the 

information gathered by a belt latch or 

webbing spool-out sensor to the rest of 

the warning system. A rear-belt warning 

system may therefore, as several 

commenters to the RFC noted,180

present potential wiring complexities, 

particularly in vehicles with removable, 

folding, rotating, or stowable seats. 

These types of seats might present an 

issue for a rear seat belt warning system 

because the electrical connection might 

not be automatically reestablished for 

these seats when the seat is reinstalled. 

There could be instances with manual 

connection seats where the driver either 

forgets to make the connection or makes 

an improper connection. Even for seats 

where the connections are automatically 

established when the seat is reinstalled, 

the automatic connectors might 

malfunction. If the electrical connection 

is not reestablished, the warning system 

could malfunction or provide inaccurate 

information. Removable seats are 

mainly found in the second row of 

minivans.181 Foldable, rotating or 

otherwise stowable seats (e.g., Stow-nGo, Flip and Fold) are prominent in the 

third row of minivans or large SUVs. 

Foldable or stowable seats in the second 

row are not as prominent in minivans. 

Neither Euro NCAP nor ECE R16 have 

any requirements that address the 

potential for improper electrical 

connections for such seats. The ECE 

regulations provide that the rear seat 

belt warning requirements would not 

apply to folding rear seats or to seats 

fitted with an s-type belt (including a 

harness belt) until September 2022.182

Euro NCAP does not exclude folding 

seats and includes all seating positions 

including optional and removable seats, 

but does not require the monitoring of 

the buckle status for rear seat belt 

secondary buckles that require a tool to 

unlock. 

Comments 

Three commenter stated that 

removable, suspension and folding seats 

are complex and raise reliability and 

technological readiness concerns and 

should be exempted from the warning 

requirements until it would be 

practicable. Two of these commenters 

said that if a seat belt warning were 

required for such seats, significant lead 

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

platform was updated) would be 

necessary. 

Commenters stated that a rule should 

include some or all of these seat types. 

A commenter stated that, although these 

seats may present challenges for rear 

seat belt warning systems, NHTSA has 

provided no evidence that, in cases 

other than removable seats, the 

challenges would be insurmountable, or 

quantified the portion of the target 

population represented by occupants of 

these types of seats, which likely 

includes many children. Another 

commenter stated that removable seats 

would not need to be exempted from the 

requirements (as they currently are from 

ECE R16) if specific types of electrical 

connections or technology (e.g., wired 

buckle switch, wireless buckle switch, 

belt extension) were not required. 

Commenters said that electrical 

connections for removable, rotating, 

flipping and folding seats should not 

require any action on the part of the 

consumer because vehicles with these 

seats frequently transport children, and 

believed that NHTSA should also 

consider requiring wireless connections 

and a warning for an improper 

connection. 

Commenters were against any 

prescriptive design requirements related 

to the connection between the vehicle 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61701 

183As we note in Section X.C.7 below, we also 

propose that the owner’s manual (which includes 

information provided by the vehicle manufacturer 

to the consumer, whether in digital or printed form) 

include instructions on how to make any manual 

electric connections for readily removable seats. 

184We estimate that minivans make up 3.6% of 

vehicles produced based on MY 2015 WardsAuto 

production data. The number of minivans that 

would potentially be affected by this proposed 

requirement is less than 3.6%, because some 

minivans only have foldable/stowable rear seats, 

not removable seats. 

and any removeable, folding, rotating, or 

stowable seats, and in favor of a robust 

set of compliance options to facilitate 

new technology (although one 

commenter also said that any additional 

time it would take NHTSA to develop 

such options would not be justified by 

the limited benefits and relatively small 

number of affected vehicles). A 

commenter said that NHTSA should 

instead include a reliability requirement 

(e.g., lifetime warranty). 

Two commenters expressed concerns 

with wiring complexities associated 

with buses. One of these commenters 

specifically noted track-mounted seats, 

which can be repositioned by the end 

user, which are also subject to improper 

connections and for which wireless 

communication technology is not 

currently available. 

Agency Response 

We have tentatively decided not to 

exempt any of these seat types from the 

proposed requirements. We are not 

exempting suspension and/or folding 

seats; the electrical connections should 

not be disturbed because these seats are 

not readily removable, and they would 

potentially just require additional 

wiring to accommodate the folding or 

stowing process. We are also not 

exempting removable seats because we 

tentatively believe that concerns with 

improper electrical connections will be 

addressed by the proposed warning 

requirement discussed below. Applying 

the requirements to these seats also 

harmonizes with ECE R16 (which will 

soon fully phase in the rear belt 

requirements for these seats) and Euro 

NCAP. We do not consider a phase-in 

necessary for suspension and/or folding 

seats because we believe the solution for 

these seats is simple. For removable 

seats a phase-in is unnecessary because 

readily attachable electrical connections 

appear feasible. We do not believe buses 

would be subject to these requirements, 

given our definition of readily 

removable seats. 

We have tentatively decided not to 

propose any requirements with respect 

to the electrical connections for folding, 

rotating, or stowable seats. Because 

these seats are not readily removable, 

the electrical connections should not be 

disturbed and could be accommodated 

with additional wiring. We are, 

however, proposing two requirements 

related to the electrical connections for 

readily removable seats. 

First, we are proposing that readily 

removable seats must either 

automatically connect the electrical 

connections when the seat is put in 

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

to take any additional action to 

reconnect the electrical connections 

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

manual connection is required (i.e., the 

user must reconnect the electrical 

system), the connectors must be readilyaccessible.183 By readily-accessible 

connectors we mean connectors that are 

easy for an ordinary consumer to see 

and access. A system utilizing a wireless 

connection could be classified as either 

automatic or manual, depending on 

whether the user needs to take any 

additional actions to establish the 

wireless connection. We agree with the 

commenters who recommended no 

prescriptive requirements in order to 

ensure OEMs have flexibility in system 

design. We think the proposal balances 

flexibility and the need to ensure that a 

proper connection is made. 

Second, we are proposing that 

vehicles utilizing the negative-only 

compliance option provide a visual 

warning to the driver if a proper 

electrical connection has not been 

established for a readily removable seat. 

We are concerned that consumers could 

reinstall removable seats (with either 

automatic or manual connections) 

without making a proper electrical 

connection. There could be instances for 

manual connection seats where the 

driver either forgets to make the 

connection or makes an improper 

connection. Even for seats where the 

connections are automatically 

established when the seat is reinstalled, 

the automatic connectors might 

malfunction (e.g., debris, broken 

connector) and a proper connection may 

not be made. If the electrical connection 

is not reestablished, the warning system 

could malfunction or provide inaccurate 

information. We are only proposing to 

require the warning for negative-only 

systems because a faulty connection 

would result in the system not triggering 

any warning of an unbelted rear seat 

occupant. Moreover, the driver would 

otherwise have no reason to suspect that 

the system was malfunctioning, and so 

might mistake the lack of a warning as 

an indication that the rear seat occupant 

was belted. 

These potentially serious problems 

are not present in full-status or positiveonly warning systems. First, it is our 

expectation that a faulty connection for 

a full-status system would affect both 

the occupant detection and belt status. 

However, if for some reason this is not 

the case and the occupant detection of 

a full-status system is working properly, 

but the seat belt buckle sensor is not 

connected properly, then no visual 

warning should activate without input 

from the buckle sensor and the driver 

should easily recognize the system is 

not working properly. If for this same 

scenario, the system interprets a lack of 

input from the seat belt sensor as an 

unbuckled seat belt when the driver 

verifies or requests the rear seat 

occupant to buckle their seat belt and 

the occupant is already buckled, then 

the driver would again be aware the 

system is not working properly. If the 

occupant detection sensors are not 

connected properly, the driver would be 

aware of the number of rear seat 

occupants being transported, and would 

thus be aware that the system is not 

operating correctly when there is not a 

warning for each occupant. Similarly, if 

there were not a good connection in a 

vehicle with a positive-only system, an 

unbelted rear seat occupant would not 

register as belted, which would be 

accurate; a belted passenger would also 

not register as belted, but since the 

passenger would be belted, there would 

be no adverse consequences from the 

system error if a crash were to occur. 

We believe that both of these 

requirements would mainly affect 

minivans, which make up a small 

percentage of the fleet.184 We believe it 

might be possible to utilize the rear seat 

belt visual warning signal, with slight 

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

The agency seeks comments on this 

proposal, particularly on the safety need 

for such warnings, costs, and feasibility 

of the proposed warning. We also seek 

comment on whether this telltale should 

be added to table 2 of FMVSS No. 101, 

Controls and displays. 

None of the regulations or statutes 

administered by NHTSA require 

manufacturers to provide a lifetime 

warranty. However, if a vehicle or item 

of equipment is determined (by the 

manufacturer or NHTSA) to have a 

safety-related defect or fails to meet an 

applicable FMVSS, the Safety Act 

requires the manufacturer to notify the 

owner of the defect or noncompliance 

and (if the vehicle or item is not more 

than 15 years old) remedy the vehicle or 

item without charge to the vehicle 

owner. 

7. Owner’s Manual Instructions 

The ANPRM sought comment on 

requiring the owner’s manual to provide 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61702 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

185The National Child Restraint Use Special 

Study found that only 13 percent of drivers 

reported reading the vehicle owner’s manual. 

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

Washington, DC: U.S. Department of 

Transportation, National Highway Traffic Safety 

Administration, p. 10. 

186As noted earlier, NHTSA recommends 

buckling unused seat belts that are within reach of 

children to prevent seat belt entanglement and/or 

strangulation. 

187FMVSS No. 101, S5.5.5. See discussion supra, 

Section X.C.4, Telltale characteristics. 

information on the warning system’s 

features, including the location, format, 

and meaning of the visual warnings. 

Because the owner’s manual readership 

may be relatively low,185 we also sought 

comment on whether this information 

should be displayed in the vehicle 

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

manual. 

Comments 

None of the commenters opposed 

such a requirement. Several commenters 

supported including such information 

in the owner’s manual. Some 

commenters requested flexibility in 

describing the functionality of the 

system. One commenter suggested that 

the owner’s manual could include 

information on the seating positions 

where a rear-seat reminder is provided, 

a description of the visual and audible 

warning(s), an indication of whether the 

system incorporates driver monitoring 

(including any limitations), instructions 

for deactivating or cancelling any 

warning(s), any limitations related to 

CRS, and information related to the 

connection of removable, folding, 

rotating, or stowable seats. 

A commenter believed that 

information should also be displayed invehicle, especially for one-time vehicle 

users (renters, friends, family), and 

especially with respect to electrical 

connections for removable/stowable 

seats. Another commenter believed that 

more research on the best way to 

communicate this to owners is needed. 

A commenter stated that information 

on how a rear seat belt reminder affects 

CRS installation should be provided, 

including whether the system is able to 

detect a CRS (and avoid false warnings). 

Agency Response 

We propose that the owner’s manual 

(which includes information provided 

by the vehicle manufacturer to the 

consumer, whether in digital or printed 

form) describe the warning system’s 

features, including the location, format, 

and meaning of the visual warnings. We 

also propose that the owner’s manual 

include instructions on how to make 

any manual electrical connections for 

readily removable seats. This will 

provide manufacturers flexibility for 

how they describe the functionality of 

the system. These proposed additions to 

the owner’s manual requirements in 

FMVSS No. 208 would require a 

revision to the approved collection of 

information OMB No. 2127–0541. Later 

in this proposed rule, we seek comment 

on this revision. 

With regard to including system 

functionality information in the vehicle 

itself, these types of vehicle features are 

not normally explained visually in the 

vehicle, other than information on air 

bags which pose safety risks. This level 

of detail is best described in the owner’s 

manual. 

We are aware of at least one 

manufacturer that provides information 

in the owner’s manual on how their rear 

belt warning system with occupant 

detection functions when a CRS is 

installed with LATCH and guidance on 

how to avoid activating the warning (for 

example, it informs the consumer that 

fastening the seat belt prior to installing 

a CRS with LATCH will avoid activating 

the warning system for that seat).186 We 

seek comment on whether we should 

require including such information in 

the owner’s manual (which includes 

information provided by the vehicle 

manufacturer to the consumer, whether 

in digital or printed form). 

8. Interaction With Other Vehicle 

Warnings 

The ANPRM also solicited comment 

on whether a rear seat belt warning 

could conflict with other in-vehicle 

warnings, and how this might be 

addressed. 

Comments 

A few commenters believed that the 

rear belt reminder could conflict with 

other warnings. One commenter 

believed that there are conflicts and that 

the rear seat belt warnings should be 

given priority over other warnings. Two 

commenters recommended that NHTSA 

provide flexibility for rear-seat reminder 

system alerts (or aspects of the alert) to 

be temporarily suppressed or paused 

where it is necessary to alert or redirect 

the driver’s attention to higher-priority 

warnings—for example, related to the 

operation of the vehicle or a potential 

safety risk within the external roadway 

environment, such as an alert provided 

by an advanced driver assistance system 

(ADAS), crash avoidance system or 

automated driving system (ADS) request 

to intervene. Another commenter 

recommended that the existing FMVSS 

No. 101 Seat Belt Unfastened Telltale be 

utilized as a persistent ‘‘baseline’’ 

warning when there is an active seat 

belt warning for any occupant, even in 

the event that the display of detailed 

seat belt information is prevented by a 

higher priority warning. 

Other commenters did not believe 

there would be conflicts with other 

warnings, and one manufacturer did not 

believe there would be a conflict if the 

audible warning is accompanied by a 

visual warning. 

Agency Response 

NHTSA is proposing that the rear seat 

belt reminder telltale must not be 

overridden by other visual warnings for 

the required duration. This is consistent 

with the current requirements in 

FMVSS No. 101 for the driver’s seat belt 

warning which specify, among other 

things, that the seat belt telltale must 

displace any other symbol or message in 

that common space while the 

underlying condition for the telltale’s 

activation exists.187 We do not believe 

that the seat belt warning requirements 

will interfere with other warnings for 

safety systems since they have 

dedicated warning signals. This should 

give manufacturers the flexibility to 

determine the best way to implement 

their warnings. For instance, warnings 

for a potential safety risk can be more 

aggressive than those for the seat belts. 

With regard to available space, the 

visual signal might be displayed as a 

telltale light on the instrument panel or 

on the vehicle’s information display 

screen. Manufacturers will also have to 

determine whether the driver and rear 

passenger seat belt visual warning will 

be treated the same. 

D. Alternative Warning Signals 

The ANPRM sought comment on 

requiring or specifying as a compliance 

option a rear seat belt warning that 

differs from the type of audio-visual 

warning that is currently required for 

the driver’s seat belt. Alternatives to a 

visual warning on vehicle start-up could 

include an audible signal, either 

electronic or mechanical, or a haptic 

warning (e.g., steering wheel or seat 

vibration). Similarly, an audible or 

visual warning of a change in the status 

of rear seat belts could be either 

electronic or mechanical and could 

include a haptic signal. We also sought 

comment on alternative solutions that 

would alert the driver when a rear seat 

passenger buckles and/or unbuckles 

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

buckled, or the sound of the latch plate 

clicking into the buckle). 

Comments 

Many commenters recommended 

requiring the traditional audio-visual 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61703 

188With respect to Blue Bird’s argument 

regarding the practicability of a rear warning for 

buses, see Section X.B, Applicability. 

189Mazzae, E.N., Baldwin, G.H.S., & Andrella, 

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

prototype seat belt misuse detection system (Report 

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

Highway Traffic Safety Administration. 

190Section 8.4.5. 

191Section 8.4.5.1. 

192Section 3.4.3.1.2. 

193S5.5.6(b). 

warnings currently used for the front 

seats. One commenter stated that 

warning specifications should be based 

on effectiveness and that audio-visual 

warnings would likely be highly 

effective given occupants’ familiarity 

with them; it did not believe that a lesssophisticated warning, such as a 

specialized system of mirrors, would be 

sufficient to inform the driver about the 

status of the rear seat belts. Two 

commenters noted the potential for 

confusion/distraction if an alternative 

warning were used. A commenter stated 

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

certainly evidence of a buckled seat belt, 

can easily be missed by the driver and 

other occupants, as it could be masked 

not only by the drivers’ own belt 

clicking, but also by ambient noise in 

the vehicle, and that, given the research 

supporting the effectiveness of an audiovisual signal, an alternative warning 

system would not be acceptable. Two 

commenters said that an alternate 

warning is not necessary because ECE 

R16’s requirements are adequate. 

A commenter said that, in addition to 

requiring an audio-visual warning, the 

proposed rule should require a 

notification on the instrument cluster if 

a seat belt is unbuckled that must be 

acknowledged by the driver before any 

other use of the instrument panel is 

permitted. 

A commenter stated that rear seat belt 

warnings are not practicable for buses, 

but if they were used, an audible alarm 

similar to that required for emergency 

exits would be necessary to provide an 

effective notice to the driver. The 

commenter believed that the interior 

mirror on buses designed to permit the 

driver to view the passengers, while not 

as effective in determining proper seat 

belt use as an electronic monitoring 

system, has been effective in aiding the 

driver to observe passengers that were 

obviously not properly belted. The 

commenter did not support the use of 

haptic signals on buses. A public 

commenter suggested use of cameras. 

Agency Response 

We agree with the commenters who 

believe that an alternative warning is 

not necessary and that an audio-visual 

warning would be appropriate.188

Cameras would be unnecessary and 

would add cost. The agency believes 

that mirrors alone would not be as 

effective as an audio-visual warning and 

may pose risks, as drivers would have 

to study the view to determine belt 

status, assuming they could clearly see 

the belts. In addition, as explained 

above, the proposed rule would not 

apply to school buses. 

We are specifying minimum 

performance requirements in order to 

balance the effectiveness and 

acceptability of these systems. 

Manufacturers can go beyond our 

requirements, such as by providing a 

warning on the instrument panel that 

must be acknowledged by the driver 

before any other use of the instrument 

panel is permitted. 

E. Resistance to Intentional and 

Inadvertent Defeat and Deactivation 

The ANPRM sought comment on 

whether NHTSA should propose 

requirements to address circumvention. 

We pointed to agency research on the 

development of a seat belt misuse 

detection system that identified a 

number of ways in which a rear seat belt 

warning system might be intentionally 

defeated, as well as potential 

countermeasures.189 For example, a 

warning system could be defeated if: 

• The belt is buckled before the 

occupant sits in the seat. This could be 

addressed by requiring a sequential 

logic system. A sequential logic system 

would require that the belt be buckled 

after the seat has been occupied in order 

for the system to recognize the seat belt 

as being buckled. 

• An occupant buckles the seat belt 

behind themselves. This could be 

addressed by utilizing both seat belt 

latch and spool-out sensors and 

deactivating the warning only if the 

webbing were spooled out more than a 

predetermined length. However, even 

these sensors could be defeated by 

pulling out additional webbing and 

clipping it off to prevent retraction. 

• The seat belt and/or occupant 

detection sensors utilized by the rear 

warning system in vehicles with 

removable rear seats are intentionally 

disconnected. 

We also noted some ways in which 

the warning could be inadvertently 

circumvented (for example, when the 

driver uses a remote engine starter so 

that the initial warning activates before 

the driver is in the vehicle). 

We also sought comment on whether 

a feature allowing single-trip manual 

deactivation would diminish the 

likelihood of circumvention. The ECE 

regulations allow the rear seat belt 

warning system to incorporate a shortterm and/or a long-term deactivation 

feature for the audible change-of-status 

warning.190 Under those regulations, a 

short-term deactivation may only be 

effectuated by specific controls that are 

not integrated in the safety-belt buckle, 

and only when the vehicle is 

stationary.191 When the ignition or 

master control switch is deactivated for 

more than 30 minutes and activated 

again, a short-term deactivated safetybelt reminder must reactivate. A longterm deactivation may only be 

effectuated by a sequence of operations 

that are detailed only in the 

manufacturer’s technical manual or 

which require tools that are not 

provided with the vehicle. It must not 

be possible to provide either short- or 

long-term deactivation of the visual 

warning. Under Euro NCAP, the system 

may allow the driver to acknowledge 

the signal and switch it off for that 

unique event, except for change-ofstatus events; a new trigger of the 

warning should not be prevented.192 We 

therefore understand there to be two 

distinct but related concepts in the ECE 

regulations and Euro NCAP: 

acknowledgement and deactivation. The 

former allows the driver to turn off the 

signal once it is activated, while the 

latter prevents the signal from activating 

altogether. In addition, FMVSS No. 101 

provides that telltales for several 

functions (such as high beams), but not 

including the driver’s seat belt warning, 

must not be cancelable while the 

underlying condition for their activation 

exists.193

Comments 

Several commenters supported 

addressing intentional and/or 

inadvertent defeat. A commenter stated 

that, given the relatively small 

proportion of hard-core nonusers, the 

proportion of the potential target 

population seeking to intentionally 

defeat the systems is relatively small. 

Nonetheless, the commenter stated that, 

if mitigation strategies can be built into 

the systems, such an advance would 

likely help address at least some portion 

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

exhibiting inadvertent misuse. 

Commenters believed that the cost of 

the potential countermeasures would be 

minimal, and they should be required to 

the extent feasible. A commenter stated 

that the rear warning system should 

include appropriate requirements for 

inadvertent defeat, but not intentional 

defeat. Another commenter supported 

investigating the possibility of 

eliminating the ‘‘false comply’’ 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61704 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

194 DOT 2009 Seat Belt Study at 2; Transportation 

Research Board Study at 8. 

condition of buckling behind the back 

or extracting and ‘‘pinning’’ the belt 

without buckling. One potential option 

is to replicate current systems used to 

identify seat belt use for front seated 

occupants, as occupant detection 

systems can also assist with identifying 

misuse. They also commented that 

sensor technology that identifies belt 

pullout, occupant location, and buckle 

switches can add redundancy and 

reduce the risk of intentional and 

inadvertent defeat. 

Other commenters disagreed with 

hardening the system against 

circumvention because it would be 

burdensome and unnecessary (minimal 

benefits). One commenter noted the 

relatively small proportion of drivers 

who circumvent the seat belt warning. 

With respect to deactivation, three 

commenters supported following R16, 

and IEE supported following R16 and/ 

or Euro NCAP. Three other commenters 

opposed allowing deactivation because 

it would drastically weaken system 

effectiveness. 

We also received comments on the 

interaction with a remote engine starter 

and the warning. A commenter believed 

that adopting the requirements of R16 

should help address this issue, as 

warnings must be provided when the 

ignition switch (or master control 

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

being driven). The commenter also 

believed that the current driver’s 

warning requirements (where the 

warning is provided beginning when the 

vehicle ignition switch is moved to the 

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

this issue. Another commenter 

recommended that NHTSA specify the 

start of the drive as the moment when 

the ignition is activated in the mode 

where the vehicle is capable of being 

driven. A commenter stated that this 

potential issue can easily be avoided 

with occupant detection, because the 

warning cycle would only be triggered 

based on the actual presence of 

occupants. 

Agency Response 

We have tentatively decided not to 

propose any system-hardening features. 

In drafting this proposal, the agency 

focused on extending the rear seat belt 

warning technologies currently in a 

relatively small proportion of vehicles 

to the rest of the fleet. These existing 

systems generally do not provide 

mechanisms to limit circumvention. We 

decided not to include requirements to 

address circumvention for a variety of 

reasons. Most importantly, doing so 

would increase cost and complexity. For 

example, since we are not proposing to 

require occupant detection technology, 

we are not proposing a sequential logic 

system. We also believe that because the 

proposed warnings are minimally 

intrusive—a relatively short-duration 

visual warning on start-up, and an 

additional short audio-visual warning 

for a seat belt that is subsequently 

unbuckled—attempts to defeat the 

system will be rare. 

We have also tentatively decided not 

to allow acknowledgement or 

deactivation of the required warning 

signals. While some commenters 

suggested adopting the R16 

requirements, they did not offer further 

information on the need or use of these 

options, except for one commenter that 

noted it would diminish the safety value 

of the system. Therefore, we believe that 

proposing to allow an acknowledgment, 

short-term deactivation, and or longterm deactivation option would have a 

net negative impact on the effectiveness 

of the proposed warning system (the 

driver would not get the full benefit of 

the warning). As discussed earlier in 

this proposed rule, we believe that the 

proposed warnings are minimally 

intrusive and have relatively short 

durations (visual-only at start-up and 

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

the positive-only compliance option 

would mitigate warnings for 

unoccupied seats. In addition, we 

believe that allowing the driver to turn 

off the change-of-status warning would 

not meet the need for safety. Since we 

cannot justify allowing such options 

from a safety perspective (allowing it 

would negatively impact the 

effectiveness of the systems) or 

consumer acceptance perspective 

(warning signals are unobtrusive and 

vehicle manufacturers could opt for the 

positive-only option), we have 

tentatively decided not to allow either a 

deactivation or acknowledgment option. 

For this reason, we also propose 

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

adding the seat belt telltale to the list of 

telltales that may not be cancellable 

while the underlying condition for the 

telltale exists. This would apply to both 

the front and rear seat belt warnings. 

This would mean that the seat belt 

warning telltale would not be allowed to 

be acknowledged (i.e., cancelled) until 

the minimum warning duration had 

been reached. 

We seek comment on vehicle 

manufacturers’ desire to provide such 

options, and, if they currently offer such 

options, how they have implemented 

them. We also seek comment on 

whether allowing such options would 

affect manufacturers’ choice of 

compliance option (e.g., if we allowed 

acknowledging or deactivating the 

warning signals, would they be more 

inclined to choose the negative-only or 

full-status compliance options?). We 

also seek comment on our proposed 

revision of FMVSS No. 101. 

In vehicles with a remote engine 

starter, the driver would potentially not 

be present to witness the initial warning 

signals if they are designed to meet our 

minimum requirements. This could 

potentially be addressed by 

programming the system to require 

input from the door sensors or occupant 

sensors to verify that the driver is in the 

vehicle, or by requiring the signals to 

initiate when the transmission is moved 

out of the park mode. We have chosen 

not to propose a strategy for this 

scenario, but request comments on 

practicable solutions to this problem 

that could be implemented in the final 

rule and the potential cost impacts. New 

technologies or solutions may be 

available that may address these 

scenarios without limiting the design 

flexibility of manufacturers or 

significantly increasing the cost. 

F. Consumer Acceptance 

In the ANPRM we explained that in 

order for the proposed rear seat belt 

warning to have a lasting impact on seat 

belt use, it must balance effectiveness 

and acceptability. For a seat belt 

warning system to induce an unbelted 

occupant to buckle up, the warning 

must be noticeable enough to attract the 

occupant’s attention, or, for a warning 

directed at the driver, the driver’s 

attention. However, if the warning is 

overly intrusive, consumers may not 

accept the technology.194 Therefore, the 

warning must be noticeable enough to 

prompt occupants to buckle their seat 

belts, but not so intrusive that the public 

does not accept the warning system, or 

that an occupant will circumvent or 

disable it. Consumer acceptance of any 

eventual seat belt warning requirements 

is an important consideration, given the 

potential safety benefits of rear seat belt 

warnings, the history of seat belt 

warning technologies, and the fact that 

consumers have not yet had widespread 

exposure to rear seat belt warnings. 

NHTSA is especially aware of this 

concern, given the agency’s experience 

with public and Congressional backlash 

in the 1970s over the ignition interlock 

and continuous warning buzzer 

regulations. 

We also noted research by NHTSA 

and others suggesting that consumers 

would accept the new technology. The 

2004 Transportation Research Board 

Report observed that ‘‘the data available 

to date provide strongly converging 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61705 

195Transportation Research Board Study at 75– 

76. 

196 Id. at pg. 10. 

197Paul Schroeder & Melanie Wilbur, Survey of 

Principal Drivers of Vehicles with a Rear Seat Belt 

Reminder System. Washington, DC: National 

Highway Traffic Safety Administration (2015). The 

vehicles with seat belt warning systems were 

Volvos and certain Cadillac and Chevrolet models. 

198Citing www.norc.org/Research/Projects/Pages/ 

underutilized-strategies-in-traffic-safety-results-ofa-nationally-representative-survey.aspx (last 

accessed Oct. 25, 2021). 

199Citing Highway Loss Data Inst., Ins. Inst. for 

Highway Safety, Unbelted: Adults Admit They 

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

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

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

accessed Oct. 25, 2021). 

200Citing David G. Kidd & Anne T. McCartt 

(2014) Drivers’ Attitudes Toward Front or Rear 

Child Passenger Belt Use and Seat Belt Reminders 

at These Seating Positions, Traffic Injury 

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

15389588.2013.810333. 

201We identified three manufacturers that 

produce vehicles with visual warnings that last for 

at least 60 seconds. One manufacturer provides 

vehicles where the visual warning stays active until 

the belt is fastened. 

202 In the ANPRM it was 13% based on MY2019 

vehicle data. 

203See Docket No. NHTSA–2010–0061 (GM 

comment). 

204See Docket No. NHTSA–2010–0061 (Volvo 

comment). 

205 Kidd, McCartt, & Oesch. Attitudes Towards 

Seat Belt Use and In-Vehicle Technologies for 

Encouraging Belt Use. Insurance Institute for 

Highway Safety. January 2013. The study oversampled part-time belt users and nonusers. 

evidence in support of both the 

potential effectiveness and consumer 

acceptance of many new seat belt use 

technologies[.]’’ 195 As part of the 

research for the report, NHTSA 

conducted focus-group interviews with 

part-time and hard-core nonusers. The 

report noted that ‘‘many part-time users 

interviewed by NHTSA—the primary 

target group for the technology—were 

receptive to the new systems. Nearly 

two-thirds rated the reminders 

‘‘acceptable,’’ and approximately 80 

percent thought that they would be 

‘‘effective.’’ 196 The ANPRM also 

pointed to a telephone survey of drivers 

of vehicles with and without a rear seat 

belt warning system that NHTSA 

conducted in 2015.197 The rear warning 

systems in those vehicles had 

characteristics that were similar to the 

proposed requirements: a visual 

warning on start-up and an audio-visual 

change-of-status warning. The survey 

found, among other things, that 81% of 

drivers of vehicles with a rear seat belt 

warning were ‘‘very satisfied’’ with the 

system; less than 2% were dissatisfied. 

Among drivers of vehicles without a 

rear seat belt warning, attitudes towards 

rear belt warnings were generally 

positive as well: a majority (55%) 

indicated that it was important to them 

that their next vehicle be equipped with 

a rear belt warning system. 

Comments 

Several commenters believed that 

consumers would accept rear seat belt 

warnings. Commenters said that 

NHTSA’s research shows that a large 

proportion of the consumer population 

will accept rear seat belt warnings and 

it noted that at the time of the interlock 

issue in the 1970s, seat belt use rates 

were much lower than today, and a 

larger proportion of the population were 

hard-core nonusers. A commenter stated 

that its survey of 2,000 drivers showed 

that 70 percent favored a law requiring 

seat belt reminders that continuously 

chime until the seat belt is buckled, 

including rear seat passengers.198

Another commenter noted a 2012 IIHS 

survey showing that most motorists 

supported enhanced belt reminders that 

were ‘‘more persistent and intense’’ than 

what most automakers offered at the 

time.199 The commenter also noted the 

results of NHTSA’s 2015 survey. 

Another commenter said that IIHS has 

found that the majority of drivers in the 

U.S. who transport passengers would 

accept a rear seat belt reminder 

system.200 This study found that parents 

believed an audible alert to be 

especially useful in alerting the driver to 

a child unbuckling in the back seat 

during a trip. A commenter suggested 

that consumers would accept R16- 

conforming systems. 

One commenter said that further 

studies are necessary because there is 

insufficient data on consumer 

acceptance. 

Agency Response 

NHTSA has tentatively concluded 

that the proposed warning system 

would be acceptable to consumers in 

light of the specific characteristics of the 

proposed warning signals, real-world 

experience with seat belt reminder 

systems, and research and consumer 

surveys by NHTSA and others. 

We believe that the proposed 

requirements are specified so that the 

potential for consumer disapproval is 

minimized. Our intent was to specify 

minimum warning requirements that 

would result in an effective yet 

acceptable warning. With respect to the 

warning on start-up, we propose 

requiring only a visual warning, and not 

a more intrusive audible alert. The 60- 

second duration is comparable to the 

visual rear seat belt warnings provided 

by currently deployed systems. For 

example, the visual rear belt warning in 

some MY2022 vehicles lasts for at least 

60 seconds.201 The change-of-status 

warning would involve an audio-visual 

alert lasting at least 30 seconds. While 

most vehicle models currently available 

in the U.S. with rear seat belt warning 

systems have a change-of-status warning 

that meets this 30-second minimum 

duration, we are aware of two available 

models that exceed this duration for the 

rear change-of-status warning. False 

positives would also be minimized 

because the positive-only compliance 

option only necessitates a buckle sensor, 

not occupant detection, which is more 

prone to false positives. 

Recent field experience also suggests 

that consumers would accept the 

proposed requirements. As noted 

earlier, an increasing number of vehicles 

sold in the United States have rear seat 

belt warning systems; based on 2022 

Purchasing with Safety in Mind: What 

to Look For When Buying a Vehicle 

information, 46.9% of the total vehicle 

projected sales are equipped with rear 

SBWS.202 Moreover, in connection with 

the 2010 RFC, GM commented that it 

has not received any complaints about 

its rear seat belt warning system in 

either the United States or Europe,203

and Volvo indicated that it had found a 

high level of acceptance for its 

system.204 In addition to this, many 

OEMs have implemented enhanced seat 

belt warnings for the front outboard 

seats over the past two decades. 

Consumers’ acceptance of these 

warnings also suggests that they would 

accept warnings for the rear seats. 

Finally, in addition to the research 

noted in the ANPRM we note the 

studies cited by the commenters that 

support our tentative conclusion that 

consumers would accept the proposed 

warnings. In 2012, IIHS conducted a 

national telephone survey of drivers and 

passengers about seat belt use. Using 

this survey data, it proceeded to 

conduct several studies. 

One study, cited by the commenters, 

was on the attitudes towards seat belt 

use and in-vehicle technologies for 

encouraging seat belt use.205 All 

respondents were asked questions 

regarding their belt use habits and 

perceptions of different types of seat 

belt interlocks. Part-time belt users and 

nonusers were additionally questioned 

about different types of reminders and 

reminder strategies. The survey found 

that enhanced reminders are more 

acceptable than seat belt interlocks and 

are viewed as having the potential to be 

as effective as interlocks if sufficiently 

persistent. A larger proportion of parttime belt users and nonusers said they 

would be more likely to buckle up in 

response to auditory and haptic 

reminders than visual reminders. More 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61706 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

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

attitudes toward front or rear child passenger belt 

use and seat belt reminders at these seating 

positions. Insurance Institute for Highway Safety, 

January 2013. 207For example, in NHTSA 2015 phone survey, 

for drivers of vehicles without a rear belt warning, 

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

the front outboard passenger seats) annoying, and 

16% would not need or want a seat belt warning 

system in their vehicle. 208See also, e.g., Highway Loss Data Inst., Ins. 

Inst. for Highway Safety, Unbelted: Adults Admit 

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

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

nonusers are not hard-core nonusers). 

209See also Section XIV, Overview of Benefits 

and Costs. 

than two-thirds of part-time belt users 

and at least one-third of nonusers said 

they would be more likely to buckle up 

in response to seat belt reminders that 

become more intense or continue 

indefinitely; these reminders would be 

acceptable to about half of part-time belt 

users and around one-fifth of nonusers. 

Another study cited by the 

commenters used the same survey that 

also collected information about drivers’ 

attitudes towards passenger belt use and 

belt reminders for front passengers and 

children in back seats.206 This study 

used the 477 respondents (of the 1,218 

total surveyed) that were drivers who 

transport a front-seat passenger at least 

once a week and 254 were drivers who 

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

the back seat. The respondents were 

asked about their attitudes toward seat 

belt use by their front passengers or rear 

child passengers and preferences for 

different passenger belt reminder 

features. The study found that nearly 

every driver who transports children in 

the back seat would encourage their belt 

use, regardless of the driver’s belt use 

habits. Most drivers who transport front 

passengers wanted passenger seat belt 

reminders to encourage passengers to 

buckle up. As far as signal 

characteristics, the study found that 

front and rear passenger reminder 

signals that last indefinitely would be 

acceptable to most drivers who 

transport these passengers, and that an 

audible alert may be especially useful to 

alert drivers to children unbuckling in 

the rear seat during a trip. 

We therefore tentatively conclude that 

consumers would accept the proposed 

warnings. NHTSA recognizes that there 

is some proportion of the public that 

may not desire a rear belt warning 

system.207 However, based on extensive 

research by NHTSA and others, we 

agree with commenters that consumers 

are more accepting of seat belt warnings 

now than in the 1970s.208 We are also 

mindful of Congress’s repeal of the 

duration limitation on the audible 

warning for the driver’s seat belt, as well 

as its directive to NHTSA to initiate a 

rulemaking for rear seat belt use 

systems. We believe this likewise 

suggests that the public would be 

amenable to appropriately specified 

warnings. NHTSA welcomes public 

comment on this issue. 

G. Technological and Economic 

Feasibility 

The ANPRM sought comment on the 

technological and economic feasibility 

of rear belt warning systems. 

Comments 

Several commenters stated that rear 

warnings are technically feasible. Four 

commenters stated that rear warning 

requirements in foreign markets show 

that such systems are technically 

feasible and available. Two commenters 

also noted that rear reminders are 

already available in a number of makes 

and models in the United States, with 

a commenter noting that Volvo has been 

offering such a system in the United 

States since 2009. 

A commenter said that because 

technological complexity and cost will 

depend on the specifics of the particular 

system, NHTSA should provide OEMs 

flexibility by establishing baseline 

performance requirements with 

compliance options that would allow 

for more advanced system 

characteristics. 

Another commenter stated that buses 

present challenges for a rear seat belt 

warning system with respect to the 

number of passengers and harshness of 

the interior environment. The 

commenter also said that it would be 

difficult integrating a passenger seat 

system with rear seat belt warnings that 

are the same as the OEM driver and 

copilot warning system, so that the 

warnings may not match. The 

commenter said that there are seat belt 

warning systems being developed that 

utilize wireless technology and such a 

system would be less complex than a 

wired electrical connection system. The 

limitation of a wireless system is the 

battery life, and more system features 

such as individual passenger alerts 

would reduce battery life further. 

However, a battery-operated wireless 

system would be much simpler for large 

vehicles with many passengers, as it 

would reduce the need for complex 

wiring systems. Another commenter 

believed that larger vehicles with many 

rear designated seating positions could 

present technical challenges, including 

the ability of a system to differentiate 

between objects that might be placed on 

seats and actual passengers of various 

weights and sizes. 

Agency Response 

NHTSA has tentatively concluded 

that the proposed requirements are 

technologically and economically 

practicable.209 Based on 2022 

Purchasing with Safety in Mind: What 

to Look For When Buying a Vehicle 

information, 46.9% of the total U.S. 

vehicle projected sales are equipped 

with rear seat belt warning systems. For 

vehicles that do not already incorporate 

a rear seat belt warning system, the 

positive-only compliance option would 

require seat belt sensors, wiring, and 

display adjustments. All of this 

technology is readily available. The seat 

belt latch sensors that would be needed 

for all three systems are already used by 

many manufacturers to comply with the 

existing driver seat belt requirements. 

Occupant detection might present 

technological challenges but would not 

be necessary for a positive-only warning 

system. As we explain in more detail in 

Section XIV, Overview of Costs and 

Benefits, we estimate that the minimum 

cost to comply with the rear seat belt 

warning requirements (the positive-only 

system) would be $167.8 million. This 

is based on a per-vehicle cost of $19.59 

for 53.1% of 16M affected new vehicles. 

As explained later, our preliminary 

regulatory impact analysis indicates that 

the proposed requirements are costbeneficial across a range of discount 

rates and reasonable effectiveness 

estimates. 

As we noted in the ANPRM, 

implementing a visual warning may 

require physical redesign of the 

instrument panel. Such redesign would 

have to take into account visibility, 

interaction with existing signals and 

displays, available space on the 

instrument panel, and effectiveness, as 

well as other factors. In some instances, 

a visual signal might be displayed as a 

telltale on the instrument panel or on 

the vehicle’s information display screen. 

Manufacturers would also have to 

determine whether driver and rear 

passenger seat belt warning visual 

signals would be treated the same. 

We also recognize that vehicles with 

many rear designated seating positions 

may present some challenges, but we 

have tentatively concluded that they 

should be subject to the proposed 

requirements (with the exception of 

school buses) because those vehicles 

would be at least as likely, if not more 

likely, to have rear occupants. In 

addition, multiple rear seats may 

increase the difficulty of the driver in 

ascertaining rear seat belt use, so a 

warning could prove especially useful 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61707 

210 In Section XIII.C we discuss the potential for 

more than one front outboard passenger seat in 

ADS-equipped vehicles. 

211See, 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.’’). 

212Section 8.4.1.1. 

213National Center for Statistics and Analysis. 

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

results (Traffic Safety Facts Research Note. Report 

No. DOT HS 813 072). National Highway Traffic 

Safety Administration. 

214There are some compliance options for certain 

trucks and MPVs that permit passive protection in 

lieu of seat belts at the front outboard seating 

positions. See S4.2.3 (compliance options for trucks 

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

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

van-type trucks and vehicles designed to be sold 

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

less). 

in these vehicles. We also recognize the 

intent of the MAP–21 requirements in 

improving protection for rear occupants, 

and given the proven benefits of seat 

belts, believe the warning should be 

broadly applied. Our main motivation 

for including small buses is to capture 

large capacity passenger vans; these 

vehicles might utilize the option of a 

warning that indicates the number of 

seat belts fastened. However, we do seek 

comment on whether it would be 

appropriate to exclude additional 

vehicle types. 

Overall, we believe that the proposed 

compliance options would provide 

manufacturers with the flexibility to 

innovate and develop new technologies, 

while also ensuring a minimum level of 

safety. We seek comments on the 

practicability of the proposed 

compliance options. 

XI. Warning Requirements for Front 

Outboard Seats 

We propose several changes and 

enhancements to the seat belt warning 

requirements for the front outboard 

seats. There are three main changes we 

are proposing. 

First, we are proposing a requirement 

for an audio-visual warning on vehicle 

start-up for the front outboard passenger 

seat. Currently, the standard requires a 

short duration (4–60 seconds, 

depending on the compliance option) 

audio-visual seat belt warning on 

vehicle start-up for the driver’s seat belt 

for most vehicles with a GVWR under 

10,000 lb (excluding medium-sized 

buses), but not for any other front seats. 

The vast majority of the vehicles being 

sold today (approximately 96.6% of the 

fleet, according to information 

submitted by vehicle manufacturers to 

NHTSA for NCAP in MY 2022) already 

provide a seat belt warning for the front 

outboard passenger seat. We propose to 

require a seat belt warning for this seat 

to ensure that all vehicles have this 

important safety feature. 

Second, we propose to close the 

current gap for a driver’s seat belt 

warning in medium-sized buses. We are 

unaware of any such buses that do not 

already provide a driver’s seat belt 

warning; requiring this would ensure 

that they continue to have a driver seat 

belt warning in the future. 

Third, we propose several changes to 

the current requirements for the audiovisual warning signal that currently 

apply to the driver’s seat that would 

also apply to the front outboard 

passenger seat. The most notable of 

these is that we propose to require that 

the audio-visual warning on vehicle 

start-up last until the belts at any 

occupied front outboard seats are 

fastened, and a change-of-status warning 

for any front outboard seat that would 

also last until the seat belt is refastened 

(unless a front door is open). 

These proposals are explained in 

more detail below. 

A. Seat Belt Warning for Front Outboard 

Passenger Seat 

This document proposes to require an 

audio-visual seat belt warning for any 

front outboard passenger seat.210

FMVSS No. 208 currently requires an 

audio-visual seat belt warning for the 

driver’s seat in passenger cars and 

trucks, buses, and MPVs with a GVWR 

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

buses with a GVWR greater than 3,855 

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

4,536 kg (10,000 lb). NHTSA’s 

regulations currently do not require seat 

belt warnings for any seating position 

other than the driver’s seat.211 Although 

the ANPRM did not discuss extending 

the seat belt warning requirements to 

any front passenger seats, two 

commenters recommended that NHTSA 

amend FMVSS No. 208 to require a seat 

belt warning for all front seats, and 

another commenter recommended 

adopting the ECE R16 requirements for 

front outboard seating positions. ECE 

R16 requires an audio-visual seat belt 

warning for the front outboard 

passenger seat.212

We believe there is good reason to do 

so, as the reasons for ensuring the driver 

is buckled apply equally to front 

outboard passenger. About 10.4% of 

right-front passengers do not always 

fasten the belt 213 and unbelted 

occupants are overrepresented in fatal 

crashes. The lack of a seat belt warning 

requirement for the front outboard 

passenger seat dates to the 1970s, when 

seat belt use rates were much lower and 

seat belt warnings were not as 

acceptable to consumers as they are 

today. Further, almost all (96.6%) 

vehicles offered for sale in the U.S. that 

participate in the NCAP information 

request are already equipped with a seat 

belt warning at this position, so 

requiring such a warning would ensure 

that all vehicles be equipped with a seat 

belt warning at this position. 

We are proposing an audio-visual 

warning on vehicle start-up because 

research by NHTSA and others suggests 

that seat belt warnings that use an 

audio-visual signal are more effective 

than visual warnings alone. In addition, 

the potential technological, consumer 

acceptance, and cost issues associated 

with requiring an audible warning for a 

rear seat belt warning do not apply to 

an audible warning for the front 

outboard passenger seat because, 

although the audible warning would 

entail use of occupant detection 

technology, most vehicles are already 

equipped with both an audible seat belt 

warning and occupant detection for the 

front outboard passenger seat. This 

proposal would not require that the 

audible warning be specific to either the 

driver or front outboard passenger seat; 

therefore, manufacturers could utilize 

the same audible warning for both seats 

as is done with some of the existing 

front belt warning systems. 

The proposed front outboard 

passenger seat requirements would 

apply to all the vehicles to which the 

proposed rear belt warning 

requirements would apply: all front 

outboard designated seating positions in 

passenger cars, and all front outboard 

designated seating positions certified to 

a compliance option requiring seat belts 

in trucks, MPVs, and buses with a 

GVWR of 4,536 kg (10,000 lb) or less.214

We have tentatively decided not to 

extend the seat belt warning 

requirements to front center seats 

because our preliminary regulatory 

impact analysis found that a system for 

the front center seat without occupant 

detection would provide limited benefit 

due to the low occupancy of the front 

center seat and the limited number of 

vehicles in the fleet with a front center 

seat. See Section XIII, Regulatory 

Alternatives, and the PRIA for a more 

detailed analysis. 

Occupant Detection 

Because we are proposing an audiovisual warning, we are also proposing to 

require that any front outboard 

passenger seat be equipped with an 

occupant detection system; an audiovisual warning is typically only 

appropriate for occupied seats because 

having an audible warning activate for 

an unoccupied seat could be a nuisance 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61708 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

215Occupant detection is utilized by the 

advanced air bags to properly classify the occupant 

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

so that the advanced frontal air bag systems can 

determine if and with what level of power the front 

air bag will inflate. We also believe that occupant 

detection is voluntarily used in the front passenger 

seat to avoid having an audible seat belt warning 

activate for an unoccupied seat. 

216Occupant detection systems are less 

challenging for the front outboard passenger seat 

than for the rear seats because the front outboard 

passenger seat is not typically subject to as many 

of the potential complications to occupant detection 

(such as large occupants spanning multiple seating 

positions). There may be infrequent situations 

where occupant detection sensors may incorrectly 

register the presence of an occupant when the seat 

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

occupant). However, if cargo placed on the seat 

causes a false occupant detection reading and 

inadvertent activation of the front passenger seat 

belt warning signal, the driver can readily discern 

it is a false reading and can easily either place the 

cargo on the floor or fasten the seat belt to disable 

the signal. 217S7.3. 

218The laboratory procedures are not part the 

regulatory text. Published separately by NHTSA’s 

Office of Vehicle Safety Compliance, they are 

intended to provide laboratories contracted by 

NHTSA with additional guidelines for obtaining 

compliance test data. 

219Citing www.norc.org/Research/Projects/Pages/ 

underutilized-strategies-in-traffic-safety-results-ofa-nationally-representative-survey.aspx (last 

accessed Oct. 25, 2021). 

220Citing Highway Loss Data Inst., Ins. Inst. for 

Highway Safety, Unbelted: Adults Admit They 

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

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

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

accessed Oct. 25, 2021). 

for the occupants and might desensitize 

them to the warning or lead them to 

circumvent the system. Requiring 

occupant detection is consistent with 

Euro NCAP, which requires occupant 

detection for the front passenger seat 

belt warning. In the United States, 

occupant detection is already widely 

deployed in the front outboard 

passenger seat, either as part of an 

advanced air bag system, or as part of 

a voluntary seat belt warning system.215

Based on compliance and consumer 

information data submitted to NHTSA 

by vehicle manufacturers, NHTSA is not 

aware of any vehicles to which the 

proposed requirements would apply 

that are not already equipped with 

occupant detection for this seating 

position. This demonstrates that the 

technology is feasible and that an 

occupant detection requirement would 

not result in any additional costs.216 It 

would also ensure that vehicles 

produced in the future would be 

equipped with the technology. 

We propose that the warning system 

consider this seating position 

‘‘occupied’’ when an occupant who 

weighs at least 46.7 kg (103 lb) and is 

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

the seat. These values are the weight 

and height criteria currently specified in 

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

who is used as an alternative for the 5th 

percentile adult female test dummy for 

compliance testing of advanced air bag 

systems utilizing static suppression. 

These criteria are consistent with the 

agency’s recommendation on not 

transporting children in the front seat, 

as well as Euro NCAP and the ECE R16 

test procedures. As described below, in 

connection with the proposed test 

procedures (Section XII.B, Test 

Procedures), the agency would use 

either a person or test dummy meeting 

these criteria. 

B. Driver’s Seat Belt Warning for 

Medium-Sized Buses 

FMVSS No. 208 currently does not 

require buses with a GVWR greater than 

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

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

GVWR less than or equal to 3,855 kg 

(8,500 lb) and an unloaded weight 

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

equipped with a driver seat belt 

warning. We are proposing to amend 

FMVSS No. 208 to close this loophole. 

We are unaware of any such buses 

that do not already have a driver seat 

belt warning that meets or surpasses the 

warning specified in FMVSS No. 208. 

Accordingly, we believe this 

requirement would have minimal, if 

any, costs or benefits. Requiring a driver 

seat belt warning for these buses would 

ensure that they continue to have a 

driver seat belt warning in the future. 

We invite comments on this proposal 

and these assumptions. 

C. Amendments to the Current Warning 

Signal Requirements 

The current driver’s seat belt warning 

requirements provide manufacturers 

with two compliance options.217 The 

first option requires that if the key is in 

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

belt is not in use, the vehicle must 

provide a visual warning for at least 60 

seconds, and an audible warning that 

lasts 4 to 8 seconds. Under the second 

option, when the key is turned to the 

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

must provide a visual warning for 4 to 

8 seconds (regardless of whether the 

driver seat belt is fastened) and an 

audible warning lasting 4 to 8 seconds 

if the driver seat belt is not in use. 

We propose to modify these 

requirements in three main ways. First, 

we propose a single compliance option 

that requires a start-of-trip audio-visual 

warning that lasts until the seat belt at 

any occupied front outboard seat is 

fastened. Second, we propose to require 

an audio-visual change-of-status 

warning if a buckled belt at either of 

these seating positions is unfastened in 

the middle of a trip. Third, we propose 

some additional requirements for the 

audible warning related to increasing 

the duration (for example, specifying a 

minimum 0.20 duty cycle for the 

audible warning); however, we 

generally do not propose requirements 

beyond what is currently in the 

standard related to other aspects of the 

warning. These proposals are explained 

in more detail below. 

1. Increasing the Duration of the AudioVisual Warning on Vehicle Start-Up 

The current eight-second limitation 

on the duration of the audible warning 

was based on a statutory restriction, 

enacted in 1974, that limited the length 

of the audible warning. MAP–21 

repealed this limitation. In light of 

MAP–21’s repeal of the 8-second 

limitation, the ANPRM sought comment 

on removing the corresponding 

limitation in FMVSS No. 208. 

Comments 

Several commenters supported 

removing this restriction. One 

commenter said that removing it would 

provide manufacturers with greater 

regulatory certainty in deploying 

enhanced seat belt reminders, although, 

the commenter stated, there needs to be 

an upper bound on the duration of the 

required warning to ensure an objective 

and repeatable test for the purposes of 

vehicle certification. The commenter 

recommended maintaining the current 

4- to 8-second warning thresholds 

defined in table 4 of the FMVSS No. 208 

laboratory test procedures.218 Another 

commenter encouraged NHTSA to allow 

enhanced seat belt reminder systems as 

a compliance option, possibly in lieu of 

the currently required 4 to 8 second 

alarm. A commenter recommended 

increasing the minimum duration for 

the audible warning to at least 90 

seconds because the current audible 

signal duration upper limit is ineffective 

for increasing seat belt use (and cited 

studies to support this 

recommendation). Related to this, a 

commenter stated that a survey of 2,000 

drivers it commissioned showed that 70 

percent favored a law requiring seat belt 

reminders that continuously chime until 

the seat belt is buckled, including rear 

seat passengers,219 and a commenter 

noted a 2012 IIHS survey showing that 

most motorists supported enhanced belt 

reminders that were ‘‘more persistent 

and intense’’ than what most 

automakers offered at the time.220

On the other hand, a commenter 

recommended that NHTSA incorporate 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61709 

221What is now the second compliance option 

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

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

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

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

second (and original) compliance option requires an 

‘‘advisory’’ visual warning that is required to 

activate regardless of whether the seat belt is 

buckled; the purpose for this, as NHTSA explained 

in 1974, was so the ‘‘reminder would remain 

effective even if the belt were disabled to silence 

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

rulemaking preamble also suggested that this would 

serve to remind other occupants to buckle their 

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

selected ‘‘because an irritating light can be easily 

ignored or disabled, a visual signal can effectively 

serve only a reminder function, and as such, it 

should be as simple as possible. The NHTSA 

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

calculated to accomplish the advisory function.’’ 39 

FR 42692. The first compliance option was added 

in response to a petition for rulemaking from 

General Motors to allow manufacturers to use a 

safety belt warning system meeting the 

requirements for automatic safety belt warning 

systems as an alternative to the warning system that 

was specified for manual belt systems. 

222See Section III, Regulatory and Legislative 

History. Similarly, an advisory warning for other 

seating positions is not necessary because if the 

proposal is adopted the front outboard passenger 

seat and the rear seats would have warnings 

specifically for those seats. 

223See supra note 38. 

224Specifically, we received information on 

driver visual warning duration for 599 models for; 

driver audible warning duration for 599 models; 

front outboard passenger visual warning duration 

for 564 models; and front outboard passenger 

audible warning duration for 558 models. The 

number of models differs because some models for 

which a vehicle manufacturer submitted 

information did not include complete information 

on the front outboard seat belt warnings and some 

vehicles are not equipped with a front passenger 

seat belt warning system. 

225The 300–329 second interval consists of 

vehicles from just one manufacturer, all of which 

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

interval includes a variety of different-make vehicle 

models with different reminder durations. 

the Euro NCAP enhanced seat belt 

reminder requirements in the U.S. 

NCAP program if the agency wants to 

encourage enhanced seat belt reminders 

that provide driver warnings beyond 8- 

seconds. 

A commenter recommended that the 

front and rear requirements be 

consistent with respect to the required 

duration of the audible warning. 

Agency Response 

NHTSA has tentatively decided to 

increase the required duration for the 

audio-visual warning provided on 

vehicle start-up to occupants of the front 

outboard seats. The extremely short 

duration currently required for the 

driver’s seat belt warning—which 

originated in the early 1970s—is 

outdated.221 It was premised on the 

since-repealed eight-second statutory 

limitation on the audible warning 

duration, then-existing low seat belt use 

rates, and consumer resistance to 

enhanced warnings, and the related lack 

of such warnings in most vehicles. 

These circumstances no longer hold. 

There are several respects in which the 

current requirements are therefore not 

relevant to today’s market. 

First, the existing requirements are 

significantly exceeded by the warnings 

provided in current vehicles. Although 

NHTSA did not previously have the 

authority to require a seat belt warning 

with an audible signal lasting more than 

8 seconds, starting in at least the early 

2000s, manufacturers voluntarily began 

providing enhanced audio-visual 

warnings exceeding the FMVSS No. 

208-minimum durations.222 In order to 

get a better sense of the warning 

durations in currently sold vehicles, 

NHTSA analyzed data on the seat belt 

warning durations for MY 2022 vehicle 

models provided to the agency by 

vehicle manufacturers for NCAP; this 

data covers most vehicles offered for 

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

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

less.223 In total, we received seat belt 

duration information on over 500 

different vehicle models.224 For each 

vehicle model, we looked at the warning 

durations for the visual and audible 

warnings for the driver and front 

outboard passengers seat belts, as well 

as the reported projected sales for that 

model as a proportion of the total 

projected sales for all of the vehicle 

models for which data was provided to 

NHTSA. We then tabulated this data to 

determine how warning durations were 

distributed across the new vehicle fleet. 

Specifically, we divided the range of 

warning durations provided—ranging 

from six seconds to indefinitely long— 

into intervals. For each interval, we 

summed up the projected vehicle sales 

of all the vehicle models providing a 

warning with a duration falling within 

that interval and divided that sum by 

the total projected sales of all vehicle 

models. In general, we found that 

roughly half of new light vehicles 

provide a visual warning that lasts until 

the belt is fastened and an audible 

warning that lasts at least two minutes 

(120 sec). In the discussion later, we 

discuss this data in more detail. We also 

looked at the warning durations 

provided in new vehicles tabulated by 

vehicle model instead of projected sales. 

The results are generally the same, 

although there are some differences 

compared to the vehicle sales analysis 

presented here. These data and results 

are presented in appendix A. 

With respect to the driver visual 

warning, the majority of new vehicles— 

over 60% as a percentage of total 

projected sales volume—have a warning 

that lasts until the belt is fastened 

(Figure 3). The remainder of the fleet is 

about equally divided between a 5- 

minute (300 second) visual warning and 

a visual warning lasting at least 1.5 

minutes, but less than 2 minutes (90– 

119 seconds).225 Less than 2% of the 

fleet has a warning lasting less than 1.5 

minutes (90 sec). The results for the 

front outboard passenger visual warning 

are essentially the same as for the driver 

seat belt visual warning. See Figure 4. 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61710 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

226For the driver audible warning, the 0–29 

second interval consists of a number of different 

vehicle makes, all of which provide either a six or 

eight-second warning. 

With respect to the driver audible 

warning, all of the vehicles for which 

NHTSA had data have an audible 

warning lasting longer than the 

regulatory minimum of 4 seconds. A 

small number of vehicles (about 1% as 

a share of total projected sales volume) 

have an audible warning that last six or 

eight seconds.226 See Figure 5. Thus, a 

very small proportion of the current 

vehicle fleet provide the very lowduration audible warning currently 

required by FMVSS No. 208. 

Instead, almost all new vehicles 

provide a driver audible warning that 

significantly exceeds the current 

minimum. Overall, about 99% of 

vehicles (by share of total projected 

sales volume) provide an audible 

warning that lasts at least 30 seconds, 

and about 92% of vehicles provide an 

audible warning that lasts at least 1.5 

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

of the fleet (47%) provide an audible 

warning that lasts two minutes or more 

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

audible warning with a finite length, the 

sales-weighted mean is 2.9 minutes (174 

seconds) and the median is 1.7 minutes 

(100 seconds). 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP07SE23.002</GPH> EP07SE23.003</GPH>
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61711 

227 90, 96, 100, and 108 seconds are the most used 

durations in that range, but there are other 

durations too. 100 seconds is the most used. 

228The only warning duration provided in the 

300–329 sec interval is 300 sec. 

229Specifically, these are all on vehicles from one 

manufacturer, which provide an audible warning 

lasting 261 s. 

230The sale-weighted mean for the front 

passenger audible warning is 176.57 and the 

median is 96. 

231 It also might be the case that so-called ‘‘hardcore’’ nonusers, who comprise about 11–17% of 

nonusers, would use the belt if the reminder were 

sufficiently annoying, although, for the purposes of 

our effectiveness (and benefits) analysis, we 

conservatively assume that the increase in belt use 

would be due entirely to part-time nonusers. 232 DOT 2009 Belt Warning Study, p. 1 

(‘‘Although improvements in seat belt use rates 

appear to result from ESBRs, there is not yet good 

evidence concerning what works best and why a 

given system may influence occupant behavior.’’). 

233See, e.g., DOT 2009 Belt warning Study, pp. 

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

The effects of persistent audible seat belt reminders 

and a speed-limiting interlock on the seat belt use 

of drivers who do not always use a seat belt. 

Insurance Institute for Highway Safety (2019) 

(‘‘Persistent enhanced reminders with longer-lasting 

or more frequent auditory chimes have been found 

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

(citing NHTSA research). 

Turning to the specific durations 

provided for the driver audible seat belt 

warning, about half of new vehicles 

(45.5% as a share of total projected sales 

volume) provide a warning that lasts 

90–to–119 s (1.5 s¥1.98 s).227 See 

Figure 5. The longest-duration audible 

warnings, provided by two vehicle 

manufacturers, last until the belt has 

been buckled (accounting for about 8% 

of new vehicles sold). The longest 

limited-duration audible warnings, 

lasting 5 and 8 minutes (300 and 480 

seconds) are provided by two 

manufacturers (about 22% of new 

vehicles).228 The other duration that is 

used in a non-trivial share of new 

vehicles is from 4 min¥4.5 min (240 

s¥269 s) (about 12% of new 

vehicles).229 The corresponding analysis 

for the front outboard passenger seat 

belt warning is very similar.230 See 

Figure 7 and Figure 8. 

Second, we tentatively agree with 

IIHS that the current audible signal 

duration upper limit of eight seconds is 

ineffective for increasing seat belt use. 

From the vehicle survey data presented 

here, it is clearly not a factor affecting 

vehicle design. As discussed earlier in 

this preamble, front seat belt use rates 

have plateaued in recent years so that 

about 10% of front-row occupants do 

not always use a seat belt. Coupled with 

this, we note that approximately 83– 

89% of nonusers are part-time nonusers 

who would be open to using a belt.231

Although research may not yet have 

firmly established which exact system 

specifications are optimal,232 research 

by NHTSA and others suggests that 

audio-visual warnings are more effective 

than visual warnings alone and that 

longer duration warnings are more 

effective than shorter duration 

warnings.233 NHTSA’s earlier research 

estimated that an enhanced reminder, 

on average, increased seat belt use three 

to four percentage points compared to 

the basic reminder currently required by 

FMVSS No. 208. IIHS in its comment 

cited recent research it had conducted 

that evaluated the effectiveness of three 

different driver’s seat belt reminders. 

All of the reminders had a visual 

warning that persisted until the seat belt 

was fastened but had audible reminders 

of varying duration. The research found 

that, compared to a short intermittent 

audible reminder (specifically, three 

intermittent 7-second audible 

reminders), an audible reminder with an 

indefinite duration increased seat belt 

use by 34%, and an audible reminder 

with a 100-second duration increased 

seat belt use by 30%. However, we note 

that more than 90% of MY 2022 

vehicles already have audible warnings 

of at least 90 seconds, but only about 

8% have an indefinite reminder. For 

more information on these effectiveness 

estimates, see Section XIV, Costs and 

Benefits. 

Third, we tentatively believe that 

contemporary consumers would accept 

a longer warning. As we discussed 

earlier in this preamble, in the early 

1970s, NHTSA faced consumer backlash 

when it required long-lasting seat belt 

warnings. However, consumer behavior 

and attitudes have changed since then— 

seat belt use is more widespread, and 

opposition to using a seat belt is much 

less prevalent than it was in the 1970s. 

This is evidenced by MAP–21’s repeal 

of the eight-second audible seat belt 

warning limitation, and by the fact that 

almost all light vehicles sold in the U.S. 

now feature relatively long duration 

visual and audible warnings for the 

front outboard seats. Research by 

NHTSA and others suggests that 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP07SE23.004</GPH>
61712 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

234 Kidd, McCartt, & Oesch. Attitudes Towards 

Seat Belt Use and In-Vehicle Technologies for 

Encouraging Belt Use. Insurance Institute for 

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

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

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

intense enhanced reminders is a promising way to 

increase belt use among part-time belt users, but 

public acceptance still is a concern because the 

characteristics that make reminders more effective 

also are the characteristics that make them more 

annoying. It is not clear how intense a reminder 

needs to be to increase belt use among the 

remaining part-time belt users and non-users and 

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

(citation omitted). 

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

attitudes toward front or rear child passenger belt 

use and seat belt reminders at these seating 

positions. Insurance Institute for Highway Safety, 

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

auditory front passenger reminders might not be 

acceptable to these drivers, so it is important to find 

ways to reduce the potential annoyance of front 

passenger reminders without compromising their 

effectiveness.’’). 

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

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

237See, e.g., DOT 2009 Seat Belt Study at 54, 58 

(while research to date on front seat systems 

suggests that features such as a longer-lasting 

flashing visual warning might be more effective 

than a basic system, some warnings that may be 

more effective could also be more annoying to 

occupants). 

238See DOT 2009 Seat Belt Study at 60. 

239 DOT 2009 Belt Warning Study, p. 8; Schroeder 

& Wilbur, supra, p. 33. 

240N. Lerner et al. 2007. Acceptability and 

Potential Effectiveness of Enhanced Seat Belt 

Reminder System Features. DOT HS 810 848. 

Washington, DC: National Highway Traffic Safety 

Administration, p. 41–42 

consumers would potentially accept an 

appreciably longer duration warning. As 

we noted above in connection with the 

rear seat belt warning (Section X.F, 

Consumer Acceptance), NHTSA’s 

research suggests that part-time belt 

users are receptive to seat belt warning 

technologies, including front seat belt 

warnings. Furthermore, more recent 

research by others suggests support for 

more persistent reminders. IIHS’s 

research has found that, while public 

acceptance of intense reminders was a 

concern, seat belt reminders that 

become more intense or continue 

indefinitely would be acceptable to 

about half of part-time belt users and 

around one-fifth of nonusers.234

Another IIHS study found that, while its 

data was subject to some limitations, 

‘‘most drivers who transport front 

passengers wanted . . . reminders that 

last indefinitely until the front 

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

that stronger front passenger reminders, 

such as those meeting Euro NCAP’s 

design requirements, may be acceptable 

to most drivers who transport front 

passengers.’’ 235 We also note the studies 

cited by NSC and CAS suggesting strong 

support for more persistent—and even 

indefinitely long—reminders. At the 

same time, we do acknowledge that 

while enhanced warnings are 

potentially more effective, they are also 

more intrusive.236 They therefore 

present potential consumer acceptance 

challenges that may reduce their 

effectiveness.237 NHTSA’s earlier 

research suggests that it may be 

challenging to design a warning system 

with effective yet acceptable 

characteristics,238 and that no clear 

consensus exists about which warning 

system features are most acceptable.239

It also noted that while it appears that 

a majority of the general public accepts 

seat belt reminders, the data on public 

acceptance is somewhat limited and 

anecdotal, and that resistance by a 

minority of the public could limit 

overall public acceptability.240

However, based on the best data 

available to us, we tentatively believe 

that consumers would accept an audiovisual front seat belt reminder with a 

significantly longer duration than the 

standard currently requires, including 

an indefinite duration. 

Fourth, the technology necessary to 

implement such an enhanced warning is 

already standard equipment on almost 

all light vehicles. An enhanced warning 

that activates for an unoccupied seat 

could be a nuisance that either 

desensitizes the occupants to the 

warning, or leads them to circumvent or 

defeat the warning. Enhanced warnings 

therefore generally need to work in 

conjunction with an occupant detection 

system. This makes light vehicle front 

outboard seats well-suited for enhanced 

warnings, because almost all front 

outboard seats are already equipped 

with occupant classifications systems in 

order to comply with the advanced air 

bag requirements. Seat belt warnings for 

the front outboard seats are therefore 

capable of being activated only when an 

unbelted occupant is present, which 

greatly diminishes the risk of false 

warnings. Accordingly, increasing the 

reminder duration would entail 

minimal costs. 

Finally, a longer-duration is 

consistent with seat belt warning 

durations required or encouraged in 

other markets and ratings programs. ECE 

R16 requires that for the front seats 

there be a 30 second visual warning 

when the front seat belts are not 

fastened and the ignition is activated. It 

also requires an audio-visual warning 

that must activate for at least 30 seconds 

if the seat belt remains unfastened and 

specific onset criteria are met (e.g., 

distance traveled, speed, etc.). To 

prevent unnecessary signals, both ECE 

R16 and Euro NCAP require that the 

system be capable of detecting whether 

the front passenger seat is occupied. The 

Euro NCAP assessment protocol 

requires a visual signal that remains 

active until the seat belt is fastened, and 

a two-stage audible signal; the initial 

audible signal must not exceed 30 

seconds and the final audible signal 

must be at least 90 seconds. Similar to 

Euro NCAP, under the IIHS seat belt 

reminder system ratings protocol, the 

primary audible reminder signal for the 

front outboard seats must be at least 90 

seconds in total duration in order to 

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

Although ECE R16 does not require an 

indefinite reminder, such a reminder 

would comply with that standard, as 

they do not contain a maximum length. 

We are therefore proposing to increase 

the minimum duration of the audiovisual warning for the front outboard 

seat belts on vehicle start-up. In 

developing this proposal, we considered 

a range of alternative warning durations. 

At the upper end of the range is an 

indefinite reminder—a reminder that 

remains activated until the occupant 

fastens the seat belt. Short of this are 

reminders that have relatively long 

durations, but do not last indefinitely. 

Because there is a large range of 

durations that could be selected, in 

order to help structure the proposal (and 

aid comment) we considered the 

following ‘‘buckets’’ of reminder 

durations, based on the front audible 

warning durations provided in MY 2022 

light vehicles offered for sale in the U.S. 

as well as the durations specified in ECE 

R16, Euro NCAP, and the IIHS ratings 

protocol: 

• Less than thirty seconds (less than 

required in Europe and provided in only 

about 1% of new vehicles offered for 

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

• 30 seconds up to but not including 

90 seconds (1.5 minutes) (consistent 

with ECE R16, and provided in about 

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

• 90 seconds (1.5 minutes) up to but 

not including 2 minutes (consistent 

with Euro NCAP, and provided in about 

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

• 2 minutes (120 sec) up to (and 

including) 5 minutes (300 seconds) (the 

approximate mid-range of the audible 

warning durations provided in MY 2022 

vehicles in the U.S.); 

• Greater than 5 minutes (300 sec) but 

not indefinite (which includes the 

longest limited-duration audible 

warning, 8 minutes (480 sec) (provided 

in about 8% of new vehicles in the 

U.S.); and 

• Indefinite duration (currently 

adopted by two vehicle manufacturers, 

accounting for about 8% of new 

vehicles in the U.S.). 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61713 

We have tentatively decided to 

propose requiring an audio-visual 

reminder that lasts until the belts are 

fastened at any occupied front outboard 

seating position, in light of the increase 

in roadway fatalities and the lack of 

improvement of front seat belt use rates. 

We also tentatively believe this is 

supported by the favorable ratio of parttime to hard-core seat belt nonusers, 

surveys indicating a significant level of 

acceptance for enhanced seat belt 

warnings, and the fact that a non-trivial 

share of currently sold vehicles have an 

indefinite-duration reminder. These 

vehicles incorporating the indefinite 

warning support the practicability of the 

proposal. Additionally, the small 

percentage of market penetration 

provides the greatest opportunity for 

potential benefit (see section XIII). We 

also believe that other warning signal 

characteristics—such as duty cycle, 

frequency, volume, or timbre—can be 

adjusted to balance effectiveness and 

consumer acceptance; manufacturers 

would have the flexibility to adjust 

these or other aspects of the warning, 

within certain limits, as discussed 

further below. We do not agree with 

Global that an upper bound on the 

warning duration is necessary for 

objectivity. The warning simply would 

be required to remain active as long as 

the belt were unfastened at an occupied 

seat; NHTSA’s compliance test would 

necessarily have to stop at some point, 

but NHTSA could make the test time as 

long as it wanted and manufacturers 

would have to certify that the warning 

would be indefinite. 

NHTSA seeks comment on this 

proposal. If opposed to an indefinite 

warning, what data support limiting its 

duration? If NHTSA were to instead 

require an enhanced but limitedduration warning, how long should the 

warning be? We also seek comment 

from manufacturers (and others) about 

the basis for the warning durations 

provided in current vehicles, 

particularly the warnings that exceed 

the Euro NCAP duration (90 sec); for 

example, the basis for the 5-minute 

warning, or the 8-minute warning, or 

the indefinite warning. We also seek 

comment on the effectiveness and 

consumer acceptance of the proposed 

and alternative durations. One reason a 

shorter duration could be more effective 

is that some seat belt nonusers might be 

more likely to habitually circumvent an 

indefinite-duration warning as opposed 

to a limited-duration warning. However, 

such an assumption presupposes there 

is some limited duration for which a 

nonuser would be less likely to 

circumvent. What would such a 

duration be, and would it have a 

reduced effectiveness over a longer or 

indefinite limit such that the benefit 

from reduced circumvention was offset 

by a lower effectiveness? We also seek 

any additional data on effectiveness or 

acceptance, or any relevant studies that 

NHTSA has not identified in the 

preamble or the PRIA. 

We also seek comment on whether the 

required durations for the visual and 

audible components of the warning 

should be identical or different (for 

example, requiring an indefinitely long 

visual warning and an audible warning 

that is of a relatively long, but limited, 

duration)? Similarly, should the 

warning durations for the driver and 

passenger differ or be identical? We also 

recognize that duration is not the only 

warning signal characteristic that might 

increase effectiveness (and affect 

acceptance); we seek comment on 

whether NHTSA should set minimum 

performance requirements for other 

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

audible warning and frequency of visual 

flashing warning and intermittent 

audible warning) in lieu of or in 

addition to an increase in the warning 

duration, and the empirical support for 

such a choice. We discuss proposed 

limits and seek comment on certain 

parameters related to the audible 

warning below. 

2. Requiring an Audio-Visual Change-ofStatus Warning 

NHTSA also proposes to require an 

audio-visual warning whenever the 

driver or front outboard passenger seat 

belt is unfastened during a trip. 

Although the driver may be aware that 

the front outboard passenger seat belt 

has been unfastened, we believe a 

change-of-status warning may encourage 

or remind front outboard passengers to 

refasten their seat belt. We propose an 

audio-visual warning consisting of a 

continuous or flashing visual warning of 

icons or text visible to the driver and 

any front outboard passenger and a 

continuous or intermittent audible 

signal lasting until the seat belt is 

refastened. The warning would be 

required to activate when the vehicle’s 

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

position, the vehicle’s transmission 

selector is in a forward or reverse gear, 

and the driver and or front outboard 

passenger seat belt status changes from 

in use to not in use. However, similar 

to the Euro NCAP protocol 

requirements, if the change-of-status 

occurs and a front door on the same side 

of the vehicle as the belt triggering the 

warning is open, the system can 

consider that the start of a new trip. The 

proposed indefinite duration is longer 

than the minimum 30-second duration 

proposed for the rear seat belt changeof-status warning. We tentatively 

believe a longer duration for the front 

seat belt warning is justified because it 

does not pose the same potential for 

driver distraction as it does for the rear 

seat belt warning. Additionally, if the 

change-of-status is finite, this would 

essentially provide a method of 

circumventing the indefinite startup 

warning, i.e., an occupant could be 

buckled at startup, but then unbuckle 

during the trip and only receive a fixed 

duration warning. 

ECE R16 essentially requires the same 

change-of-status warning requirements 

for the front and rear seats (the duration 

is generally about 30 seconds unless the 

belt is fastened sooner), so the reader is 

referred to the discussion of the changeof-status warning in connection with the 

rear seat belt warning proposal (Section 

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

change-of-status warning must 

essentially meet the requirements of the 

initial warning, but those requirements 

are different for the front and rear seats. 

Again, for the front seats, Euro NCAP 

specifies that for the initial warning a 

visual signal shall remain active until 

the seat belt is fastened, and specifies a 

two-stage audible signal; the initial 

audible signal must not exceed 30 

seconds and the final audible signal 

must be at least 90 seconds. 

We seek comment on the proposed 

change-of-status warning. What types of 

change-of-status warnings are vehicle 

manufacturers currently using for the 

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

duration, etc.)? NHTSA is also 

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

warning, a limited-duration change-ofstatus warning. Would a limitedduration change-of-status warning be 

preferable? And should it be identical to 

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

reason to require different warnings 

(with respect to any warning signal 

characteristic, but especially duration)? 

How are vehicle manufacturers 

currently handling change-of-status 

events that occur when the vehicle is 

stopped or at low vehicle speeds, 

without a door being opened? Similarly, 

how are change-of-status events handled 

when passengers exit the vehicle 

without the vehicle being in the park 

gear? 

3. Audible Warning Characteristics 

If the proposed indefinite audible 

warning were adopted, manufacturers 

would almost certainly design audible 

warnings that were not continuous but 

instead cycled, in order to avoid the 

excessive annoyance of a fully 

continuous, long-lasting audible 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61714 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

241Mark Freedman et al., Effectiveness and 

Acceptance of Enhanced Seat Belt Reminder 

Systems: Characteristics of Optimal Reminder 

Systems Final Report. DOT HS 811 097. 

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

R; Jenness, J; ‘‘Acceptability and Potential 

Effectiveness of Enhanced Seat Belt Reminders 

System Features,’’ (2007) 

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

users to enhanced seat belt reminder systems of 

different duty cycles and duration. Transportation 

Research Part F, 15, 525–534. 

warning and to fine-tune annoyance and 

effectiveness. In light of this, NHTSA 

believes that it is necessary to more 

fully specify the audible warning 

characteristics than was necessary for a 

brief audible warning to ensure that the 

warnings have at least a minimum level 

of persistence. 

We therefore propose to define a set 

of terms objectively describing the 

audible warning: warning cycle, chime 

frequency, and duty cycle: 

• A warning cycle for an intermittent 

audible warning consists of period(s) 

when the warning is active at the chime 

frequency or continuously, and inactive 

period(s). A warning cycle begins with 

an active period and is 30 seconds in 

duration. 

• Chime frequency means the 

repetition rate for an intermittent 

audible warning when the warning is 

active. 

• Duty cycle means the total amount 

of time an intermittent audible warning 

is active during a warning cycle at the 

chime frequency or continuously, 

divided by the total warning cycle 

duration (30 seconds). 

When an audible warning is emitting 

sound, it may do so continuously or 

intermittently. We believe if the chime 

frequency of the warning is too low, the 

warning may become less effective. In a 

2009 agency study that focused on 

analyzing characteristics of optimal 

reminder systems, we found that, among 

the reminder systems analyzed, the one 

with the highest belt use rate had the 

longest average single-cycle duration 

and the highest maximum sound 

frequency.241 However, the agency 

wishes to provide ample design latitude 

with respect to the chime frequency. In 

a 2007 agency-funded study on 

enhanced seat belt reminder features, 

the ‘‘slow chime’’ warning evaluated 

had a 0.83 Hz frequency.242 We are 

proposing a minimum frequency of 0.5 

Hz. The warning will be considered 

active when the audible warning is 

emitting a continuous sound or a sound 

at a 0.5 Hz frequency or higher. We seek 

comment on the proposed specification 

for minimum chime frequency. 

Another important characteristic for 

an indefinite warning is the duty cycle. 

The duty cycle is the ratio of the total 

time when the audible warning is active 

divided by the total warning cycle time. 

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

second warning cycle means that the 

warning is active throughout the entire 

30 seconds. In order for the duty cycle 

specification to be meaningful, the 

warning cycle time must be specified. 

We are proposing that the warning cycle 

be fixed at 30 seconds. Therefore, 

because we are proposing that the 

audio-visual warning continue until an 

unfastened seat belt at an occupied seat 

is buckled, the audible warning will be 

composed of a continuous series of 30- 

second warning cycles that continues 

until the belt is buckled. 

We have tentatively decided to 

require a minimum duty cycle of 0.20 or 

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

second warning cycle). We have 

tentatively selected this because we are 

aware of research data that suggests that 

a 20 percent duty cycle is effective but 

are not aware of data that a lower duty 

cycle would be sufficiently effective. In 

2012, IIHS published a study examining 

the effects of duty cycle and duration on 

seat belt reminder effectiveness and 

annoyance.243 The study examined four 

duty cycle conditions: 100, 50, and 20 

percent, and a basic reminder (as ratios 

1.0, 0.5 and 0.2). The warning cycles 

were consecutive 30 intervals. In the 

100 percent duty cycle condition, the 

flashing icon and 1 Hz frequency chime 

were present for the entire 30-second 

reminder cycle. In the 50 percent duty 

cycle condition, the flashing icon and 1 

Hz frequency chime were present for the 

first 15 seconds of the reminder cycle, 

and a continuously illuminated icon 

was present for the final 15 seconds. In 

the 20 percent duty cycle condition, the 

flashing icon and 1 Hz frequency chime 

were present for the first 6 seconds of 

the reminder cycle followed by a 

continuously illuminated icon for the 

remaining 24 seconds. In the basic 

reminder system condition, the flashing 

icon and chime were present for the first 

6 seconds of the first reminder cycle 

only, and then icon was continuously 

illuminated for the remainder of the 

warning. In terms of effectiveness, the 

20 percent duty cycle reminder was 

rated no less effective than the 100 

percent duty cycle reminder. 

The chime frequency and duty cycle 

can also be adjusted to optimize the 

warning. As chime frequencies and/or 

duty cycle increase, effectiveness 

generally (though not necessarily) 

increases, and annoyance generally 

increases. Given the proposed indefinite 

warning duration for the front seats, 

vehicle manufacturers would almost 

certainly design warnings with duty 

cycles of less than 100 percent in order 

to address consumer acceptance issues. 

For instance, the 2012 IIHS study found 

that a decrease in the duty cycle could 

reduce annoyance while not appreciably 

reducing effectiveness. The enhanced 

reminders, however, were not equally 

annoying. Forty percent of participants 

in the 1.0 duty cycle reminder condition 

and 40 percent of participants in the 0.5 

duty cycle reminder condition agreed or 

strongly agreed that the reminder 

distracted them while they were 

driving. However, only 25 percent of 

participants in the 0.2 duty cycle 

reminder condition indicated the 

reminder distracted them. 

Manufacturers can also balance the duty 

cycle against the chime frequency. 

These proposed specifications differ 

somewhat from Euro NCAP and ECE 

R16. Rather than directly specifying a 

duty cycle, Euro NCAP specifies that for 

the front seats the audible signal must 

not have gaps greater than 10 seconds, 

and that gaps longer than 3 seconds 

would not count toward the warning’s 

total duration. ECE R16 also does not 

count warning gaps longer than 3 

seconds toward the required minimum 

warning duration requirement. We are 

not specifying a limit on the maximum 

duration of audible gaps for the 

purposes of determining the warning’s 

total duration since we are not 

proposing a minimum warning duration 

requirement. The 10 second limit Euro 

NCAP specifies, in addition to its 

specification of a 3 second gap limit 

toward the calculation of the warning’s 

total duration, would not be sufficient to 

ensure a 0.20 duty cycle warning (that 

is supported by the IIHS research). For 

instance, a system with a warning cycle 

that is 11 seconds long and a 10 second 

gap would result in a duty cycle of 0.09 

which would likely not be as effective 

as a system meeting our proposed 

requirements. 

We seek comment on our proposed 

method of specifying the audible 

warning duty cycle and the limits 

proposed. 

4. Visual Warning Characteristics 

We are retaining the existing 

requirements with respect to some 

aspects of the visual warning and 

modifying them in other respects. 

We are retaining the current 

requirements that the warning be 

continuous or intermittent (flashing) 

and must display either the identifying 

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

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

of FMVSS No. 101. We have tentatively 

decided not to specify minimum 

requirements for the duty cycle or flash 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61715 

244See DOT 2009 Seat Belt Study at 67–68. 

245Section 3.7.5.5. 

246 DOT 2009 Seat Belt Study at 67–68. 

247Section 3.4.1.6. 

248Section 8.4.2.4.3 (warning can cease if vehicle 

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

rates analogous to what we are 

proposing for the audible warning; we 

tentatively believe that manufacturers 

will design the visual warning features 

in conjunction with and in a way that 

complements the audible warning 

characteristics. We have decided to 

retain the requirement for the symbols 

or text specified in FMVSS No. 101 

because these visual warning have been 

in place for decades and we believe that 

consumers are accustomed to them. 

Removing the requirement may have 

unintended negative effects if drivers 

and front passengers are not accustomed 

to new visual warnings or do not find 

the new visual warnings as effective. 

This means that if a manufacturer chose 

to use a pictogram format for the rear 

seat belt warning, it could include the 

front seat belts in this pictogram, but it 

would also have to provide the 

warnings specified in FMVSS No. 101, 

table 2. We believe manufactures are 

already doing this. We seek comment on 

all of these tentative decisions. 

We are also proposing requirements 

with respect to telltale visibility. We 

propose requiring that if there is a 

driver’s designated seating position, the 

visual warning for the driver’s seat belt 

must be visible from the driver’s seat 

and the visual warning for the front 

outboard passenger seat belt must be 

visible from the driver’s seat and the 

front outboard passenger seat. (For the 

case where there is not a driver’s 

designated seating position (which is 

the case with an ADS-equipped vehicle 

without any manual driving controls), 

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

require that the visual warning be 

visible to both the driver and any front 

outboard passenger because NHTSA’s 

study on front seat belt warning systems 

suggests that visual warnings for front 

outboard passenger seat belts are more 

effective when they are visible to the 

passenger as well as the driver.244 Euro 

NCAP similarly recommends that the 

visual warning be visible to the front 

passenger.245 We believe it would be 

practicable for manufacturers to comply 

with this requirement; for example, the 

warning could be located in the center 

console display (which might be a 

salient place to present visual displays, 

both because of its location and because 

it may allow larger size icons or text).246

Some manufacturers already provide a 

passenger seat belt warning in close 

proximity to the passenger air bag status 

indicator, which is visible to both the 

driver and front passenger. 

We have tentatively decided not to 

specify more detailed criteria for the 

location or visibility of the telltale as, 

for example, are provided in S19.2.2 for 

the passenger air bag telltale. A visual 

warning for the driver’s seat belt has 

been required since the early 1970s and 

we are not aware of any issues with the 

visibility of that telltale, so we 

tentatively believe this is unnecessary. 

5. Other Warning Signal Features and 

Criteria 

We have tentatively decided not to 

specify requirements or criteria for other 

aspects of the front outboard seat belt 

warnings. 

Warning activation criteria. Global 

and Honda commented that NHTSA 

should consider updates to the driver 

seat belt reminder requirements to 

include additional trigger thresholds 

beyond the vehicle ignition switch 

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

position. The commenters believed 

advances in vehicle sensor technology 

enable warnings to be provided for a 

range of conditions, such as when the 

vehicle speed reaches a certain limit, or 

when the transmission is moved from 

the park position. One commenter 

suggested that the front and rear 

warning requirements be consistent in 

this respect. 

Euro NCAP and ECE R16 specify 

additional trigger requirements above 

and beyond the ignition being engaged 

and a seat belt not fastened for some 

aspects of the front seat belt warnings. 

Euro NCAP specifies trigger criteria 

related to factors such as speed, distance 

traveled, and time elapsed for the 

change-of-status warning, the audible 

warning at the start of a trip, and the 

final (loud and clear) warning. ECE R16 

specifies, for both the start of trip 

warning and the change-of-status 

warning, additional activation criteria 

for the second-level warning related to 

vehicle speed, distance traveled, and 

time elapsed. 

We have tentatively decided not to 

specify trigger criteria other than the 

criteria proposed above. The reasons for 

doing so mirror the reasons given in the 

analogous discussions in the rear seat 

belt warning discussion. See Section 

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

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

warning). 

Warning duration criteria. Euro NCAP 

and ECE R16 also specify additional 

duration criteria other than a minimum 

time and the seat belt becoming 

fastened. Euro NCAP specifies, for the 

audible warning duration (for both the 

start-of-trip and change-of-status 

warnings) criteria related to vehicle 

speed, door/belt status, running time, 

and distance traveled.247 ECE R16 

specifies, for the second-level audiovisual warning duration for the front 

seat belts an additional criterion related 

to vehicle speed.248 We have tentatively 

decided not to include more complex 

criteria. The reasons for this mirror the 

reasons given for the rear seat belt 

change-of-status warning duration in 

Section X.C.2. 

Warning circumvention, 

acknowledgment and deactivation. We 

have tentatively decided not to propose 

features to harden the system against 

circumvention (such as a sequential 

logic system which would evaluate 

whether the belt was fastened prior to 

an occupant sitting in the seat or sensors 

that can determine seat belts fastened 

behind an occupant’s back) because 

such features would increase the cost 

and complexity of the systems. Neither 

ECE R16 nor Euro NCAP require such 

features. 

We have also tentatively decided not 

to allow features which would permit 

the driver to acknowledge the warning 

and cancel it prior to the required 

duration or to deactivate the warning for 

an entire trip or for a specified time 

period (thus preventing it from 

activating in the first place). ECE R16 

allows both short-term and long-term 

deactivation of the audible warning 

(with a variety of restrictions, such as 

that it be more difficult to effectuate a 

short-term deactivation than to buckle 

the belt). Euro NCAP does not provide 

any specifications for deactivation or 

acknowledgement of the warnings for 

the front seats; it only allows 

acknowledgement of warnings for rear 

seats, except for change-of-status 

warnings. We seek comment on this. 

Should a final rule incorporate either or 

both of these features? Would this 

unacceptably impact the effectiveness of 

the warning and essentially negate its 

indefinite duration? Or could it 

facilitate acceptance and thus either not 

impact effectiveness or even have a 

positive impact on effectiveness, to the 

extent it might make it less likely that 

the occupant habitually completely 

circumvents the system? Or should 

cancelation or deactivation be allowed 

for the passenger seat belt audible 

warning but not the driver seat belt 

warning, in order to mitigate the 

potential for false positives (due to cargo 

on the seat that the occupant detection 

system classifies as a person, etc.)? We 

note that, since we are not proposing 

hardening requirements, the proposal 

would not preclude designs that do not 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61716 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

249The 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. 

250For anthropomorphic test devices, this would 

include the 50th percentile male, 5th percentile 

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

dummies. 

251 87 FR 18560 (Mar. 30, 2022). 

252An [ADS-Equipped] Dual-Mode Vehicle is 

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

designed for both driverless operation and 

operation by a conventional driver for complete 

trips.’’ SAE J3016_201806 Taxonomy and 

activate a passenger seat belt warning if 

the seat belt is fastened and no one is 

in the seat. Thus, such nuisance 

warnings due to cargo could be 

prevented by buckling the seat belt or 

simply placing the cargo somewhere 

else. 

Should the final rule allow for 

permanent or short-term deactivation of 

front seat audible warnings when the 

vehicle is traveling below a certain 

speed? This might allow for situations 

such as someone needing to drive to a 

mailbox on a road located on private 

property or perhaps driving in a parking 

lot. Below what speed could such a 

deactivation be implemented without 

potential loss of benefits? Would such 

an allowance cause confusion and be 

counterproductive to the goal of the 

proposal? 

XII. Other Issues 

A. Automatic Belts 

This proposal applies to automatic 

belts. Automatic belts are belts that 

secure without any action by the 

occupant. The agency is not aware of 

any currently produced vehicles that 

would be affected by the proposed 

requirements that have automatic belts. 

We propose that a seating position with 

an automatic belt would have to meet 

the same seat belt warning requirements 

that apply to manual belts. We are not 

including provisions in the proposed 

test procedures specific to automatic 

seat belt systems because we believe the 

seat belt use definitions provide 

sufficient guidance. We seek comments 

on this issue. 

B. Test Procedures 

This NPRM includes procedures for 

how the agency would test the front 

outboard passenger and rear seat belt 

warning systems for compliance with 

the proposed requirements. 

We note that ECE R16 (in Annex 18) 

sets out some limited test procedures. 

With respect to the front passenger belt 

warning, it sets out procedures for 

testing the warning when the seat belt 

is unbuckled at the onset of a trip and 

procedures for testing the change-ofstatus warning. For the rear seat belt 

warning system, it has procedures for 

testing the change-of-status warning. In 

Europe and other countries around the 

world, compliance with safety standards 

is based on type approval. Type 

approval is the confirmation that 

production samples of a design will 

meet specified performance standards. 

For type approval, manufacturers 

submit product specifications to 

governmental authorities, which then 

require third party approval testing, 

certification, and a production 

conformity assessment by an 

independent body. Test procedures in 

FMVSS, on the other hand, are more 

extensive and detailed, because an 

FMVSS must be objective, so that 

manufacturers can self-certify that their 

vehicles are in compliance. 

The proposed test procedures in this 

NPRM specify that NHTSA could test 

any system under any combination of 

seat occupancy or seat belt use status. 

The test procedures also specify how 

the agency would test a seat belt 

warning system with a designated 

seating position that is occupied. 

In order to test a seat belt warning 

system with a front seating position that 

is occupied, the agency would use 

either any anthropomorphic test device 

specified in part 572 or a person 

meeting or exceeding the proposed 

weight and height criteria (at least 46.7 

kg and 139.7 cm, respectively, 

corresponding to the 5th percentile 

adult female test dummy specified in 

part 572). The human beings or test 

dummies used would be seated, the seat 

belt use and ignition conditions would 

be applied, and the required signals 

must operate (that is, either activate or 

not activate) accordingly. For example, 

if the agency placed the appropriate test 

dummies in both front outboard seating 

positions and fastened both outboard 

seat belts so that the seat belts were in 

use, the front seat belt warning system 

would not be permitted to activate the 

audible or visual signals under the 

current first compliance option and 

could only activate the visual signal 

under the current second compliance 

option.249 The test could be conducted 

with the seat and adjustable belt 

anchorages in any position. 

For rear warning systems that utilize 

occupant detection (either negative-only 

or full-status systems), the agency 

would use either a person or any 

anthropomorphic test device specified 

in part 572 that meets the proposed 

weight and height criteria (at least 21 kg 

and 114 cm, respectively).250 The 

agency would perform the test with the 

seat in any position, the seat back in the 

manufacturer’s nominal design riding 

position, and any adjustable anchorages 

in any position. 

We seek comment on all aspects of 

the test procedures. We also seek 

comment on whether the R16 Annex 18 

test procedures affect how the 

requirements in R16 should be 

interpreted, and whether any deviations 

between the proposed test procedures 

and the Annex 18 test procedures are 

undesirable. We also seek comment on 

whether the proposed procedures are 

sufficiently detailed and objective. 

C. Considerations for Automated 

Driving Systems 

The ANPRM did not address 

considerations related to automated 

driving systems (ADSs). 

Comments 

A commenter recommended avoiding 

any additional references to the ‘‘driver’’ 

in FMVSS No. 208 to avoid introducing 

further barriers to the deployment of 

automated driving systems. 

Agency Response 

NHTSA is actively addressing how 

the FMVSS might be revised to take 

vehicles with different types of ADSs 

into account. On March 30, 2022, 

NHTSA published a final rule updating 

the occupant protection standards (200- 

series FMVSS) to account for ADSequipped vehicles, particularly those 

without driving controls.251 The final 

rule amended the 200-series FMVSS to 

account for future vehicles that do not 

have the traditional manual controls 

associated with a human driver because 

they are equipped with ADSs. 

One aspect of this NPRM is a 

requirement specifically tailored to an 

ADS-equipped vehicle without a driver 

DSP. For the amendment to the driver’s 

seat belt warning, we are proposing that 

the front passenger warning apply to 

‘‘any’’ front outboard passenger. The 

addition of the term ‘‘any’’ makes it 

clear that, in some vehicles, there may 

be more than one front outboard 

passenger seating position. This would 

be the situation of an ADS-equipped 

vehicle that has no manually operated 

driving controls. The agency views this 

as a means for maintaining the same 

level of occupant protection in ADSequipped vehicles that exists in 

conventional vehicles, i.e., both will be 

required to have seat belt warnings in 

both outboard seating positions. We 

note that in a dual mode vehicle,252 the 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61717 

Definitions for Terms Related to Driving 

Automation Systems for On-Road Motor Vehicles. 

253The discussion in this preamble focuses on 

Euro NCAP and R16. NCAP programs in other 

regions are largely similar to Euro NCAP or R16, so 

our analysis of these requirements will adequately 

cover the requirements of the NCAP programs in 

other regions. 

254H.R. 3684 (117th Congress) (2021). 

255The ANPRM sought comment on this in the 

context of various aspects of the rear seat belt 

warning, and this is what the comments likely 

concerned, but the discussion in the agency 

response below also includes the front seats. 

256Some comments specifically identified version 

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

revised that regulation. The current version is 

Revision 10. We assume commenters favoring 

harmonization intended that we harmonize with 

the most current version of R16. 

left front seat is still by definition a 

driver’s seat, regardless of the 

operational status of the vehicle, so a 

provision to just have a warning for the 

driver and right outboard passenger 

would be sufficient to assure that all 

front seat occupants receive a warning. 

We are also proposing that if there are 

multiple front outboard passenger seats 

in an ADS-equipped vehicle without 

manual driving controls, then both front 

outboard seat belt warnings and changeof-status warnings must be visible to 

both front outboard passengers. The 

rationale for this is as follows. Although 

an ADS-equipped vehicle without 

manually operated controls by 

definition does not have a driver, it is 

reasonable to assume that one of the 

front outboard passengers may be 

performing the management role for the 

duration of a trip, such as might be the 

case of a parent in a vehicle with 

children under their care. In such a 

situation, the manager of the trip may be 

seated in either front outboard seat. 

Thus, to be most beneficial, the visual 

warning must be seen by an occupant 

choosing to sit in either front outboard 

seat. Additionally, if the agency 

restricted the warning visibility to just 

the right outboard passenger and not 

‘‘any’’ outboard passenger, in an ADSequipped vehicle with no driving 

controls and a lone vehicle occupant in 

the left front seat, that occupant would 

not receive a seat belt use warning. 

The 2022 ADS final rule also 

addressed situations where an ADSequipped vehicle without manual 

driving controls has one or no outboard 

seats in the front row (e.g., an ADSequipped vehicle with only two seats in 

the front row, one or both of which 

would be classified as inboard 

passenger seating positions under 571.3) 

and requires seat belt warnings for 

certain inboard seats in such vehicles. 

We are proposing that these front 

inboard passenger seats have the same 

seat belt warnings as front outboard 

seats. 

The agency acknowledges that the 

proposal does not address the influence 

of ADS-equipped vehicles on the 

visibility of the rear seat belt warning. 

As proposed, the rear seat belt warning 

is only required to be visible from the 

driver’s seat. As previously discussed, 

there may be no driver’s DSP in an ADSequipped vehicle. Thus, no vehicle 

occupant will be required to see the rear 

seat belt warning. NHTSA 

acknowledges the inadequacy of this 

situation and we believe there are many 

potential solutions. For example, it 

could be required that for a vehicle 

without manually operated driving 

controls, any front seat occupant receive 

the rear seat belt warning. Another 

approach would be to require that in 

such vehicles, all seating positions be 

apprised of the seat belt use in all other 

DSPs in the vehicle. The agency has 

determined that it is not prepared to 

propose a solution for the visibility of 

rear seat belt warnings for ADSequipped vehicles and that it is beyond 

the scope of this proposed rule. As we 

stated in the March 30, 2022 final rule, 

the agency plans future agency work 

related to telltales and indicators for 

ADS-equipped vehicles. 

XIII. Regulatory Alternatives 

NHTSA has considered alternatives to 

the proposal. In the preceding sections 

of this document, we have discussed 

various alternatives for different aspects 

of the proposed requirements. In this 

section we address five major 

alternatives that we considered: ECE 

R16 and Euro NCAP; occupant detection 

and enhanced warning signals for the 

rear seat belt warning; non-regulatory 

alternatives; requiring a warning for the 

front center seat; and requiring an 

audio-visual seat belt warning for the 

front outboard seating positions with a 

duration not less than 90 seconds. For 

three of these alternatives (rear-seat 

occupant detection, front center seat, 

and 90-second front warning), we also 

quantified the costs and benefits (see 

Section XIV). 

A. ECE R16 and Euro NCAP 

The ANPRM sought comment on the 

extent to which any requirements 

should be based upon or differ from 

other regulatory requirements (such as 

ECE requirements) or consumer 

information programs such as Euro 

NCAP.253 As discussed in more detail in 

the regulatory analyses section below, 

Executive Order 13609 provides that 

International regulatory cooperation can 

reduce, eliminate, or prevent 

unnecessary differences in regulatory 

requirements. Similarly, § 24211 of the 

Infrastructure, Investment, and Jobs 

Act 254 instructs DOT to harmonize the 

FMVSS with global regulations to the 

maximum extent practicable (for 

example, to the extent that 

harmonization would be consistent with 

the Safety Act). 

Comments 255

Several commenters recommended 

harmonizing with R16.256 Two 

commenters stated that almost all 

automakers have already developed 

systems to conform to the R16 

requirements, and that 

disharmonization would increase costs 

without any benefits. Two commenters 

said that harmonization would 

accelerate introduction of seat belt 

reminders. A commenter said that R16 

represents a ‘‘sweet spot’’ between 

safety benefits, consumer acceptance, 

harmonization, and compliance costs. 

The commenter also said that the 

benefits from harmonization can be 

substantial, such as flexibility to 

innovate, cost minimization, and 

efficiency of global research, 

development, and production processes; 

a non-harmonized approach could also 

necessitate system redesign for the 

United States market. 

Some commenters recommended 

harmonizing with NCAP programs in 

other regions, such as Euro NCAP. For 

example, a commenter supported 

harmonization with Euro NCAP; 

another supported harmonization with 

Euro NCAP (or, if not that, then with 

R16), and a third commenter suggested 

using other NCAP programs as a model 

when empirical data is lacking. A 

commenter recommended 

harmonization with Euro NCAP and 

IIHS’s assessment protocol. 

A few commenters, while 

acknowledging that harmonization is 

generally desirable, commented that the 

proposed rule should not harmonize at 

the expense of safety/effectiveness. 

Commenters said that the requirements 

should be evidence-based. 

Agency Response 

In developing this proposal, our 

intent was to harmonize with ECE R16 

and Euro NCAP as much as possible but 

deviate where we believed it was 

justified with respect to the Safety Act 

criteria (need for safety, objectivity, 

practicability). The tentative reasons for 

following or deviating in any of these 

respects are explained in detail in the 

relevant section of the preamble. In 

general, we believe that although the 

proposal deviates from R16 in some 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61718 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

257https://www.iihs.org/media/f15e5be9-ac62- 

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

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

20Test%20Protocol.pdf. 

ways, the two are not incompatible, so 

that it is possible to design a rear 

reminder system that complies with the 

proposed requirements and is 

compatible with R16. 

On December 2021, IIHS released its 

Seat Belt Reminder System Test and 

Rating protocol.257 It sets out general 

requirements for the seat belt reminder 

visual and audible signals for front 

outboard and rear seating positions. It 

does not put much emphasis on the 

visual warning for front-outboard 

seating positions other than specifying 

that a visual signal needs to be 

displayed in the instrument panel, 

overhead panel, or center console, 

indicating an unfastened belt. On the 

other hand, for the audible warning 

there are requirements for when it must 

begin if the seat belt is unfastened at 

ignition and for change-of-status, and 

when it can cease (when the seat belt is 

unfastened, vehicle is no longer in 

motion, or seat is no longer occupied). 

It also has sound pressure level and 

frequency requirements for the audible 

warning. 

For the rear seats, it specifies that the 

visual signal must activate within 10 

seconds of the ignition being turned on, 

that the signal must indicate whether 

the seat belt at each rear seating position 

is fastened or unfastened, and that it 

must last at least 60 seconds. It does not 

require a visual signal if the seat belts 

at all occupied rear seats are fastened or 

if no rear occupants are present. It 

allows the visual signal to be cancelled 

by the driver. For a seat belt change-ofstatus in the rear seats when the vehicle 

is in motion, it requires an audible and 

visual signal that lasts at least 30 

seconds. It further specifies that the 

audible and visual signal can stop when 

seat belts at the occupied rear seats are 

fastened, the vehicle is no longer in 

motion, or the seats are no longer 

occupied. 

For the front seats, under the IIHS 

ratings protocol, the primary audible 

reminder signal for the front outboard 

seats must be at least 90 seconds in total 

duration in order to obtain an 

‘‘acceptable’’ or ‘‘good’’ rating. 

Unlike Euro NCAP the IIHS rating 

system provides ratings instead of 

points (poor, marginal, acceptable, 

good). For instance, if the frontpassenger seat has an audible signal that 

lasts less than 8 seconds it would be 

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

rating’’ both the driver and frontpassenger belt reminder must have an 

audible signal that lasts at least 90 

seconds and meet the rest of the belt 

reminder system requirements 

(essentially meet the requirements for 

an ‘‘Acceptable’’ rating) and meet the 

requirements set forth for the rear seat 

belt reminder system. Accordingly, a 

vehicle cannot receive a ‘‘Good’’ rating 

without having a rear seat belt reminder 

system, and a rear seat belt reminder 

system is not required for all the other 

ratings. It does not specify occupancy 

criteria. We do not believe our 

requirements impede meeting the 

requirements of the IIHS protocol. 

B. Occupant Detection and Enhanced 

Warning Signals for the Rear Seat Belt 

Warning 

Rear seat warning systems that 

employ occupant detection have 

potential advantages over systems 

without it. With occupant detection, a 

warning system can provide more 

informative warnings. The system can 

determine whether any seats are 

occupied by an unbelted occupant, as 

opposed to simply notifying the driver 

which belts, if any, are fastened. Such 

systems are also better able to provide 

enhanced warnings. Enhanced warnings 

refer (for the purposes of this document) 

to warnings that are relatively longerlasting or have an audible component. 

Having an audible or longer-duration 

visual warning activate for an 

unoccupied seat could be a nuisance for 

the driver and might either desensitize 

the occupants to the warning signal or 

lead them to circumvent or defeat the 

system. Enhanced warnings therefore 

generally need to work in conjunction 

with an occupant detection system. 

In the ANPRM we observed, however, 

that occupant detection for the rear seats 

may present technical or cost 

challenges. Rear seats are used in ways 

that can complicate occupant detection. 

Rear seats may frequently be used to 

transport cargo such as groceries, pets, 

and other heavy objects that could be 

mistaken for an occupant. In addition, 

rear seats may be less well-defined than 

front seats, which could impede 

accurate detection. For example, it may 

be technically challenging for an 

occupant detection system to recognize 

a large occupant spanning multiple 

seating positions as a single occupant 

rather than two occupants. This could 

lead to false warnings, which can lead 

occupants to disregard or attempt to 

circumvent the system. Occupant 

detection would also be more 

expensive. While approximately 46.9% 

of MY 2022 projected vehicle sales in 

the United Sates have rear seat belt 

warning systems, only about 7% are 

equipped with occupant detection. 

Occupant detection is optional but 

not required by both ECE R16 and Euro 

NCAP. Accordingly, neither Euro NCAP 

nor ECE R16 require an audible warning 

on vehicle start-up for the rear seats. 

Euro NCAP specifies that, if there is no 

occupant detection, only a 60-second 

visual signal is needed for the rear 

warning in order to earn bonus points, 

and R16 requires a 60-second visual 

signal. For systems with occupant 

detection in all rear seats, Euro NCAP 

specifies that the visual signal does not 

need to indicate the number of seat belts 

in use or not in use, but the signal must 

remain as long as the seat belts remain 

unfastened on any of the occupied rear 

seats. Neither R16 nor Euro NCAP 

require a visual signal if the system can 

determine there are no occupants in the 

rear. 

The ANPRM sought comment on 

whether NHTSA should propose rear 

seat belt warning system requirements 

that would necessitate occupant 

detection or enhanced warning signals. 

Comments 

Many commenters recommended 

requiring occupant detection in the rear 

seats. Other commenters argued that 

occupant detection would reduce false 

signals, and some argued that occupant 

detection was feasible and already 

available in numerous vehicle models. 

A commenter stated that NHTSA had 

provided no literature review of 

available systems and their capabilities, 

and that NCAP programs throughout the 

world had concluded that these systems 

are feasible and important to advancing 

safety. Two commenter said that some 

of the technological challenges NHTSA 

identified in the ANPRM have already 

been addressed in systems developed 

for the right front passenger seat. A 

commenter also noted that various 

NCAP programs award points for 

occupant detection. Another commenter 

said that the residual technical 

challenges appear to be mostly 

associated with accommodating certain 

child restraint systems. The commenter 

believed that occupant detection with 

the option of temporary driver override 

for the duration of an individual trip is 

a reasonable approach that balances 

notification with recognition that seats 

may be occupied by objects other than 

unrestrained human occupants. 

Commenters also said that occupant 

detection systems are cost-efficient, 

with a number of systems costing less 

than $10. 

On the other hand, several 

commenters opposed requiring 

occupant detection. Commenters 

suggested harmonizing with ECE R16, 

which does not require occupant 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61719 

258See Section X.C.1.a, Visual Warning at Start of 

Trip with Three Compliance Options. 

detection. Some commenters brought up 

the technological and use challenges. 

For example, a commenter stated that it 

is difficult to distinguish actual rear 

occupants from other rear objects 

because consumers tend to use rear 

seats in a wider variety of conditions 

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

and various types of cargo); its 

experience shows that occupant 

detection in rear seats leads to false 

alarms and reduced consumer 

acceptance. Several commenters raised 

concerns about cost. One commenter 

believed that the cost of such systems 

would not justify any additional 

benefits. Another commenter believed 

that there were insufficient data 

available to demonstrate that occupant 

detection would actually increase 

system effectiveness because without 

occupant detection the driver knows 

how many occupants are in the vehicle. 

On the other hand, a commenter said 

that costs are not prohibitive; the 

commenter also stated that rear seat 

occupant detection systems are 

available that can take into 

consideration the specific challenges of 

the rear seat compared to a front seat, 

including robust sensors to help avoid 

false positive warnings. At the same 

time, commenters requested that any 

requirements not prohibit innovation 

and provide manufacturers with 

flexibility. One commenter opposed 

requiring occupant detection on buses 

because such systems would be 

complicated (e.g., the number of seats 

and seating configurations, challenges 

with LATCH). It also stated that it is 

unaware of any occupant detection 

systems currently available for buses, so 

all rear passenger seats currently in use 

will require significant development 

efforts. 

As noted earlier,258 several 

commenters favored requiring an audiovisual warning at the start of the trip. A 

commenter also supported requiring the 

most effective warnings. 

On the other hand, commenters 

argued against requiring enhanced 

warnings. A commenter recommended 

requiring only a visual warning on startup to avoid false alarms and consumer 

acceptance issues because occupant 

detection is currently not affordable. 

Another commenter also stated that 

consumer acceptance of enhanced 

warning systems in the United States is 

not well understood. Commenters 

recommended following R16 with 

respect to enhanced warnings, because 

it strikes an appropriate balance of 

benefits, acceptance, harmonization, 

and costs. Two commenters suggested 

that NHTSA instead consider updating 

NCAP to include enhanced warnings. A 

commenter said that the reminder 

system should use existing audio/visual 

warning patterns because the driving 

public likely would be able to 

understand those more easily. 

Agency Response 

We have tentatively decided not to 

require occupant detection in the rear 

seats because we tentatively believe that 

occupant detection continues to present 

technical challenges. While it can 

reduce false warnings for unoccupied 

seats it can also result in false warnings, 

due to the limitations of the sensors and 

different use scenarios in the rear seats. 

We acknowledge that most of the 

components necessary to meet the 

proposed minimum performance 

requirements for a system with 

occupant detection are readily available, 

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

vehicle projected sales, based on the 

MY2022 NCAP data, are equipped with 

rear SBWS with occupant detection. 

However, these potential issues 

surrounding the implementation of 

occupant detection could reduce the 

effectiveness and/or acceptance of these 

systems and thus we tentatively decided 

against requiring occupant detection. 

Occupant detection would be costbeneficial only if rear seat belt use 

increased substantially more than we 

estimate that it would for a warning 

system without occupant detection. Our 

teardown analysis indicates that 

occupant detection components cost 

$39.75 per vehicle, which, added to the 

$19.59 per vehicle cost of the buckle 

sensor, results in a combined warning 

system cost of $59.33 per vehicle 

(2020 $). We estimate that the total new 

fleet cost of a rear seat belt warning 

system with occupant detection would 

be about $758 million (2020 $). As 

explained in more detail in Section XIV, 

Overview of Costs and Benefits, and in 

the PRIA, in order for benefits and costs 

to be equal for this regulatory option, 

seat belt use for rear seat occupants 11 

years and older would need to increase 

by approximately 9.4 percent when 

discounted at 3 percent and 11.6 

percent when discounted at seven 

percent. A 9 to 12 percent increase in 

seat belt use is about 2 to 3 times greater 

than that estimated for the proposed 

SBWS requirement. While we would 

expect some possible increase in seat 

belt use from that specific functionality, 

it is doubtful that it would double or 

triple the increase in seat belt use 

estimated for SBWS without occupant 

detection. Therefore, we do not expect 

this regulatory alternative to be costeffective or net beneficial. 

This tentative decision is based on 

current information on factors such as 

the needed increase in seat belt use for 

this regulatory alternative to have 

positive net benefits. This proposal does 

not preclude manufacturers from 

choosing to use occupant detection and 

includes compliance options that 

involve the use of occupant detection. 

This harmonizes with R16 and Euro 

NCAP. Vehicle manufacturers may in 

the future implement rear seat occupant 

detection technology for other functions 

(such as advanced occupant restraint 

functions or warnings for unattended 

children in the rear seating positions 

after the vehicle motor is turned off), 

which would relieve some of the cost 

burden and facilitate the integration of 

occupant detection technology for rear 

seat belt warning systems. Because we 

are not requiring occupant detection, we 

are therefore also not requiring 

enhanced warnings (such as an audible 

warning on vehicle start-up) for the rear 

seat belt reminder. The proposal, 

however, gives manufacturers the 

flexibility to innovate and optimize 

warning signal characteristics, including 

providing enhanced warnings. We seek 

comment on these issues. 

C. Non-Regulatory Alternatives 

The ANPRM sought comment on 

whether NHTSA should consider nonregulatory approaches. It identified two 

potential non-regulatory approaches: 

awarding NCAP bonus points and 

voluntary guidelines. 

Comments 

Some commenters supported 

including rear seat belt reminders in 

NCAP in addition to, but not in lieu of, 

a regulatory requirement in order to 

accelerate adoption of advanced 

systems. Two commenters also believed 

that inclusion in NCAP could encourage 

adoption. One commenter was opposed 

to voluntary guidelines. The commenter 

said that inclusion of occupant 

detection in NCAP would be the most 

appropriate way to incentivize such 

systems and familiarize industry with 

their implementation. 

Agency Response 

In light of the MAP–21 mandate and 

our tentative conclusion that the 

proposed requirements would meet the 

section 30111 criteria, we have decided 

to issue this proposal, and not pursue 

non-regulatory alternatives. However, 

we would like to note that on March 9, 

2022, NHTSA published an RFC notice 

announcing its current and future plans 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61720 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

259 87 FR 13452 (Mar. 9, 2022). 

260See Traffic Safety Facts 2013, NHTSA, DOT 

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

occupant injuries are reported. The number of 

passenger car occupants injured was not reported 

because it was less than 500. 

261Citing Li, R., Pickrell, T.M. (2019, February). 

Occupant restraint use in 2017: Results from the 

NOPUS controlled intersection study (Report No. 

DOT HS 812 594). Washington, DC: National 

Highway Traffic Safety Administration, at: https:// 

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

ViewPublication/812594.pdf. 

262Citing Aarian Marshall, A Third of Americans 

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

Jan. 8, 2019, https://www.wired.com/story/uber-lyftride-hail-stats-pew-research/ (last accessed Nov. 26, 

2019). 

263Citing Jessica Jermakian & Rebecca Weast, 

Passenger use of and attitudes toward rear seat 

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

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

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

use by adult rear seat passengers in private 

passenger, taxi, and rideshare vehicles, Proceedings 

of the Human Factors and Ergonomics Society 

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

10.1177/1541931213601896 (last accessed Nov. 26, 

2019). 

264Citing Rear Seat Belt Use: Little Change in 

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

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

for updating NCAP.259 The RFC notice 

included a section on seat belt 

interlocks that requested comment on 

whether NCAP should consider credit 

for enhanced seat belt reminder systems 

and whether NCAP should include a 

seat belt interlock assessment and, if so, 

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

types, what seats would be covered, 

etc.). The notice requested data on both 

topics. Our preliminary review of the 

comments about whether NCAP should 

consider credit for enhanced seat belt 

reminders found that the majority of 

commenters were in support of such an 

initiative. A commenter stated that, 

rather than considering credit for 

enhanced seat belt reminders, NHTSA 

should regulate more persistent 

reminders as allowed under MAP–21. 

D. Requiring a Warning System for the 

Front Center Seat 

The agency also considered requiring 

a seat belt warning system for the front 

center seating position but is not 

proposing doing so for a few reasons. 

First, there is low occupancy for the 

front center seat. According to 2013 

FARS and GES data, only 0.4 percent of 

the occupants of passenger cars and 

light trucks with a GVWR of 10,000 lb 

or less involved in fatal or injury-only 

crashes were seated in the front center 

seating position. This is due to the rarity 

of front center seats in the modern 

vehicle fleet, not because this position 

is safer. More specifically, 62 occupants 

of these vehicles seated in the front 

center seat were killed. Of those 

fatalities, 79 percent (49 occupants) 

were unrestrained. In addition, there 

were 8,000 occupants of these vehicles 

that were injured while seated in the 

front center seat. Of those front center 

seat occupants injured, approximately 

8.2 percent (656 occupants) were 

unrestrained.260

Next, a system for the front center seat 

without occupant detection would 

likely not be effective. Without 

occupant detection, a belt reminder 

system for the front center seat would be 

limited to providing a positive-only 

visual signal (for the reasons discussed 

regarding the front and rear seats and 

occupant detection). We believe that 

such a signal would not be likely to 

result in meaningful safety benefits for 

the front center seat. Because it would 

be only a visible and not an audible 

warning, it would likely not provide the 

occupant in the front center seat much 

incentive to fasten the seat belt or 

provide the driver an additional 

incentive to request the front center 

passenger to fasten the seat belt. 

Finally, a system with occupant 

detection would not be cost-effective or 

net-beneficial. When discounted at three 

and seven percent, the cost per ELS is 

approximately $88.9 million and $110.0 

million, respectively and the net 

benefits are negative for this regulatory 

alternative. Because the cost per ELS is 

higher than the comprehensive cost of a 

fatality and the net benefits are negative, 

this regulatory alternative is not costeffective or net-beneficial. 

E. Requiring a 90 Second Duration Seat 

Belt Warning System for the Front 

Outboard Seating Positions 

As explained earlier (see Section 

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

alternative warning durations for the 

front outboard seat belt warning. 

NHTSA quantified the costs and 

benefits for one of these alternate 

durations (90 seconds). NHTSA selected 

the 90 second duration length as an 

alternative because this is the most 

common audible warning duration for 

the front outboard seats, based on our 

NCAP data. About 92.4 percent of the 

new vehicle fleet is already equipped 

with an audible seat belt warning with 

a duration of 90 seconds or greater. 

Therefore, a requirement for a minimum 

of 90 second duration audible warning 

would only affect 7.6 percent of the new 

vehicle fleet. The benefit and cost 

analysis was conducted in a similar 

manner as that for the indefinite 

duration seat belt warning described in 

Section XIV. Our analysis found that a 

requirement for a 90-second audible 

warning would save 7 equivalent lives 

with no change in the estimated cost. 

These benefits are significantly lower 

than those for the proposed warning 

that remains on until the seat belt is 

buckled. 

We seek comment on these issues. 

XIV. Overview of Benefits and Costs 

In this section, we briefly present our 

estimates of the benefits and costs of the 

proposed rear and front seat belt 

warning requirements, as well as three 

of the major regulatory alternatives we 

considered. For a more detailed 

discussion, please refer to the 

Preliminary Regulatory Impact Analysis 

(PRIA) in the docket for this rulemaking. 

NHTSA seeks comment on its 

methodology, data sources, and 

estimates. 

A. Proposed Requirements 

NHTSA quantified the benefits and 

costs of the proposed requirements. In 

this section we present a summary of 

these estimates for the rear seat belt 

warning system, front outboard seat belt 

warning system, and then the combined 

costs and benefits for both proposals. 

1. Rear Seat Belt Warning System 

The ANPRM sought comment on the 

potential effectiveness, benefits, and 

costs of a rear seat belt warning. 

Comments 

NHTSA received several comments 

on the potential target population. For 

example, a commenter said that 

approximately 900 second row 

unrestrained occupants are killed and 

another 19,000 are injured each year, 

and a portion of this target population 

would likely have injuries mitigated or 

eliminated through the use of rear seat 

belt warning systems. Another 

commenter brought up the increasing 

number of rear seat passengers,261

including the rise of rideshare 

vehicles.262 Two 263 commenters 264 also 

stated that studies have found rear seat 

passengers in rideshare or taxis (for hire 

vehicles) are less likely to buckle up 

than those in privately owned (not for 

hire) vehicles, and one of the 

commenters noted that children usually 

sit in the back row, and they may 

unfasten their seat belt out of boredom 

during a trip. A commenter also said 

that restraint non-use exceeds the 

national average (47%) in the 

population of occupants starting at age 

8–12, and the unrestrained percentage 

for younger occupants is 36% for 4–7 

year olds and 22% for occupants less 

than 4 years old. 

Several commenters noted a relative 

lack of data regarding the effectiveness 

of rear seat belt warnings. A commenter 

stated that the first vehicles with an 

advanced rear seat belt reminder system 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61721 

265M. Akamatsu, H. Hashimoto and S. Shimaoka, 

‘‘Assessment Method of Effectiveness of Passenger 

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

0050, 2012. This study is discussed in the PRIA 

(Section 2.3). 

266Citing Highway Loss Data Inst., Ins. Inst. for 

Highway Safety, Unbelted: Adults Admit They 

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

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

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

accessed Nov. 26, 2019). 

267See PRIA, Appendix D. 

268See PRIA, Table 29. 269Motoyuki Akamatsu et al., Assessment 

Method of Effectiveness of Passenger Seat Belt 

Reminder. 2012–01–0050, SAE International (2012). 270Survey of Principal Drivers of Vehicles with 

a Rear Seat Belt Reminder System at 47. 

only entered the Japanese and EU 

markets in recent years, and there are 

not yet any field data available on 

effectiveness. 

However, a few commenters did 

provide rough effectiveness estimates. 

One commenter estimated that it was 

likely similar to front seat effectiveness 

(3–4%). Two other commenters pointed 

to a 2012 SAE paper that compared the 

effect of various visual and audible 

warnings on rear belt use based on a 

series of experiments.265 One of the 

commenters said that its research has 

found that seat belt warning systems 

with persistent audible tones lasting at 

least 90 seconds increase the seat belt 

use of drivers who do not routinely use 

a seat belt by 34%. The commenter also 

referenced a Volvo survey of Volvo 

owners in Sweden and Italy in 2005 

showing that a rear belt warning system 

had an effectiveness of approximately 

50%. 

Several commenters commented 

generally that a rear belt reminder 

would be effective while not providing 

specific effectiveness estimates. A 

commenter agreed with NHTSA that the 

proportion of occupants who actively 

seek to avoid restraint use is small 

compared to the proportion of part-time 

nonusers who would likely be amenable 

to warnings. Another commenter 

similarly stated that many consumers do 

not prioritize rear belt use but rather 

consider it unnecessary (for short trips 

in particular), forget to buckle up, or 

perceive no deterrent threat from traffic 

enforcement, and enforcement of seat 

belt laws is more challenging for the 

back seat due to more difficult visibility. 

A commenter said that there is 

extensive evidence of the effectiveness 

of front seat belt reminders and there is 

no reason to believe that rear seat belt 

reminder effectiveness would 

significantly differ. Commenters noted 

the NHTSA research on seat belt 

warnings discussed in Section V, 

showing a generally positive increase in 

use rates. Commenters referred to an 

IIHS survey showing that, of 1,172 

respondents who had ridden in the back 

seat during the preceding six months, 

75% said they would be more likely to 

wear the rear seat belt if someone in the 

car reminded them, 62% would if there 

was an audible belt reminder, and 50% 

would if there was a visual belt 

reminder.266

With respect to costs, a commenter 

said that seat belt reminder systems 

require a relatively small investment, 

and low-cost 2–D or digital cameras 

(which are cheaper than seat sensors) 

could be used to detect a rear seat 

passenger. Two commenters said that 

the cost will decrease further if rear seat 

belt reminder systems are required in all 

vehicles. A commenter said that for 

passenger cars already equipped with 

rear seat buckle monitoring (13% in US 

for MY 2019; almost 100% of new 

vehicle models in the EU market, legally 

required in EU for new types from 

September 2019 onwards), the 

additional costs for the occupant 

detection technology to cover the 

second row seating positions are in the 

low two-digit range. The commenter 

also stated that among vehicles available 

in the EU with advanced rear seat SBR 

systems, a couple are vehicle models 

that belong to the high-volume, costsensitive vehicle segments (small/ 

compact cars), showing that the 

additional costs for the rear seat 

occupant detection are not prohibitive. 

The commenter said that the occupant 

detection sensors for a seat belt warning 

system are available at lower costs than 

occupant classification (e.g., for front air 

bags) sensors. 

Agency Response 

Based on FARS and NASS–CDS data 

from 2011 to 2015, on average 1,002 

unrestrained rear seat occupants were 

killed in crashes and 7,820 were 

injured.267 After adjusting these to 

account for future decreases in fatalities 

and injuries projected to occur in the 

absence of the proposed requirements 

due to the introduction of other 

mandatory safety technologies (e.g., 

electronic stability control), there were, 

on average, 475 fatalities and 7,036 

injuries to unrestrained rear seat 

occupants each year. This is the overall 

target population—the annual deaths 

and injuries that the proposed 

requirements are aimed at reducing. 

We estimated the benefits we expect 

to result from the proposed rear seat belt 

warning requirements. The benefits are 

the fatalities and injuries that we 

estimate would be prevented by the 

proposed requirements. The benefits 

depend, principally, on the 

effectiveness of seat belts in preventing 

deaths and injuries and the expected 

increase in seat belt use due to the 

proposed rear seat belt warning system 

requirements. Seat belt effectiveness for 

rear seat occupants is 55 percent for 

passenger cars and 74 percent for light 

trucks and vans.268

NHTSA believes that the proposed 

minimum required warning signal 

characteristics would be effective at 

informing the driver of the use status of 

the rear seat belts and facilitating the 

driver to request that a rear passenger 

fasten an unfastened belt. A seat belt 

warning system can increase rear seat 

belt use in two ways: it can remind an 

occupant to fasten their belt, and it can 

inform the driver that a passenger is 

unbuckled, so that the driver can 

request the occupant to fasten their 

belt.269 Without a rear seat belt warning, 

the driver must turn around to ascertain 

whether a rear seat occupant is using a 

seat belt (or ask the occupant); in some 

vehicles, belt use may not be evident to 

the driver, even if he or she turned 

around, due to line-of-sight limitations. 

As noted above, in NHTSA’s 2015 

survey, 65% of drivers of vehicles 

equipped with rear seat belt reminders 

reported that the rear seat belt reminder 

made it easier to encourage the rear seat 

passengers to buckle up.270 Also, as 

noted earlier, part-time users—the 

predominant nonuser group—are 

amenable to seat belt warnings. In 

addition, children, who might be 

particularly compliant to driver 

requests, are proportionally much more 

likely to be rear seat passengers than are 

adults.271

We believe that any of the three 

compliance options would be effective 

at doing this. While some provide more 

information than others, and some 

would require the driver to fill in some 

informational gaps, even the most basic 

system (positive-only) would inform the 

driver about which belts are fastened; 

the driver would readily be able to 

determine whether there were any 

unbelted occupants. We also believe 

that the 60-second visual warning 

would be effective. NHTSA could have 

proposed a more intrusive warning 

signal, such as an audible warning and/ 

or a longer-duration visual warning. 

However, because such warnings 

necessitate occupant detection and we 

have tentatively decided not to require 

occupant detection, we have also 

tentatively decided not to propose more 

aggressive warnings. 

NHTSA estimated the effectiveness of 

the proposed rear seat belt warnings. 

Available research regarding seat belt 

use indicates that seat belt warning 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61722 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

272See PRIA, Table 33. 

273See PRIA, Table 33. 

274See PRIA, Table 47. 

275The 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. 

276See PRIA, Table 72. 

277See PRIA, Table 79. 

systems are effective at increasing seat 

belt use; however, estimates of the 

amount of increased belt usage that can 

be attributed to warning systems vary. 

In arriving at our estimates of increased 

seat belt usage, we examined research 

conducted by NHTSA and others, as 

well as information submitted in 

response to the request for comments. 

For rear seat passengers eleven years old 

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

3.4 percentage points, and a ‘‘high’’ 

estimate of 5.1 percentage points.272 For 

rear seat passengers from six to eleven 

years old, we used a low estimate of 

0.27 percentage points and a high 

estimate of 0.41 percentage points.273

(The estimated increases for younger 

passengers are much lower because they 

already have high rates of seat belt use). 

For simplicity, we refer to these 

scenarios as ‘‘Low’’ and ‘‘High,’’ or 

‘‘3%’’ and ‘‘5%.’’ 

Based on these belt and warning 

system effectiveness estimates, we 

estimate that the proposed rear seat belt 

warning requirements would prevent 22 

fatalities and 75 injuries annually under 

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

scenario, we estimate that 34 fatalities 

and 112 injuries would be prevented 

annually.274 See table 9. Another way to 

measure benefits is by calculating 

equivalent lives saved. Equivalent lives 

saved are the number of prevented 

fatalities added to the number of 

prevented injuries, with the prevented 

injuries expressed in terms of fatalities 

(that is, with an injury expressed as a 

fraction of a fatality, so that the more 

serious the injury, the higher the 

fraction). The estimated equivalent lives 

saved are presented in table 10. 

TABLE 9—ESTIMATED ANNUAL BENEFITS—LIVES SAVED AND INJURIES PREVENTED FOR POSITIVE-ONLY SBWS (REAR

SEATS), WITH ESTIMATED 3 & 5 PERCENTAGE POINT INCREASE IN BELT USE

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

MAIS 1 275 ................................................................................................................................................................ 23.2 34.3 

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

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

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

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

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

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

TABLE 10—ESTIMATED ANNUAL BENEFITS—EQUIVALENT LIVES SAVED—POSITIVE-ONLY SBWS (REAR SEATS) 276

Belt use increase 3% Discount 

rate 

7% Discount 

rate 

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

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

We also estimated the costs of the 

proposed requirements. To comply with 

the minimum proposed requirements 

(the positive-only compliance option), 

the system would need to have seat belt 

buckle sensors (to determine if the belt 

is fastened) and wiring and wire 

conduits to provide information on the 

belt buckle status from the rear seats to 

the computer processor controlling the 

warning system. Based on the results of 

NHTSA’s teardown analysis, we 

estimate a cost of $6.28 per seat. Given 

an average of 3.12 rear seats per vehicle, 

this yields a final cost of $19.59 per 

vehicle. Based on this, the cost to the 

fleet to comply with the proposed 

minimum requirements (the positiveonly system) is $167.8 million (M). 

Based on the forgoing, we performed 

benefit-cost and cost-effectiveness 

analyses. A benefit-cost analysis 

calculates net benefits, which is the 

difference between the benefits flowing 

from injury and fatality reductions and 

the cost of the rule. Our net benefit 

estimates are presented in table 11. The 

cost-effectiveness analysis derives the 

cost per equivalent life saved, which is 

equal to the total cost of the rule divided 

by the total fatal equivalents that it 

prevents. These estimates are presented 

in table 12. 

TABLE 11—NET BENEFITS—POSITIVE-ONLY SBWS (REAR SEATS) 277

[2020 Dollars, in millions] 

Seat position and belt use increase 3% Discount 

rate 

7% Discount 

rate 

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

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


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61723 

278See PRIA, Table 73. 

279National Center for Statistics and Analysis. 

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

results (Traffic Safety Facts Research Note. Report 

No. DOT HS 813 241). National Highway Traffic 

Safety Administration. 

280May Chu, ‘‘Statistical brief #62: Characteristics 

of Persons Who Seldom or Never Wear Seat Belts 

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

publications/st62/stat62.pdf. 

281Spado, 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. 

282Compared to the 2016 MVOSS, which had, 

depending on the question, sample sizes of 

approximately 5,000 to 10,000. 

283For example, the 2016 MVOSS found that 

about 6% of drivers reported using their belt 

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

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

284 ‘‘The effects of persistent audible seat belt 

reminders and a speed-limiting interlock on the seat 

belt use of drivers who do not always use a seat 

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

for Highway Safety, Jeremiah Singer Westat, Inc. 

TABLE 12—COST-EFFECTIVENESS ANALYSIS (COST PER EQUIVALENT LIFE SAVED)—PROPOSED POSITIVE-ONLY

SYSTEM 278

[2020 Dollars, in millions] 

Seat position and belt use increase ELS Cost Cost/ELS 

3% Discount Rate 

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

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

7% Discount Rate 

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

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

2. Front Seat Belt Warning System 

Based on FARS and NASS–GES data 

from 2011 to 2015, on average 7,503 

unrestrained drivers and 1,453 

unrestrained front outboard passengers 

of passenger cars and light trucks were 

killed annually in traffic crashes. 

Additionally, 53,113 unrestrained 

drivers and 10,324 unrestrained front 

outboard passengers were, on average, 

injured annually. After adjusting these 

to account for future decreases in 

fatalities and injuries projected to occur 

in the absence of the proposed 

requirements due to the introduction of 

other mandatory safety technologies 

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

were, on average, 6,733 fatalities and 

47,952 injuries to unrestrained front seat 

occupants each year. This is the overall 

target population—the annual deaths 

and injuries that the proposed 

requirements are aimed at reducing. 

According to the NOPUS, 90.6% of 

the drivers used the seat belt in 2021, 

which is slightly higher when compared 

to passengers in the right-front seating 

position with an observed belt use rate 

of 89.4%.279 In order to estimate the 

percentage of drivers and front 

passengers who do not always use a seat 

belt, we used the results from a 2004 

analysis using data from the Household 

Component of the 2002 Medical 

Expenditure Panel Survey (MEPS– 

HC) 280 that found that among persons 

16–64 years of age, 87.7 percent 

reported always or nearly always using 

seat belts when driving or riding in a 

car. Another 6.9 percent reported 

sometimes using seat belts, while 5.4 

percent reported seldom or never using 

seat belts when driving or riding in a 

car. These results are summarized in 

table 13. This means, when an 

observation is made about the 

percentage of drivers who use the seat 

belts, the observed belt use rate is higher 

than 87.7% since the other groups 

would contribute to the observed belt 

use rate although they are not always 

using the seat belts. NHTSA recognizes 

that driving habits may or may not have 

changed since 2002 as seat belt use rates 

have increased and as new generations 

of drivers and passengers are on the 

road. NHTSA considered, but 

tentatively decided not to use, the 

results of more recent studies, such as 

the (2016) Motor Vehicle Occupant 

Safety Survey 281 to estimate the 

percentage of drivers and front 

passengers who do not always use a seat 

belt. While the 2016 MVOSS is more 

recent, we decided to use the 2004 

study because we tentatively concluded 

that the data provided by the 2004 study 

best suited the needs of our analysis. 

Given that most data on seat belt use is 

self-reported, the 2004 study has a high 

sample size (approximately 25,000) 282

and provides robust categorizations of 

seat belt use that fits the needs of our 

analysis. Furthermore, when comparing 

this data to the findings of the 2016 

MVOSS, we did not find evidence that 

these trends have significantly changed 

over time.283 NHTSA seeks comment on 

instead using the results of more recent 

studies, such as the 2016 MVOSS, or 

other data sources commenters are able 

to identify. 

TABLE 13—SEAT BELT USE

CHARACTERISTICS

Belt user and related items Rate 

(%) 

A reported ‘‘sometimes using 

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

A reported ‘‘seldom or never 

using seat belts when driving or riding in a car’’ ........ 5.4 

Percentage of drivers who 

always use seat belts, calculated ............................... 87.7 

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

As we did for the rear seats, NHTSA 

estimated the effectiveness and benefits 

associated with requiring a seat belt 

warning system that remains activated 

until the seat belts are buckled for the 

driver and front outboard passenger 

seats. In developing this estimate, 

NHTSA used the results of a study 

conducted by the Insurance Institute for 

Highway Safety (IIHS) by Kidd et al. 

(2019) 284 In the Kidd et al. (2019) study, 

part-time belt users (who had a recent 

seat belt citation and reported not 

always using a seat belt) drove two 

vehicles for a certain period of time, a 

Chevrolet with three intermittent 7- 

second audible warnings followed by 

either a BMW with a 100-second 

audible warning (n=17) or a Subaru 

with an audible warning that continues 

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

of the vehicles provided a visual 

warning that lasted until the seat belt 

was buckled.) Kidd et al. found that, 

relative to the intermittent reminder 

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

BMW warning with the 100-second 

audible reminder increased seat belt use 

by 30% and the Subaru warning with 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61724 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

285There were several limitations in this study, 

the main one being that the number of study 

participants was small, and, consequently, there 

was limited statistical power when comparing the 

change in rate of belt use between the different 

vehicle technology conditions. The study further 

discusses this and other limitations, such as how 

the demographics of the study sample differs from 

part-time belt users nationwide. 

286See PRIA, Table 30. 

287See PRIA, Table 30. 

the indefinite audible warning increased 

belt use by 34%.285

NHTSA estimates, based on the 

NOPUS, Chu, and IIHS studies, that a 

requirement for an indefinite duration 

audible seat belt warning would 

increase the overall observed seat belt 

use rate by 2.8 percentage points for the 

driver and 2.4 percentage points for the 

front outboard passenger from current 

observed seat belt use levels. 

NHTSA also reviewed manufacturer 

data for model year 2020 vehicles to 

determine market penetration of 

indefinite duration seat belt warning 

systems in the front outboard seats and 

that of a 90-second or greater duration 

warning and obtained the estimates in 

table 14. 

TABLE 14—MARKET PENETRATION OF

DIFFERENT DURATION SEAT BELT

AUDIBLE WARNING SYSTEMS

SBWS system Percentage 

of sales 

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

90 second and 90+ but not 

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

Enhanced—Warning until 

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

For front seat occupants, seat belts 

reduce the risk of fatality by 44% (for 

passenger cars) and 73% (for light 

trucks and vans).286 Seat belts reduce 

the risk of moderate to greater severity 

injuries by up to 50%.287

Based on the estimated seat belt 

warning system effectiveness in 

increasing seat belt use, the market 

penetration of different duration seat 

belt audible warning systems, and the 

effectiveness of seat belts in mitigating 

fatalities and injuries, NHTSA estimates 

that requiring an audio-visual seat belt 

warning that remains activated until the 

seat belt is buckled (indefinite duration) 

would prevent 65 driver fatalities, 11 

front outboard passenger fatalities, and 

a total of 211 injuries annually, as 

shown in table 15. This results in 92 

equivalent lives saved (Table 16). 

TABLE 15—ESTIMATED ANNUAL BENEFITS—LIVES SAVED AND INJURIES PREVENTED—INDEFINITE SBWS (FRONT

OUTBOARD SEATS) 

Injury level Driver Front 

passenger Total 

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

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

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

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

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

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

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

The estimated annual benefits in 

terms of equivalent lives saved is shown 

in Table 17. 

TABLE 16—ESTIMATED ANNUAL BENEFITS—EQUIVALENT LIVES SAVED—INDEFINITE SBWS 

[Front Outboard Seats] 

Undiscounted 3% Discount 

rate 

7% Discount 

rate 

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

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

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

We also estimated the costs of the 

proposed requirements. Since all driver 

seats are required to have at least the 

basic warning system, the incremental 

cost of enhanced seat belt warning for 

the driver seat is zero. We assume there 

would be some labor costs associated 

with software updates needed to extend 

the warning. However, as this is a 

simple programming change, this cost 

would be amortized over each vehicle’s 

production and is therefore considered 

de minimis. Though there are no 

requirements for a seat belt warning 

system for the front outboard passenger 

seat, NHTSA estimates that 96 percent 

of vehicles have seat belt warning 

systems on the front outboard passenger 

seat. NHTSA estimated the cost of 

equipping a seat belt warning system in 

the front outboard passenger seat to be 

$2.13 per seat. Therefore, the cost of 

equipping the remaining 4 percent of 

the 16 million new vehicle fleet is $1.36 

million (= 16 million × 4 percent × 

$2.13). 

Based on the foregoing, we performed 

benefit-cost and cost-effectiveness 

analyses. The estimated net benefits are 

presented in table 17 and the costeffectiveness estimates are presented in 

Table 18. 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61725 

TABLE 17—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% % % % 

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 

TABLE 18—COST-EFFECTIVENESS ANALYSIS (COST PER EQUIVALENT LIFE SAVED)—INDEFINITE SBWS (FRONT

OUTBOARD SEATS) 

[2020 dollars, in millions] 

Discount rate ELS Cost Cost/ELS 

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

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

3. Overall Benefits and Costs of Proposal 

In Table 19, we combine the benefits 

and costs for the proposed rear and front 

seat belt warning requirements. We 

estimate positive net benefits under all 

discount rates and effectiveness 

estimates. 

TABLE 19—NET BENEFITS FROM THE PROPOSAL (SBWS FOR REAR SEATING POSITIONS AND INDEFINITE SBWS FOR

FRONT OUTBOARD SEATING POSITIONS) 

[2020 dollars, in millions] 

3% Discount 

rate 

7% Discount 

rate 

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

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

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

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

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

In Table 20, we combine the 

equivalent lives saved and cost for the 

proposed rear and front seat belt 

warning requirements to determine the 

cost per equivalent life saved. 

TABLE 20—COST PER EQUIVALENT LIVES SAVED FROM THE PROPOSAL (SBWS FOR REAR SEATING POSITIONS AND

INDEFINITE SBWS FOR FRONT OUTBOARD SEATING POSITIONS) 

[2020 dollars, in millions] 

Category % 

3% Discount rate 7% Discount rate 

Equivalent 

lives saved Cost 

Cost per 

equivalent 

lives saved 

Equivalent 

lives saved Cost 

Cost per 

equivalent 

lives saved 

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

5 32.9 5.05 26.7 6.23 

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

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

5 109.4 1.53 88.7 1.89 

B. Regulatory Alternatives 

In the preceding sections of this 

document, we discussed various 

alternatives for different aspects of the 

proposed requirements. In Section XIII, 

Regulatory Alternatives, we identified 

five major alternatives that we 

considered. We quantified the costs and 

benefits of three of these alternatives 

(rear-seat occupant detection, a 90- 

second front outboard seat belt warning, 

and front center seat belt warning). 

Below, we briefly summarize our 

results. For a more detailed discussion, 

the reader is referred to the Preliminary 

Regulatory Impact Analysis in the 

docket for this rulemaking. 

1. Occupant Detection in Rear Seats 

For the rear seat belt reminder, 

NHTSA is proposing to specify three 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61726 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

different compliance options. One of 

these (the positive-only system) would 

not necessitate occupant detection, 

while the other two (the negative-only 

and full-status) would necessitate 

occupant detection. NHTSA estimated 

the costs and benefits of requiring a 

system with occupant detection. 

NHTSA’s teardown analysis indicates 

that occupant detection components 

cost $39.75 per vehicle, which, added to 

the $19.59 per vehicle cost of the buckle 

sensor, results in a combined warning 

system cost of $59.33 per vehicle (2020 

$). NHTSA estimates that about 47 

percent of new vehicles have a SBWS 

for the rear seating positions and 7 

percent of new vehicles have occupant 

detection in rear seats. If NHTSA 

selected the regulatory alternative where 

occupant detection is required, this 

would result in a total cost of $757.7M. 

This cost estimate is based on the 

assumption that 53 percent of new 

vehicles would need to install a seat belt 

sensor in the rear seats and 93 percent 

would need to also install occupant 

detection in the rear seats to comply 

with the regulatory requirement. 

Because there is uncertainty in how 

much more effective a SBWS with 

occupant detection would be in 

increasing seat belt use compared to the 

already estimated increase in seat belt 

use with the proposed SBWS without 

occupant detection, NHTSA did not 

conduct a cost-effectiveness and net 

benefits analysis. Instead, NHTSA 

estimated the minimum increase in seat 

belt use for this regulatory alternative 

that would result in overall benefits 

equal to the overall costs (zero net 

benefits). The agency estimated that seat 

belt use for rear seat occupants 11 years 

and older would need to increase by 

approximately 9.4 percent when 

discounted at 3 percent and 11.6 

percent when discounted at 7 percent 

for this regulatory alternative to result in 

zero net benefits. Therefore, increase in 

seat belt use from this regulatory 

alternative would need to be greater 

than 9.4 percent at 3 percent discount 

rate and greater than 11.6 percent at 7 

percent discount rate for positive net 

benefits. A 9 to 12 percent increase in 

seat belt use is about 2 to 3 times greater 

than that estimated for the proposed 

SBWS requirement. The SBWS 

considered under this regulatory 

alternative are capable of letting the 

driver know, for occupied rear seats, 

either which occupants are not using 

their seat belts or how many of the rear 

seat occupants are not using their seat 

belts. While we would expect some 

possible increase in seat belt use from 

that specific functionality, it is doubtful 

that it would double or triple the 

increase in seat belt use estimated for 

SBWS without occupant detection. 

Therefore, we do not expect this 

regulatory alternative to be cost-effective 

or net beneficial. 

2. 90-Second Front Outboard Seat Belt 

Warning 

NHTSA also estimated the costs and 

benefits if it were to require a 90-second 

audio-visual warning for the front 

outboard seats instead of the proposed 

requirement for a warning that lasts 

until the belt and any occupied seat is 

buckled. NHTSA estimated the benefits 

in a similar manner as that for the 

proposed seat belt warning for front seat 

occupants where the warning remains 

on until the seat belt is buckled. One 

difference is that, for the 90-second 

duration alternative, we assumed that 

the drivers and passengers who identify 

as never using a seat belt would likely 

not use the seat belt with a 90-second 

duration warning. Another difference is 

that this alternative only affects 7.6 

percent of the vehicle fleet with front 

seat occupant seat belt warning with 

duration less than 90 seconds. 

The benefits of this alternative are 

presented in Table 21. 

TABLE 21—INJURIES PREVENTED, LIVES SAVED, AND EQUIVALENT LIVES SAVED IN FRONT OUTBOARD SEATS BY A 90- 

SECOND DURATION SBWS 

Injury level 

Injuries and fatalities prevented Equivalent lives saved 

Driver Front 

passenger Driver Front passenger 

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

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

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

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

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

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

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

About 7 equivalent lives are saved by 

this alternative, which is significantly 

lower than the 86 equivalent lives saved 

by a warning that remains on until the 

seat belt is buckled. The cost of this 

alternative is the same as that for the 

proposed warning. The only cost is that 

for the 4 percent of vehicles without a 

seat belt warning system in the front 

outboard passenger seat (cost = $1.36 

million). The annual monetized 

benefits, costs, and net benefits of this 

alternative are shown in Table 22. 

TABLE 22—ANNUAL MONETIZED BENEFITS, COSTS AND NET BENEFITS FOR A 90-SECOND DURATION SBWS IN FRONT

OUTBOARD SEATS 288

[2020 dollars, in millions] 

Vehicle type 

Driver Front passenger Driver and front passenger 

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

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

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

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


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61727 

288See PRIA, Table 92. 

TABLE 22—ANNUAL MONETIZED BENEFITS, COSTS AND NET BENEFITS FOR A 90-SECOND DURATION SBWS IN FRONT

OUTBOARD SEATS 288—Continued 

[2020 dollars, in millions] 

Vehicle type 

Driver Front passenger Driver and front passenger 

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

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

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

While this regulatory alternative is 

cost effective, the benefits are 

significantly lower than that of the 

proposed warning. 

3. Seat Belt Warning for Front Center 

Seat 

The agency also considered requiring 

a seat belt warning system for the front 

center seating position. To estimate 

incremental benefits, NHTSA used the 

2011–2015 FARS data, the adjustment 

factors to account for safety impacts of 

new required safety technologies, and 

the injury-to-fatality ratios by injury 

severity to establish the target 

population addressed by this regulatory 

alterative (Table 23). 

TABLE 23—ANNUAL ADJUSTED FATALITIES AND NON-FATAL INJURIES TO FRONT CENTER SEAT PASSENGERS

Vehicle type Injury severity Restrained Unrestrained Total 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Due to a lack of data, NHTSA is 

unable to establish the seat belt use rate 

for front center passengers under the 

baseline. Also, due to this limitation, 

the agency cannot estimate the increase 

in seat belt use rates under this 

regulatory alternative. Since front center 

seat passengers are most similar to right 

front seat passengers, NHTSA used the 

effectiveness rates calculated for 

indefinite duration seat belt warning 

system for the front outboard passenger 

seat to estimate incremental benefits as 

shown in Table 24. 

TABLE 24—INCREMENTAL BENEFITS FOR INDEFINITE DURATION SBWS IN FRONT CENTER SEATING POSITION

Injury severity Observed injuries 

Calculated 

effectiveness of 

indefinite duration 

SBWS for front 

outboard 

passenger seats 

(%) 

Incremental 

benefits 

Passenger Cars 

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

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

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

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

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

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

LTVs 

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


ddrumheller on DSK120RN23PROD with PROPOSALS2
61728 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

TABLE 24—INCREMENTAL BENEFITS FOR INDEFINITE DURATION SBWS IN FRONT CENTER SEATING POSITION—Continued 

Injury severity Observed injuries 

Calculated 

effectiveness of 

indefinite duration 

SBWS for front 

outboard 

passenger seats 

(%) 

Incremental 

benefits 

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

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

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

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

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

The cost for front center passenger 

seats would include the cost for a 

buckle sensor and occupant detection. 

Therefore, the cost per vehicle for this 

regulatory alternative is $14.86 in 2020 

dollars. This cost estimate reflects a cost 

of $2.13 to add a buckle sensor and the 

cost to add occupant detection for 

$12.73. 

In assessing the number of vehicles 

that would be impacted by this 

regulatory alternative, we consider that 

the front center seat is not a common 

feature in new light vehicles. Based on 

our engineering judgement, we expect 

that 800,000 vehicles or five percent of 

the new vehicle fleet include a center 

seating position. Table 25 presents the 

total cost to meet the requirements 

under this regulatory alternative for an 

indefinite duration SBWS for front 

center passenger seats. 

TABLE 25—TOTAL COST OF INDEFINITE DURATION SBWS FOR FRONT CENTER PASSENGER SEATS

Number of vehicles impacted Per vehicle 

cost Total cost 

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

Table 26 presents the of the costeffectiveness analysis and Table 27 

presents the benefit-cost analysis for 

this regulatory alternative. When 

discounted at three and seven percent, 

the cost per ELS is approximately $88.9 

million and $110.0 million, respectively 

and the net benefits are negative for this 

regulatory alternative. Because the cost 

per ELS is higher than the 

comprehensive cost of a fatality and the 

net benefits are negative, this regulatory 

alternative is not cost-effective. 

TABLE 26—COST-EFFECTIVENESS ANALYSIS FOR SBWS FRONT CENTER SEAT PASSENGERS

[Millions] 

Category 

Discounted at 3% Discounted at 7% 

Equivalent 

lives saved Cost 

Cost per 

equivalent 

lives saved 

Equivalent 

lives saved Cost 

Cost per 

equivalent 

lives saved 

Front Center Seat .................................... 0.1337 $11.89 $88.91 0.1081 $11.89 $110.00 

TABLE 27—BENEFIT-COST ANALYSIS FOR SBWS FRONT CENTER SEAT PASSENGERS

[Millions] 

Category 

Discounted at 3% Discounted at 7% 

Monetized 

benefits Cost Net benefits Monetized benefits Cost Net benefits 

Front Center Seat .................................... $1.60 $11.89 ¥$10.29 $1.29 $11.89 ¥$10.59 

XV. Proposed Effective Date 

We received one comment responding 

to the ANPRM on the effective date. The 

commenter said that adequate lead-time 

and phase-ins should be provided. With 

respect to eliminating the eight-second 

limitation for the front seat 

requirements, the commenter stated that 

R16 and the corresponding FMVSS 

requirements are safety neutral, so 

compliance with either of these 

requirements should be permitted for a 

sufficient period of time to permit the 

orderly phase-out of current models 

with long product refresh cycle 

durations. 

In order to accelerate the fleet 

penetration of the proposed seat belt 

warning requirements and to achieve 

the associated benefits as quickly as 

reasonably possible, NHTSA proposes 

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 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61729 

289 36 FR 4600 (Mar. 10, 1971). 

290 49 CFR part 5, subpart B; Department of 

Transportation Order 2100.6A, Rulemaking and 

Guidance Procedures, June 7, 2021. 291H.R. 3684 (117th Congress) (2021). 

rear seat belt warning system 

requirements, with optional early 

compliance permitted. 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), multistage manufacturers and alterers would 

have an additional year to comply. 

To equip vehicles with one of the 

proposed rear seat belt warning systems, 

a manufacturer could utilize existing 

vehicle components such as door 

sensors, audible signals, and the center 

console display. Integrating a rear seat 

belt warning system in vehicles would 

require equipping the rear seats with 

certain components most vehicles do 

not already have, such as the 

appropriate seat belt use sensing 

technology (seat belt latch sensors, 

which are readily available). 

Manufacturers would also have to 

redesign the hardware and software as 

necessary to incorporate the required 

signals, incorporate new visual signals 

in the instrument panel (if the visual 

signal is located there) and validate the 

performance of these components and 

systems. These endeavors take time, 

which we estimate to be two years. 

On the other hand, almost all vehicles 

(96%) already have a front outboard 

passenger seat belt warning system. The 

majority of vehicle manufacturers 

would simply have to make software 

adjustments necessary to ensure it meets 

the proposed requirements. Occupant 

detection technology is readily available 

and the majority of the front outboard 

passenger seats already have a seat belt 

warning or occupant sensing technology 

needed to meet the proposed 

requirements. We acknowledge that a 

small portion of vehicles (4%) that do 

not have a front outboard passenger seat 

belt warning system will require 

hardware and software adjustments, but 

this is not a new technology and we 

believe manufacturers can focus their 

resources accordingly to meet the front 

seat belt warning system requirements 

earlier than the rear seat belt warning 

system requirements. 

Overall, the proposed seat belt 

warning requirements should not 

require much interior redesign, nor 

should they require the use of much 

new technology. When the FMVSS No. 

208 driver seat belt warning was first 

required in 1971, less than a year of lead 

time was given for vehicles that chose 

a compliance option that required the 

warning.289 We believe that the 

proposed effective dates will provide 

manufacturers with sufficient time to 

integrate the proposed rear and front 

passenger seat belt warnings (if one is 

not already in place). 

At the same time, we appreciate the 

challenges multi-stage manufacturers 

and alterers may face as a result of these 

new rear seat belt warning requirements 

in terms of obtaining and implementing 

the necessary hardware. We note, 

however, that most of the components 

necessary to meet the proposed 

minimum performance requirements for 

the proposed seat belt warnings are 

readily available from original 

equipment manufacturers and we do not 

foresee any major delays in obtaining 

them. In order to provide flexibility to 

these small businesses, and in 

accordance with 49 CFR 571.8(b), multistage manufacturers and alterers would 

have an extra year of lead time. 

We seek comment on these issues. If 

a commenter believes one year does not 

provide sufficient lead time for the front 

seat warning, NHTSA seeks comment 

on the types of vehicles for which 

additional lead time is requested and 

the basis for such a request. 

Alternatively, if a commenter believes 

the compliance period is too long in 

light of the safety considerations 

addressed in this NPRM, NHTSA seeks 

comment on an alternative compliance 

period. 

XVI. Regulatory Analyses 

Executive Order 12866, Executive Order 

14094, Executive Order 13563, and DOT 

Regulatory Policies and Procedures 

We have considered the potential 

impact of this proposed rule under 

Executive Order 12866, Executive Order 

14094, Executive Order 13563, DOT 

Order 2100.6A and the Department of 

Transportation’s regulatory policies and 

procedures.290 The Office of 

Management and Budget has 

determined that this proposed rule is a 

significant regulatory action and was 

reviewed under section 3(f)(1) of E.O. 

12866, as amended by E.O. 14094. 

Pursuant to E.O. 12866 and the 

Department’s policies, we have 

identified the problem this proposed 

rule addresses, assessed the benefits and 

costs, and considered alternatives. 

These analyses have been summarized 

in Section VI, Safety Need and Section 

XIV, Overview of Benefits and Costs and 

are discussed in more detail in the 

docketed preliminary regulatory impact 

analysis. 

Promoting International Regulatory 

Cooperation 

The policy statement in section 1 of 

Executive Order 13609 provides that the 

regulatory approaches taken by foreign 

governments may differ from those 

taken by the United States to address 

similar issues, and that in some cases 

the differences between them might not 

be necessary and might impair the 

ability of American businesses to export 

and compete internationally. It further 

recognizes that in meeting shared 

challenges involving health, safety, and 

other issues, international regulatory 

cooperation can identify approaches 

that are at least as protective as those 

that are or would be adopted in the 

absence of such cooperation and can 

reduce, eliminate, or prevent 

unnecessary differences in regulatory 

requirements. 

In addition, section 24211 of the 

Infrastructure, Investment, and Jobs Act, 

Global Harmonization, provides that 

DOT ‘‘shall cooperate, to the maximum 

extent practicable, with foreign 

governments, nongovernmental 

stakeholder groups, the motor vehicle 

industry, and consumer groups with 

respect to global harmonization of 

vehicle regulations as a means for 

improving motor vehicle safety.’’ 291

In developing this proposal, our 

intent was to harmonize with ECE R16 

and Euro NCAP as much as possible, 

but deviate where we believed it was 

justified with respect to the Safety Act 

criteria (need for safety, objectivity, 

practicability). The tentative reasons for 

following or deviating in any of these 

respects are explained in detail in the 

relevant section of the preamble. In 

general, we believe that although the 

proposal deviates from R16 in some 

ways, the two are not incompatible, so 

that it is possible to design a rear 

reminder system that complies with the 

proposed requirements and is 

compatible with R16. Further, almost all 

international NCAP programs, including 

those in Europe, Japan, China, Korea, 

Latin America, Southeast Asia, and 

Australia and New Zealand award 

points to vehicles that are equipped 

with seat belt warning systems for 

passenger seating positions. Thus, the 

proposed requirements are consistent 

with these international programs and 

complement those international efforts 

to increase seat belt use by all vehicle 

occupants. 

Regulatory Flexibility Act 

Pursuant to the Regulatory Flexibility 

Act (5 U.S.C. 601 et seq., as amended by 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61730 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

292For a discussion of NHTSA’s certification 

regulations for final stage manufacturers, see 71 FR 

28168, May 15, 2006, Docket No. NHTSA–2006– 

24664, Response to petitions for reconsideration of 

a final rule implementing regulations pertaining to 

multi-stage vehicles and to altered vehicles. The 

Background section of that document provides 

concepts and terminology relating to the 

certification of multi-stage vehicles. 

the Small Business Regulatory 

Enforcement Fairness Act (SBREFA) of 

1996), whenever an agency is required 

to publish an NPRM or final rule, it 

must prepare and make available for 

public comment a regulatory flexibility 

analysis (RFA) that describes the effect 

of the rule on small entities (i.e., small 

businesses, small organizations, and 

small governmental jurisdictions). The 

Small Business Administration’s 

regulations at 13 CFR part 121 define a 

small business, in part, as a business 

entity ‘‘which operates primarily within 

the United States.’’ (13 CFR 121.105(a)). 

No regulatory flexibility analysis is 

required if the head of an agency 

certifies that the rule will not have a 

significant economic impact on a 

substantial number of small entities. 

SBREFA amended the Regulatory 

Flexibility Act to require Federal 

agencies to provide a statement of the 

factual basis for certifying that a rule 

will not have a significant economic 

impact on a substantial number of small 

entities. 

NHTSA has considered the effects of 

this proposed rule under the Regulatory 

Flexibility Act. According to 13 CFR 

121.201, the Small Business 

Administration’s size standards 

regulations used to define small 

business concerns, manufacturers of the 

vehicles covered by this final rule 

would fall under North American 

Industry Classification System (NAICS) 

No. 336211, Automobile Manufacturing, 

which has a size standard of 1,000 

employees or fewer. 

NHTSA estimates that there are three 

small light vehicle manufacturers in the 

U.S. We estimate that there are several 

hundred second-stage or final-stage 

manufacturers and alterers that could be 

impacted by a final rule. The agency has 

analyzed the economic impact on these 

entities. For the reasons discussed 

below and in the PRIA, we tentatively 

conclude that if made final, this 

proposed rule would not have a 

significant economic impact on a 

substantial number of small entities. 

The proposed rule would directly 

affect motor vehicle manufacturers. 

However, we believe that the proposed 

rule would not have a significant 

economic impact on these entities. 

Small manufacturers are already 

certifying their vehicle’s compliance, for 

the driver position, with FMVSS No. 

208’s seat belt warning system 

requirements. The means they use to 

certify to the current requirements 

would be similar to or the same as those 

they would use to certify to the 

proposed rear seat belt warning 

requirements. 

Further, the proposed compliance test 

is a relatively simple test, involving a 

test technician positioning a person or 

test dummy in a seat and checking if the 

requisite signals activate. Checking to 

see if visual and audible warnings 

activate for the driver seat belt warning 

system has been a part of FMVSS No. 

208 compliance testing for many years, 

and manufacturers are knowledgeable 

about conducting such tests. 

Small manufacturers have options 

available to certify compliance, none of 

which will result in a significant 

economic impact on these entities. The 

manufacturers can and do obtain seating 

systems from seat suppliers and install 

the seats on the body following the 

instructions of the seat supplier. Seat 

and seat belt suppliers are large entities 

with resources available to assist small 

manufacturers in incorporating the seat 

belt warning systems, if manufacturers 

need technical assistance (which we do 

not think they will need, given the 

simplicity of the systems, particularly 

those rear systems that do not involve 

occupant detection). We do not believe 

that current manufacturing practices 

would have to change significantly as a 

result of a final rule. 

In addition, we also believe that the 

proposed rulemaking would not have a 

significant impact on small and limitedline vehicle manufacturers because the 

market for the vehicles produced by 

these entities is highly inelastic. 

Purchasers of these vehicles are 

attracted by the desire to have an 

unusual vehicle. Further, all light 

vehicles would have to comply with the 

proposed requirements. Since the price 

of complying with the proposed rule 

would likely be passed on to the final 

consumer, the price of competitor’s 

models would increase by similar 

amounts. Further, we do not believe that 

raising the price of a vehicle to include 

the cost of a rear seat belt warning 

system would have much, if any, effect 

on vehicle sales. 

There are a significant number 

(several hundred) of second-stage or 

final-stage manufacturers and alterers 

that would be impacted by a final rule. 

These manufacturers buy incomplete 

vehicles to finish as complete vehicles 

or modify previously-certified vehicles. 

Many of these latter vehicles are van 

conversions; there are a variety of 

vehicles affected. 

To produce a vehicle, a final-stage 

manufacturer can either stay within the 

incomplete vehicle document (IVD) 

furnished by the incomplete vehicle 

manufacturer (which are typically large 

vehicle manufacturers, such as GM or 

Ford), or the final-stage manufacturer 

can work with incomplete vehicle 

manufacturers to enable the final-stage 

manufacturer to certify to the new 

requirements.292 The final-stage 

manufacturer can also certify to the 

standard using due care based on an 

assessment of the information available 

to the manufacturer. 

While there are a substantial number 

of multi-stage manufacturers that could 

be impacted by the proposed rule, we 

believe that the impact on them would 

not be significant. We note that these 

manufacturers are already certifying 

their vehicles to FMVSS No. 208’s seat 

belt warning system requirements that 

apply to the driver seating position. 

They are already familiar with the 

equipment and manufacturing processes 

involved to certify their vehicles to seat 

belt warning system requirements. 

Further, we anticipate that final-stage 

manufacturers will base their vehicles 

on incomplete vehicles that already 

have the SBRS installed rather than 

install the systems themselves. 

For final-stage manufacturers working 

with incomplete vehicles that do not 

have rear seats or SBRSs already 

installed, we tentatively believe that 

completing vehicles to meet the 

proposed requirements would be 

practicable. The manufacturers can 

obtain seats and seat belt systems (with 

seat belt warning system) from 

suppliers. NHTSA recognizes that the 

suppliers might be supplying larger 

vehicle manufacturers during the 

development and lead time period, and 

do not have the capabilities to handle 

all of the smaller manufacturers, 

including final-stage manufacturers. The 

rulemaking proposal accounts for this 

limitation by proposing to allow finalstage manufacturers an additional year 

to comply with the proposed 

requirements, to provide flexibility to 

these small entities and reduce the 

economic impact of the proposed rule 

on them. (See also 49 CFR 571.8(b).) 

For an alterer (a person who alters by 

addition, substitution or removal of 

components [other than readily 

attachable components] a certified 

vehicle before the first purchase of the 

vehicle other than for resale), the 

impacts of the proposed rule would not 

be significant. The proposed rule would 

allow alterers an additional year to 

comply with the proposed 

requirements. If an alterer is removing 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61731 

rear seats, the person making the 

alteration would simply have to be 

careful not to affect the compliance of 

the seat belt warning system for the 

remaining seats. (See 49 CFR 571.8(b).) 

An alterer that is adding rear seats 

could obtain seating systems with seat 

belt warning systems from seat 

suppliers and install the seats on the 

body following the instructions of the 

seat supplier. Changes may have to be 

made to the instrument panel area to 

add the requisite visual signal, but the 

proposed rule provides flexibility to 

manufacturers in providing the visual 

signal. 

Executive Order 13132 (Federalism) 

NHTSA has examined this proposed 

rule pursuant to Executive Order 13132 

(64 FR 43255; Aug. 10, 1999) and 

concluded that no additional 

consultation with States, local 

governments, or their representatives is 

mandated beyond the rulemaking 

process. The agency has concluded that 

the proposed rule does not have 

sufficient federalism implications to 

warrant consultation with State and 

local officials or the preparation of a 

federalism summary impact statement. 

The proposed rule does not have 

‘‘substantial direct effects on the States, 

on the relationship between the national 

government and the States, or on the 

distribution of power and 

responsibilities among the various 

levels of government.’’ 

NHTSA rules can have preemptive 

effect in two ways. First, the National 

Traffic and Motor Vehicle Safety Act 

contains an express preemption 

provision: When a motor vehicle safety 

standard is in effect under this chapter, 

a State or a political subdivision of a 

State may prescribe or continue in effect 

a standard applicable to the same aspect 

of performance of a motor vehicle or 

motor vehicle equipment only if the 

standard is identical to the standard 

prescribed under this chapter. 49 U.S.C. 

30103(b)(1). It is this statutory command 

by Congress that preempts any nonidentical State legislative and 

administrative law address the same 

aspect of performance. 

The express preemption provision 

described above is subject to a savings 

clause under which ‘‘[c]compliance 

with a motor vehicle safety standard 

prescribed under this chapter does not 

exempt a person from liability at 

common law.’’ 49 U.S.C. 30103(e). 

Pursuant to this provision, State 

common law tort causes of action 

against motor vehicle manufacturers 

that might otherwise be preempted by 

the express preemption provision are 

generally preserved. However, the 

Supreme Court has recognized the 

possibility, in some instances, of 

implied preemption of State common 

law tort causes of action by virtue of 

NHTSA’s rules—even if not expressly 

preempted. 

This second way that NHTSA rules 

can preempt is dependent upon the 

existence of an actual conflict between 

an FMVSS and the higher standard that 

would effectively be imposed on motor 

vehicle manufacturers if someone 

obtained a State common law tort 

judgment against the manufacturer— 

notwithstanding the manufacturer’s 

compliance with the NHTSA standard. 

Because most NHTSA standards 

established by an FMVSS are minimum 

standards, a State common law tort 

cause of action that seeks to impose a 

higher standard on motor vehicle 

manufacturers will generally not be 

preempted. However, if and when such 

a conflict does exist—for example, when 

the standard at issue is both a minimum 

and a maximum standard—the State 

common law tort cause of action is 

impliedly preempted. See Geier v. 

American Honda Motor Co., 529 U.S. 

861 (2000). 

Pursuant to Executive Order 13132, 

NHTSA has considered whether this 

proposed rule could or should preempt 

State common law causes of action. The 

agency’s ability to announce its 

conclusion regarding the preemptive 

effect of one of its rules reduces the 

likelihood that preemption will be an 

issue in any subsequent tort litigation. 

To this end, the agency has examined 

the nature (e.g., the language and 

structure of the regulatory text) and 

objectives of this proposed rule and 

does not foresee any potential State 

requirements that might conflict with it. 

NHTSA does not intend that this 

proposed rule preempt state tort law 

that would effectively impose a higher 

standard on motor vehicle 

manufacturers than that established by 

this proposed rule. Establishment of a 

higher standard by means of State tort 

law would not conflict with the 

standards proposed in this NPRM. 

Without any conflict, there could not be 

any implied preemption of a State 

common law tort cause of action. 

National Environmental Policy Act 

NHTSA has analyzed this NPRM for 

the purposes of the National 

Environmental Policy Act. The agency 

has determined that implementation of 

this action would not have a significant 

impact on the quality of the human 

environment. 

Executive Order 12988 (Civil Justice 

Reform) 

With respect to the review of the 

promulgation of a new regulation, 

section 3(b) of Executive Order 12988, 

‘‘Civil Justice Reform’’ (61 FR 4729, 

February 7, 1996) requires that 

Executive agencies make every 

reasonable effort to ensure that the 

regulation: (1) Clearly specifies the 

preemptive effect; (2) clearly specifies 

the effect on existing Federal law or 

regulation; (3) provides a clear legal 

standard for affected conduct, while 

promoting simplification and burden 

reduction; (4) clearly specifies the 

retroactive effect, if any; (5) adequately 

defines key terms; and (6) addresses 

other important issues affecting clarity 

and general draftsmanship under any 

guidelines issued by the Attorney 

General. This document is consistent 

with that requirement. 

Pursuant to this Order, NHTSA notes 

as follows. The issue of preemption is 

discussed above in connection with E.O. 

13132. NHTSA notes further that there 

is no requirement that individuals 

submit a petition for reconsideration or 

pursue other administrative proceeding 

before they may file suit in court. 

Paperwork Reduction Act 

Under the procedures established by 

the Paperwork Reduction Act of 1995 

(PRA) (44 U.S.C. 3501, et. seq.), Federal 

agencies must obtain approval from the 

OMB for each collection of information 

they conduct, sponsor, or require 

through regulations. A person is not 

required to respond to a collection of 

information by a Federal agency unless 

the collection displays a valid OMB 

control number. In this NPRM, NHTSA 

is proposing new information collection 

requirements. The OMB has 

promulgated regulations describing the 

process through which an agency may 

request and receive clearance for its 

information collections. Under OMB’s 

regulation (at 5 CFR 1320.8(d)), an 

agency must ask for public comment on 

the following: (a) whether the proposed 

collection of information is necessary 

for the proper performance of the 

functions of the agency, including 

whether the information will have 

practical utility; (b) the accuracy of the 

agency’s estimate of the burden of the 

proposed collection of information, 

including the validity of the 

methodology and assumptions used; (c) 

how to enhance the quality, utility, and 

clarity of the information to be 

collected; and (d) how to minimize the 

burden of the collection of information 

on those who are to respond, including 

the use of appropriate automated, 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61732 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

293For a full description of the currently 

approved information collection, please see the 60- 

day notice NHTSA published on February 22, 2022 (87 FR 9787) and the 30-day notice NHTSA 

published on October 14, 2022 (87 FR 62489). 

electronic, mechanical, or other 

technological collection techniques or 

other forms of information technology, 

e.g. permitting electronic submission of 

responses. In compliance with these 

requirements, NHTSA asks for public 

comments on the Information Collection 

Request (ICR) described below for a 

revision to NHTSA’s existing clearance 

titled ‘‘Consolidated Vehicle Owner’s 

Manual Requirements for Motor 

Vehicles and Motor Vehicle Equipment’’ 

(OMB Control No. 2127–0541, which is 

being forwarded to OMB for review and 

approval. 

Title: Consolidated Vehicle Owner’s 

Manual Requirements for Motor 

Vehicles and Motor Vehicle Equipment. 

OMB Control Number: 2127–0541. 

Type of Request: Revision of a 

previously approved collection. 

Type of Review Requested: Regular. 

Requested Expiration Date of 

Approval: 3 years from the date of 

approval. 

Summary of the Collection of 

Information: 

The National Traffic and Motor 

Vehicle Safety Act authorizes the 

Secretary of Transportation (NHTSA by 

delegation), at 49 U.S.C. 30111, to issue 

Federal Motor Vehicle Safety Standards 

(FMVSS) that set performance standards 

for motor vehicles and items of motor 

vehicle equipment. Further, the 

Secretary (NHTSA by delegation) is 

authorized, at 49 U.S.C. 30117, to 

require manufacturers to provide 

information to first purchasers of motor 

vehicles or items of motor vehicle 

equipment related to performance and 

safety in printed materials that are 

attached to or accompany the motor 

vehicle or item of motor vehicle 

equipment. NHTSA has exercised this 

authority to require manufacturers to 

provide certain specified safety 

information to be readily available to 

consumers and purchasers of motor 

vehicles and items of motor vehicle 

equipment. This information is most 

often provided in vehicle owners’ 

manuals and the requirements are found 

in 49 CFR parts 563, 571, and 575. This 

information collection request only 

covers requirements or requests to 

provide information that is not provided 

verbatim in the regulation or standard. 

The information requirements or 

requests are included in: Part 563, 

‘‘Event data recorders;’’ FMVSS No. 108, 

‘‘Lamps, reflective devices, and 

associated equipment;’’ FMVSS No. 110, 

‘‘Tire selection and rims;’’ FMVSS No. 

138, ‘‘Tire Pressure Monitoring 

Systems;’’ FMVSS No. 202a, ‘‘Head 

restraints;’’ FMVSS No. 205, ‘‘Glazing 

materials;’’ FMVSS No. 208, ‘‘Occupant 

crash protection;’’ FMVSS No. 210, 

‘‘Seat belt assembly anchorages;’’ 

FMVSS No. 213, ‘‘Child restraint 

systems;’’ FMVSS No. 225; ‘‘Child 

restraint anchorage systems:’’ FMVSS 

No. 226, ‘‘Ejection mitigation;’’ FMVSS 

No. 303, ‘‘Fuel System Integrity of 

Compressed Natural Gas Vehicles;’’ 

§ 575.103, ‘‘Truck-camper loading;’’ 

§ 575.104, ‘‘Uniform tire quality grading 

standards;’’ and § 575.105, ‘‘Vehicle 

rollover.’’ NHTSA is seeking approval 

from OMB for a revision of this 

currently approved collection.293

In this NPRM, we propose requiring 

that the owner’s manual describe the 

vehicle’s seat belt warning system 

features, including the location, format, 

and meaning of the visual warnings. We 

also propose that the owner’s manual 

include instructions on how to make 

any manual electrical connections for 

readily removable seats. The need for 

the proposed collection is discussed in 

Section X.C.7. If the proposed 

requirements are made final, we will 

ensure we obtain OMB approval for the 

proposed information collection prior to 

the effective date of the final rule. 

Description of the likely respondents: 

Vehicle manufacturers. 

Estimated Number of Respondents: 

52. 

Estimated Total Annual Burden 

Hours: 10,172. 

This revision would increase the 

estimated annual burden hours for 

FMVSS No. 208 by 1,544 hours to 4,294 

hours (1,544 hours + 2,750 hours) and 

the total estimated annual burden hours 

to 10,172. The change in burden reflects 

changes as a result of the rulemaking 

requiring the development of new 

information for the owner’s manual 

amortized over the 3 years the 

information collection is approved for. 

NHTSA believes all manufacturers 

already have the engineering staff on 

hand needed to write the required 

instructions, if not already available, 

which they will accomplish in the 

regular performance of their duties. 

More details on the ICR and burden 

calculations are found in the 30-day 

notice NHTSA published on October 14, 

2022 (87 FR 62489). 

Table 28 provides a summary of the 

estimated hour burden and associated 

labor costs. 

TABLE 28—ESTIMATED ANNUAL HOUR BURDEN AND ASSOCIATED LABOR COSTS

Part/section Brief title 

Number of 

respondents 

annually 

Number of 

responses 

annually 

(i.e., number 

owner’s 

manuals) 

Estimated total 

annual burden 

hours 

Estimated total 

annual labor 

costs at 

$50.44/hour 

563 .................................................... Event Data Recorders ...................... 22 9,405,000 203 $10,239 

571.108 ............................................. Lighting—VHAD ............................... 34 9,405,000 383 19,319 

571.108 ............................................. Lighting—SABs ................................ 22 15,048,000 613 30,920 

571.110 ............................................. Tire Selection and Rims ................... 0 0 0 0 

571.138 ............................................. Tire Pressure Monitoring .................. 22 18,810,000 438 22,093 

571.202a ........................................... Head Restraints ............................... 22 18,810,000 876 44,185 

571.205 ............................................. Glazing ............................................. 34 19,140 176 8,877 

571.208 ............................................. Crash Protection .............................. 22 19,360,000 4,294 216,589 

571.210 ............................................. Belt Anchors ..................................... 22 18,810,000 438 22,093 

571.213 ............................................. Child Restraints ................................ 22 968,000 20 1,009 

571.225 ............................................. Child Restraint Anchorages ............. 22 18,810,000 876 44,185 

571.226 ............................................. Ejection Mitigation ............................ 22 18,810,000 1,205 60,755 

571.303 ............................................. CNG Fuel Systems .......................... 15 22,000 18.00 908 

575.103 ............................................. Truck-Camper Loading .................... 18 2,542,100 35.00 1,765 

575.104 ............................................. Tire Quality ....................................... 34 15,243,030 579.00 29,205 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61733 

TABLE 28—ESTIMATED ANNUAL HOUR BURDEN AND ASSOCIATED LABOR COSTS—Continued 

Part/section Brief title 

Number of 

respondents 

annually 

Number of 

responses 

annually 

(i.e., number 

owner’s 

manuals) 

Estimated total 

annual burden 

hours 

Estimated total 

annual labor 

costs at 

$50.44/hour 

575.105 ............................................. Utility Vehicles .................................. 22 2,970,000 18.00 908 

Totals ......................................... ........................................................... ........................ ........................ 10,172 513,050 

There are no proposed recordkeeping 

requirements associated with this 

collection of information. 

Estimated total annual costs of the 

proposed collection of information: 

$8,726,501. 

The FMVSS No. 208 seat belt 

reminder system owner’s manual 

information requirements would require 

an estimated additional 4 pages to cover 

the general system information and the 

information on manual electrical 

connections for readily removable rear 

seats. The only cost associated with 

publishing this information would be 

the cost of printing the required text. 

NHTSA estimates there are 17,600,000 

new vehicles each year that include the 

FMVSS No. 208 occupant crash 

protection information in the owner’s 

manual. Therefore, the estimated annual 

cost to manufacturers would be 

increased by $755,040 (4 pages × 300 

words per page × $0.00013 per word × 

.25 cost factor × 1.1 production factor × 

17,600,000 manuals) bringing the total 

estimated annual cost to $8,726,501. 

The total annual cost to the 

respondents for the currently approved 

collection of information published in 

vehicles’ owner’s manuals is 

summarized in table 29 below. More 

details on the ICR and cost calculations 

are found in the 30-day notice NHTSA 

published on October 14, 2022 (87 FR 

62489). 

TABLE 29—ESTIMATED ANNUAL COSTS

Part/section Brief title 

Estimated total 

costs to 

respondents 

563 ............................................................ Event Data Recorders .................................................................................................. $30,566 

571.108 ..................................................... Lighting—VHAD ........................................................................................................... 38,208 

571.108 ..................................................... Lighting—SABs ............................................................................................................ 244,530 

571.110 ..................................................... Tire Selection and Rims ............................................................................................... 0 

571.138 ..................................................... Tire Pressure Monitoring Systems ............................................................................... 244,530 

571.202a ................................................... Head Restraints ........................................................................................................... 733,590 

571.205 ..................................................... Glazing ......................................................................................................................... 131 

571.208 ..................................................... Occupant Crash Protection .......................................................................................... 4,152,720 

571.210 ..................................................... Seat Belt Assembly Anchors ....................................................................................... 244,530 

571.213 ..................................................... Child Restraints Systems ............................................................................................. 15,730 

571.225 ..................................................... Child Restraints anchorage systems ........................................................................... 943,800 

571.226 ..................................................... Ejection Mitigation ........................................................................................................ 1,833,975 

571.303 ..................................................... Fuel System Integrity of Compressed Natural Gas Vehicles ...................................... 36 

575.103 ..................................................... Truck-Camper Loading ................................................................................................ 39,657 

575.104 ..................................................... Uniform Tire Quality Grading Standards ..................................................................... 193,205 

575.105 ..................................................... Vehicle Rollover ........................................................................................................... 11,293 

Total Costs ........................................ ....................................................................................................................................... 8,726,501 

Public Comments Invited: You are 

asked to comment on any aspects of this 

information collection, including (a) 

whether the proposed collection of 

information is necessary for the proper 

performance of the functions of the 

Department, including whether the 

information will have practical utility; 

(b) the accuracy of the Department’s 

estimate of the burden of the proposed 

information collection; (c) ways to 

enhance the quality, utility and clarity 

of the information to be collected; and 

(d) ways to minimize the burden of the 

collection of information on 

respondents, including the use of 

automated collection techniques or 

other forms of information technology. 

Please submit any comments, 

identified by the docket number in the 

heading of this document, by the 

methods described in the ADDRESSES

section of this document to NHTSA and 

OMB. Although comments may be 

submitted during the entire comment 

period, comments received within 30 

days of publication are most useful. 

National Technology Transfer and 

Advancement Act 

Under the National Technology 

Transfer and Advancement Act of 1995 

(NTTAA) (Pub. L. 104–113), ‘‘all Federal 

agencies and departments shall use 

technical standards that are developed 

or adopted by voluntary consensus 

standards bodies, using such technical 

standards as a means to carry out policy 

objectives or activities determined by 

the agencies and departments.’’ 

Voluntary consensus standards are 

technical standards (e.g., materials 

specifications, test methods, sampling 

procedures, and business practices) that 

are developed or adopted by voluntary 

consensus standards bodies, such as 

SAE (formerly, the Society of 

Automotive Engineers). The NTTAA 

directs this agency to provide Congress, 

through OMB, explanations when the 

agency decides not to use available and 

applicable voluntary consensus 

standards. 

While the agency is not aware of any 

voluntary standards that exist regarding 

the seat belt warnings contemplated in 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61734 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

this proposed rule, the agency has 

examined relevant regulations in other 

countries, such as the European Union 

standard ECE R16. As discussed above, 

although we are not aware of any 

foreign regulations that require seat belt 

warnings for the front outboard 

passenger or rear seat belts or for the 

driver seat on small buses, we believe 

that requiring seat belt warnings for 

these seating positions and for the 

driver seats on small buses meets a 

safety need and is practicable. 

Severability 

The issue of severability of FMVSSs is 

addressed in 49 CFR 571.9. It provides 

that if any FMVSS or its application to 

any person or circumstance is held 

invalid, the remainder of the part and 

the application of that standard to other 

persons or circumstances is unaffected. 

NHTSA seeks comment on the issue of 

severability. 

Unfunded Mandates Reform Act 

The Unfunded Mandates Reform Act 

of 1995 (Pub. L. 104–4) (UMRA) 

requires agencies to prepare a written 

assessment of the costs, benefits, and 

other effects of proposed or final rules 

that include a Federal mandate likely to 

result in the expenditures by States, 

local or tribal governments, in the 

aggregate, or by the private sector, of 

$100 million or more (adjusted annually 

for inflation with base year of 1995) in 

any one year. Adjusting this amount by 

the implicit gross domestic product 

price deflator for 2022 results in $177 

million (111.416/75.324 = 1.48). The 

assessment may be included in 

conjunction with other assessments, as 

it is here. 

UMRA requires the agency to select 

the ‘‘least costly, most cost-effective or 

least burdensome alternative that 

achieves the objectives of the rule.’’ As 

discussed above, the agency considered 

alternatives to the final rule and has 

concluded that the requirements are the 

most cost-effective alternatives that 

achieve the objectives of the rule. 

The proposed rule on SBRS is not 

likely to result in expenditures by State, 

local or tribal governments of more than 

$100 million annually. However, it is 

estimated to result in the expenditure by 

automobile manufacturers and/or their 

suppliers by approximately $168 

million annually. The estimated costs 

are discussed in Section XIV and the 

PRIA. 

We have tentatively concluded that 

the requirements we are proposing in 

this NPRM are the most cost-effective 

alternatives that achieve the objectives 

of the rule. 

Plain Language 

Executive Order 12866 and E.O. 

13563 require each agency to write all 

rules in plain language. Application of 

the principles of plain language 

includes consideration of the following 

questions: 

• Have we organized the material to 

suit the public’s needs? 

• Are the requirements in the rule 

clearly stated? 

• Does the rule contain technical 

language or jargon that isn’t clear? 

• Would a different format (grouping 

and order of sections, use of headings, 

paragraphing) make the rule easier to 

understand? 

• Would more (but shorter) sections 

be better? 

• Could we improve clarity by adding 

tables, lists, or diagrams? 

• What else could we do to make the 

rule easier to understand? 

If you have any responses to these 

questions, please include them in your 

comments on this proposal. 

Regulation Identifier Number (RIN) 

The Department of Transportation 

assigns a regulation identifier number 

(RIN) to each regulatory action listed in 

the Unified Agenda of Federal 

Regulations. The Regulatory Information 

Service Center publishes the Unified 

Agenda in April and October of each 

year. You may use the RIN contained in 

the heading at the beginning of this 

document to find this action in the 

Unified Agenda. 

Privacy Act 

In accordance with 5 U.S.C. 553(c), 

DOT solicits comments from the public 

to better inform its rulemaking process. 

DOT posts these comments, without 

edit, to www.regulations.gov, as 

described in the system of records 

notice, DOT/ALL–14 FDMS, accessible 

through www.dot.gov/privacy. In order 

to facilitate comment tracking and 

response, we encourage commenters to 

provide their name, or the name of their 

organization; however, submission of 

names is completely optional. Anyone 

is able to search the electronic form of 

all comments received into any of our 

dockets by the name of the individual 

submitting the comment (or signing the 

comment, if submitted on behalf of an 

association, business, labor union, etc.). 

You may review DOT’s complete 

Privacy Act Statement in the Federal 

Register published on April 11, 2000 

(Volume 65, Number 70; Pages 19477– 

78). 

XVII. Public Participation 

How do I prepare and submit 

comments? 

Your comments must be written and 

in English. To ensure that your 

comments are correctly filed in the 

Docket, please include the docket 

number indicated in this document in 

your comments. 

Your comments must not be more 

than 15 pages long. (49 CFR 553.21). We 

established this limit to encourage you 

to write your primary comments in a 

concise fashion. However, you may 

attach necessary additional documents 

to your comments. There is no limit on 

the length of the attachments. 

If you are submitting comments 

electronically as a PDF (Adobe) file, 

NHTSA asks that the documents be 

submitted using the Optical Character 

Recognition (OCR) process, thus 

allowing NHTSA to search and copy 

certain portions of your submissions. 

Please note that pursuant to the Data 

Quality Act, in order for substantive 

data to be relied upon and used by the 

agency, it must meet the information 

quality standards set forth in the OMB 

and DOT Data Quality Act guidelines. 

Accordingly, we encourage you to 

consult the guidelines in preparing your 

comments. OMB’s guidelines may be 

accessed at https://

www.transportation.gov/regulations/ 

dot-information-dissemination-qualityguidelines. 

How can I be sure that my comments 

were received? 

If you wish the Docket to notify you 

upon its receipt of your comments, 

enclose a self-addressed, stamped 

postcard in the envelope containing 

your comments. Upon receiving your 

comments, the Docket will return the 

postcard by mail. 

How do I submit confidential business 

information? 

You should submit a redacted ‘‘public 

version’’ of your comment (including 

redacted versions of any additional 

documents or attachments) to the docket 

using any of the methods identified 

under ADDRESSES. This ‘‘public version’’ 

of your comment should contain only 

the portions for which no claim of 

confidential treatment is made and from 

which those portions for which 

confidential treatment is claimed has 

been redacted. See below for further 

instructions on how to do this. 

You also need to submit a request for 

confidential treatment directly to the 

Office of Chief Counsel. Requests for 

confidential treatment are governed by 

49 CFR part 512. Your request must set 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61735 

forth the information specified in part 

512. This includes the materials for 

which confidentiality is being requested 

(as explained in more detail below); 

supporting information, pursuant to 

§ 512.8; and a certificate, pursuant to 

§ 512.4(b) and part 512, appendix A. 

You are required to submit to the 

Office of Chief Counsel one unredacted 

‘‘confidential version’’ of the 

information for which you are seeking 

confidential treatment. Pursuant to 

§ 512.6, the words ‘‘ENTIRE PAGE 

CONFIDENTIAL BUSINESS 

INFORMATION’’ or ‘‘CONFIDENTIAL 

BUSINESS INFORMATION 

CONTAINED WITHIN BRACKETS’’ (as 

applicable) must appear at the top of 

each page containing information 

claimed to be confidential. In the latter 

situation, where not all information on 

the page is claimed to be confidential, 

identify each item of information for 

which confidentiality is requested 

within brackets: ‘‘[ ].’’ 

You are also required to submit to the 

Office of Chief Counsel one redacted 

‘‘public version’’ of the information for 

which you are seeking confidential 

treatment. Pursuant to § 512.5(a)(2), the 

redacted ‘‘public version’’ should 

include redactions of any information 

for which you are seeking confidential 

treatment (i.e., the only information that 

should be unredacted is information for 

which you are not seeking confidential 

treatment). 

NHTSA is currently treating 

electronic submission as an acceptable 

method for submitting confidential 

business information to the agency 

under part 512. Please do not send a 

hardcopy of a request for confidential 

treatment to NHTSA’s headquarters. 

The request should be sent to Dan 

Rabinovitz in the Office of the Chief 

Counsel at Daniel.Rabinovitz@dot.gov. 

You may either submit your request via 

email or request a secure file transfer 

link. If you are submitting the request 

via email, please also email a courtesy 

copy of the request to John Piazza at 

John.Piazza@dot.gov. 

Will the agency consider late 

comments? 

We will consider all comments 

received before the close of business on 

the comment closing date indicated 

above under DATES. To the extent 

possible, we will also consider 

comments that the docket receives after 

that date. If the docket receives a 

comment too late for us to consider in 

developing a final rule (assuming that 

one is issued), we will consider that 

comment as an informal suggestion for 

future rulemaking action. 

How can I read the comments submitted 

by other people? 

You may read the comments received 

by the docket at the address given above 

under ADDRESSES. The hours of the 

docket are indicated above in the same 

location. You may also see the 

comments on the internet. To read the 

comments on the internet, go to https:// 

www.regulations.gov. Follow the online 

instructions for accessing the dockets. 

Please note that even after the 

comment closing date, we will continue 

to file relevant information in the docket 

as it becomes available. Further, some 

people may submit late comments. 

Accordingly, we recommend that you 

periodically check the Docket for new 

material. You can arrange with the 

docket to be notified when others file 

comments in the docket. See 

www.regulations.gov for more 

information. 

Appendix A—Front Outboard Seat Belt 

Warnings—Additional Data 

In Section XI we looked at the 

durations of the visual and audible seat 

belt warnings for the driver and front 

outboard passenger seats provided on 

new (MY 2022) vehicles. There we 

tabulated warning durations by the 

proportion of total projected sales of the 

vehicle models within each durational 

range. In this appendix, we provide a 

brief discussion of, and data for, the 

warning durations provided in new 

vehicles tabulated by the number of 

vehicle models within each durational 

range. The results are largely the same 

but do show some differences. The 

differences could be attributed to lack of 

projected sales data for some vehicle 

models, but we provide other potential 

explanations below. 

For example, when tabulated by 

vehicle model instead of as a share of 

total projected sales, a larger proportion 

of vehicles have a very short duration 

audible seat belt warning. As we saw in 

the discussion in Section XI, only a very 

small proportion of new vehicles 

projected to be sold have a very shortduration audible warning lasting six or 

eight seconds (about 1% for the driver 

warning, and .3% for the passenger 

warning). However, the share of 

vehicles with such short warnings is 

substantially higher when tabulated as a 

proportion of vehicle models (about 

17% for the driver warning and 14% for 

the passenger warning) (see Figure A.1). 

This could be because these vehicles are 

not expected to have a high sales 

volume. 

The same situation holds for longer 

duration audible warnings. A large 

proportion of the vehicles projected to 

be sold provide a warning that lasts at 

least 1.5 min (90 + sec) (92% for the 

driver warning, 76% for the passenger 

warning), while the share of vehicles 

with this warning duration is 

substantially lower when tabulated as a 

proportion of vehicle models (about 

80% for both the driver and passenger 

warnings) (see Figure A.1). In this case 

these vehicle models are likely high 

sales volume vehicles. Similar 

differences are also apparent for the 

visual warning. See Figure A.2. 

BILLING CODE 4910–59–P 


ddrumheller on DSK120RN23PROD with PROPOSALS2
61736 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

We believe the analysis in terms of 

sales volume is more meaningful, 

because that reflects the number of 

vehicles that are actually equipped 

with—and occupants that are actually 

exposed to—such warnings. For 

example, while only a small proportion 

of vehicles (about 1% by sales volume) 

have a very short-duration driver 

audible warning (six or eight seconds), 

these vehicles account for about 17% of 

vehicle models for which we had data. 

That is, very short warnings appear to 

be provided in a relatively high 

proportion of small-volume vehicle 

models. However, the sales volume data 

better reflects how common these short 

duration warnings are—relatively not 

that common in the sense that only a 

small proportion of new vehicles sold 

have these very short duration 

warnings. 

List of Subjects in 49 CFR Part 571 

Imports, Motor vehicle safety, Motor 

vehicles. 

Proposed Regulatory Text 

For the reasons discussed in the 

preamble, the National Highway Traffic 

Safety Administration proposes to 

amend 49 CFR part 571 as follows: 

PART 571—FEDERAL MOTOR 

VEHICLE SAFETY STANDARDS 

Subpart B—Federal Motor Vehicle 

Safety Standards 

■ 1. The authority citation for part 571 

continues to read as follows: 

Authority: 49 U.S.C. 322, 30111, 30115, 

30117, and 30166; delegation of authority at 

49 CFR 1.95. 

■ 2. Amend § 571.101 by: 

■ a. Revising paragraph S5.5.6; and 

■ b. Revising table 1 and table 2. 

The revisions read as follows. 

§ 571.101 Standard No. 101; Controls and 

displays. 

* * * * * 

S5.5.6(a) Except as provided in 

S5.5.6(b) and (c), messages displayed in 

a common space may be cancelable 

automatically or by the driver. 

(b) Telltales for high beams, turn 

signal, low tire pressure, and passenger 

air bag off, and telltales for which the 

color red is required in table 1 to 

§ 571.101 must not be cancelable while 

the underlying condition for their 

activation exists. 

(c) Telltales for the seat belts must not 

be cancellable by the driver before the 

minimum durations are satisfied but 

may be cancellable automatically as 

specified in FMVSS No. 208. 

* * * * * 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP07SE23.005</GPH>
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61737 

Table 1 to § 571.101 Controls, Telltales, 

and Indicators With Illumination or 

Color Requirements 1


ddrumheller on DSK120RN23PROD with PROPOSALS2EP07SE23.006</GPH>
61738 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP07SE23.007</GPH>
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61739 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP07SE23.008</GPH>
61740 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

Notes: 

1An identifier is shown in this table if it 

is required for a control for which an 

illumination requirement exists or if it is 

used for a telltale for which a color 

requirement exists. If a line appears in 

column 2 and column 3, the control, telltale, 

or indicator is required to be identified, 

however the form of the identification is the 

manufacturer’s option. Telltales are not 

considered to have an illumination 

requirement, because by definition the 

telltale must light when the condition for its 

activation exists. 2Additional requirements in FMVSS 108. 

3Framed areas of the symbol may be solid; 

solid areas may be framed. 4Blue may be blue-green. Red may be redorange. 5Symbols employing four lines instead of 

five may also be used. 6The pair of arrows is a single symbol. 

When the controls or telltales for left and 

right turn operate independently, however, 

the two arrows may be considered separate 

symbols and be spaced accordingly. 7Not required when arrows of turn signal 

telltales that otherwise operate 

independently flash simultaneously as 

hazard warning telltale. 8Separate identification is not required if 

function is combined with master lighting 

switch. 9Refer to FMVSS 105 or FMVSS 135, as 

appropriate, for additional specific 

requirements for brake telltale labeling and 

color. If a single telltale is used to indicate 

more than one brake system condition, the 

brake system malfunction identifier must be 

used. 10Requirement effective September 1, 

2011. 11A manufacturer may use this telltale in 

flashing mode to indicate ESC operation. 12This symbol may also be used to indicate 

the malfunction of related systems/functions, 

including traction control, trailer stability 

assist, comer brake control, and other similar 

functions that use throttle and/or individual 

wheel torque control to operate and share 

common components with ESC. 13Combination of the engine oil pressure 

symbol and the engine coolant temperature 

symbol in a single telltale is permitted. 14Use when engine control is separate 

from the key locking system. 15 If the speedometer is graduated in both 

miles per hour and in kilometers per hour, 

the scales must be identified ‘‘MPH’’ and 

‘‘km/h’’, respectively, in any combination of 

upper- and lowercase letters. 16The letters ‘P’, ‘R’, ‘N’, and ‘D’ are 

considered separate identifiers for the 

individual gear positions. Their locations 

within the vehicle, and with respect to each 

other, are governed by FMVSS 102. The letter 

‘D’ may be replaced by another alphanumeric 

character or symbol chosen by the 

manufacturer. 17Required only for FMVSS 138 compliant 

vehicles. 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP07SE23.009</GPH>
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61741 

18Alternatively, either low tire pressure 

telltale may be used to indicate a TPMS 

malfunction. See FMVSS 138. 19Required only for vehicles manufactured 

on or after September 1, 2007. 20A symbol may be used at the 

manufacturer’s option as provided in FMVSS 

No. 208 S7.5. 

21These are the colors for the symbols if 

symbols are chosen. If a symbol is used to 

indicate to the driver how many or which 

rear seat belts are in use, the color of the 

illuminated symbol must be green. If symbols 

are used to indicate to the driver how many 

or which rear seat belts are not in use the 

color of the illuminated symbol must be red. 

See FMVSS 208 S7.5(c)(1). 

Table 2 to § 571.101 Identifiers for 

Controls, Telltales and Indicators With 

No Color or Illumination Requirements 

BILLING CODE 4910–59–C 

Notes: 

1. Use when engine control is separate 

from the key locking system. 

2. Any combination of upper- or lowercase 

letters may be used. 

3. Framed areas may be filled. 

4. If a line appears in Column 2 and 

Column 3, the Control, Telltale or Indicator 

is required to be identified, however the form 

of the identification is the manufacturer’s 

option. 

5. Separate identification not required if 

function is combined with Master Lighting 

Switch. 

■ 3. Amend § 571.208 by: 

■ a. Adding paragraphs S4.1.5.7, 

S4.1.5.7.1, S4.1.5.8, S4.1.5.8.1, S4.2.8, 

S4.2.8.1, S4.2.9, S4.2.9.1, S4.4.3.4, 

S4.4.3.4.1, S4.4.3.5, S4.4.3.5.1, and 

S4.5.1.(f)(3); 

■ b. Revising paragraph S4.5.3.3(b); and 

■ c. Adding paragraph S7.5. 

The revisions and additions read as 

follows: 

§ 571.208 Standard No. 208; Occupant 

crash protection. 

* * * * * 

S4.1.5.7. Front seat belt warnings for 

passenger cars manufactured on or after 

[insert date the first September 1 that is 

one year after the date of publication of 

a final rule]. 

S4.1.5.7.1 Any front outboard 

designated seating position and any 

inboard designated seating position for 

which a seat belt warning is specified in 

S4.1.5.6 shall comply with S7.5. 

S4.1.5.8. Rear seat belt warnings for 

passenger cars manufactured on or after 

[insert date the first September 1 that is 

two years after the date of publication 

of a final rule]. 

S4.1.5.8.1. All rear designated seating 

positions, except in law enforcement 

vehicles, shall comply with S7.5. 

* * * * * 

S4.2.8 Front seat belt warnings for 

trucks and multipurpose passenger 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP07SE23.010</GPH>
61742 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 

vehicles manufactured on or after 

[insert date the first September 1 that is 

one year after the date of publication of 

a final rule] with a GVWR of 4,536 kg 

(10,00 lb) or less. 

S4.2.8.1. All front outboard 

designated seating positions certified to 

a compliance option requiring a seat 

belt shall comply with S7.5. 

S4.2.9 Rear seat belt warnings for 

trucks and multipurpose passenger 

vehicles manufactured on or after 

[insert date the first September 1 that is 

two years after the date of publication 

of a final rule] with a GVWR of 4,536 

kg (10,00 lb) or less. 

S4.2.9.1. All rear designated seating 

positions certified to a compliance 

option requiring a seat belt, except law 

enforcement vehicles, shall comply with 

S7.5. 

* * * * * 

S4.4.3.4 Front seat belt warnings for 

buses manufactured on or after [insert 

date the first September 1 that is one 

year after the date of publication of a 

final rule] with a GVWR of 4,536 kg 

(10,000 lb) or less. 

S4.4.3.4.1 All front outboard 

designated seating positions shall 

comply with S7.5. 

S4.4.3.5 Rear seat belt warnings for 

buses manufactured on or after [insert 

date the first September 1 that is two 

years after the date of publication of a 

final rule] with a GVWR of 4,536 kg 

(10,000 lb) or less. 

S4.4.3.5.1 All rear designated seating 

positions certified to a compliance 

option requiring a seat belt, except for 

school buses and law enforcement 

vehicles, shall comply with S7.5. 

* * * * * 

S4.5.1 Labeling and owner’s manual 

information. 

* * * * * 

(f) * * * 

(3) The owner’s manual (which 

includes information provided by the 

vehicle manufacturer to the consumer, 

whether in digital or printed form) for 

any vehicle equipped with a seat belt 

warning system must include an 

accurate description of the system 

features and warning signals, including 

the location and format of the visual 

warnings, in an easily understandable 

format. The description shall include 

information on when the different 

features of the warning system will 

activate and how to interpret the visual 

warnings. For vehicles with any rear 

designated seating position that is a 

readily removable seat (a seat designed 

to be easily removed and replaced by 

means installed by the manufacturer for 

that purpose) equipped with manual 

electrical connections that are utilized 

by the rear seat belt warning system, the 

owner’s manual (which includes 

information provided by the vehicle 

manufacturer to the consumer, whether 

in digital or printed form) must include 

a description of the purpose of the 

connection, instructions on how to 

achieve a proper connection in an easily 

understandable format, and a 

description of how not achieving a 

proper connection may affect the proper 

functioning of the system. 

* * * * * 

S4.5.3.3 An automatic seat belt 

furnished pursuant to S4.5.3 shall: 

* * * * * 

(b) Conform to the seat belt warning 

system requirements of S7.5. 

* * * * * 

S7.5 Seat belt warning systems for 

front outboard seat belt assemblies in 

vehicles manufactured on or after 

[insert date the first September 1 that is 

one year after the date of publication of 

a final rule] provided in accordance 

with the requirements of S4.1.5.7, 

S4.2.8, S4.4.3.4, and S4.5.3.3, and rear 

seat belt assemblies in vehicle 

manufactured on or after [insert date 

the first September 1 that is two years 

after the date of publication of a final 

rule] provided in accordance with the 

requirements of S4.1.5.8, S4.2.9, 

S4.4.3.5, and S4.5.3.3. 

(a) Definitions for S7.5. (1) A manual 

seat belt is not in use when the seat belt 

latch mechanism is not fastened. A seat 

belt is in use when the seat belt latch 

mechanism is fastened. An automatic 

seat belt is not in use when the seat belt 

latch mechanism is not fastened or, if 

the automatic belt is non-detachable, the 

emergency release mechanism is in the 

released position. If the automatic seat 

belt is motorized, whether the seat belt 

is in use is determined when the seat 

belt webbing is in its locked protective 

mode at the anchorage point. 

(2) A front outboard passenger seating 

position is occupied when an occupant 

or dummy that weighs 46.7 kg (103 lb) 

or greater and is 139.7 cm (55 inches) 

tall or taller is seated in the seat. 

(3) A rear seating position is occupied 

when an occupant or dummy that 

weighs 21 kg (46.5 lb) or greater and is 

114 cm (45 inches) tall or taller is seated 

in the seat. 

(4) A warning cycle for an 

intermittent audible warning consists of 

period(s) when the warning is active at 

the chime frequency or continuously, 

and of inactive period(s). A warning 

cycle begins with an active period and 

is 30 seconds in duration. 

(5) Chime frequency means the 

repetition rate for an intermittent 

audible warning when the warning is 

active. 

(6) Duty cycle means the total amount 

of time an intermittent audible warning 

is active during a warning cycle at the 

chime frequency or continuously, 

divided by the total warning cycle 

duration (30 seconds). 

(b) Front outboard seat belt warning 

system. For vehicles subject to this 

requirement, a driver’s designated 

seating position and any front outboard 

passenger designating seating position 

must be equipped with an audio-visual 

seat belt warning meeting the 

requirements of S7.5(b)(1) through (5) 

when tested in accordance with S7.5(d). 

(1) Activation and duration—(i) Start 

of trip warning. An audio-visual 

warning must activate when the ignition 

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

position if the seat is occupied and the 

seat belt is not in use. The audio-visual 

warning must continue until the seat 

belt that triggered the warning is in use. 

The audio-visual warning is otherwise 

not permitted to activate except to 

comply with S7.5(b)(1)(ii). 

(ii) Change-of-status warning. An 

audio-visual warning must activate 

when the ignition switch is in the ‘‘on’’ 

or ‘‘start’’ position, the vehicle is in 

forward or reverse drive mode, and the 

status of the seat belt changes from in 

use to not in use, unless a front door on 

the same side of the vehicle as the seat 

belt triggering the warning is open, in 

which case a warning is not required 

and the system may consider this as a 

new trip with respect to that seat belt 

and reset the warning system. The 

audio-visual warning must continue 

until the seat belt that triggered the 

warning is in use. 

(2) Visual warning. (i) If there is a 

driver’s designated seating position, the 

visual warning for the driver’s seat belt 

must be visible from the driver’s seat 

and the visual warning for the front 

outboard passenger seat belt must be 

visible from the driver’s seat and the 

front outboard passenger seat. 

(ii) If there is not a driver’s designated 

seating position, the visual warning for 

each outboard passenger designated 

seating position must be visible from 

each outboard passenger designated 

seating position. 

(iii) The visual warning may be 

continuous or intermittent and must 

display the identifying symbol or the 

words specified in table 2 of FMVSS 

101. 

(iv) For telltales associated with 

multiple front outboard seats, the seat 

with which each telltale is associated 

must be clearly recognizable to a driver 

and to any front outboard passenger. 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules 61743 

(3) Audible warning. The audible 

warning may be continuous or 

intermittent. If intermittent, the audible 

warning when active must be 

continuous or have a chime frequency 

of at least 0.5 Hz and a duty cycle of at 

least 0.2. The same audible warning 

may be used for all seats. 

(4) Cancellation. The warning must 

not be able to be canceled or 

deactivated. 

(5) Override. The warning must not be 

overridden by other warnings. 

(c) Rear passenger seat belt warning 

system. For vehicles subject to this 

requirement, all rear designated seating 

positions must be equipped with a 

warning system that conforms to the 

requirements of S7.5(c)(1) through (6) 

when tested in accordance with S7.5(d). 

(1) Activation and duration—(i) Start 

of trip warning. A visual warning must 

activate when the ignition switch is 

placed in the ‘‘on’’ or ‘‘start’’ position 

and last for at least 60 seconds, except 

for systems certified to S7.5(c)(2)(i)(B) 

when there are no occupied rear seats 

with a seat belt that is not in use. 

(ii) Change-of-status warning. An 

audio-visual warning must activate 

when the ignition switch is in the ‘‘on’’ 

or ‘‘start’’ position, the vehicle is in 

forward or reverse drive mode, and the 

status of the seat belt changes from in 

use to not in use, unless any rear door 

is open, in which case a change-ofstatus warning is not required and the 

system may consider this situation as a 

new trip with respect to that seat belt 

and reset the warning system. The 

audio-visual warning must last for at 

least 30 seconds or until the seat belt 

that triggered the warning is in use. 

(2) Visual warning. (i) The visual 

warning may be continuous or 

intermittent and must consist of 

symbols or text visible from the driver’s 

seat indicating: 

(A) How many or which rear seat belts 

are in use; 

(B) For the occupied rear seats, how 

many or which rear seat belts are not in 

use; 

(C) 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; or 

(D) (For the change-of-status warning 

only) that a seating position experienced 

a seat belt change-of-status from in use 

to not in use. 

(ii) The warning must not indicate a 

seat belt is not in use for an unoccupied 

seat. 

(iii) If symbols are used to indicate to 

the driver how many or which rear seat 

belts are in use, the color of the 

illuminated symbols must be green. If 

symbols are used to indicate to the 

driver how many or which rear seat 

belts are not in use, the color of the 

illuminated symbols must be red. 

(iv) If text is used to indicate to the 

driver how many or which rear seat 

belts are in use or not in use, the text 

must contain the words ‘‘rear belt(s) in 

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

(v) The visual warning must not be 

overridden by other visual warnings. 

(3) Audible warning. The audible 

warning may be continuous or 

intermittent. If intermittent, inactive 

periods longer than 3 seconds will not 

be counted toward the total duration of 

the audible warning. The same audible 

warning may be used for all rear seats, 

and the same audible warning may be 

used for the rear as for the front. 

(4) Cancellation. The warning must 

not be able to be canceled or 

deactivated. 

(5) Override. The warning must not be 

overridden by other warnings. 

(6) Seat electrical connection 

requirements. Any rear designated 

seating position consisting of a readily 

removable seat (a seat designed to be 

easily removed and replaced by means 

installed by the manufacturer for that 

purpose) that is equipped with electrical 

connections utilized by the rear seat belt 

warning system must either— 

(i) Automatically connect the 

electrical connections when the seat is 

put in place; or 

(ii) If a manual electrical connection 

is required, the connectors must be 

readily accessible. 

(7) Electrical connection warning 

signal. Vehicles that provide a visual 

warning according to S7.5(c)(2)(i)(B) 

and are equipped with any readily 

removable rear seat(s) (a seat designed 

to be easily removed and replaced by 

means installed by the manufacturer for 

that purpose) must, when the ignition 

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

position, provide an intermittent visual 

warning visible from the driver’s seat if 

a seat has been installed and a proper 

electrical connection has not been 

made. The visual warning must remain 

active until all the rear seat electrical 

connections are properly made. 

(d) Test procedures—(1) In general. (i) 

If testing with any designated seating 

position occupied, use the seating 

procedures in S7.5(d)(2) for front 

designated seating positions and the 

seating procedures in S7.5(d)(3) for rear 

designated seating positions. 

(ii) Place the ignition switch in the 

‘‘on’’ or ‘‘start’’ position and verify that 

the seat belt warnings function as 

specified in S7.5(b) and S7.5(c), for any 

combination of seat belt use or seat 

occupancy at any designated seating 

position(s). 

(2) Seating procedures for front 

designated seating positions—(i) 

Anthropomorphic test devices used for 

testing. The anthropomorphic test 

device (test dummy) is any of the 

anthropomorphic test devices specified 

in part 572 that meet the criteria 

specified in S7.5(a)(2). 

(ii) Seating procedure. (A) With the 

seat back in the manufacturer’s nominal 

design riding position, any other seat 

adjustments in any position, and any 

adjustable seat belt anchorages in any 

position, seat the test dummy such that 

the midsagittal plane of the dummy is 

vertical and within ± 10 mm of the seat 

centerline, with the torso and pelvis in 

contact with the seat back. 

(B) At the option of the manufacturer 

(irrevocably selected prior to or at the 

time of certification of the vehicle), 

instead of using test dummies, a human 

being (dressed in a cotton T-shirt, full 

length cotton trousers, and sneakers) 

may be used whose weight and height 

(including this clothing) meet the 

criteria specified in S7.5(a)(2). The 

person should be seated in order to 

match, to the extent possible, the final 

physical position specified in 

S7.5(d)(2)(ii)(A). 

(3) Seating procedures for rear 

designated seating positions—(i) 

Anthropomorphic test devices used for 

testing. The anthropomorphic test 

device is any of the anthropomorphic 

test devices specified in part 572 that 

meet the criteria specified in S7.5(a)(3). 

(ii) Seating procedure. (A) With the 

seat back in the manufacturer’s nominal 

design riding position, any other seat 

adjustments in any position, and any 

adjustable anchorages in any position, 

seat the test dummy such that the 

midsagittal plane of the dummy is 

vertical and within ± 10 mm of the seat 

centerline, with the torso and pelvis in 

contact with the seat back; or 

(B) At the option of the manufacturer 

(irrevocably selected prior to or at the 

time of certification of the vehicle), 

instead of using test dummies, a human 

being (dressed in a cotton T-shirt, full 

length cotton trousers, and sneakers) 

may be used whose weight and height 

(including this clothing) meet the 

criteria specified in S7.5(a)(3). The 

person should be seated in order to 

match, to the extent possible, the final 

physical position specified in 

S7.5(d)(3)(ii)(A). 

* * * * * 

Issued under authority delegated in 49 CFR 

1.95, 501.4, and 501.5. 

Ann Carlson, 

Acting Administrator. 

[FR Doc. 2023–18413 Filed 9–6–23; 8:45 am] 

BILLING CODE 4910–59–P 


ddrumheller on DSK120RN23PROD with PROPOSALS2