Document ID: NHTSA-2022-0053-0001
Agency: nhtsa
Document Type: Rule
Title: Federal Motor Vehicle Safety Standards: Rear Impact Guards, Rear Impact Protection
Posted Date: 2022-07-15T04:00Z

[Federal Register Volume 87, Number 135 (Friday, July 15, 2022)]
[Rules and Regulations]
[Pages 42339-42373]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-14330]

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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. NHTSA-2022-0053]
RIN 2127-AL58

Federal Motor Vehicle Safety Standards; Rear Impact Guards, Rear 
Impact Protection

AGENCY: National Highway Traffic Safety Administration (NHTSA), 
Department of Transportation (DOT).

ACTION: Final rule.

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SUMMARY: This final rule upgrades NHTSA's safety standards addressing 
rear underride protection in crashes of passenger vehicles into 
trailers and semitrailers by adopting similar requirements to Transport 
Canada's standard for rear impact guards. Adopting these standards will 
require rear impact guards to provide sufficient strength and energy 
absorption to protect occupants of compact and subcompact passenger 
cars impacting the rear of trailers at 56 kilometers per hour (km/h) 
(35 miles per hour (mph)). Upgraded protection will be provided in 
crashes in which the passenger motor vehicle hits: the center of the 
rear of the trailer or semitrailer; and, in which 50 percent of the 
width of the passenger motor vehicle overlaps the rear of the trailer 
or semitrailer. This rulemaking commenced in response to petitions for 
rulemaking from the Insurance Institute for Highway Safety (IIHS) and 
from Ms. Marianne Karth and the Truck Safety Coalition (TSC). This 
final rule responds to and fulfills the rulemaking mandate of the 
November 2021 Bipartisan Infrastructure Law (BIL) that directs the 
Secretary to upgrade current Federal safety standards for rear impact 
guards. NHTSA is also issuing this final rule pursuant to DOT's January 
2022 National Roadway Safety Strategy, which describes the five key 
objectives of the Department's Safe System Approach: safer people, 
safer roads, safer vehicles, safer speeds, and post-crash care. One of 
the key Departmental actions to enable safer vehicles is to issue a 
final rule to upgrade existing requirements for rear impact guards on 
newly manufactured trailers and semitrailers.

DATES: 
    Effective date: This final rule is effective on January 11, 2023.
    Compliance date: July 15, 2024. Optional early compliance is 
permitted.
    Petitions for reconsideration: Petitions for reconsideration of 
this final rule must be received no later than August 29, 2022.

ADDRESSES: Petitions for reconsideration of this final rule must refer 
to the docket and notice number set forth above and be submitted to the 
Administrator, National Highway Traffic Safety Administration, 1200 New 
Jersey Avenue SE, West Building, Washington, DC 20590. All petitions 
received will be posted without change to https://www.regulations.gov, 
including any personal information provided.
    Privacy Act: DOT will post any petition for reconsideration, and 
any other submission, without edit, to www.regulations.gov, as 
described in the system of records notice, DOT/ALL-14 FDMS, accessible 
through https://www.transportation.gov/individuals/privacy/privacy-act-system-records-notices. Anyone is able to search the electronic form of 
all submissions to any of our dockets by the name of the individual 
submitting the submission (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 (65 FR 19477-78).

FOR FURTHER INFORMATION CONTACT: For technical issues: Ms. Lina 
Valivullah, National Highway Traffic Safety Administration, 1200 New 
Jersey Avenue SE, West Building, Washington, DC 20590 (telephone) 202-
366-8786, (email) [email protected].
    For legal issues: Ms. Deirdre Fujita, Office of the Chief Counsel, 
National Highway Traffic Safety Administration, 1200 New Jersey Avenue 
SE, West Building, Washington, DC 20590, (telephone) 202-366-2992, 
(email) [email protected].

SUPPLEMENTARY INFORMATION: 

Table of Contents

I. Executive Summary
    a. Overview
    b. NHTSA's Statutory Authority and Response to BIL
    1. National Traffic and Motor Vehicle Safety Act
    2. Bipartisan Infrastructure Law
    3. Implementation of BIL
    c. DOT National Roadway Safety Strategy
    d. NTSB Recommendation
    e. Impacts of This Rulemaking
    f. No Significant Changes to the NPRM
II. Background
    a. Current Requirements
    b. Petitions
    c. Summary of Proposed Changes
III. Summary of Comments
IV. Response to Comments on the Proposed Amendments

[[Page 42340]]

    a. General Strength and Energy Absorption Requirements
    b. Alternative Guard Designs
    c. 700 kN Energy Absorption Test Option
    d. Ground Clearance
    e. Requiring Attachment Hardware To Remain Intact
    f. Definition of Rear Extremity
    g. Low Chassis Vehicle Correction
    h. Technical Correction
V. Response to Comments on Issues Not Proposed in the NPRM
    a. Vehicles Excluded From FMVSS No. 224
    b. Testing on a Trailer Rather Than a Fixture
    c. Low Overlap Crash Performance
    d. Half-Guard Testing
    e. Retrofitting
VI. Lead Time
VII. Benefit-Cost Analysis
VIII. Regulatory Notices and Analyses

I. Executive Summary

a. Overview

    NHTSA is issuing this final rule to upgrade Federal Motor Vehicle 
Safety Standard (FMVSS) No. 223, ``Rear impact guards,'' and FMVSS No. 
224, ``Rear impact protection,'' which together provide protection for 
occupants of passenger vehicles in crashes into the rear of trailers 
and semitrailers. FMVSS No. 223, an equipment standard, specifies 
strength and energy absorption requirements in quasi-static force tests 
of rear impact guards sold for installation on new trailers and 
semitrailers. FMVSS No. 224, a vehicle standard, requires new trailers 
and semitrailers with a gross vehicle weight rating (GVWR) of 4,536 
kilogram (kg) (10,000 pounds (lb)) or more to be equipped with a rear 
impact guard meeting FMVSS No. 223.\1\ The notice of proposed 
rulemaking (NPRM) preceding this final rule was published on December 
16, 2015.\2\
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    \1\ NHTSA established the two-standard approach to address 
compliance burdens on small trailer manufacturers, of which there is 
a significant number. Under FMVSS No. 223, the guard may be tested 
for compliance while mounted to a test fixture or to a complete 
trailer, at the manufacturer's option. FMVSS No. 224 requires the 
guard to be mounted on the trailer or semitrailer in accordance with 
the instructions provided with the guard by the guard manufacturer. 
Under this two-standard approach, a small manufacturer that produces 
relatively few trailers can certify its trailers to FMVSS No. 224 
with assurance without having to undertake destructive testing of 
what could be a substantial portion of its production. The two-
standard approach was designed to provide small trailer 
manufacturers a practicable and reasonable means of certifying to 
FMVSS No. 224.
    \2\ 80 FR 78417.
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    Rear underride crashes occur when a passenger vehicle crashes into 
the rear end of a generally larger vehicle, and the front end of the 
passenger vehicle slides under (i.e., underrides) the rear end of the 
larger vehicle. Underride may occur in collisions between a passenger 
vehicle and the rear end of a large trailer or semitrailer (referred to 
in this rule collectively as ``trailers'') because the bed and chassis 
of the trailer is often higher than the front of the passenger vehicle. 
In extreme underride crashes, ``passenger compartment intrusion'' (PCI) 
may occur when the passenger vehicle underrides the rear end of the 
trailer to such an extent that the rear end of the trailer strikes and 
enters the passenger compartment of the colliding passenger vehicle. 
PCI can result in severe injuries and fatalities to the occupants of 
the passenger vehicle.
    Rear impact guards are mounted on the rear of trailers to prevent 
underride and PCI. In a collision between a passenger vehicle and the 
rear of a trailer equipped with a rear impact guard, the rear impact 
guard engages the striking passenger vehicle and prevents it from 
sliding too far under the struck vehicle's bed and chassis. FMVSS Nos. 
223 and 224 ensure a rear impact guard is configured low and wide to 
impede a striking passenger vehicle, is strong enough to withstand a 48 
km/h (30 mph) impact of the colliding vehicle, and has energy-absorbing 
capability to further mitigate harm to occupants in the striking 
vehicle.
    NHTSA designed FMVSS No. 223 and 224 to work in conjunction with 
FMVSS No. 208, ``Occupant crash protection,'' so that occupants are 
protected with seat belts and air bags in the underride crash--thus 
maximizing the likelihood of avoiding serious or fatal injury in the 
impact into the guard. When FMVSS Nos. 223 and 224 were issued in 1996, 
FMVSS No. 208 required passenger cars to provide crash protection in a 
48 km/h (30 mph) rigid barrier crash test. The agency designed the 
underride protection standards so that occupants would be reasonably 
protected in underride crashes up to 48 km/h (30 mph). Since then, 
FMVSS No. 208's test speed has been increased to provide high levels of 
occupant protection in a 56 km/h (35 mph) frontal crash.
    With FMVSS No. 208 now providing crash protection up to 56 km/h (35 
mph), NHTSA is amending FMVSS Nos. 223 and 224 to mandate the guards 
withstand crash velocities up to that speed. This final rule adopts 
requirements of Canada Motor Vehicle Safety Standard (CMVSS) No. 223, 
``Rear impact guards.'' \3\ CMVSS No. 223 requires rear impact guards 
with sufficient strength and energy absorption capability to protect 
occupants of compact and subcompact passenger cars impacting the rear 
of trailers at 56 km/h (35 mph). Under this final rule, the impacting 
vehicle's FMVSS No. 208 occupant protection technologies could absorb 
enough of the crash forces from the impact to reduce significantly the 
risk of fatality and serious injury to occupants of the colliding 
vehicle. As the current requirements in FMVSS Nos. 223 and 224 were 
developed with the intent of providing underride crash protection to 
occupants of passenger vehicles in impacts up to 48 km/h (30 mph), 
increasing the robustness of the trailer/guard design such that it will 
be able to withstand crash velocities up to 56 km/h (35 mph) represents 
a substantial increase in the stringency of our standards. There is a 
36 percent increase in crash energy in a 56 km/h (35 mph) impact of a 
vehicle compared to a 48 km/h (30 mph) impact of the same vehicle.
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    \3\ This final rule also adopts Transport Canada's definition of 
``rear extremity'' to define where aerodynamic fairings are to be 
located on a trailer to avoid posing a safety hazard in rear 
underride crashes.
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    This final rule is based on the best available science. The 
underlying field data used in the December 16, 2015 NPRM and this final 
rule are from a 2013 NHTSA-funded study conducted by the University of 
Michigan Transportation Research Institute (UMTRI) to supplement 
UMTRI's Trucks Involved in Fatal Accidents (TIFA) survey data for years 
2008 and 2009. (The 2013 NHTSA-funded study is referred to in this 
preamble as the 2013 UMTRI Study.) 4 5 The TIFA database had 
analyzed FARS data to obtain more detailed information on fatal large 
truck crashes, and had provided more detailed information than in FARS 
on the involved large trucks, motor carriers, and sequence of events 
leading to the crash.\6\ The 2013 UMTRI Study supplemented these TIFA 
data by collecting specific data pertaining to trailer rear extremity 
crashes. In the 2013 UMTRI Study, UMTRI also determined whether a rear 
impact guard was required, and if not required, the criterion that had 
excluded the vehicle. The 2013 UMTRI Study collected detailed 
information on fatal vehicle crashes into the rear of trailers, the 
relative impact velocity, and the extent of underride in these crashes. 
The data from the 2013 UMTRI Study

[[Page 42341]]

enabled NHTSA to establish national estimates of rear impact crashes 
into heavy vehicles that resulted in PCI. Because of the detailed 
analysis and the supplemental information collected for each crash, the 
2013 UMTRI Study forms the most comprehensive and valid data set 
available to inform NHTSA about crashes involving trucks and trailers 
and the incidence and extent of underride.
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    \4\ NHTSA discussed the results of this study in detail in 
Appendix A of the NPRM. See 80 FR 78447-78452.
    \5\ Heavy-Vehicle Crash Data Collection and Analysis to 
Characterize Rear and Side Underride and Front Override in Fatal 
Truck Crashes, DOT HS 811 725, March 2013, https://www.nhtsa.gov/sites/nhtsa.gov/files/811725.pdf.
    \6\ The TIFA survey data contain data for all trucks with a GVWR 
greater than 4,536 kg (10,000 lb) that were involved in fatal 
traffic crashes in the 50 U.S. States and the District of Columbia.
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b. NHTSA's Statutory Authority and Response to BIL

1. National Traffic and Motor Vehicle Safety Act
    This final rule is issued under the National Traffic and Motor 
Vehicle Safety Act (Safety Act) (49 U.S.C. 30101 et seq.). Under the 
Safety Act, the Secretary of Transportation (NHTSA by delegation) \7\ 
is responsible for prescribing motor vehicle safety standards that are 
practicable, meet the need for motor vehicle safety, and are stated in 
objective terms.\8\ ``Motor vehicle safety'' is defined in the 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.'' 
\9\ ``Motor vehicle safety standard'' means a minimum performance 
standard for motor vehicles or motor vehicle equipment.\10\ When 
prescribing such standards, the agency must consider all relevant, 
available motor vehicle safety information, and consider whether a 
standard is reasonable, practicable, and appropriate for the types of 
motor vehicles or motor vehicle equipment for which it is 
prescribed.\11\ The agency must also consider the extent to which the 
standard will further the statutory purpose of reducing traffic crashes 
and associated deaths.\12\
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    \7\ 49 CFR 1.95. The Secretary also delegated to NHTSA the 
authority set out for Section 101(f) of Public Law 106-159 to carry 
out, in coordination with the Federal Motor Carrier Safety 
Administrator, the authority vested in the Secretary by subchapter 
311 and section 31502 of title 49, U.S.C., to promulgate safety 
standards for commercial motor vehicles and equipment subsequent to 
initial manufacture when the standards are based upon and similar to 
a Federal Motor Vehicle Safety Standard promulgated, either 
simultaneously or previously, under chapter 301 of title 49, U.S.C.
    \8\ 49 U.S.C. 30111(a).
    \9\ 49 U.S.C. 30102(a)(8).
    \10\ 49 U.S.C. 30102(a)(9).
    \11\ 49 U.S.C. 30111(b).
    \12\ Id.
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2. Bipartisan Infrastructure Law
    On November 15, 2021, President Biden signed the Infrastructure 
Investment and Jobs Act (IIJA),\13\ commonly referred to as the 
Bipartisan Infrastructure Law (BIL). Section 23011 of BIL specifies 
provisions for underride protection measures for trailers and 
semitrailers. As discussed in detail below, the provisions direct the 
Secretary to upgrade current Federal safety standards for rear impact 
guards and conduct additional research, report to Congress on the 
effectiveness, feasibility, costs, and benefits of side guards, 
establish an advisory committee on underride protection, and implement 
the recommendations issued by the Government Accountability Office 
(GAO) on improved data collection, inspection and research of truck 
underride guards.
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    \13\ Public Law 117-58.
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    Section 23011(b)(1)(A) of BIL states that, not later than 1 year 
after the date of enactment of the Act, the Secretary shall promulgate 
regulations that revise FMVSS No. 223 and FMVSS No. 224 to require new 
trailers and semitrailers to be equipped with rear impact guards that 
are designed to prevent PCI from a trailer or semitrailer when a 
passenger vehicle traveling at 56 km/h (35 mph) makes an impact: (a) 
``in which the passenger motor vehicle impacts the center of the rear 
of the trailer or semitrailer'' (full overlap with the rear of the 
trailer or semitrailer); (b) ``in which 50 percent of the width of the 
passenger motor vehicle overlaps the rear of the trailer or 
semitrailer''; and (c) ``in which 30 percent of the width of the 
passenger motor vehicle overlaps the rear of the trailer or 
semitrailer, if the Secretary determines that a revision of [FMVSS Nos. 
223 and 224] to address such an impact would meet the requirements and 
considerations described in subsections (a) and (b) of section 30111 of 
title 49, United States Code'' (i.e., the Safety Act). Section 
23011(b)(1)(B) states that the regulations promulgated under Section 
23011(b)(1)(A) shall require full compliance not later than two years 
after the date on which those regulations are promulgated.
    Section 23011(b)(2) of BIL directs the Secretary to conduct 
additional research on the design and development of rear impact guards 
that can: prevent PCI in cases in which the passenger motor vehicle is 
traveling at speeds of up to 65 mph; and that can protect occupants 
against severe injury in crashes of passenger vehicles into the rear of 
trailers and semitrailers at speeds up to 104.5 km/h (65 mph). Section 
23011(b)(3) directs that, not later than 5 years after the date the 
regulations under Section 23011(b)(1)(A) are promulgated, the Secretary 
shall review and evaluate the need for changes to FMVSS No. 223 and 
FMVSS No. 224 in response to advancements in technology and update the 
standards accordingly.\14\
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    \14\ There are also provisions relating to the Federal Motor 
Carrier Safety Regulations.
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    Section 23011(c)(1)(A) of BIL directs the Secretary to complete, 
not later than 1 year after enactment of the Act, additional research 
on side underride guards to better understand the overall effectiveness 
of the guards. Section 23011(c)(1)(B) requires the Secretary to assess, 
among other matters, the feasibility, benefits, and costs of, and any 
impacts on intermodal equipment, freight mobility (including port 
operations), and freight capacity associated with, installing side 
underride guards on new trailers and semitrailers within one year of 
enactment of BIL, and if warranted, develop performance standards for 
side underride guards. Section 23011(c)(3) also directs the Secretary 
to publish the results of the side underride guard assessment specified 
in Section 23011(c)(1)(B) within 90 days of completion of the 
assessment and provide an opportunity for public comment. It also 
directs that, within 90 days from the date the comment period closes, 
the Secretary shall submit a report to Congress on the assessment 
results, a summary of comments received, and a determination whether 
the Secretary intends to develop performance requirements for side 
underride guards, including any analysis that led to that 
determination.
    Section 23011(d) of BIL directs the Secretary to establish an 
advisory committee on underride protection to provide advice and 
recommendations to the Secretary on safety regulations to reduce 
underride crashes and fatalities relating to underride crashes. This 
section also provides details on the membership of the advisory 
committee, frequency of meetings of the advisory committee, the 
Secretary's support to the advisory committee, and details of a 
biennial report to Congress that the advisory committee is required to 
submit.
    Section 23011(e) of BIL directs the Secretary to implement the 
recommendations on truck underride guard data collection issued by the 
Government Accountability Office

[[Page 42342]]

(GAO) on March 14, 2019,\15\ within 1 year after the date of enactment 
of the Act.
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    \15\ GAO Report to Congressional Requestors, ``Truck Underride 
Guards--Improved Data Collection, Inspections, and Research 
Needed,'' March 14, 2019, (GAO-19-264), https://www.gao.gov/assets/gao-19-264.pdf.
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3. Implementation of BIL
    This final rule fulfills the BIL rulemaking mandate to NHTSA set 
forth in Section 23011(b). As directed by Sections 23011(b)(1)(A)(i) 
and (ii), this final rule revises FMVSS Nos. 223 and 224 to require 
trailers and semitrailers to be equipped with rear impact guards that 
prevent passenger compartment intrusion from a trailer or semitrailer 
when a passenger motor vehicle traveling at 35 miles per hour makes: 
(a) an impact in which the passenger motor vehicle impacts the center 
of the rear of the trailer or semitrailer; and (b) an impact in which 
50 percent of the width of the passenger motor vehicle overlaps the 
rear of the trailer or semitrailer.
    This final rule fulfills these BIL rulemaking mandates of Sections 
23011(b)(1)(A)(i) and (ii) and achieves, effectively and expeditiously, 
the Congressional goal that focuses on improving rear impact guard 
performance. The 2015 NPRM proposed to adopt the Canadian quasi-static 
test requirements for rear impact guards, which ensure rear impact 
guards provide sufficient strength and energy absorption to protect 
occupants of compact and subcompact passenger cars impacting the rear 
of trailers at 56 km/h (35 mph).\16\ The NPRM reported on crash tests 
conducted by IIHS that showed that rear impact guards installed on 
trailers that were designed to the proposed requirements were able to 
prevent PCI in 35 mph crashes of a passenger vehicle into the rear of 
the trailer where: (a) the front end of the passenger vehicle fully 
overlapped the rear of the trailer (full overlap crash); and (b) 50 
percent of the width of the front end of the passenger vehicle 
overlapped the rear of the trailer (50 percent overlap crash). These 
data show that trailers and semitrailers equipped with rear impact 
guards meeting the requirements of this final rule will have guards 
that are designed to prevent PCI when a passenger motor vehicle 
traveling at 35 mph impacts the center of the rear of the trailer or 
semitrailer, or makes impact in which 50 percent of the width of the 
passenger vehicle overlaps the rear of the trailer or semitrailer, in 
accordance with BIL.
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    \16\ At the time of enactment of BIL, the agency's December 16, 
2015 NPRM upgrading FMVSS No. 223 and FMVSS No. 224 had been 
published and DOT's work was close to completion on the final rule. 
BIL provides a very short timeframe (1 year) for issuance of a final 
rule. The short timeframe is indicative of Congress's intent that a 
final rule based on the 2015 NPRM will complete the rulemaking 
proceedings specified in Section 23011(b)(1)(A) of the Act.
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    NHTSA's work on this final rule also meets the BIL mandate in 
Section 23011(b)(1)(A)(iii). In developing this rule, the agency 
considered a requirement that rear impact guards withstand a 56 km/h 
(35 mph) crash of a passenger vehicle into the rear of a trailer in 
which only 30 percent of the width of the passenger motor vehicle 
overlaps the rear of the trailer or semitrailer (30 percent overlap 
crash). After analyzing the issue, we determined such a standard would 
not meet the requirements and considerations of Sections 30111(a) and 
(b) of the Safety Act. Our consideration of this matter is discussed 
below.
Sections 30111(a) and 30111(b)
    The provision at 49 U.S.C. 30111(a) of the Safety Act authorizes 
the Secretary (NHTSA, by delegation) to prescribe Federal motor vehicle 
safety standards that are practicable, meet the need for motor vehicle 
safety, and are stated in objective terms. ``Motor vehicle safety'' is 
defined in the 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.'' \17\
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    \17\ 49 U.S.C. 30102(a)(8).
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    The provision at 49 U.S.C. 30111(b) specifies that, when 
prescribing such standards, the Secretary must, among other things, 
consider all relevant, available motor vehicle safety information, 
consider whether a standard is reasonable, practicable, and appropriate 
for the types of motor vehicles or motor vehicle equipment for which it 
is prescribed, and consider the extent to which the standard will 
further the statutory purpose of reducing traffic crashes and 
associated deaths and injuries. NHTSA has considered the factors in 
Section 30111(b) and concludes that available data do not show that a 
standard for a 30 percent overlap crash at 35 mph would be reasonable, 
practicable, or appropriate for all the vehicles subject to FMVSS No. 
223 and FMVSS No. 224. Accordingly, NHTSA cannot conclude that a 
Federal mandate for such a requirement for all trailers is warranted at 
this time.
    Rear impact guards are designed to absorb energy and prevent PCI by 
attaching to substantial structural elements of a trailer or 
semitrailer, such as the chassis longitudinal frame rails, by way of 
vertical support members. The vertical members of the rear impact guard 
usually attach to the longitudinal frame rails so that impact loads are 
directly transmitted to the frame rails with minimal or no damage to 
the overall trailer structure. The test results from the initial 
testing at IIHS reported in the NPRM show that in the 30 percent 
overlap crashes, only a small lateral portion of the rear impact guard 
(about 22 percent of the guard width) engaged with the front end of the 
passenger vehicle. This small lateral portion did not include a 
vertical support member of the guard, so when a Chevy Malibu test 
vehicle struck this small lateral portion of the guard, the guard 
deformed locally and did not prevent PCI. In these initial IIHS crash 
tests, only the Manac rear impact guard was able to prevent PCI in the 
Chevy Malibu in the 56 km/h (35 mph) full overlap, 50 percent overlap, 
and 30 percent overlap crash test conditions. NHTSA believes the Manac 
performed this way because, unlike most trailer designs where the 
vertical members of the rear impact guard attach directly to the 
longitudinal frame rails of the trailer, the vertical members of the 
Manac rear impact guard were located further outboard from the location 
of the trailer longitudinal frame rails and were attached to a 
reinforced floor section of the trailer.
    While the more outboard vertical supports of the Manac guard could 
withstand the force from the 30 percent low overlap crash of the 
Malibu, data suggest the further outboard vertical supports may reduce 
guard strength near the center of the horizontal member of the rear 
impact guard. In the 56 km/h (35 mph) full overlap crash tests of the 
Malibu, the greatest amount of underride (1,350 mm) was in the test 
with the Manac trailer. (In contrast, the extent of the underride was 
990 mm in the test with the Wabash trailer.) NHTSA found this 
observation critical because it indicated that trailers that have the 
main vertical supports for the guard more outboard may not perform as 
well in full overlap crashes as trailers
that have the vertical supports more inboard. This finding was of key 
concern because full and 50 percent overlap crashes are more frequent 
than low overlap (30 percent or less) crashes. NHTSA seeks not to amend 
FMVSS No. 223 in a manner that could reduce safety in the more frequent 
crash conditions.

[[Page 42343]]

    Further, data indicate that most fatal light vehicle crashes into 
the rear of trailers are at speeds much higher than 56 km/h (35 mph). 
The agency is concerned that adopting requirements to mitigate PCI in 
30 percent low overlap crashes could result in rear impact guard 
designs that may reduce protection against PCI in higher speed crashes. 
NHTSA remains concerned about potential negative safety consequences if 
a final rule were to adopt requirements that result in moving the 
vertical members of rear impact guards more outward laterally to 
prevent underride in a 56 km/h (35 mph) 30 percent low overlap crash, 
at the expense of protection against higher speed crashes. The agency 
believes this issue should be more fully explored before possibly 
adopting a 30 percent low overlap requirement.
    NHTSA has estimated the benefits and costs of adopting performance 
requirements to mitigate underride in low overlap (30 percent or lower 
overlap) crashes based on available information. We estimate 0.75 to 
1.5 fatalities would be prevented annually if this rule included 
requirements to mitigate PCI in 30 percent overlap crashes at 56 km/h 
(35 mph) impact speed. (This estimate does not account for the possible 
dis-benefits in full and 50 percent offset crashes resulting from a low 
overlap requirement, discussed in the paragraph above.) The 0.75 to 1.5 
fatalities prevented is based on an estimated 5.8--11.5 annual 
fatalities in low overlap crashes into the rear of trailers (crashes 
where 30 percent or less of the front end of the impacting vehicle 
overlaps the rear of the trailer) and a 13 percent effectiveness of 
rear impact guards with 30 percent overlap crash protection in 
mitigating fatalities.
    To prevent PCI in 30 percent overlap crashes, designs would have to 
either: (a) add additional vertical members at the lateral edge of the 
rear impact guard that connect to the trailer's transverse floor beam 
and strengthen the transverse floor beam of the trailer to withstand 
the loads transmitted from these vertical members at the edge of the 
guard; or (b) considerably strengthen the rear impact guard member so 
it would not deform locally in the 30 percent overlap crash. Both these 
approaches would add significant weight to the vehicles because they 
involve adding more vertical members, strengthening the floor beams, or 
strengthening the guard itself. Additionally, some guard designs may 
have restrictions in intermodal operations at loading docks and may not 
be practicable for all types of trailers covered by FMVSS No. 224.
    NHTSA is required by Section 1 of Executive Order 12866 to conduct 
a benefit-cost analysis of any intended regulation.\18\ NHTSA estimates 
that the annual minimum and average incremental fleet cost of equipping 
all new applicable trailers \19\ with rear impact guards that mitigate 
PCI in 30 percent overlap crashes would be $9.9 million and $30.3 
million, respectively. The total minimum to average undiscounted 
incremental lifetime fuel cost due to increase in weight is estimated 
to be $93 million to $130 million. The overall undiscounted cost 
increase (material cost and lifetime fuel cost) is a minimum of $103 
million to on average $161 million.
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    \18\ ``Significant'' actions are also subject to Section 6's 
requirements for a benefit-cost analysis.
    \19\ There were 211,807 new trailers sold in 2020, among which 
65 percent (137,675 = 211,807 x 0.65) are required to be equipped 
with rear impact guards. Among applicable trailers, 28 percent are 
already equipped with guards that mitigate PCI in 30 percent overlap 
crashes.
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    Using the estimate of 0.75 to 1.5 fatalities that would be 
prevented annually, the undiscounted cost per life saved using the 
minimum cost estimate ranges from $69 million to $151 million. The 
undiscounted cost per life saved using the average cost estimate ranges 
from $183 million to $215 million. The Department of Transportation has 
recently updated the value of a statistical life, consistent with 
Office of Management and Budget (OMB) Circular A-4, to $11.6 
million.\20\ Therefore, a requirement for equipping all new applicable 
trailers with rear impact guards that mitigate PCI in 30 percent 
overlap crashes is not cost-effective.\21\ This indicates that total 
costs of such a requirement exceed overall benefits.
---------------------------------------------------------------------------

    \20\ For more information on the value of a statistical life, 
see a 2021 Office of the Secretary memorandum on the ``Guidance on 
Treatment of the Economic Value of a Statistical Life in U.S. 
Department of Transportation Analyses--2021 Update.'' https://www.transportation.gov/office-policy/transportation-policy/revised-departmental-guidance-on-valuation-of-a-statistical-life-in-economic-analysis. Circular A-4 provides OMB's guidance to Federal 
agencies on the development of a regulatory analysis required under 
Section 6 of E.O. 12866.
    \21\ Cost-effectiveness represents a measure of the average 
monetary cost per unit of change (benefit). In regulatory analyses 
for safety policies, cost-effectiveness generally measures the 
average estimated change in total costs per unit improvement in 
safety (e.g., cost per life saved). A policy alternative can be 
considered cost-effective if the estimated cost per unit increase is 
less than an appropriate benchmark. For example, a proposed safety 
standard could be considered cost-effective if the average cost per 
life saved equivalent (i.e., combining lives saved and injuries 
avoided, weighted by the relative values of injuries to fatalities) 
under the proposed standard were less than the comprehensive 
economic cost of a fatality ($11.6 million in 2020 dollars). That 
is, the proposed standard would yield safety benefits at a lower 
cost than the benchmark value for those benefits.
---------------------------------------------------------------------------

    For the above reasons, NHTSA has determined that requirements to 
mitigate PCI in a 30 percent overlap crash at 56 km/h (35 mph) would 
not meet the requirements of Section 30111(a) of the Safety Act. We 
have decided that an FMVSS that requires all covered vehicles (trailers 
and semitrailers) to provide rear impact protection in full-frontal, 50 
percent overlap, and 30 percent overlap crashes at 56 km/h (35 mph) 
impact speed would not be reasonable or practicable for this FMVSS and 
would not meet the requirements of Sections 30111(a) and (b) of the 
Safety Act for issuance of Federal motor vehicle safety standards. 
Accordingly, based on all available data, we have decided that a 
Federal mandate for a 30 percent overlap crash for all vehicles subject 
to FMVSS Nos. 223 and 224 is not reasonable at this time.
    However, while NHTSA cannot conclude that the data and science 
currently available for agency decision-making support mandating 
installation of a rear impact guard that prevents PCI in all three 
overlap conditions (full, 50 percent, and 30 percent overlap) on all 
vehicles, the Federal standards act as a floor, not a ceiling, to 
establish the minimum level of performance that meet the safety needs 
presented by the data. FMVSS are written in terms of minimum 
performance requirements for motor vehicles or motor vehicle equipment 
to protect the public against unreasonable risk of injury and death in 
crashes. Manufacturers have flexibility in design as long as their 
products comply with applicable FMVSS. There are rear impact guard 
designs in the current trailer and semitrailer market that prevent PCI 
in all three crash conditions described in Section 23011(b)(1)(A) of 
BIL: (1) full overlap crash, (2) 50 percent overlap crash, and (3) 30 
percent overlap crash at 56 km/h impact speed. This final rule does not 
preclude these designs from the trailer and semitrailer market, as long 
as they meet all requirements of the FMVSS to ensure adequate 
protection in (1) and (2), above.
    In response to the research mandate in Section 23011(b)(2) of BIL, 
NHTSA is conducting additional research on the design and development 
of rear impact guards that can prevent underride and protect passengers 
in crashes into the rear of trailers at crash speeds up to 104.5 km/h 
(65 mph). As part of this research effort, NHTSA will also evaluate 
potential cost-effective rear impact guard designs that could improve 
protection in the less-frequent 30 percent low overlap crashes while

[[Page 42344]]

enhancing protection in full and 50 percent overlap crashes at higher 
speeds.
    NHTSA is also working on implementing the other provisions of 
Section 23011 of BIL.

c. DOT National Roadway Safety Strategy

    This final rule accords with DOT's January 2022 National Roadway 
Safety Strategy to address the rising numbers of transportation deaths 
occurring on the country's streets, roads, and highways.\22\ At the 
core of this strategy is the Department-wide adoption of the Safe 
System Approach, which focuses on five key objectives: safer people, 
safer roads, safer vehicles, safer speeds, and post-crash care. DOT 
announced it will launch new programs, coordinate and improve existing 
programs, and adopt a foundational set of principles to guide this 
strategy. The National Roadway Safety Strategy includes issuing a final 
rule to upgrade existing requirements for rear impact guards on newly 
manufactured trailers and semitrailers as a key Departmental action to 
enable safer vehicles.\23\
---------------------------------------------------------------------------

    \22\ https://www.transportation.gov/sites/dot.gov/files/2022-01/USDOT_National_Roadway_Safety_Strategy_0.pdf.
    \23\ Id., p. 31.
---------------------------------------------------------------------------

d. NTSB Recommendation

    This final rule accords with an April 3, 2014 recommendation from 
the National Transportation Safety Board (NTSB) regarding tractor-
trailer safety (H-14-004). NTSB recommended that NHTSA revise FMVSS 
Nos. 223 and 224 to ensure that newly manufactured trailers over 4,536 
kg (10,000 lb) GVWR provide adequate protection of passenger vehicle 
occupants from fatalities and serious injuries resulting from full-
width and offset trailer rear impacts. In its recommendation, NTSB made 
favorable reference to IIHS's petition for rulemaking (the petition is 
discussed below).

e. Impacts of This Rulemaking

    NHTSA has issued a Final Regulatory Evaluation (FRE) that analyzes 
the potential impacts of this final rule. The FRE is available in the 
docket for this rule.\24\
---------------------------------------------------------------------------

    \24\ The FRE may be obtained by downloading it or by contacting 
Docket Management at the address or telephone number provided at the 
beginning of this document.
---------------------------------------------------------------------------

    NHTSA estimates that 94 percent of new trailers sold in the U.S. 
subject to FMVSS Nos. 223 and 224 are already designed to comply with 
CMVSS No. 223. The agency estimates that about 0.56 lives and 3.5 
serious injuries would be saved annually by requiring all trailers 
covered by Standard No. 224 to be equipped with CMVSS No. 223 compliant 
guards. The undiscounted equivalent lives saved are 1.4 per year.
    Considering that 94 percent of applicable trailers already have 
CMVSS compliant guards, the annual average incremental fleet cost of 
equipping all applicable trailers with CMVSS No. 223 rear impact guards 
is estimated to be $2.10 million in 2020 dollars. In addition, the 
added weight of 48.9 pounds per vehicle would result in an estimated 
annual fleet fuel cost of approximately $4.43 million and $5.59 million 
discounted at 7% and 3%, respectively. As such, the total incremental 
cost would range from $6.54 million to $7.69 million discounted at 7% 
and 3%, respectively, as shown in Table 1.

                         Table 1--Cost of the Final Rule With Average Increase in Weight
                                          [In millions of 2020 dollars]
----------------------------------------------------------------------------------------------------------------
                          Discount rate                            Undiscounted         3%              7%
----------------------------------------------------------------------------------------------------------------
Material *......................................................           $2.10           $2.10           $2.10
Fuel............................................................            6.90            5.59            4.43
                                                                 -----------------------------------------------
    Total.......................................................            9.00            7.69            6.54
----------------------------------------------------------------------------------------------------------------
* Material costs are not discounted since they occur at the time of purchase

    The estimated equivalent lives saved (ELS) ranges from 0.90 lives 
to 1.14 lives discounted at 7% and 3%, respectively. The cost of the 
final rule is the regulatory cost and ranges from $6.54 million to 
$7.69 million discounted at 7% and 3%, respectively. The cost per ELS 
ranges from $6.77 million to $7.25 million discounted at 3% and 7%, 
respectively, as shown in Table 2 below.

                                    Table 2--Cost per Equivalent Lives Saved
                                          [In millions of 2020 dollars]
----------------------------------------------------------------------------------------------------------------
                          Discount rate                            Undiscounted         3%              7%
----------------------------------------------------------------------------------------------------------------
Total cost......................................................           $9.00           $7.69           $6.54
Equivalent lives saved..........................................            1.40            1.14            0.90
Cost per ELS....................................................           $6.42           $6.77           $7.25
----------------------------------------------------------------------------------------------------------------

    The net benefit of the final rule is the difference between the 
comprehensive benefit and the total cost. The estimated net benefit 
ranges from $4.36 million to $6.04 million discounted at 7% and 3%, 
respectively, as shown in Table 3 below.

                                              Table 3--Net Benefits
                                          [In millions of 2020 dollars]
----------------------------------------------------------------------------------------------------------------
                         Discounted rate                           Undiscounted         3%              7%
----------------------------------------------------------------------------------------------------------------
Comprehensive benefit...........................................          $16.96          $13.73          $10.90

[[Page 42345]]

 
Total cost......................................................            9.00            7.69            6.54
                                                                 -----------------------------------------------
    Net benefit.................................................            7.96            6.04            4.36
----------------------------------------------------------------------------------------------------------------

    Table 4 summarizes the total costs, comprehensive benefits, and net 
benefits for both 3 and 7 percent discount rates.

                                                               Table 4--Costs and Benefits
                                                              [In millions of 2020 dollars]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                      Comprehensive
                      Discount rate                          Material cost        Fuel cost         Total costs          benefits         Net benefits
--------------------------------------------------------------------------------------------------------------------------------------------------------
3%.......................................................              $2.10              $5.59              $7.69             $13.73              $6.04
7%.......................................................               2.10               4.43               6.54              10.90               4.36
--------------------------------------------------------------------------------------------------------------------------------------------------------

f. No Significant Changes to the NPRM

    After carefully reviewing the comments, NHTSA is adopting most of 
the proposed rule, while clarifying the wording that attachment 
hardware remain intact during quasi-static load tests in FMVSS No. 223. 
NHTSA is also making a technical correction to the citation referenced 
in the definition of ``temporary living quarters'' in FMVSS No. 224.

II. Background

a. Current Requirements

    FMVSS No. 223 requires rear impact guards to meet the strength 
requirements and energy absorption requirements of the standard at 
certain specified test locations. Test locations P1, P2, and P3 are 
depicted in Figure 1. Test location P1 is 3/8th of the width of the 
horizontal member from the centerline on either side of the horizontal 
member. Test location P2 is at the centerline of the horizontal member. 
Test location P3 is 355 millimeters (mm) (14 inches) to 635 mm (25 
inches) from the horizontal member centerline. The strength tests are 
conducted separately from the energy absorption test.
    The strength requirements (S5.2.1) specify that the guard must 
resist the following force levels without deflecting by more than 125 
mm (4.9 inches):
     50,000 Newtons (N) (or 50 kiloNewtons (kN)) at P1 on 
either the left or the right side of the guard;
     50,000 N at P2; and,
     100,000 N at P3 on either the left or the right side of 
the guard.
    In the strength test, the force is applied by a force application 
device (rectangular rigid steel solid face of 203 mm x 203 mm and 
thickness of 25 mm) until the force level is exceeded or until the 
displacement device is displaced at least 125 mm, whichever occurs 
first.
    The energy absorption requirements (S5.2.2) specify that a guard 
(other than a hydraulic guard) must absorb, by plastic deformation, 
within the first 125 mm of deflection at least 5,650 Joules (J) of 
energy at each test location P3. In the test procedure, force is 
applied to the guard using the force application device until 
displacement of the device has reached 125 mm, recording the value of 
force at least 10 times per 25 mm of displacement. The force is then 
reduced until the guard no longer offers resistance to the force 
application device. A force versus deflection diagram is plotted with 
deflection (measured displacement of the force application device) 
along the abscissa (x-axis) and the measured force along the ordinate 
(y-axis), as shown in Figure 2, and the energy absorbed by the guard is 
determined by calculating the shaded area bounded by the curve in the 
diagram.

[[Page 42346]]

[GRAPHIC] [TIFF OMITTED] TR15JY22.000

[GRAPHIC] [TIFF OMITTED] TR15JY22.001

    FMVSS No. 224 requires each vehicle to be equipped with a rear 
impact guard certified to FMVSS No. 223 and attached to the vehicle's 
chassis in accordance with installation instructions that the guard 
manufacturer provided pursuant to FMVSS No. 223. Standard No. 224 
specifies that the ground clearance (vertical distance of the bottom of 
the horizontal member from ground) of the rear impact guard be no more 
than 560 mm (22 inches) and

[[Page 42347]]

located not more than 305 mm (12 inches) forward of the rear extremity 
of the trailer and extend laterally to within 100 mm (4 inches) of each 
side of the vehicle as shown in Figure 3.
[GRAPHIC] [TIFF OMITTED] TR15JY22.002

b. Petitions

    IIHS requested, among other things, that NHTSA upgrade rear impact 
guard strength requirements, reduce the number of exempted vehicles to 
provide occupant protection in higher speed crashes and move the P1 
test location farther outboard to improve crash protection in low 
overlap conditions. IIHS requested that NHTSA require attachment 
hardware to remain intact for the duration of the quasi-static test or 
until reaching a force threshold ``much higher than that required for 
the guard itself.'' \25\ The Karth/TSC petition asked that NHTSA 
improve the safety of rear impact guards. In later correspondence with 
NHTSA, these petitioners state that if FMVSS No. 223 were amended to be 
equivalent to CMVSS No. 223, injuries and fatalities could be 
avoided.\26\ We provided a detailed discussion of the petitions, and 
our response to them, in the NPRM preceding this final rule.
---------------------------------------------------------------------------

    \25\ After submitting its petition in 2011, IIHS conducted 
additional crash tests of a 2010 Chevrolet Malibu at 56 km/h (35 
mph) into eight guard/trailers: A 2011 Wabash, 2012 Manac, 2012 
Stoughton, 2013 Great Dane, 2012-2013 Hyundai, 2013 Strick, 2013 
Utility, and 2013 Vanguard, all of which were certified as complying 
with CMVSS No. 223. NHTSA included a summary of the IIHS tests in 
the December 16, 2015 NPRM. 80 FR 78452-78460. All eight trailers 
were able to prevent PCI with 100 percent overlap. In the tests with 
50 percent overlap, apart from the 2013 Vanguard trailer, the 
remaining seven guard/trailers were able to prevent PCI. The rear 
impact guard on the 2013 Vanguard failed at the attachments where 
the bolts sheared off during the crash resulting in PCI.
    \26\ NHTSA responded to the Karth/TSC petition by issuing two 
separate notices, one of which was the NPRM preceding this final 
rule (July 10, 2014; 79 FR 39362). The other was an advanced notice 
of proposed rulemaking (ANPRM) published on July 23, 2015 (80 FR 
43663) pertaining to the agency's estimated benefits and costs of 
rear impact guards for single unit trucks (SUTs) and of an 
alternative of increasing the conspicuity of SUTs through 
conspicuity tape. FMVSS No. 108, ``Lamps, reflective devices, and 
associated equipment,'' requires retroreflective material on the 
rear and sides of trailers to improve the conspicuity of the 
vehicles to other motorists as a means of preventing underride 
crashes. The ANPRM analyzed estimated benefits and costs of 
requiring similar tape for SUTs. NHTSA will follow up on the ANPRM 
in a document separate from this final rule.
---------------------------------------------------------------------------

c. Summary of Proposed Changes

    NHTSA proposed to adopt requirements of Transport Canada's standard 
for rear impact guards, which require rear impact guards to provide 
sufficient strength and energy absorption to protect occupants of 
compact and subcompact passenger cars impacting the rear of trailers at 
56 km/h (35 mph). The NPRM proposed the following specific changes to 
FMVSS Nos. 223 and 224.\27\
---------------------------------------------------------------------------

    \27\ In addition, we proposed a few housekeeping amendments. We 
proposed to add back ``low chassis vehicles'' into the list of 
vehicles excluded from FMVSS No. 224 in the applicability section 
(S3). The vehicles were excluded from the standard in the January 
24, 1996 final rule establishing FMVSS No. 224 (61 FR 2035) but were 
inadvertently omitted from S3 when S3 was amended by a final rule 
responding to petitions for reconsideration (63 FR 3654, January 26, 
1998). We also proposed to correct typographical errors in the 
standards. We make these changes in this final rule.
---------------------------------------------------------------------------

Performance Requirements
    NHTSA proposed that the loading and performance requirements of 
FMVSS No. 223 adopt the specifications in CMVSS No. 223. Specifically:
     The NPRM proposed to amend FMVSS No. 223 to require rear 
impact guards (except as noted below) to resist a uniform distributed 
load of 350,000 N without deflecting more than 125 mm, while absorbing 
at least 20,000 J of

[[Page 42348]]

energy by plastic deformation within the first 125 mm of deflection;
     Alternatively, guards may resist a minimum uniform 
distributed load of 700,000 N without deflecting 125 mm.
     In accordance with CMVSS No. 223, we proposed to require 
that rear impact guards be required to maintain a ground clearance 
after the energy absorption test not exceeding 560 mm. For rear impact 
guards with strength exceeding 700,000 N in the uniform distributed 
load test, the post-test ground clearance is measured after the uniform 
distributed load test. A definition of ``ground clearance'' would be 
added to FMVSS No. 223.
     We proposed that FMVSS No. 223 require that any portion of 
the rear impact guard and attachments not separate from their mounting 
structure after completion of FMVSS No. 223's uniform distributed 
loading test and the energy absorption test.
Definition of ``Rear Extremity'' \28\
---------------------------------------------------------------------------

    \28\ We sought to further harmonize FMVSS No. 224 with CMVSS No. 
223.
---------------------------------------------------------------------------

    We proposed to replace the current definition of ``rear extremity'' 
in FMVSS No. 224 with that specified in CMVSS No. 223. The change was 
intended to ensure that aerodynamic fairings are located within a 
certain safe zone at the rear of the trailer. Aerodynamic fairings on 
the rear of trailers, also known as ``boat tails,'' are rear-mounted 
panels on trailers that reduce aerodynamic drag and fuel consumption. 
The safety concern about boat tails is that they generally extend 
beyond the rear extremity of trailers and thus can negate the crash 
protection provided by rear impact guards. That is, there is a 
possibility that a boat tail can protrude so far rearward that it can 
intrude into the passenger compartment in a crash and cause injury, 
notwithstanding the presence of an upgraded rear impact guard.

III. Summary of Comments

    NHTSA received fifty (50) comments on the NPRM.\29\ Ten comments 
were received from the three petitioners (IIHS, Ms. Marianne Karth 
(with her husband Mr. Jerry Karth), and the TSC), one comment was 
received from the National Transportation Safety Board (NTSB), six 
comments were received from industry associations (the Recreation 
Vehicle Industry Association (RVIA), the Truck Trailer Manufacturers 
Association (TTMA), the American Trucking Association, Inc. (ATA), the 
National Truck Equipment Association (NTEA), and the National Propane 
Gas Association (NPGA)), two comments were received from trailer 
manufacturers (Strick Trailers, LLC (Strick) and the Wabash National 
Corporation (Wabash)), seven comments were received from engineers (the 
Mechanical Engineering Underride Design Group at Virginia Tech (VT 
Group), Seven Hills Engineering, LLC (Seven Hills), Batzer Engineering, 
Inc. (Batzer), and Mr. Aaron Kiefer), two comments were received from 
attorneys (Mr. D.J. Young, III and Mr. Andy Young), ten comments were 
received from advocacy groups (e.g., Underride Network, Road Safe 
America (RSA), and Advocates for Highway and Auto Safety (AHAS)), and 
twelve comments were received from individual members of the general 
public.
    Comments were generally in favor of upgrading rear impact guard 
performance. The petitioners, NTSB, engineers, attorneys, advocacy 
groups, and individuals from the general public argued, however, for 
increasing the stringency of FMVSS Nos. 223 and 224 beyond what was 
proposed in the NPRM. These groups also suggested that NHTSA take other 
actions suggested in the initial IIHS and Karth/TSC petitions that 
NHTSA had not proposed in the NPRM. The industry associations and 
trailer manufacturers were generally in favor of the proposed rule and 
opposed further changes to it. Comments also covered issues such as 
alternative guard designs, NHTSA's benefit-cost analysis, the proposed 
lead time, retrofitting issues, and side and front guards.

IV. Response to Comments on the Proposed Amendments

a. General Strength and Energy Absorption Requirements

    In the NPRM, NHTSA proposed to harmonize FMVSS No. 223's test and 
performance requirements to those specified in CMVSS No. 223 by 
replacing the current quasi-static point load test at the P3 location 
with a uniform distributed load test of 350,000 N. Under this test, 
NHTSA proposed that the rear impact guard must resist the 350,000 N 
load without deflecting more than 125 mm, absorb at least 20,000 J of 
energy within 125 mm of guard deflection, and have a ground clearance 
not exceeding 560 mm after completion of the test.
Comments Received
    Commenters supported upgrading FMVSS No. 223's requirements as 
proposed, but most also suggested that NHTSA issue requirements more 
stringent than those proposed. Multiple commenters argued that, because 
93 percent of trailers already comply with CMVSS No. 223 according to 
the NPRM, the proposed requirements would make little tangible 
difference and not prevent the underride injuries that are still 
occurring. The Underride Network (Network) stated that NHTSA's proposal 
would only ``upgrade the standard as basically existed in 1996,'' 
without going further to include technological improvements made for 
rear impact guards. Wabash, on the other hand, suggested that even 
though most new trailers currently adhere to CMVSS No. 223, there is 
still a benefit to the proposed requirements. Wabash argued that 
adopting the proposed requirements would both mandate that the 
remaining portion of the new trailer fleet adopt upgraded rear impact 
guards and allow NHTSA to take enforcement action against any company 
that fails to install upgraded rear impact guards.
    Some commenters also urged NHTSA not to adopt a proposal that only 
provides protection against underride at impact speeds up to 56 km/h 
(35 mph), stating that these crashes only represent a fraction of all 
rear underride crashes. These commenters remarked that NHTSA should do 
more to provide protections for underride crashes that occur at greater 
speeds. Some commenters suggested specific requirements that they 
believed NHTSA should adopt instead of those proposed in the NPRM. 
Network requested that the quasi-static loading tests use a force of 
200 (kN) at the P1 and P2 test locations and 100 kN at the P3 test 
location. Mr. Kiefer suggested that rear impact guards should be quasi-
statically tested to ``at least 80% of reasonable crash pulse 
loadings.'' Mr. Karth referenced what he called a ``new Australian/New 
Zealand proposed rule'' and asked NHTSA to use that as a basis for its 
standards. According to Mr. Karth, the Australian/New Zealand proposed 
rule states that current vehicle crashworthiness technology can protect 
passengers in collisions with a deformable barrier at impact speeds 
around 64 km/h (40 mph) and that energy absorbing rear impact guards 
could reduce injury at higher speeds. Ms. Karth echoed this point, 
stating that adopting the Australian/New Zealand proposed rule would 
save more lives than adopting standards based on CMVSS No. 223. These 
and all other relevant comments are address below.
Agency Response
    After reviewing the comments, NHTSA is adopting the strength and 
energy absorption standards as proposed in the NPRM. NHTSA recognizes 
that many commenters have asked NHTSA to require rear impact

[[Page 42349]]

guards to provide protection against underride at impact speeds beyond 
56 km/h (35 mph). As discussed below, NHTSA is researching this area. 
However, based on available data, the agency does not believe that such 
increased requirements are reasonable or practicable at this time. Rear 
impact guards are meant to work with passenger vehicle safety features 
to protect occupants of the vehicle during a collision. For these 
passenger vehicle safety features to activate, the passenger vehicle 
must collide with the rear impact guard, and this collision itself 
poses risks to passenger safety. Currently, FMVSS No. 208 requires 
passenger vehicles to provide protection in front collisions at speeds 
up to 56 km/h (35 mph). Even if a rear impact guard were to prevent PCI 
at impact speeds above 56 km/h (35 mph), a passenger vehicle in 
compliance with FMVSS No. 208 may not be able to protect the vehicle's 
occupants at speeds above 56 km/h (35 mph) in a collision with a rear 
impact guard. Commenters did not provide data showing current passenger 
vehicle safety features would prevent injuries in underride collisions 
above 56 km/h (35 mph). Accordingly, NHTSA concludes it is appropriate 
for this final rule to align the requirements in FMVSS Nos. 223 and 224 
with those in FMVSS No. 208 and CMVSS No. 223, as proposed in the NPRM. 
This final rule adopts those proposed requirements.
    Further, the 56 km/h (35 mph) crash speed accords with Section 
23011(b)(1)(A) of BIL. BIL states that, not later than 1 year after the 
date of enactment of the Act, the Secretary shall promulgate 
regulations that revise FMVSS No. 223 and FMVSS No. 224 to require new 
trailers and semitrailers to be equipped with rear impact guards that 
are designed to prevent PCI from a trailer or semitrailer when a 
passenger vehicle traveling at 56 km/h (35 mph) makes an impact into 
the center of the rear of the trailer or semitrailer and in which 50 
percent of the width of the passenger motor vehicle overlaps the rear 
of the trailer or semitrailer. This final rule's adoption of the NPRM's 
proposed test speed meets the BIL statutory mandate within the 
timeframe directed by the Act, and meets the requirements for FMVSSs 
required by the Safety Act.
    In response to the research mandate in Section 23011(b)(2) of BIL, 
NHTSA is conducting additional research on the design and development 
of rear impact guards that can prevent underride and protect passengers 
in crashes into the rear of trailers at crash speeds up to 104.5 km/h 
(65 mph). After the completion of this research, NHTSA will evaluate 
potential requirements for rear impact guards for preventing underride 
and protecting occupants at impact speeds greater than 35 mph.
    Commenters also referred to guard designs and recommendations 
developed by third parties that claim to offer greater protection at 
higher impact speeds than guards currently in use. There is no evidence 
that any have been finalized, implemented, and proven feasible for 
commercial use. The Intelliguard/Impact Project, a design source cited 
by Mr. Karth, explicitly stated, ``The guard needs, however, further 
optimization to become commercially feasible.''
    Network asked NHTSA to test rear impact guards ``at real world 
speeds,'' arguing that the Federal Highway Administration (FHWA) tests 
crash attenuators at 100 km/h (62.2 mph) and that NHTSA should crash 
test rear impact guards at similar speeds. In response, NHTSA notes, 
first, that it did not propose to test at highway speeds in the NPRM 
and believes this request may be outside the scope of this rulemaking. 
Further, NHTSA does not believe that Network's comparison of rear 
impact guards and FHWA roadside crash attenuators is appropriate. 
Roadside crash attenuators are stationary barriers placed alongside 
roads that are designed to absorb a colliding vehicle's energy and 
safely redirect the vehicle or bring it to a stop. A typical crash 
attenuator system is 50 feet long. In contrast, rear impact guards are 
structures attached to the rear of mobile trailers to mitigate 
underride of the impacting vehicle. Roadside crash attenuators, 
therefore, are designed for a different environment than a rear impact 
guard, have different performance requirements,\30\ and have fewer 
operational and practical restrictions on their size and weight versus 
rear impact guards. Similar performance for truck rear impact guards at 
highway speeds has not been shown to be technically feasible.
---------------------------------------------------------------------------

    \30\ Roadside crash barriers, guardrails and other roadside 
safety features installed along U.S. highways undergo 
crashworthiness testing in accordance with the American Association 
of State Highway and Transportation Officials (AASHTO) Manual for 
Assessing Safety Hardware (MASH). The AASHTO MASH was updated in 
2016 and includes vehicle crash testing at 6 different test levels 
(TL-1 to TL-6) based on the type of crash attenuator, type of road, 
and traffic patterns.
     TL-1: Cars and trucks--31 mph
     TL-2: Cars and trucks--44 mph
     TL-3: Cars and trucks--62 mph
     TL-4: Cars, trucks, and single unit trucks--62 mph and 
56 mph respectively
     TL-5: Cars, trucks, and tractor trailers--62 and 50 mph 
respectively
     TL-6: Cars, trucks, and tractor tank trailers--62 and 
50 mph respectively
---------------------------------------------------------------------------

    In terms of specific standards suggested by commenters, these 
commenters unfortunately did not provide sufficient information to 
warrant modifying the proposed requirements. Commenters did not provide 
data showing the extent to which guards compliant with these various 
standards are superior to the Canadian guards. NHTSA notes that the 
``Australian/New Zealand proposed rule'' referenced by Mr. and Ms. 
Karth is not a regulatory requirement, but rather is an industry design 
guideline created by Standards Australia and Standards New Zealand. 
These guidelines do not provide information to warrant modifying 
NHTSA's proposal. In terms of rear impact guards performing at impact 
speeds above 56 km/h (35 mph), the guidelines only conjecture that 
guards could be developed that reduce serious injury to vehicle 
occupants at speeds above 70 km/h; they do not provide instructions on 
how to design such guards or data regarding practicability, 
effectiveness or performance. Not enough is known about these standards 
to assess the need for them or whether adopting them would meet the 
requirements of the Safety Act.

b. Alternative Guard Designs

    Based on tests conducted by Transport Canada showing that a CMVSS 
No. 223 compliant guard was able to prevent PCI in 56 km/h (35 mph) 
vehicle impacts into the rear of trailers with 100 percent and 50 
percent overlap, NHTSA proposed to adopt CMVSS No. 223's strength and 
energy absorption requirements.
Comments Received
    NHTSA received many comments arguing that the proposed standards 
were inadequate because rear impact guards generally meet them already. 
Advocates and IIHS referred to a 2011 Wabash guard, involved in the 
tests conducted by IIHS, to argue that the guard exceeded the CMVSS 
force requirements by more than 70 percent in quasi-static tests. Other 
commenters also mentioned that they believed it possible to design a 
rear impact guard that could provide protection for rear underride 
crashes at speeds greater than 56 km/h (35 mph), several pointing to 
testing conducted by third parties to support these claims. Network and 
Mr. Karth stated that the Monash University Accident Research Centre 
(MUARC) tested energy-absorbing guards to 75 km/h (47 mph) in the early 
1990s. They also claimed that the Impact Project had

[[Page 42350]]

tested energy-absorbing guards to 40 mph with computer modeling showing 
that the guards might be able to perform at 50 mph or more. Mr. Young 
noted that the VC-Compat project is ``currently proposing and 
recommending stronger rear impact guards to meet higher speeds.''
    Other commenters stated that they personally were either developing 
or had seen rear impact guards that were improvements over guards 
meeting the current and proposed standards. Mr. Karth pointed to a 
design developed by the VT Group which, he claimed, ``shows promise of 
greatly improving the current standard at a reasonable cost.'' Mr. 
Kiefer stated that he had developed a rear guard system that will 
exceed the proposed standards. Mr. Karth stated that he was told by a 
Mr. Sicking that he ``can design a system which will prevent underride 
guard failures'' that occur ``at much higher speeds.''
Agency Response
    NHTSA has evaluated the data from IIHS and other research groups 
provided by the commenters and cannot agree that the information forms 
a technical basis for modifying the proposed requirements. Advocates 
and IIHS argued that rear impact guards could provide protection at 
speeds higher than 56 km/h (35 mph) because the Wabash guard exceeded 
CMVSS No. 223 force requirements by ``more than 70 percent'' in tests 
conducted by IIHS. Our analysis of the comment, however, determined 
that IIHS's tests were different than, and not comparable to, the CMVSS 
No. 223 tests. IIHS conducted a point load test at P3, which is very 
different than the uniform distributed load specified in CMVSS No. 223 
and this final rule.\31\ As the tests are not comparable, it cannot be 
concluded that the Wabash guard exceeded the CMVSS No. 223 force 
requirement by more than 70 percent. Additionally, the data do not show 
that the guard would provide better crash protection in dynamic impacts 
above 56 km/h (35 mph). I.e., the data did not link IIHS's quasi-static 
test values to evidence of actual dynamic crash performance at higher 
impact speeds.
---------------------------------------------------------------------------

    \31\ A point load test applies a concentrated load to a focused 
point. The uniform distributed load tests specified in CMVSS No. 223 
and this final rule apply the test load over a wider area.
---------------------------------------------------------------------------

    Section 1 of E.O. 12866 requires agencies to base their decisions 
on the best reasonably available scientific, technical, economic, and 
other information on the need for, and consequences of, the intended 
regulation. In accordance with the E.O., this final rule will complete 
the upgrade of Standard No. 223 to the Canadian standard as proposed, 
as it is based on the best information reasonably available at this 
time. However, while the commenters' information does not form a 
comprehensive or complete basis for modifying the rear impact guard 
requirements above that which was proposed, NHTSA is continuing to 
research this area in response to BIL. Pursuant to the research mandate 
in BIL Section 23011(b)(2), NHTSA is conducting additional research on 
the design and development of rear impact guards that prevent underride 
and protect passengers in crashes into the rear of trailers at crash 
speeds up to 104.5 km/h (65 mph). The results of this research and 
other information will provide more data and other information that can 
guide decisions about updating the rear impact guard standards at a 
future date.
    In response to commenters, NHTSA also reviewed guard designs and 
recommendations developed by third parties (MUARC, VT group, Aaron 
Kiefer, Sickling) that several commenters believed could offer greater 
protection at higher impact speeds than rear impact guards currently in 
use.\32\ As these guards have not been finalized, implemented, proven 
effective or shown feasible for commercial use in the industry, the 
agency could not reasonably include requirements for these guards in 
FMVSS Nos. 223 and 224 at this time.\33\ Also, not enough is known 
about the rationale for various specifications of the experimental 
guards. For instance, MUARC, an organization favorably cited by many 
commenters, stated \34\ that it had designed a guard which prevented 
PCI in a 75 km/h (46 mph) centered impact test and recommended that 
guards be able to absorb 50 kiloJoules (kJ) and quasi-static forces of 
200 kN at the P1 location, 100 kN at the P2 location, and 200 kN at the 
P3 location. It is unclear how MUARC developed these quasi-static test 
recommendations and how these recommendations relate to dynamic crash 
test performance. Further, MUARC's 50 kJ and the 100 kJ energy 
absorption recommendation does not specify the degree of deflection at 
which the guard must meet this energy absorption requirement, and the 
experimental guard designed by MUARC never advanced beyond the proof-
of-concept phase.\35\ There is no information on the long term 
durability and costs of a MUARC guard since it is not available for 
purchase and installation, nor can NHTSA know if such a guard can be 
feasibly and effectively used for different types of trailers, such as 
those with unique geometry.
---------------------------------------------------------------------------

    \32\ The petitioners, the attorney commenters, UN, AHAS, Seven 
Hills, Aaron Kiefer, and Andy Young cited design testing conducted 
by the Intelliguard/Impact Project, the VT Group, VC-Compat, MUARC, 
and Aaron Kiefer to support claims that guards with greater crash 
protection at higher impact velocities are feasible.
    \33\ Section 23011 (b)(1) of BIL requires a regulation revising 
FMVSS No. 223 and No. 224 not later than 1 (one) year after the 
November 15, 2021, date of enactment of the Act.
    \34\ MUARC discussed its research in a 2001 submission to the 
International Technical Conference on the Enhanced Safety of 
Vehicles. Rechnitzer, G., Powell, C., and Seyer, K., ``Performance 
Criteria, Design, and Crash Tests of Rear Underride Barriers for 
Heavy Vehicles,'' Proceedings of the Seventeenth International 
Technical Conference on the Enhanced Safety of Vehicles, Paper No. 
218, https://www-esv.nhtsa.dot.gov/Proceedings/17/00189.pdf.
    \35\ Federal regulations in Australia for rear impact guards are 
similar to those in Europe and Australia. The MUARC recommendations 
are not used as performance requirements in Australian Federal 
standards and there are no manufacturers in Australia voluntarily 
designing their guards to meet the MUARC recommendations.
---------------------------------------------------------------------------

    NHTSA has the same concerns with the experimental guards described 
by the Impact Project, the VC-Compat project, the VT Group, Mr. Kiefer, 
and Mr. Sicking. Commenters did not provide information that the guards 
are effective at providing protection at impact speeds beyond 56 km/h 
(35 mph) and failed to provide a verifiable relationship between the 
results of the dynamic crash tests and quasi-static specifications that 
NHTSA relies on in FMVSS No. 223. In the absence of such data, there is 
insufficient information supporting using these experimental guards to 
form the requirements for FMVSS Nos. 223 and 224. As discussed above, 
however, NHTSA will continue researching guard performance in higher 
speed crashes in response to BIL and anticipates obtaining more 
comprehensive information about the performance and other features of 
potential guards designed for higher speed impacts.

c. 700 kN Energy Absorption Test Option

    The NPRM proposed to include an option from CMVSS No. 223 
permitting a rear impact guard not to meet the energy absorption 
requirements of the uniform distributed load test detailed above if it 
is able to resist 700,000 N (700 kN) of force without deflecting more 
than 125 mm and maintain a ground clearance of 560 mm after completion 
of the test. NHTSA noted in the NPRM that it did not believe that 
guards will likely be manufactured to this test but sought comment on

[[Page 42351]]

whether this alternative testing option should be included in FMVSS No. 
223.
Comments Received
    Commenters were divided in their support of the 700 kN test option. 
TTMA stated in support that keeping this as an option would allow TTMA 
members to retain needed flexibility. Batzer asserted in support that, 
since passenger vehicles have improved their energy absorbing 
characteristics since the 1996 final rule, NHTSA does not need to 
require that rear impact guards meet an energy absorption requirement 
as long as the guards can provide a certain level of resistance force. 
Network stated that this option ``might make sense,'' but also stated 
that rear impact guards must be able to absorb a minimum of 50 kJ, and 
preferred that guards be able to absorb 100 kJ. Ms. Wood agreed that 
rear impact guards must be able to absorb at least 50 kJ. The VT Group 
disagreed with including the 700 kN test, stating that doing so would 
afford manufacturers the ability to omit a horizontal member from a 
rear impact guard. The VT Group claimed that without a horizontally 
distributing structure, ``a minor impact more closely resembles a pole 
strike.''
Agency Response
    NHTSA agrees with TTMA and Batzer and believes it appropriate to 
adopt the 700 kN test option. Network and the VT Group expressed 
reservations about the option, but they did not provide data or other 
evidence demonstrating that this option would be detrimental to safety. 
They did not provide any further information supporting the request for 
a 50 kJ or 100 kJ energy absorption requirement, nor did they explain 
how the 700 kN test option would allow manufacturers to omit a 
horizontal member. FMVSS No. 223 S5.1 specifies that the vertical 
height of the horizontal member must be at least 100 mm and FMVSS No. 
224 S5.1 specifies geometric requirements for the rear impact guard 
that remain unchanged by this test option.
    Transport Canada developed the 700 kN test option based on rigid 
barrier crash test results suggesting that a resistance to a uniform 
load of at least 700 kN would help ensure that the rear impact guard 
will stay in place and prevent underride in an impact with a passenger 
car at impact speeds of 56 km/h (35 mph).\36\ NHTSA concludes that the 
data from Transport Canada, cited in the NPRM, demonstrate the 
effectiveness and feasibility of this option in preventing underride at 
35 mph.\37\
---------------------------------------------------------------------------

    \36\ Canada Gazette Part II, Vol. 138, No. 20, 2004-10-06, p. 
1349.
    \37\ Boucher, D., ``Heavy Trailer rear underride crash tests 
performed with passenger vehicles,'' Technical Memorandum No. TMVS-
0001, Transport Canada, Road Safety and Motor Vehicle Regulation 
Directorate, July 2000.
---------------------------------------------------------------------------

d. Ground Clearance

    NHTSA proposed maintaining the current ground clearance requirement 
of 560 mm (22 inches) (S5.1.2, FMVSS No. 224) but also proposed 
updating FMVSS No. 223 to require rear impact guards to maintain a 
ground clearance of 560 mm (22 inches) after completion of the load 
application during the energy absorption test. Due to deformation that 
may occur upon loading, NHTSA noted that this requirement may 
correspond to an initial ground clearance on the trailer that is 
actually less than 560 mm (22 inches).
Comments Received
    Many commenters suggested lowering the ground clearance 
requirement. These commenters generally argued that rear impact guards 
must align with the height of car bumpers and since NHTSA mandates that 
passenger car bumpers be 16 to 20 inches (406.4 to 508 mm) off the 
ground, NHTSA must lower the ground clearance requirement to this 
level. The VT Group stated that NHTSA's bumper standards in ``49 CFR 
581 requires a light vehicle bumper height of 16 to 20'' inches and 
that lowering ground clearance to this level ``could ensure proper 
initial engagement with light vehicle safety systems.'' Batzer 
similarly stated that the most effectively designed rear impact guard 
``would engage the bumper of the striking passenger vehicle.'' 
Commenters also suggested that, because the average guard height for 
trailers currently is 18 inches (457.2 mm), there is no need for NHTSA 
to allow for a higher ground clearance. Mr. D.J. Young, III and Mr. 
Andy Young stated that technology exists that can raise or lower rear 
impact guards, and therefore NHTSA should not be concerned that a lower 
ground clearance requirement could result in a rear impact guard 
scrapping or snagging along the ground.
Agency Response
    NHTSA proposed amending FMVSS No. 223 to require that, after the 
energy absorption test where the guard is displaced 125 mm, the rear 
impact guard has to maintain a ground clearance not exceeding 560 mm 
(22 inches) but did not propose to alter the 560 mm (22 inches) ground 
clearance requirement in FMVSS No. 224. The NPRM explicitly stated that 
NHTSA was denying the request made by petitioners to lower the ground 
clearance requirement and NHTSA did not propose such a change in the 
NPRM. The suggestions to lower the ground clearance requirement are 
thus not within the scope of this rulemaking. Further, NHTSA included 
in the NPRM its rationale for denying the request to lower the ground 
clearance requirement, and, after reviewing the comments and other 
information, NHTSA has not changed its position on these points. In the 
interest of discussion, NHTSA will briefly repeat its reasoning 
here.\38\
---------------------------------------------------------------------------

    \38\ NHTSA's entire rationale is detailed in the NPRM for this 
final rule. See 80 FR 78424-78426.
---------------------------------------------------------------------------

    Comments stating that NHTSA should modify the ground clearance 
requirement to align with NHTSA's bumper standard (49 CFR part 581) 
misunderstood the purpose of the bumper standard and repeat a concern 
to which NHTSA responded in the 1996 final rule establishing FMVSS Nos. 
223 and 224.\39\ The bumper standard under 49 CFR part 581 is designed 
to prevent damage to a car body and its safety related equipment in 
impacts of 3.2 km/h (2 mph) across the full width of the bumper and 1.6 
km/h (1 mph) on the corners. The bumper standard is not, in other 
words, intended to provide occupant protection from crashes at injury-
causing impact speeds. That function is instead performed by the 
vehicle's chassis energy-management design and its energy-absorbing 
frame rails, which rely on the engagement of the vehicle's major 
structural components with the rear impact guard.
---------------------------------------------------------------------------

    \39\ See final rule, 61 FR 2004, 2017; January 24, 1996.
---------------------------------------------------------------------------

    Nor is it the case that the major structural components of vehicles 
have been so lowered as to necessitate lowering the ground clearance 
requirement. To the contrary, the height of the top of the engine block 
appears to have increased since NHTSA promulgated the 1996 final rule 
that required the 560 mm (22 inches) ground clearance. Using engine 
block height as a suitable metric to represent a major structural 
element of the striking vehicle that would engage the rear impact 
guard, when NHTSA issued the 1996 final rule, NHTSA determined the 
typical height of the top of the engine block as between 660 and 790 mm 
(26 and 31 inches). 61 FR 2017. In contrast, as discussed in the 2015 
NPRM for this final rule, data show that the current height of the top 
of the engine block is between 739 mm (29.1 inches) and 1300 mm (51.2 
inches), with an average height of 889 mm (35 inches) (80 FR

[[Page 42352]]

78425). Thus, passenger vehicle designs have changed in years since the 
establishment of the 560 mm (22 inches) ground clearance specification 
such that there is a greater likelihood of engagement of their major 
structural components with the rear impact guard.
    Further, NHTSA is concerned that some trailers may face operational 
issues if NHTSA lowered the ground clearance requirement. Trailers may 
snag and scrape at loading docks and steep railroad crossings, 
resulting in damage to the guard, if guards were required to be lower 
to the ground. The commenters advocating for a lower ground clearance 
requirement provided no data to show that this possible risk can be 
overcome or is offset by any potential benefits. Similarly, NHTSA does 
not believe it is appropriate to lower the ground clearance requirement 
and then force operators involved in intermodal operations to possess 
trailers with rear impact guards that can be raised and lowered. Doing 
so would unnecessarily burden the industry and raise costs, and 
commenters have not identified any associated benefits that would 
justify this decision.

e. Requiring Attachment Hardware To Remain Intact

    The NPRM focused on ensuring the attachment hardware of the rear 
impact guard remained intact in the quasi-static loading tests. It 
proposed to prohibit the complete separation of any portion of the 
guard and the guard attachments from its mounting structure after 
completion of the quasi-static uniform distributed load test (proposed 
S5.2.1). NHTSA stated in the NPRM (80 FR at 48429) that it was 
interpreting ```any portion of the guard and the guard attachment 
completely separating from its mounting structure' to mean the 
condition where any member of the guard becomes detached from any other 
member of the guard or from the trailer such that the joint is no 
longer mechanically bound together.'' The agency further stated that it 
would not consider a partial separation of the members at a joint where 
there is still some degree of mechanical connection between the members 
as a ``complete separation.'' Id. NHTSA sought comment on this proposed 
performance criterion and whether its objectivity could be improved by, 
e.g., specifying the percentage of fasteners or welds that remain 
intact during the test.
Comments Received
    Commenters had different views regarding the proposed requirement 
that attachment hardware remain attached throughout the quasi-static 
test. Notably, commenters in favor of such a requirement still asked 
NHTSA to refine the language used in the regulatory text. The NTSB 
stated that it supported developing performance criteria to determine 
objectively the degree of separation that may significantly reduce rear 
impact guard performance, but the commenter did not provide information 
on what the criteria should be. IIHS stated that the standard should 
require rear impact guards to withstand the quasi-static load tests 
without any separation between the guard and guard attachments rather 
than adopt the criterion of complete separation that NHTSA proposed. 
IIHS believed that NHTSA's language in the preamble, stating that the 
agency would consider partial separation acceptable as long as there 
was still some degree of mechanical connection between the guard's 
members, was vague. Due to this perceived ambiguity, IIHS questioned 
whether NHTSA would consider a joint where 3 of 4 bolts were sheared to 
constitute a partial separation.
    The TTMA, on the other hand, expressed concerns with making the 
standard overly complicated in trying to make it more objective, 
stating that setting specific requirements for numbers of welds or 
fasteners to remain intact ``would unnecessarily complicate the 
standard compared to the Canadian equivalent, and could preclude the 
use of designs with components that may be designed to shear or tear as 
part of an energy mitigation strategy.'' Seven Hills remarked that 
TTMA's concerns could be alleviated by modifying the design of rear 
impact guards.
Agency Response
    NHTSA agrees with the comments that FMVSS No. 223 should require 
attachment hardware to remain attached during the quasi-static load 
test. However, NHTSA does not agree with IIHS's specific suggestion of 
a requirement that there be no separation at any point. Guards may be 
designed to have attachment hardware shear away from the guard during 
impact to absorb the impact energy. The agency does not find it 
necessary to prohibit these kinds of guards if they meet the criterion 
discussed below.
    While NHTSA requested comments on an objective criterion that would 
keep guards from separating from their attachment hardware (other than 
by prohibiting a ``complete separation''), the agency did not receive 
any data or bases to aid NHTSA on this issue. NHTSA agrees with 
commenters, though, that the language the agency used in describing the 
requirement in the NPRM could be clearer. NHTSA proposed in S5.2.1 that 
a tested guard must resist the force levels specified in S5.2.1(a) 
through (c) without deflecting by more than 125 mm and ``without 
complete separation of any portion of the guard and guard attachments 
from its mounting structure.'' This final rule replaces the phrase 
``without complete separation of any portion of the guard and guard 
attachments from its mounting structure'' in proposed S5.2.1 and 
S5.2.2(a)(1) with the phrase ``without eliminating any load path that 
existed before the test was initiated.'' ``Load path'' is a standard 
engineering term. The agency is defining ``load path'' to mean a route 
of force transmission from the horizontal member of the guard to the 
chassis.\40\
---------------------------------------------------------------------------

    \40\ ``Chassis'' is defined in FMVSS No. 223, S4, as the load 
supporting frame structure of a motor vehicle.
---------------------------------------------------------------------------

    Load paths represent how forces applied to the guard will transmit 
through the guard to the chassis based on the geometry of the guard. 
For the purposes of FMVSS No. 223, NHTSA will determine load paths by 
visual inspection prior to conducting the quasi-static load tests. 
NHTSA will assess whether any load paths are eliminated after any force 
applied during the test using the force application device is removed. 
``Eliminating a load path'' means that a load path designed to transmit 
force from the horizontal member of the rear impact guard to the 
chassis, can no longer transmit the force.
    If two or more members in the load path are joined using multiple 
bolts, NHTSA will not consider each bolt to be an individual load path. 
For instance, if the vertical member of a rear impact guard was 
attached to the horizontal member by four bolts, NHTSA would not 
consider the load path to have been eliminated if one, two, or three of 
the bolts sheared off or otherwise became disconnected during testing. 
On the other hand, if all four bolts sheared off, or otherwise became 
disconnected, the agency would consider this to constitute an 
eliminated load path, even if the guard's members remained in contact 
due to friction or the structural integrity of another portion of the 
guard. To use another example, if two members in a load path are 
connected by a single weld and if the weld developed one or more 
discontinuous cracks during testing, NHTSA would not consider this to 
constitute an eliminated load path. If, however, a continuous crack 
developed during testing along the entire length of the weld holding 
the two members together, this would constitute an eliminated load path 
as a route of force

[[Page 42353]]

transmission would have been eliminated even if the members remained in 
contact through friction or the structural integrity of another portion 
of the guard. When all mechanical connection along a route of force 
transmission from the horizontal member of the guard to the chassis is 
lost, we would consider this to be an eliminated load path. If the two 
members in a load path were connected by two welds and a continuous 
crack developed along the entire length of only one of the welds, this 
would not constitute an eliminated load path.

f. Definition of Rear Extremity

    The NPRM proposed replacing the current definition of ``rear 
extremity'' in FMVSS No. 224 with the definition from CMVSS No. 223. 
NHTSA proposed this change to account for aerodynamic fairings, also 
known as ``boat tails,'' which are rear-mounted panels that reduce 
aerodynamic drag and fuel consumption. The proposed change to the 
definition of ``rear extremity'' was meant to ensure that aerodynamic 
fairings would be placed where, in a collision, they would not 
jeopardize the safety of occupants in vehicles striking the rear of the 
trailer.
Comments Received
    Network, TTMA, and NTSB all supported NHTSA's proposed change. The 
VT Group and Batzer raised concerns that aerodynamic fairings could 
pierce windshields in instances of partial underride and pose an 
impalement hazard. Batzer further suggested that NHTSA require every 
trailer manufacturer and/or user with a non-standard end profile to do 
a formal engineering analysis of their equipment to document that they 
have considered the safety implications of their design.
Agency Response
    After reviewing the comments on this issue, NHTSA agrees with 
commenters supporting the proposal. The proposed definition for ``rear 
extremity'' is based on the Canadian definition, which Transport Canada 
arrived at after extensive research into aerodynamic fairings. While 
commenters raised concerns over impalement risks, aerodynamic fairings 
are typically lightweight structures and no commenter provided evidence 
showing a risk of vehicle occupant impalement by such fairings. NHTSA 
will continue to monitor rear impact collisions and revisit the 
definition if necessary. Requiring trailer manufacturers to do a formal 
engineering analysis on aerodynamic fairings, as Batzer suggested, is 
beyond the scope of the proposal.

g. Low Chassis Vehicle Correction

    FMVSS No. 224 excludes several types of trailers from application 
of the standard (S3). As noted in the NPRM, low chassis vehicles \41\ 
were originally excluded from FMVSS No. 224 in a 1996 final rule 
establishing the standard (61 FR 2035) but NHTSA inadvertently did not 
list the vehicles in S3 in a 1998 amendment that responded to petitions 
for reconsideration (63 FR 3654). The agency proposed to correct the 
omission and list low chassis vehicles back in S3.
---------------------------------------------------------------------------

    \41\ A ``low chassis vehicle'' is defined in FMVSS No. 224 as a 
trailer or semitrailer having a chassis that extends behind the 
rearmost point of the rearmost tires and a lower rear surface that 
meets the configuration requirements of S5.1.1 through 5.1.3 of 
Standard No. 224.
---------------------------------------------------------------------------

    Although the NPRM did not propose to expand the applicability of 
FMVSS No. 224, NHTSA received many comments urging NHTSA to apply the 
standard to vehicles now excluded from it. We discuss these comments in 
Section V below. As to correcting S3 to add low chassis vehicles back 
into S3, NHTSA did not receive any comments opposed to the correction. 
Accordingly, this final rule corrects S3 as proposed.

h. Technical Correction

    The NPRM's proposed regulatory text for FMVSS No. 224 included 
restated current text in S3 that excluded vehicles with temporary 
living quarters ``as defined in 49 CFR 529.2.'' RVIA commented on this 
proposed wording, stating that the NPRM's reference to ``temporary 
living quarters as defined in 49 CFR 529.2'' was an incorrect 
reference. RVIA suggested that the definition of temporary living 
quarters should point to 49 CFR 523.2.
    RVIA is correct that the NPRM's reference to 49 CFR 529.2 as 
providing a definition for temporary living quarters was erroneous. The 
regulations at 49 CFR 529.2 do not include any definition for temporary 
living quarters. The preamble for the 1996 final rule properly referred 
to 49 CFR 523.2 (61 FR 2022), but the regulatory text for the 1996 
final rule mistakenly referenced 49 CFR 529.2 (61 FR 2035). NHTSA is 
taking this opportunity to make a technical correction to FMVSS No. 224 
and make clear that the definition of temporary living quarters is 
defined in 49 CFR 523.2.

V. Response to Comments on Issues Not Proposed in the NPRM

    NHTSA received a number of comments on aspects of FMVSS No. 223 and 
224 that the agency did not propose to change. Although these comments 
were beyond the scope of the rulemaking, we discuss them here to 
further our dialogue in this area.

a. Vehicles Excluded From FMVSS No. 224

    FMVSS No. 224 (S3) excludes pole trailers, pulpwood trailers, road 
construction controlled horizontal discharge trailers, special purpose 
vehicles, wheels back vehicles, or temporary living quarters (S3). 
NHTSA did not propose to remove any of these exclusions. We evaluated 
the exclusions when we were drafting the NPRM and decided not to change 
them (80 FR 78426-78428). The decision was based on our analysis of 
data provided by the 2013 UMTRI Study.\42\
---------------------------------------------------------------------------

    \42\ As discussed earlier in this preamble, the 2013 UMTRI Study 
collected supplemental data to that collected in TIFA for the years 
2008 and 2009. The supplemental survey data included details of the 
truck rear extremity, whether a rear impact guard was required, 
relative impact speed of the crash, and the extent of underride.
---------------------------------------------------------------------------

Comments Received
    A number of commenters disagreed with NHTSA's continued exclusion 
of various vehicles. Commenters raised the most concerns about the 
exclusions for single unit trucks (SUTs) \43\ and wheels back trailers.
---------------------------------------------------------------------------

    \43\ SUTs are trucks with a GVWR greater than 4,536 kg (10,000 
lb) with no trailer. They are primarily straight trucks, in which 
the engine, cab, drive train, and cargo area are mounted on one 
chassis. As SUTs are not trailers, they are not subject to FMVSS 
Nos. 223 and 224.
---------------------------------------------------------------------------

    SUTs. VT Group believed that regulating SUTs was necessary, citing 
data NHTSA included in the NPRM that, of the 121 light vehicle fatal 
crashes annually that result in PCI, 19 percent occur in impacts with 
SUTs without guards. NTSB argued that the adverse effects of SUT 
crashes have been underestimated in the past ``because these trucks are 
frequently misclassified and thus undercounted.'' Based on previous 
research findings portraying underride as underreported in 
FARS,44 45 Ms. Karth stated that NHTSA's analysis for SUTs 
was skewed by what she believed to be inaccurate, underreported 
information about PCI from underride. Mr. Young commented that further 
consideration of ways to engineer guards for SUTs ``is warranted

[[Page 42354]]

despite the difficulties associated with those vehicles.''
---------------------------------------------------------------------------

    \44\ Braver, E.R.; Mitter, E.L.; Lund, A.K.; Cammisa, M.X.; 
Powell, M.R.; and Early, N. 1998. A photograph-based study of the 
incidence of fatal truck underride crashes in Indiana. Accident 
Analysis and Prevention, vol. 30, no. 2, pp. 235-243.
    \45\ Blower D and Campbell K. 1999. Underride in Rear-End Fatal 
Truck Crashes, The University of Michigan Transportation Research 
Institute, 1999.
---------------------------------------------------------------------------

    Agency Response. Because of prior research findings raising the 
possibility of underreporting of underride in FARS, NHTSA initiated 
research in 2010 with UMTRI that formed the basis of the 2013 UMTRI 
Study. The purpose of this research was to gather accurate data on the 
rear geometry of SUTs and trailers, the configuration of rear impact 
guards on SUTs and trailers, and the incidence and extent of underride 
and fatalities in rear impacts with SUTs and trailers. UMTRI collected 
the supplemental information as part of the TIFA survey for the years 
2008 and 2009.46 47 These data enabled NHTSA to obtain 
national estimates of rear impact crashes into heavy vehicles that 
resulted in PCI. Using information derived by reviewing police crash 
reports,\48\ UMTRI estimated the relative speed of fatal light vehicle 
crashes into the rear of SUTs and trailers. Because of the detailed 
analysis and the supplemental information collected for each crash, the 
2013 UMTRI Study forms the most comprehensive and valid data set 
available to inform the agency regarding crashes involving SUTs and 
trailers and the incidence and extent of underride.
---------------------------------------------------------------------------

    \46\ Analysis of Rear Underride in Fatal Truck Crashes, 2008, 
DOT HS 811 652, August 2012, infra.
    \47\ Heavy-Vehicle Crash Data Collection and Analysis to 
Characterize Rear and Side Underride and Front Override in Fatal 
Truck Crashes, DOT HS 811 725, March 2013, infra.
    \48\ Information included police estimates of travel speed, 
crash narrative, crash diagram, and witness statements. The impact 
speed was estimated from the travel speed, skid distance, and an 
estimate of the coefficient of friction.
---------------------------------------------------------------------------

    Regarding NTSB assertions that SUT crashes are underestimated in 
FARS because trucks are frequently misclassified, and with respect to 
Ms. Karth's comment that underride and PCI are underreported in FARS, 
NHTSA did not use FARS data in developing this rulemaking and instead 
used TIFA data for the years 2008 and 2009 with supplemental 
information reported in the 2013 UMTRI Study.\49\ As explained earlier 
in this preamble, the TIFA database is supplemental to FARS, and has 
improved the accuracy of FARS data on fatal large truck crashes. It 
provides more detailed information than in FARS on the involved large 
trucks, motor carriers, and sequence of events.\50\ The TIFA and 2013 
UMTRI Study comprise the best scientific data on underride crashes. 
Thus, this rulemaking used the most accurate estimate of SUT crashes, 
as determined by the best available scientific data in the area, and we 
do not believe SUT crashes were underestimated.
---------------------------------------------------------------------------

    \49\ Heavy-Vehicle Crash Data Collection and Analysis to 
Characterize Rear and Side Underride and Front Override in Fatal 
Truck Crashes, DOT HS 811 725, March 2013.
    \50\ NTSB stated in a 2013 safety study, ``The TIFA database 
provides more accurate classifications of large truck vehicle body 
types by using information from the vehicle identification number 
(VIN) and by collecting additional data for all fatal large truck 
crashes.'' Crashes involving single-unit trucks that resulted in 
fatalities and injuries, National Transportation Safety Board Safety 
Study, NTSB/SS-13/01, PB2013-106637, June 2013.
---------------------------------------------------------------------------

    With further regard to whether NHTSA's data underreported 
underride, we believe that the data appear to include some crashes that 
did not actually result in underride. In the 2013 UMTRI Study, the 
extent of underride was estimated in terms of the amount of the 
striking vehicle that went under the rear of the struck vehicle and/or 
the extent of deformation or intrusion of the striking vehicle. The 
categories were ``no underride,'' ``less than halfway up the hood,'' 
``more than halfway but short of the base of the windshield,'' and ``at 
or beyond the base of the windshield.'' NHTSA believes it is most 
relevant for this rulemaking to consider the relevant crashes to be as 
an underride that resulted in PCI beyond the base of the windshield. 
However, since the 2013 UMTRI Study determined the extent of underride 
by the extent of deformation and intrusion of the vehicle, there were a 
number of TIFA cases involving large vans and large pickups that did 
not actually underride the truck or trailer, but that had sustained PCI 
because of the high speed of the crash and/or because of the very short 
front end of the vehicle. Because these large striking vehicles did not 
underride the struck vehicle, NHTSA's interpretation in the NPRM of PCI 
from the 2013 UMTRI Study potentially overestimated the occurrence of 
PCI due to underride. We believe, in other words, that NHTSA's analysis 
using data in the 2013 UMTRI Study potentially overestimated PCI due to 
underride.
    NHTSA responded to the Karth/TSC petition by publishing two 
separate notices.\51\ NHTSA first published an advance notice of 
proposed rulemaking (ANPRM) on July 23, 2015, pertaining to issues 
concerning rear impact guards for single unit trucks (SUTs), including 
whether to apply FMVSS No. 224 to the vehicle type and whether to apply 
FMVSS No. 108's requirements for conspicuity tape.\52\ Second, NHTSA 
published the NPRM preceding this final rule upgrading rear impact 
guards on December 16, 2015. Comments relating to the application of 
FMVSS No. 224 to SUTs will be addressed in a follow up document to the 
2015 ANPRM and will not be addressed in this final rule.
---------------------------------------------------------------------------

    \51\ 79 FR 39362.
    \52\ 80 FR 43663.
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    Wheels Back Vehicles. TSC opposed FMVSS No. 224's exclusion of 
wheels back trailers. Similarly, Advocates suggested that the NPRM's 
discussion of the involvement of wheels back vehicles in fatal crashes 
did not support the agency's conclusion that excluding wheels back 
trailers ``may not have significant safety consequences.'' \53\ The 
commenter criticized the 2013 UMTRI Study that NHTSA relied on, stating 
that the sort of speed estimates used in the study are notoriously 
inaccurate and that data generated in the TIFA database frequently 
depend on unreliable telephone interviews and post-crash interviews. 
IIHS similarly objected to NHTSA's use of the supplemented TIFA data, 
stating that UMTRI had previously cautioned against defining degrees of 
underride, and that NHTSA's use of estimated crash speeds was 
speculative. IIHS also noted that the 2008-2009 TIFA survey found that 
one-half of wheels back trailers involved in fatal crashes were 
equipped with rear impact guards, which IIHS believed raised concerns 
``about the validity of the comparisons of underride severity by 
trailer type.'' Network stated that, as modern cars require flat 
surfaces to interact with vehicle safety systems, the safety systems 
will not engage when a vehicle impacts the rear of wheels back 
trailers, as tires on a wheels back trailer present an uneven surface 
hazard. Network also stated that agricultural trucks in North Dakota 
have shown a net benefit from adding rear impact guards.
---------------------------------------------------------------------------

    \53\ The NPRM provided data that wheels back vehicles account 
for 20 percent of fatal light vehicle impacts into the rear of 
trailers, and that 16 percent of fatal light vehicle impacts into 
wheels back trailers resulted in PCI.
---------------------------------------------------------------------------

    Agency Response. NHTSA has considered the comments but does not 
believe available data support applying FMVSS No. 224 to wheels back 
trailers.\54\ In the UMTRI study, crashes into the rear of wheels back 
trailers accounted for 6 percent of all fatal light vehicle crashes 
into the rear of trucks and trailers that resulted in PCI. Detailed 
analysis of the fatal light vehicle impacts into the rear of wheels 
back trailers that resulted in PCI in 2009 indicated that the crashes 
were generally at very high impact speeds that are considered 
unsurvivable. In all these crashes, it is unlikely that a rear impact 
guard designed to CMVSS No. 223 would have prevented PCI into these 
vehicles. A rear impact guard

[[Page 42355]]

would not have prevented these fatalities.\55\
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    \54\ 80 FR 78427-78428.
    \55\ 80 FR 78428.
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    NHTSA has also analyzed comments criticizing the 2013 UMTRI Study 
as applied to wheels back trailers and believes that the data in the 
study are sound. The UMTRI data were enhanced specifically for trailer 
rear impact analysis and the study contains enriched data specific to 
impact performance. The 2013 UMTRI Study \56\ was based on enhanced 
Trucks in Fatal Accidents (TIFA) data for the years 2008 and 2009. The 
enhanced data included supplemental information, collected as part of 
the NHTSA funded study, on the rear-end configuration of SUTs and 
trailers and the incidence and nature of underride and associated 
fatalities in crashes into the rear of SUTs and trailers, and an 
estimate of the relative velocity of the light vehicle crash.\57\ The 
data from the 2013 UMTRI Study comprise the most accurate and complete 
dataset available for evaluating the incidence of underride and are 
appropriate for use for evaluating underride incidences in light 
vehicle crashes into the rear of wheels back trailers. While commenters 
made general statements that the variables used in this data set are 
unreliable, none presented alternative data that they considered more 
accurate.
---------------------------------------------------------------------------

    \56\ Heavy-Vehicle Crash Data Collection and Analysis to 
Characterize Rear and Side Underride and Front Override in Fatal 
Truck Crashes, DOT HS 811 725, March 2013, supra. Also available at 
https://www.nhtsa.gov/sites/nhtsa.gov/files/811725.pdf.
    \57\ UMTRI estimated the relative speed of fatal light vehicle 
crashes into the rear of SUTs and trailers using all available 
information, including police estimates of travel speed, crash 
narrative, crash diagram, and witness statements. The impact speed 
was estimated from the travel speed, skid distance, and an estimate 
of the coefficient of friction. Relative velocity was computed as 
the resultant of the difference in the trailer (truck) velocity and 
the striking vehicle velocity and could only be estimated for about 
30 percent of light vehicle fatal crashes into the rear of trailers 
and SUTs.
---------------------------------------------------------------------------

    NHTSA also does not agree with IIHS that the presence of wheels 
back trailers with rear impact guards in the 2013 UMTRI Study raises 
doubts about NHTSA's conclusion there is an absence of a safety need 
for the guards. First, while IIHS references data from the TIFA data 
sets for 2008-2009 to claim that half of wheels back trailers involved 
in a fatal crash were equipped with rear impact guards, the data do not 
provide information on the guards equipped or the need for a guard. The 
data sets do not record if any of the guards were original equipment or 
were even compliant to a standard such as FMVSS No. 223. The presence 
of a rear impact guard that lacks sufficient strength and energy 
absorption characteristics specified in FMVSS No. 223 would not 
mitigate PCI in light vehicles at impact speeds 30 mph or lower.
    Further, IIHS implies that the guards prevented underride rather 
than the wheels of wheels back trailers, but does not provide 
information to substantiate the claim that the guards had prevented 
underride rather than the wheels of the trailer. IIHS provided no data 
to suggest this interaction with the guard versus the wheels is 
occurring. In the 1996 final rule that established FMVSS No. 224, NHTSA 
determined that ``a fixed rear axle with the tires mounted within 305 
mm [12 inches] . . . of the vehicle's rear extremity constitutes an 
adequate substitute for a rear impact protection guard from the 
standpoint of preventing PCI.'' \58\ This is a straightforward 
conclusion and no information has been provided to change our 
conclusion on this issue. We similarly do not find Network's statement 
that vehicle crashworthiness safety systems will not engage during 
impacts with the rear of wheels back trailers to be supported by any 
evidence. Network did not support its assertion, and it is contradicted 
by the results of past dynamic crash tests of light vehicles into the 
rear of wheels back trailers.\59\
---------------------------------------------------------------------------

    \58\ 61 FR 2024.
    \59\ Id. Two crash tests involving wheels back trailers were 
conducted in support of the 1996 final rule. For these wheels back 
trailers, the rear tires were located about 100 to 205 mm (4 to 8 
in) forward of the rear extremity of the trailer. In each test, in 
an offset crash in which a Chevrolet Impala struck the tires and in 
a centric crash in which a VW Rabbit struck the axle and other 
components between the tires, PCI was prevented at about 56 kph (35 
mph).
---------------------------------------------------------------------------

    Horizontal discharge trailers: NHTSA disagrees with TTMA and NTEA's 
views that there should be a blanket exclusion of end-dump trailers 
from FMVSS No. 224. When we modified FMVSS No. 224 to exclude road 
construction controlled horizontal discharge trailers (S4), we received 
comments similar to those sent by TTMA and NTEA that requested us to 
exclude gravity feed end-dump trailers.\60\ In response, NHTSA noted 
that end-dump trailers are versatile vehicles that may not necessarily 
interact with equipment in a way that necessitates an exception, as 
many fall under the exception for wheels back trailers and many may 
also be able to accommodate a rear impact guard. For these reasons, we 
explained that we preferred to review the necessity of exempting end-
dump trailers on a case-by-case basis in the context of temporary 
exemptions under 49 CFR part 555. NHTSA continues to believe this is 
the most appropriate approach to these vehicles.
---------------------------------------------------------------------------

    \60\ See 69 FR 67663, 67666.
---------------------------------------------------------------------------

    Trailers with lift gates: In response to Mr. Young's comment that 
trailers with lift gates should not be excluded from the standard, 
trailers with lift gates are not currently excluded from FMVSS No. 224, 
and NHTSA did not propose any changes in this regard.\61\ Trailers with 
certain kinds of lift gates may fall under the definition of ``special 
purpose vehicle,'' but the comment did not refer to such vehicles.
---------------------------------------------------------------------------

    \61\ See 69 FR 64495, 64497.
---------------------------------------------------------------------------

b. Testing on a Trailer Rather Than a Fixture

    FMVSS No. 223 currently provides that NHTSA may test a rear impact 
guard when attached, per manufacturer's instructions, to either a rigid 
test fixture or to a complete trailer, at the guard manufacturer's 
option. As discussed in the NPRM, NHTSA denied the request from the 
petitioners to remove the option of testing on a rigid test fixture. 
The agency determined that the two tests are essentially equivalent and 
that requiring that guards be tested when attached to the trailer could 
be a significant cost burden to small trailer manufacturers.
Comments Received
    Many commenters expressed a preference to NHTSA's testing guards 
only when attached to a complete trailer. Ms. Karth and Network stated 
that rear impact guards and the trailers to which they are attached are 
a system and that compliance testing should be conducted with the guard 
attached to the trailers and/or a portion of the trailer that includes 
all structures to which the guard attaches. Batzer believed that 
testing rear impact guards on the trailer on which they will be mounted 
``would produce more confidence in the design.'' IIHS and Advocates 
stated that testing on rigid test fixtures disregarded the fact that 
crash tests with rear impact guards attached to trailers resulted in 
deformation to the trailer. IIHS stated that allowing rear impact 
guards to be tested when attached to a rigid fixture rather than to an 
actual trailer is ``insufficient to guarantee underride prevention'' 
because a guard certified to meet the standards of CMVSS No. 223 may be 
attached to a trailer structure that does not have the demonstrated 
capability to resist the same force level. IIHS claimed that the 
relatively weaker structure of the trailer may deform during a crash, 
leaving ``open the possibility that guards will be attached

[[Page 42356]]

to trailer structures that are too weak to withstand the forces of a 
crash, in which case the strength of the guard itself is irrelevant.'' 
Advocates also believed that ``significant issues with the performance 
of the guard and the attachment system would not be detected'' if the 
guard was tested on a rigid test fixture. Some commenters also argued 
that the higher burdens to small manufacturers ``is an insufficient 
justification.'' TSC stated that NHTSA should require testing on a 
trailer as it reflects a real-world scenario ``even if the process is 
more costly.''
Agency Response
    We considered the suggestion to remove the option for fixture 
testing when we evaluated the petitions and ultimately concluded not to 
include it in the proposed rule. Many of the commenters raise points 
NHTSA discussed in the NPRM and points NHTSA had discussed in the 
original 1996 final rule. In the 1996 final rule, NHTSA explained that, 
even though testing on a trailer is desirable ``because there is 
nothing more `appropriately configured' for guard mounting on the 
actual trailer'' and because such testing also tests the structural 
integrity of the trailer chassis, the agency's data demonstrated that 
rear impact guards tested on rigid test fixtures performed similarly to 
their performance on an actual trailer.\62\ NHTSA reiterated this point 
in the NPRM for this final rule, and commenters did not provide any new 
information to suggest that testing on a rigid test fixture is no 
longer acceptable. NHTSA concludes that a guard shown to be compliant 
when tested on a rigid test fixture will perform to the same benchmark 
when attached to a trailer.
---------------------------------------------------------------------------

    \62\ See 61 FR 2008, 2014. NHTSA's testing showed that the 
maximum force measured in quasi-static tests of rear impact guards 
attached to a fixture is similar to the maximum force generated in 
dynamic crash tests with the rear impact guard installed on a 
trailer. Additionally, rear impact guards that were only ten percent 
stronger than the minimum level of strength necessary to pass 
quasistatic test requirements performed adequately in dynamic tests 
with the guard installed on a trailer.
---------------------------------------------------------------------------

    NHTSA stated its view that a rear impact guard attached to a rigid 
test fixture would not have a trailer to absorb a portion of the load 
so the severity of the fixture test might be higher than a trailer 
test. IIHS and Advocates seemed to argue the opposite, stating that 
testing on rigid test fixtures disregarded the fact that crash tests 
with rear impact guards attached to trailers resulted in deformation to 
the trailer. NHTSA cannot conclude that trailer deformation itself 
indicates that the total resistance of a guard-attachment-trailer 
system is lower than that of the guard alone on a rigid test fixture. 
The trailer structure may have deformed because it offered resistance 
to the dynamic loads. As stated in the NPRM, testing on a rigid test 
fixture has an advantage over trailer testing in its potential to show 
that the guard is capable of resisting all loads and absorbing all the 
energy.
    The commenters did not provide information showing that requiring 
each rear impact guard be tested on a trailer would offset the 
significant costs of doing so, especially for small trailer 
manufacturers with low sales volumes. As noted in the NPRM, if small 
manufacturers were to test the rear impact guard on the trailer, this 
testing could involve sacrificing what could constitute a substantial 
part of their overall trailer production. NHTSA does not believe there 
is a safety basis justifying these impacts on these manufacturers.
    Finally, NHTSA emphasizes the test specifications in the FMVSS 
reflect how NHTSA will perform tests to evaluate compliance; they do 
not limit how manufacturers certify compliance. Inserting a requirement 
into FMVSS No. 223 specifying how manufacturers can certify their own 
compliance, as suggested by Batzer and VT Group, is not in accordance 
with the purpose and structure of the FMVSS.

c. Low Overlap Crash Performance

    Both petitioners IIHS and TSC/Karth requested that NHTSA take steps 
to prevent underride in low overlap crashes (crashes with 30 percent 
overlap or less of the impacting vehicle with the trailer rear).\63\ 
IIHS's petition asked NHTSA to evaluate relocating the quasi-static 
point load test at the P1 location further outboard toward the end of 
the guard horizontal member so that guards are tested for strength 
further outboard. IIHS suggested that, based on its interpretation of 
the crash tests of the 2010 Chevrolet Malibu into the rear of the 2011 
Wabash trailer, doing so would provide underride protection to full, 50 
percent, and 30 percent overlap crashes.\64\
---------------------------------------------------------------------------

    \63\ Overlap is the percentage of the light vehicle width that 
interacts with the rear of the trailer in a collision. Offset means 
the centerline of the light vehicle is not aligned with the 
centerline of the trailer. Other organizations may use low overlap 
or offset to refer to different specified amounts of overlap.
    \64\ In IIHS's 30 percent overlap crash test with the Chevrolet 
Malibu, the front end of the Malibu only contacted the portion of 
the rear impact guard lateral of the vertical support member.
---------------------------------------------------------------------------

    NHTSA reviewed the requests in the petitions but did not propose to 
move the P1 location further outboard as a part of this rulemaking. The 
requests were not supported by sufficient information, as the 
petitioners did not explain why moving the P1 location further outboard 
would improve guard performance in low overlap crashes.
    NHTSA determined that the performance of rear impact guards in 
crashes other than low overlap should be enhanced before turning to 
performance specific to low overlap crashes. We analyzed the data 
collected in the 2013 UMTRI Study and found that underride crashes of 
30 percent overlap or less represented a smaller portion of the rear 
underride fatality problem than non-low overlap crashes. We decided to 
focus the NPRM on crashes other than low overlap because those were the 
more prevalent fatal crashes.
    The data do not show that improving low overlap crash performance 
would improve non-offset crash performance. In fact, data indicate a 
potential negative consequence. NHTSA expressed a concern in the NPRM 
about a potential risk that bolstering performance in a 30 percent 
overlap crash might degrade protection in 50 and 100 percent overlap 
crashes. The Manac rear impact guard features vertical supports towards 
the lateral edge of the trailer. While this guard was able to prevent 
PCI in the 56 km/h (35 mph) 30 percent overlap condition during IIHS's 
crash tests, in IIHS's 56 km/h (35 mph) full overlap crash test, the 
Manac guard had the greatest amount of deformation (1,350 mm) of any 
guard. NHTSA was concerned that these data indicated that rear impact 
guards designed like the Manac, with the main vertical supports for the 
guard more outboard, may not perform as well compared to other guards 
in full overlap crashes at crash speeds at or greater than 56 km/h (35 
mph).
    To summarize, data indicated that: (a) full and 50 percent overlap 
crashes are more frequent than 30 percent overlap crashes; (b) most 
fatal light vehicle impacts into the rear of trailers are at speeds 
greater than 56 km/h (35 mph); and, (c) improving performance against 
low overlap crashes could reduce performance of the guard in full and 
50 percent overlap crashes. Given those factors, we decided not to take 
an approach in this rulemaking that would improve guard performance in 
a 30 percent overlap crash but that could lessen protection in 50 and 
100 percent overlap crashes at higher speeds (speeds higher than the 35 
mph speed on which the amended FMVSS No. 223 would be based).

[[Page 42357]]

Comments and Agency Response
    Several commenters disagreed with NHTSA's decision to refrain from 
pursuing rulemaking on low overlap crashes. Some commenters pointed to 
existing guards (e.g., the Manac guard) that they stressed provided 
protection against crashes with low overlap. Some disagreed with 
NHTSA's concern that such a guard might not perform as well in crashes 
with full or 50 percent overlap at crash speeds greater than 56 km/h 
(35 mph). Seven Hills stated that the extent of underride seen in the 
full overlap crash test with the Manac guard was due to the Chevrolet 
Malibu fitting ``just between both uprights contacting only the 
horizontal bar,'' and that this scenario ``represents an extremely 
small fraction of possible crash scenarios.'' IIHS argued that the 
Manac design performed well and that it is not the only possible guard 
design; IIHS said it tested a 2015 Vanguard design that was also able 
to prevent severe underride at 30 percent overlap.\65\ Conversely, 
Wabash concurred that the design of the Manac guard reduced protection 
in full overlap conditions.
---------------------------------------------------------------------------

    \65\ In 2017, IIHS introduced the TOUGHGUARD award for trailers 
that mitigate PCI in a 56 km/h (35 mph) crash of a Chevrolet Malibu 
into the rear of the trailer in all three overlap conditions (full, 
50 percent, and 30 percent). IIHS awarded the TOUGHGUARD to nine 
North American trailer manufacturers that offer this feature on at 
least some trailers.
---------------------------------------------------------------------------

Agency Response
    Several commenters argued that fatal low overlap crashes occurred 
more frequently than stated by NHTSA. IIHS believed that the data 
underlying NHTSA's finding that 40 percent of light vehicle impacts 
into the rear end of trucks and trailers in fatal crashes were offset 
crashes were collected ``during phone interviews with someone who was 
familiar with each crash but may not have been at the crash scene'' and 
``took place 1-2 years after the crash.'' Advocates remarked that TIFA 
survey data ``is known to consist of notoriously suspect crash data and 
analysis.'' In response, NHTSA does not agree that the agency did not 
accurately calculate the prevalence of low overlap crashes. The 2013 
UMTRI Study forms the most scientific, comprehensive and valid data set 
available to inform the agency and safety community on this issue.
    IIHS referred to its 2010 study of passenger vehicle crashes into 
the rear of trailers and semitrailers in the Large Truck Crash 
Causation Study (LTCCS) to argue that, ``guard deformation or complete 
failure was frequent and most commonly due to weak attachments, 
buckling of the trailer chassis, or bending of the lateral end of the 
guard under narrow overlap loading.'' \66\ IIHS noted that there were 
30 LTCCS cases in the study involving trailers with guards that met the 
FMVSS No. 224 geometric requirements and among these 30 cases, 30 
percent (n=9) were crashes in which less than half of the passenger 
vehicle overlapped the trailer.
---------------------------------------------------------------------------

    \66\ Quoting from its study. Brumbelow, M.L., Blanar, L., 
``Evaluation of US Rear Underride Guard Regulation for Large Trucks 
Using Real-World Crashes,'' Stapp Car Crash Journal, Vol. 54, 
November 2010, pp. 119-131.
---------------------------------------------------------------------------

    In response, the data used in the 2010 IIHS study comprised too 
small a sample to generalize the extent of low overlap crashes in the 
U.S. NHTSA notes that in 22 of the 30 cases, it was not clear whether 
the rear impact guards on the trailers were compliant with FMVSS No. 
223 and among the 9 low overlap crashes. Seven rear impact guards on 
the trailer exhibited deformation similar to that in the IIHS 30 
percent overlap crash tests (the lateral end of the guard bent forward 
in the impact). In the other 2 cases, the rear impact guards 
experienced failure at other locations likely due to the guards being 
weak in general. Among the 30 LTCCS cases IIHS analyzed, only 8 were 
crashes of passenger vehicles into the rear of trailers with FMVSS No. 
223 compliant rear impact guards. Among these 8 trailers, 2 rear impact 
guards showed no signs of failure, 3 rear impact guards failed at the 
attachment to the trailer structure, 1 rear impact guard bent forward 
due to localized loading from a low overlap crash, and 2 rear impact 
guards were damaged too severely to determine the failure mechanism. In 
other words, the 2010 IIHS study uses too small a data sample to 
generalize the extent of low overlap crashes in the U.S. In contrast, 
the 2013 UMTRI Study provides a scientific annual estimate of all fatal 
crashes into the rear of trailers in the U.S., including offset crashes 
and the extent and type of rear impact guard damage in crashes.
    Seven Hills said it did not understand why NHTSA was considering 
the extent of guard damage, as a fatal collision involving major damage 
to a guard should be treated the same as a fatal collision that did not 
involve major damage. It also argued that minimal guard damage in fatal 
offset impacts indicates that the problem is lack of adequate guard 
strength on the outside edges of trailers. The commenter said that the 
absence of a difference in the percentage of light vehicle crashes with 
PCI in offset crashes and non-offset crashes shows a need to improve 
the performance of rear impact guards in low overlap conditions, 
particularly when such PCI is occurring in what Seven Hills viewed as 
``otherwise non-injurious speed differences.''
    In response, NHTSA believes examining the extent of rear impact 
guard damage, along with the occurrence of PCI, is important to 
determine the utility of improving guards to protect against non-offset 
crashes. Rear impact guards sustain more damage in non-offset crashes, 
which suggests that non-offset crashes are potentially more harmful and 
thus should be addressed first. Our statement that we found no 
difference between the percentage of light vehicle crashes with PCI in 
offset crashes and non-offset crashes was not meant to suggest that 
offset crashes are not a concern. Rather, because (a) more fatal light 
vehicle crashes into the rear of trucks and trailers are non-offset 
crashes, (b) non-offset occur significantly more frequently than low 
overlap crashes (crashes with 30 percent or less overlap of the 
impacting vehicle with the rear of the trailer), and (c) non-offset 
crashes appear more harmful of the two, NHTSA was explaining why it 
decided to pursue this rulemaking on non-low overlap crashes at this 
time.
    IIHS stated that guard damage is not an adequate metric for the 
severity of underride and questioned whether NHTSA could accurately 
calculate the extent of guard damage based on TIFA survey data. In 
response, NHTSA notes that the damage to the guard was not used to 
assess the severity of underride but was part of the information 
collected to determine impact severity. The 2013 UMTRI Study used 
enhanced data on the rear of the trailer to determine the extent of 
guard damage. The severity of underride and the occurrence of PCI were 
determined from the light passenger vehicle information.
    IIHS noted that the Manac rear impact guard was not the only design 
that performed well in the 30 percent overlap crash and that other 
designs such as the Vanguard rear impact guard also mitigated PCI in 30 
percent overlap crashes. The agency agrees that other rear impact guard 
designs that connect directly to the longitudinal frame rails of the 
trailer through the vertical members are able to mitigate PCI in 30 
percent overlap crashes without reducing protection against PCI in full 
and 50 percent overlap crashes. However, as shown later in the section, 
these guards add cost and weight to the trailer.
    TSC and Advocates stated that, even if the majority of fatal light 
vehicle crashes into the rear of trucks and trailers were non-offset 
crashes, this still meant that 40 percent were offset

[[Page 42358]]

crashes. Other commenters also disagreed with NHTSA's decision to focus 
this rulemaking on fatal non-low overlap crashes, despite that such 
crashes occur more frequently than low overlap crashes. In response, 
NHTSA notes that this final rule would afford protection to occupants 
involved in 56 km/h (35 mph) crashes into the rear of trailers where 
the impacting vehicle fully overlaps with the trailer rear, and in 
offset crashes where 50 percent of the light vehicle front end overlaps 
with the trailer rear, and in offset crashes where a load bearing 
vertical member connecting the rear impact guard to the trailer is 
engaged by the front end of the impacting vehicle. In response to the 
comments, we reiterate some of the details provided in the NPRM and 
provide further reasoning below for not proceeding with low overlap 
performance requirements in this final rule.
Further Analysis on Requirements for Protection in Low Overlap Crashes
    Rear impact guards are designed to absorb energy and prevent PCI by 
attaching to substantial structural elements of a trailer or 
semitrailer, such as the chassis longitudinal frame rails, by way of 
vertical support members. The test results from the initial testing at 
IIHS reported in the NPRM show that many trailer rear impact guards 
designed to CMVSS No. 223 met the proposed performance requirements in 
the NPRM in full overlap and 50 percent overlap crashes but were unable 
to prevent PCI in a 35 mph crash into the rear of the trailer where 
only 30 percent of the width of the passenger vehicle front end 
overlapped with the rear of the trailer. In these 30 percent overlap 
crashes, only a small lateral portion of the rear impact guard (about 
22 percent of the guard width) engaged with the front end of the 
passenger vehicle. This small lateral portion typically did not include 
a vertical support member of the guard, so when the passenger vehicle 
struck this small lateral portion of the guard, the guard deformed 
locally and did not prevent PCI.
    In the initial crash tests conducted by IIHS, only the Manac rear 
impact guard was able to prevent PCI in the Chevy Malibu in the 56 km/h 
(35 mph) full overlap, 50 percent overlap, and the 30 percent overlap 
test conditions. Unlike most trailer designs, however, where the 
vertical members of the rear impact guard attach directly to the 
longitudinal frame rails of the trailer, the vertical members of the 
Manac rear impact guard were located further outboard from the location 
of the trailer longitudinal frame rails and attached to a reinforced 
floor section of the trailer. While the more outboard vertical supports 
of the Manac guard improved rear impact protection in low overlap 
crashes of light vehicles into the rear of trailers, the further 
outboard vertical supports appeared to reduce guard strength near the 
center of the horizontal member of the rear impact guard. In the 56 km/
h (35 mph) full overlap crash tests of the Malibu, the greatest amount 
of underride (1,350 mm) was in the test with the Manac trailer. In 
contrast, the extent of the underride was 990 mm in the test with the 
Wabash trailer.
    The full overlap IIHS crash test results raise the possibility that 
for crash speeds greater than 56 km/h (35 mph), trailers that have the 
main vertical supports for the guard more outboard may not perform as 
well in full overlap crashes as trailers that have the vertical 
supports more inboard. Since full and 50 percent overlap crashes are 
more frequent than low overlap (30 percent or less) crashes, and 
because most fatal light vehicle impacts into the rear of trailers are 
at speeds greater than 56 km/h (35 mph), the agency is concerned that 
such guard designs may reduce protection against PCI in the more 
frequent higher speed full and 50 percent overlap crashes. NHTSA is 
concerned about potential negative safety consequences accruing from a 
rule that resulted in designs that moved the vertical members of rear 
impact guards more outward laterally to prevent underride in a 56 km/h 
(35 mph) 30 percent low overlap crash, if such a rule reduced 
protection in full and 50 percent overlap crashes.
    NHTSA has estimated the potential benefits of adopting a 30 percent 
overlap crash. The agency estimated the number of fatalities in 30 
percent or lower overlap crashes in the field based on the available 
information, estimated the effectiveness of the rear impact guards that 
prevent PCI in 30 percent overlap crashes, and estimated the lives 
saved by a requirement for rear impact guards mitigating PCI in 56 km/h 
(35 mph) 30 percent overlap crashes.
    The 2013 UMTRI Study found that 40 percent of light vehicle impacts 
into the rear ends of trucks and trailers in fatal crashes met the 
UMTRI definition of ``offset crashes,'' \67\ and that 60 percent were 
non-offset impacts. However, for a typical trailer rear width of 2,600 
mm, an offset crash defined in the 2013 UMTRI Study is when 867 mm of 
the width of the trailer from its lateral edge is engaged by the 
impacting vehicle. In contrast, as detailed in the 2015 NPRM, in the 
IIHS 30 percent overlap crash of a Malibu with the rear impact guard of 
a trailer, the Malibu interacted with only 637 mm of the rear of the 
trailer (approximately a quarter of the trailer rear width) from its 
lateral edge. This difference is important as it relates to how the 
impacting vehicle engages the vertical members connecting the rear 
impact guard to the trailer. On a typical 2,600 mm width trailer, the 
vertical members connecting the rear impact guard to the trailer are 
located at about 753 mm from the left and right lateral edge of the 
trailer. Therefore, ``offset'' crashes in the 2013 UMTRI Study included 
crashes in which a vertical member of the rear impact guard was 
engaged. In contrast, in IIHS's 30 percent overlap crashes, the 
vertical members of the rear impact guards were not engaged.
---------------------------------------------------------------------------

    \67\ UMTRI defined ``offset crashes'' as impacts with the outer 
one-third or less of the rear plane of the trailer. For a 2,600 mm 
wide trailer, one-third of the trailer width is 867 mm from the 
lateral edge of the trailer, which includes the location of the 
vertical member. In contrast, the IIHS 30 percent overlap crash test 
is a 30 percent overlap of the impacting vehicle with the trailer 
rear. For a 2,600 mm wide trailer, 30 percent overlap of a passenger 
vehicle corresponds to 637 mm from the lateral edge of the trailer, 
which does not include the location of the vertical member.
---------------------------------------------------------------------------

    Stated differently, the definition of an offset crash in the 2013 
UMTRI Study includes crashes that would not have been considered low 
overlap crashes under IIHS's test program (as they had greater than 30 
percent overlap of the front end of the vehicle). NHTSA reviewed a 
sample of the crash cases which were identified as ``offset crashes'' 
in the 2013 UMTRI Study. Based on the damage to the rear impact guard 
and the damage to the front end of the impacting vehicle in each of 
these offset crash cases, NHTSA determined that in many crashes the 
front end of the striking vehicle engaged the portion of the rear 
impact guard containing the vertical member, and therefore were not 
``low overlap'' crashes as would have been considered under the IIHS 
protocol (crashes with 30 percent or less of the impacting vehicle 
front end overlapping the rear width of the trailer). This review 
indicated that a substantial number of cases identified as ``offset 
crashes'' in the 2013 UMTRI Study were not ``low overlap'' crashes like 
those in the IIHS 30 percent overlap crash test.
    The 2013 UMTRI Study found that there are annually 72 fatalities in 
light vehicle crashes into the rear of trailers that result in PCI. 
According to this study, almost 40 percent of the impacts by light 
vehicles were ``offset,'' meaning that they occurred on the outer left 
or right third of a trailer's rear. For trailers

[[Page 42359]]

required to have rear impact guards, there was no difference in the 
extent of underride, including PCI, for offset and non-offset impacts 
of light vehicles into the rear of trailers.\68\ Therefore, we 
determined the number of annual fatalities in offset crashes with PCI 
into the rear of trailers as the product of the annual number of 
fatalities in light vehicle crashes with PCI into the rear of trailers 
(72) and the percentage of offset crashes (40%). Accordingly, the 
number of fatalities in offset crashes with PCI from the 2013 UMTRI 
Study is 28.8 (=72 x 40%). Yet, as explained above, NHTSA reviewed a 
sample of the offset crashes in the 2013 UMTRI Study and found that in 
most of these offset crashes, there was more than 30 percent overlap of 
the impacting vehicle with the rear of the trailer (demonstrated by the 
impacting vehicle having engaged the rear impact guard at the location 
of a vertical member). Thus, to estimate the benefit of a requirement 
to prevent PCI in 30 percent overlap crashes, NHTSA assumed 20 to 40 
percent of these 28.8 annual fatalities \69\ were in crashes with 30 
percent or less overlap of the front end of the impacting light vehicle 
with the trailer. Therefore, NHTSA estimated that there are 5.8-11.5 (= 
28.8 x 20% to 28.8 x 40%) annual fatalities in low overlap crashes into 
the rear of trailers.
---------------------------------------------------------------------------

    \68\ Figure 5 in the 2013 UMTRI Study. Heavy-Vehicle Crash Data 
Collection and Analysis to Characterize Rear and Side Underride and 
Front Override in Fatal Truck Crashes, DOT HS 811 725, March 2013, 
infra.
    \69\ As explained above, NHTSA's review of a sample of offset 
crashes into the rear of trailers in the 2013 UMTRI Study indicated 
that a majority of these offset crashes were with more than 30 
percent overlap of the impacting vehicle with rear of the trailer.
---------------------------------------------------------------------------

    The 2013 UMTRI Study also found that only 26 percent of crashes 
into the rear of trailers were at relative impact speeds of 56 km/h (35 
mph) or less. Though the 2013 UMTRI Study found that the crash speeds 
in offset crashes were higher than those in non-offset crashes, NHTSA 
used 26 percent to estimate the number of crashes into the rear of 
trailers with 30 percent or lower overlap that were at crash speeds 56 
km/h (35 mph) or lower. Rear impact guards may not be able to mitigate 
all fatalities in crashes into the rear of trailers with relative 
velocity of 56 km/h (35 mph) or less because some crashes may be due to 
circumstances other than underride (i.e., unrestrained status of 
occupants, elderly and other vulnerable occupants, post impact vehicle 
kinematics that could expose vehicle to subsequent impacts \70\). For 
the purpose of this analysis, NHTSA assumed that the incremental 
effectiveness of rear impact guards (CMVSS No. 223 compliant guards 
that also mitigate PCI in 30 percent overlap crashes) in preventing 
fatalities in light vehicle impacts with 30 percent overlap into the 
rear of trailers with crash speeds less than 56 km/h is 50 percent. 
Therefore, NHTSA estimated the overall effectiveness of upgrading from 
the final rule compliant guards to final rule compliant guards that 
also prevent PCI in 30 percent overlap crashes to be 13 percent (=26% x 
50%). NHTSA estimates that the annual number of lives saved in low 
overlap crashes into the rear of trailers at relative velocities of 56 
km/h (35 mph) or less to be 0.75 to 1.5 (= 5.8 x 0.13 to 11.6 x 0.13).
---------------------------------------------------------------------------

    \70\ The IIHS tests showed that in 30 percent overlap crashes 
where PCI is mitigated, the impacting light vehicle rotates during 
the crash and therefore could be exposed to impact by vehicles 
traveling in adjacent lanes.
---------------------------------------------------------------------------

    To prevent PCI in 30 percent overlap crashes, designs would have to 
either: (a) add additional vertical members at the lateral edge of the 
rear impact guard that connect to the trailer's transverse floor beam 
and strengthen the transverse floor beam of the trailer to withstand 
the loads transmitted from these vertical members at the edge of the 
guard; or (b) considerably strengthen the rear impact guard member so 
it would not deform locally in the 30 percent overlap crash. In these 
circumstances all the loads will still be taken up by the longitudinal 
chassis rails. This means that both these approaches would add 
significant weight to the vehicles because they involve adding more 
vertical members, strengthening the floor beams, or strengthening the 
guard itself.
    Currently, there are 4 trailer manufacturers that offer rear impact 
guards that prevent PCI in all three IIHS crash test conditions (35 mph 
crash of a passenger vehicle with (1) full overlap, (2) 50 percent 
overlap and (3) 30 percent overlap with the rear of the trailer) as 
standard equipment. In 2020, the total trailer output of these 4 
manufacturers is about 28 percent of the total number of trailers 
produced in 2020 (211,807).\71\ Many other trailer manufacturers offer 
rear impact guards that prevent PCI in the three IIHS crash test 
conditions as optional equipment.
---------------------------------------------------------------------------

    \71\ https://cdn.baseplatform.io/files/base/ebm/trailerbodybuilders/document/2021/04/TBB_Top_25_CY2020.6089da057e9d0.pdf.
---------------------------------------------------------------------------

    NHTSA reviewed the rear impact guard offerings in the trailer 
industry. The incremental cost and weight increase of a trailer with a 
rear impact guard that prevents PCI of passenger vehicles in all three 
overlap conditions (full, 50 percent, and 30 percent overlap) compared 
to an equivalent trailer by the same manufacturer with a rear impact 
guard that meets the performance requirements of this final rule \72\ 
ranges from $100 to $1,000 and from 25 kg (55 lb) to 118 kg (260 lb), 
respectively. The large range in cost and weight is because some 
trailers need significant modifications to accommodate rear impact 
guards with 30 percent overlap protection, the higher cost of high-
strength/light-weight materials for the guard, and other such factors. 
The weighted average (weights based on trailers produced in 2020) \73\ 
of this incremental cost and weight increase of trailers with rear 
impact guards which prevent PCI in 30 percent overlap crashes is $306 
and 35 kg (77 lb), respectively.
---------------------------------------------------------------------------

    \72\ As noted previously, the final rule requirements ensure 
preventing PCI in a 35 mph passenger vehicle crash with full and 50 
percent overlap with the rear of a trailer.
    \73\ https://cdn.baseplatform.io/files/base/ebm/trailerbodybuilders/document/2021/04/TBB_Top_25_CY2020.6089da057e9d0.pdf.
---------------------------------------------------------------------------

    Stoughton Trailer, a trailer manufacturer, produces trailers with 
rear impact guards that prevent PCI in all three overlap conditions at 
56 km/h (35 mph) as standard equipment and notes on its website that 
its rear impact guards do not add additional weight, cost, or 
negatively impact aerodynamics (presumably compared to rear impact 
guards that would meet this final rule requirements).\74\ The Stoughton 
rear impact guard, made of steel, includes two vertical supports on the 
outer ends of the horizontal member that fasten to a robust 
undercarriage of the trailer. It does not appear feasible engineering-
wise for the additional material (two steel vertical members on the 
outer edge of the horizontal member that is bolted to a reinforced 
undercarriage) not to add weight or cost to the trailer. Accordingly, 
NHTSA decided not to include this guard design in this analysis.
---------------------------------------------------------------------------

    \74\ https://www.stoughtontrailers.com/Portals/0/documents/Rear%20Underride%20Guard%20Sales%20Sheet.pdf.
---------------------------------------------------------------------------

    There are some unique rear impact guard designs that meet the 
performance requirements in this final rule and are also able to 
mitigate PCI in 30 percent overlap crashes without significant increase 
in weight. However, these unique designs may have restrictions in 
intermodal operations at loading docks \75\ and may not be practicable 
for

[[Page 42360]]

all types of trailers covered by FMVSS No. 224. The benefit-cost 
analysis assumes intermodal operability is maintained and so these 
unique rear impact guard designs were not considered for this analysis.
---------------------------------------------------------------------------

    \75\ In order to comply with Occupational Safety and Health 
Administration (OSHA) requirements (OSHA 29 CFR 1910.26(d)), loading 
docks have vehicle restraints that are designed to connect to rear 
impact guards to prevent the vehicle from moving during loading and 
unloading operations. Unique rear impact guard designs that are 
wider than 7.5 inches, with unique profiles (such as pentagonal 
shapes) have provided challenges to connect the vehicle restraints 
to the rear impact guard.
---------------------------------------------------------------------------

    There are 211,807 trailers produced in 2020 \76\ among which 65 
percent (137,675 = 211,806 x 65%) are required to be equipped with rear 
impact guards, of which 28 percent are already equipped with rear 
impact guards that meet the performance requirements of this final rule 
and mitigate PCI in 30 percent overlap crashes. The annual average and 
minimal incremental fleet cost of equipping all new applicable trailers 
\77\ (99,126 = 137,675 x 72%) with rear impact guards that mitigate PCI 
in 30 percent overlap crashes is $30.3 million (= 99,126 x $306) and 
$9.9 million (= 99,126 x $100).
---------------------------------------------------------------------------

    \76\ Id.
    \77\ There were 211,807 new trailers produced in 2020, among 
which 65 percent (137,675 = 211,807 x 0.65) are required to be 
equipped with rear impact guards. Among applicable trailers, 21 
percent are already equipped with guards that mitigate PCI in 30 
percent overlap crashes.
---------------------------------------------------------------------------

    In addition, the average weight increase of 35 kg (77 lb) from 
installing a guard that could mitigate PCI in a 30 percent overlap 
crash would increase fuel consumption. With 192,000 class 8 truck 
annual sales,\78\ the total average incremental lifetime fuel cost is 
estimated to be $130 million undiscounted, $106 million with 3 percent 
discounting, and $84 million with 7 percent discounting. If the minimum 
weight increase of 25 kg (55 lb) is used instead, the total minimum 
incremental lifetime fuel cost is estimated to be $93 million 
undiscounted, $75 million with 3 percent discounting, and $60 million 
with 7 percent discounting. The overall undiscounted cost increase 
(material cost and lifetime fuel cost) is $161 million on average and 
$103 million at a minimum.
---------------------------------------------------------------------------

    \78\ See statista for class 8 truck annual sales (https://www.statista.com/statistics/261416/class-3-8-truck-sales-in-the-united-states/).
---------------------------------------------------------------------------

    NHTSA is required by Section 1 of Executive Order 12866 to conduct 
a benefit cost analysis of any proposed regulatory requirements.\79\ 
The undiscounted cost per life saved using the average cost estimate 
ranges from $107 million to $215 million, while that using the minimum 
cost estimate ranges from $69 million to $138 million, which is 
significantly greater than the value of a statistical life ($11.6 
million).\80\ Therefore, a requirement for equipping all new applicable 
trailers with rear impact guards that mitigate PCI in 30 percent 
overlap crashes is not cost-effective.\81\ This indicates that total 
costs of such a requirement exceed overall benefits. Detailed 
calculations for the benefits, costs, and cost per life saved are 
provided in the FRE accompanying this final rule.\82\
---------------------------------------------------------------------------

    \79\ ``Significant'' regulatory actions are also subject to 
Section 6 to assess potential benefits and costs.
    \80\ For more information on the value of a statistical life, 
see a 2021 Office of the Secretary memorandum on the ``Guidance on 
Treatment of the Economic Value of a Statistical Life in U.S. 
Department of Transportation Analyses--2021 Update.'' https://www.transportation.gov/office-policy/transportation-policy/revised-departmental-guidance-on-valuation-of-a-statistical-life-in-economic-analysis.
    \81\ Cost-effectiveness represents a measure of the average 
monetary cost per unit of change (benefit). In regulatory analyses 
for safety policies, cost-effectiveness generally measures the 
average estimated change in total costs per unit improvement in 
safety (e.g., cost per life saved). A policy alternative can be 
considered cost-effective if the estimated cost per unit increase is 
less than an appropriate benchmark. For example, a proposed safety 
standard could be considered cost-effective if the average cost per 
life saved equivalent (i.e., combining lives saved and injuries 
avoided, weighted by the relative values of injuries to fatalities) 
under the proposed standard were less than the comprehensive 
economic cost of a fatality ($11.6 million in 2020 dollars). That 
is, the proposed standard would yield safety benefits at a lower 
cost than the benchmark value for those benefits.
    \82\ NHTSA has placed a copy of the FRE in the docket for this 
final rule.
---------------------------------------------------------------------------

    For the above reasons, we have determined that an FMVSS that 
requires vehicles to provide rear impact protection in 56 km/h (35 mph) 
full-frontal, 50 percent overlap, and 30 percent overlap not to be 
reasonable or practicable. We conclude that such a revision would not 
meet the requirements of Section 30111(a) and (b) of the Safety Act for 
issuance of Federal motor vehicle safety standards. Accordingly, we 
have decided to refrain from adopting a requirement for a 30 percent 
overlap crash at this time.
    However, as explained above, the Federal standards act as a floor, 
not a ceiling, to establish the minimum level of performance that meet 
the safety needs presented by the data. FMVSS are written in terms of 
minimum performance requirements for motor vehicles or motor vehicle 
equipment to protect the public against unreasonable risk of injury and 
death in crashes. Manufacturers have flexibility in design as long as 
their products comply with applicable FMVSS. There are rear impact 
guard designs in the current trailer and semitrailer market that 
prevent PCI in all three crash conditions described in Section 
23011(b)(1)(A) of BIL: (1) full overlap crash, (2) 50 percent overlap 
crash, and (3) 30 percent overlap crash at 56 km/h impact speed. While 
data do not support the agency's requiring these guards for all 
vehicles, this final rule does not preclude these designs from being on 
the trailer and semi-trailer market.
    Some commenters suggested design changes to rear impact guards that 
they viewed as increasing protection in low overlap conditions. Network 
requested that NHTSA require a barrier width within 100 mm of the 
trailer's outer frame; Advocates similarly stated that if rear impact 
guards were extended, protection against underride would be enhanced. 
Network and Ms. Wood also suggested that rear impact guards have angled 
struts attached to the ends of the guard. Batzer recommended that 
guards have support at their corners, while Seven Hills stated that a 
solution could be using three- or four-vertical support configurations. 
The VT Group suggested that stronger material selection for the 
horizontal member can improve a rear impact guard's load capability 
during low overlap crashes.
    In response, NHTSA does not believe that it is reasonable, or 
appropriate, to mandate in this rulemaking that rear impact guards have 
designs of the specificity suggested by the commenters. The design of 
rear impact guards is dependent on trailer geometry and structure and 
we do not wish to unnecessarily restrict the flexibility of 
manufacturers to design appropriate guards. NHTSA also does not believe 
that it should mandate the materials used in constructing rear impact 
guards, as our standards are performance oriented.\83\ Finally, this 
issue was not proposed in the NPRM and is not within the scope of this 
rulemaking.
---------------------------------------------------------------------------

    \83\ 49 U.S.C. 30102(a)(10).
---------------------------------------------------------------------------

d. Half-Guard Testing

    CMVSS No. 223 allows for compliance testing on half of a symmetric 
rear impact guard through an application of a 175,000 N distributed 
load at the P3 location. NHTSA determined that half guard testing was 
not needed in FMVSS No. 223 and explained in the NPRM why it did not 
propose the inclusion of half-guard testing in the proposal.
Comments Received
    Commenters on this issue all argued in favor of including an option 
allowing for testing of half of the rear impact guard. TTMA, Strick, 
and Mr. Young stated their general belief that testing on a half-guard 
will produce the same result as testing on the full guard. They further 
suggested that half-guard testing

[[Page 42361]]

is beneficial to manufacturers, as they can test one half-guard, make 
any changes to the second half-guard, and then test the modified second 
half-guard with less time and effort. TTMA also remarked that allowing 
an option for half-guard testing would ensure maximum harmonization 
with the Canadian standard CMVSS No. 223.
Agency Response
    NHTSA reviewed the comments and confirms its earlier decision that 
a half-guard testing option is not needed in FMVSS No. 223. As noted in 
the NPRM, CMVSS No. 223 allows for half-guard testing because at the 
time the standard was written, guard manufacturers lacked the equipment 
to apply a distributed force of 350,000 N as would be required in a 
test of the full guard. CMVSS No. 223 thus allowed manufacturers to use 
then existing equipment to certify rear impact guards through half-
guard testing. No commenter suggested that this rationale should be 
applied to FMVSS No. 223 or that manufacturers presently lack the 
capability to conduct tests on a full guard. Significantly, there is 
also an absence of data showing that half-guard testing provides 
results representative of full guard performance.
    NHTSA notes that the test procedures included in an FMVSS specify 
the compliance tests that NHTSA conducts. Manufacturers may use other 
reasonable methods to certify the compliance of their vehicles or 
equipment, provided that their vehicle or motor vehicle equipment 
complies. In other words, any changes to FMVSS Nos. 223 and 224 would 
not directly affect how manufacturers choose to structure their guard 
development processes, as long as the vehicle or equipment complies. If 
manufacturers believe that testing on half-guards will allow them to 
better iterate designs, the standard does not prevent them from doing 
so. The guard must meet the FMVSS when tested by NHTSA according to the 
test procedures in the standard.

e. Retrofitting

    The NPRM did not propose to require used trailers be retrofitted 
with CMVSS No. 223 compliant rear impact guards, as NHTSA had estimated 
in the NPRM that the cost of retrofitting all applicable FMVSS 
compliant trailers far exceeds the total benefits from such a retrofit 
requirement.
Comments Received
    Many commenters disagreed with NHTSA's decision not to propose that 
all trailers be retrofitted with newly compliant guards. Network 
commented that older guards can be easily fixed. Messrs. Kiefer and 
Young remarked that more lives would be saved if NHTSA required 
retrofitting. TSC remarked that NHTSA underestimated the potential 
benefits to requiring trailers be retrofitted. TSC stated that NHTSA 
based its analysis on the number of light vehicle crashes into the rear 
of trailers that resulted in PCI, which TSC claimed came from data 
sources that often do not report on intrusion. Conversely, ATA stated 
that retrofitting trailers will have a negative cost-benefit ratio, 
stating that there are more than 11.7 million commercial trailers 
registered in the states in 2012, many of which are not used on a 
regular basis. ATA argued that retrofitting them would create 
significant costs without any corresponding benefit.
Agency Response
    As further detailed in the Final Regulatory Evaluation (FRE) 
accompanying this final rule, NHTSA evaluated requiring all trailers to 
be retrofitted with CMVSS No. 223 compliant guards. This evaluation 
suggests that such a requirement would not be practicable or cost-
effective. Further, vehicle owners would need to assess each trailer-
guard combination individually to determine whether an upgraded guard 
would be compatible with the used trailer, accounting for age and 
condition of the vehicle. A used trailer may not be structurally 
capable of accommodating a new upgraded guard without the addition of 
unique parts. Owners may not have the technical expertise to know if an 
upgraded rear impact guard installed on a used trailer would be able to 
meet the intended performance level.

VI. Lead Time

    The NPRM proposed a lead time of two years following the date of 
publication of a final rule. NHTSA received mixed comments on the 
proposed lead time. Mr. Young and Network remarked that given most 
trailers already meet the proposed requirements, a two-year lead time 
was unnecessary. Mr. Young stated that NHTSA instead should require 
immediate compliance. TTMA commented that, for ``nearly all trailer 
models,'' TTMA members have the capability to manufacture to the 
proposed standard but suggested that manufacturers of other models may 
have to develop and test new rear impact guards. TTMA suggested a lead 
time that provides for an optional early compliance date may be 
worthwhile.
    Section 23011(b)(1)(B) of BIL provides that the regulations 
promulgated under subparagraph (A) shall require full compliance with 
each FMVSS revised pursuant to those regulations not later than 2 years 
after the date on which those regulations are promulgated.
    After considering the comments and Section 23011(b)(1)(B) of BIL, 
NHTSA is adopting a two-year compliance date. The agency estimates that 
94 percent of new trailers sold in the United States subject to FMVSS 
Nos. 223 and 224 already comply with the requirements of this final 
rule. This means, however, that there remain many trailer manufacturers 
who will need time and resources to design and produce new rear impact 
guards that are compliant with this final rule. Establishing too short 
a lead time will disadvantage these manufacturers, many of which may be 
small manufacturers. NHTSA proposed a two-year lead time for the 1996 
final rule and the agency believes this length of time is consistent 
with BIL and remains appropriate. Manufacturers may choose to comply 
with the new standards earlier.

VII. Benefit-Cost Analysis

    For the NPRM, NHTSA developed a Preliminary Regulatory Evaluation 
(PRE) to estimate the benefits and cost of this rulemaking. We first 
estimated the annual number of fatalities and injuries in light vehicle 
crashes with PCI into the rear of trailers that could be prevented by 
the rulemaking.\84\ We found that, annually, there are 72 light vehicle 
occupant fatalities in crashes into the rear of trailers with rear 
impact guards with PCI.\85\ About 26 percent of fatal light vehicle 
crashes into the rear of trailers occur at speeds of 56 km/h (35 mph) 
or less, the speeds at which this rule would be effective. Thus, the 
agency estimated that there are 19 fatalities (= 72 x 0.26) that occur 
in crashes with a relative velocity of 56 km/h (35 mph) or less.
---------------------------------------------------------------------------

    \84\ NHTSA did not include non-PCI crashes into the rear of 
trailers into the analysis of benefits of the final rule because the 
agency assumed that the passenger vehicle's restraint systems, when 
used, would mitigate injury.
    \85\ NHTSA only counted crashes into trailers with rear impact 
guards as these would be the only trailers that NHTSA assumes would 
equip upgraded rear impact guards and thus be affected by this rule.
---------------------------------------------------------------------------

    CMVSS No. 223 guards may not be able to mitigate all fatalities in 
crashes into the rear of trailers with relative velocity of 56 km/h (35 
mph) or less because some crashes may involve low overlap (30 percent 
or less) and some fatalities may be due to circumstances other than 
underride (e.g., unrestrained status of occupants). NHTSA thus assumed 
that the incremental effectiveness of CMVSS No. 223

[[Page 42362]]

compliant guards over FMVSS No. 224 compliant guards in preventing 
fatalities in light vehicle impacts with PCI into the rear of trailers 
with crash speeds less than 56 km/h (35 mph) is 50 percent.\86\ Since 
only 26 percent of light vehicle crashes with PCI into the rear of 
trailers are at relative velocity less than or equal to 56 km/h, NHTSA 
estimated the overall effectiveness of upgrading to CMVSS No. 223 
compliant guards to be 13 percent (= 26% x 50%).
---------------------------------------------------------------------------

    \86\ The estimation of rear impact guard effectiveness is 
detailed in the FRE. Fatalities and injuries would also depend on 
other factors such as occupant age, seat belt use, and crash 
dynamics. Considering these factors, and using engineering judgement 
we believe 50 percent is a reasonable estimate of the effectiveness 
of CMVSS compliant rear impact guards.
---------------------------------------------------------------------------

    Since a number of vehicles currently meet CMVSS No. 223, this 
benefit must be reduced by the proportion of new trailers already 
compliant with CMVSS No. 223, which the agency estimated to be 93 
percent. Assuming 13 percent effectiveness of these guards in fatal 
crashes with PCI into the rear of trailers, the agency estimated that 
about 0.66 (= 72 x (1-0.93) x 0.13) lives would be saved annually by 
requiring all applicable trailers to be equipped with CMVSS No. 223 
compliant guards. NHTSA estimated that a total of 2.7 serious injuries 
would also be prevented annually with this rear impact guard rule. 
Including fatalities and serious injuries, the agency estimated that 
1.4 equivalent lives would be saved annually.
    To determine the costs of the final rule, NHTSA considered the 
incremental fleet cost of equipping all applicable trailers with CMVSS 
No. 223 rear impact guards and the increased fuel costs resulting from 
the added weight CMVSS No. 223 compliant guards would place on 
trailers.
    The average cost of a Canadian compliant rear impact guard was 
estimated as $492. The incremental cost of equipping CMVSS No. 223 
compliant rear impact guards on applicable new trailers (those that are 
subject to FMVSS No. 223) was estimated as $229 per trailer. There were 
243,873 trailers produced in 2013,\87\ among which 65 percent were 
required to be equipped with rear impact guards. Of those, 93 percent 
were already equipped with CMVSS No. 223 compliant guards. The annual 
incremental fleet cost of equipping all applicable trailers with CMVSS 
No. 223 rear impact guards was estimated at $2.5 million (= 243,873 x 
0.65 x (1.0-0.94) x $229).
---------------------------------------------------------------------------

    \87\ https://trailer-bodybuilders.com/trailer-output/2014-trailer-production-figures-table.
---------------------------------------------------------------------------

    NHTSA determined that upgrading from the FMVSS No. 223 compliant 
guard to the CMVSS No. 223 compliant guard would add an average 
incremental weight of 22.2 kg (48.9 lb) to the trailer, thereby 
reducing the overall fuel economy during the lifetime of the trailer. 
The incremental increase in lifetime fuel cost for a 22.2 kg (48.9 lb) 
weight increase of a trailer was estimated to be $1,042.2 and $927.7 
discounted at 3 percent and 7 percent, respectively. The annual 
incremental lifetime fuel cost of equipping all applicable trailers 
with CMVSS No. 223 rear impact guards was estimated as $9.2 million and 
$8.2 million in 2013 dollars discounted at 3 percent and 7 percent, 
respectively.
    The agency estimated that the net cost per equivalent lives saved 
would be $9.1 million and $9.5 million in 2013 dollars discounted at 3 
percent and 7 percent, respectively. At 3 percent discount rate, the 
net benefit of the proposed rule would be $0.59 million. At 7 percent 
discount rate, the net benefit of the proposed rule would be $0.13 
million.
    Comments. NHTSA received several comments on the estimates provided 
in the NPRM. A few commenters suggested NHTSA should not conduct a 
benefit-cost analysis for a safety focused regulation in the first 
place and/or should comply with Vision Zero and make saving human life 
a priority over monetary issues. Some others believed that NHTSA's 
benefit-cost analysis was fundamentally flawed because, they argued: 
safety-related benefits should intrinsically outweigh costs related to 
upgrading equipment, NHTSA should not shift the costs of its rule to 
the public at the benefit of truckers, or that NHTSA should use costs 
only to compare outcomes that involved a rear impact guard not failing 
upon collision.
    Agency Response. NHTSA implements its regulatory, enforcement, and 
oversight authority provided by the National Traffic and Motor Vehicle 
Safety Act (49 U.S.C. Chapter 301) (Safety Act) to protect all members 
of the public. NHTSA's authority to issue Federal motor vehicle safety 
standard is set forth in sections 30111 of the Safety Act. Each safety 
standard must be practicable, meet the need for motor vehicle safety, 
and be stated in objective terms. When issuing a safety standard, NHTSA 
must consider, among other things, relevant motor vehicle safety 
information, whether a standard is reasonable, practicable, and 
appropriate for the particular type of motor vehicle or motor vehicle 
equipment for which it is prescribed, and the extent to which the 
standard will carry out section 30101 of the Act.\88\ NHTSA issues its 
regulations in accordance with agency and Departmental regulations and 
in conformity with Executive orders (E.O.).
---------------------------------------------------------------------------

    \88\ Section 30101 sets forth the purpose and policy of the 
Safety Act.
---------------------------------------------------------------------------

    Safety is of utmost importance, and NHTSA pursues such safety to 
the degree possible in accordance with its statutory authority and as 
instructed by Executive order. Under the Safety Act, the reasonableness 
and practicability of a standard (both technologically and 
economically) must be considered. Under E.O. 12866, agencies are 
instructed to undertake a benefit-cost analysis to inform its 
rulemaking decisions to ensure agency regulations protect and improve 
the public's health, safety, environment, and well-being and improves 
the performance of the economy without imposing unacceptable or 
unreasonable costs on society. Thus, in response to commenters who urge 
us to adopt safety standards without regard to costs, we cannot do so 
under the Safety Act and the E.O.
    NHTSA also cannot measure safety-related benefits categorically 
differently from costs, as requested by several commenters. Under E.O. 
12866, as specified in OMB Circular A-4, agencies must quantify and 
value safety impacts to compare them to the costs of the regulation. 
Agencies do so by calculating the value of the loss of life using a 
metric called the Value of a Statistical Life (VSL). The VSL includes 
costs such as medical care, reduced income, and the effects fatalities 
and injuries may have on family members. NHTSA uses the VSL to 
determine the monetary value of reducing fatalities and injuries, which 
NHTSA then compares to estimated costs of a regulation. NHTSA cannot 
arbitrarily increase the value of benefits outside of this framework.
    Some commenters also raised issues with what they viewed as 
specific shortcomings in the PRE's benefit-cost analysis. Some believed 
NHTSA did not properly consider all necessary variables in its 
analysis. For example, Network stated that NHTSA did not consider new 
technology or what it claimed to be the negative consumer choices 
fueled by fear to adopt smaller and lighter fuel-efficient vehicles due 
to increased crash incompatibility. Mr. Karth believed NHTSA should 
consider ``what a parent would pay to protect their children,'' the 
``impact upon a family if a bread-winner is injured or lost,'' and 
``the medical expenses to care for a severely injured individual.'' Ms. 
Karth believed NHTSA's benefit-cost

[[Page 42363]]

analysis did not ``take into consideration the circumstances and costs 
of the full extent of underride research.''
    NHTSA has prepared a Final Regulatory Evaluation (FRE) for this 
final rule and has placed a copy of the FRE in the docket.\89\ The FRE 
for this final rule discusses and explains the agency's final estimates 
for the benefits and cost that would result from this rulemaking. The 
analysis and findings are not significantly different from those of the 
PRE.
---------------------------------------------------------------------------

    \89\ The FRE may be obtained by downloading it or by contacting 
Docket Management at the address or telephone number provided at the 
beginning of this document.
---------------------------------------------------------------------------

    NHTSA believes that it has properly calculated the applicable 
benefits and costs to its rule using the appropriate variables. We 
sought to estimate the benefits of the rule by determining the number 
of lives and serious injuries it would prevent over the current 
situation and then monetize that number using the VSL value. We then 
compared these benefits with the cost of the rule, the increased 
material and fuel costs that requiring rear impact guard upgrades would 
necessitate. These variables encompass the benefits and costs that this 
rule would impose. In the absence of sufficient information to quantify 
changes in consumer behavior, we do not believe that factoring in 
variables such as negative consumer choices resulting from the fear of 
underride collisions is appropriate.
    Some comments remarked on what were perceived to be NHTSA's 
overestimation of projected costs. Mr. Karth questioned NHTSA's 
calculations as being overstated, particularly emphasizing that the 
fuel costs NHTSA projected in the PRE did not turn out to be accurate. 
The commenter also believed NHTSA's benefit-cost analysis is faulty 
because manufacturers have been willing to ``provide a better rear 
impact guard even without regulation.'' Ms. Karth commented that 
customers have shown they are willing to pay for trailers to be safer, 
and manufacturers have shown that they are willing to respond to that 
demand and produce safer trailers. Network believed that NHTSA used 
outdated costs when analyzing how much an upgraded rear impact guard 
would cost. Mr. Brown indicated that the costs of the regulation could 
``be distributed to many different people and products.''
    Agency Response. We disagree that we overestimated the costs of the 
rule. We determined the incremental cost of installing CMVSS No. 223 
compliant guards on all trailers that would need to upgrade to new 
guards and the resulting increase in fuel costs such installation would 
cause. While commenters pointed to factors they believed NHTSA should 
have considered, we do not believe such considerations are appropriate. 
For example, Mr. and Ms. Karth suggested that manufacturers have been 
willing to provide a better rear impact guard and that consumers have 
shown that they are willing to pay more for vehicles to have upgraded 
rear impact guards. The fact, however, that some manufacturers and 
consumers may be willing to accept increased costs is not relevant to 
estimating the increased costs of the guards, which is a factor germane 
to an analysis that seeks to quantify the costs of the rule and analyze 
societal impacts. Similarly, while Network remarked that NHTSA's 
estimates for the value of an upgraded rear impact guard were too high, 
it did so by reflecting on what it thought the cost of a guard should 
be. NHTSA determined this cost by looking to the average cost of CMVSS 
No. 223 compliant guards on the market, which the agency believes 
reflects a more realistic and accurate value.
    In response to Mr. Karth's comment regarding NHTSA's estimated fuel 
costs from the PRE, NHTSA followed well established procedures to 
estimate incremental fuel costs due to increased weight of the rear 
impact guards and the most recent information on fuel price. NHTSA 
considered the most up-to-date data in developing this final rule, 
updated its variables where necessary in the FRE and used the most 
current data available to inform this rulemaking.
    Some commentators stated that NHTSA underestimated the benefits of 
improved rear impact guards. According to Advocates, NHTSA based its 
calculation of the proposed rule's benefits on the agency's belief that 
only 26 percent of light vehicle occupant fatal crashes into the rear 
of trailers with rear impact guards that resulted in PCI occur at 
speeds of 35 mph or less. Advocates believed that using this number 
``significantly reduced the agency's estimate of the number of crashes 
and occupants that could be aided by the upgrade in rear protection 
guards'' because it is based on speed estimates, which Advocates 
considers ``notoriously inaccurate.'' TSC similarly commented that 
NHTSA derived speed estimates from ``inconsistent, unreliable sources'' 
and failed to count instances of PCI properly, resulting in NHTSA's 
underestimating the benefits of the intended rule.
    Agency Response. NHTSA has analyzed the comments and believes it 
has properly calculated the benefits of this rulemaking. The agency 
determined the number of fatalities and serious injuries this rule 
would prevent by analyzing the supplemented TIFA data from the 2013 
UMTRI Study. This data source is the most accurate available to 
determine the number of fatalities and serious injuries currently 
caused by fatal light vehicle crashes into the rear of trailers with 
PCI at speeds of 56 km/h (35 mph) or less--the crashes NHTSA is 
targeting in this rule. We have used these data appropriately for 
determining the target population and estimating the benefits and in 
accordance with OMB Circular A-4 \90\ guidance on the development of 
regulatory analysis. NHTSA also notes that, while commenters objected 
to using data based on speed estimates and determinations of PCI, they 
did not present any alternative data source they believed was more 
reliable. The TIFA data have been thoroughly apprised for accuracy and 
are the best data available for an analysis of benefits. NHTSA has 
concluded the data are sufficient to proceed with quantifying the 
benefits of this rulemaking and to proceed to a final rule.
---------------------------------------------------------------------------

    \90\ https://obamawhitehouse.archives.gov/omb/circulars_a004_a-4/.
---------------------------------------------------------------------------

Summary of the Final Regulatory Evaluation
    The estimated benefits and costs of the FRE are along the same 
lines as those in the PRE. In the FRE, NHTSA determined that 94 percent 
of applicable new trailers are now equipped with rear impact guards 
that are compliant with the updated FMVSS No. 223 requirements. 
Additionally, NHTSA updated the value of statistical life (VSL) in 
accordance with the March 2021 Department of Transportation revised 
guidance regarding the treatment of the economic value of a statistical 
life in U.S Department of Transportation regulatory analyses (2021 
Update).\91\
---------------------------------------------------------------------------

    \91\ For more information, please see a 2021 Office of the 
Secretary memorandum on the ``Guidance on Treatment of the Economic 
Value of a Statistical Life in U.S. Department of Transportation 
Analyses--2021 Update.'' https://www.dot.gov/policy/transportation-policy/economy.
---------------------------------------------------------------------------

    Assuming 13 percent effectiveness of these guards in fatal crashes 
with PCI into the rear of trailers, the agency estimates that about 
0.56 (= 72 x (1-0.94) x 0.13) lives would be saved annually by 
requiring all applicable trailers to be equipped with CMVSS No. 223 
compliant guards. The agency also estimates that a total of 3.5 serious 
injuries would be prevented annually with the rear impact guard final 
rule. Including fatalities and serious injuries,

[[Page 42364]]

the rule would result in an estimated 1.4 equivalent lives saved 
annually.
    NHTSA estimates the annual incremental fleet cost of equipping all 
applicable trailers with CMVSS No. 223 rear impact guards to be $2.1 
million based on an average increase in cost of $254.35 per guard. The 
annual incremental lifetime fuel cost, based on an average weight 
increase of 48.9 pound per vehicle, is estimated to be $5.59 million 
and $4.43 million discounted at 3 percent and 7 percent, respectively. 
Therefore, the total cost of the final rule, including material and 
fuel costs, is $7.69 million discounted at 3 percent and $6.54 million 
discounted at 7 percent.
    The agency estimates that the cost per equivalent life saved is 
$6.77 million and $7.25 million discounted at 3 percent and 7 percent, 
respectively, as shown in Table 5. A summary of the regulatory cost and 
net benefit of the final rule at the 3 percent and 7 percent discount 
rates are presented in Table 6. At 3 percent discount rate, the net 
benefit of the final rule is $6.04 million. At 7 percent discount rate, 
the net benefit of the final rule is $4.36 million.

                                     Table 5--Cost per Equivalent Life Saved
                                          [In millions of 2020 dollars]
----------------------------------------------------------------------------------------------------------------
                          Discount rate                            Undiscounted         3%              7%
----------------------------------------------------------------------------------------------------------------
Total Cost......................................................           $9.00           $7.69           $6.54
Equivalent Lives Saved..........................................            1.40            1.14            0.90
Cost per Equivalent Life Saved..................................           $6.42           $6.77           $7.25
----------------------------------------------------------------------------------------------------------------

                                              Table 6--Net Benefits
                                          [In millions of 2020 dollars]
----------------------------------------------------------------------------------------------------------------
                          Discount rate                            Undiscounted         3%              7%
----------------------------------------------------------------------------------------------------------------
Comprehensive Benefit...........................................          $16.96          $13.73          $10.90
Total Cost......................................................            9.00            7.69            6.54
                                                                 -----------------------------------------------
    Net Benefit.................................................            7.96            6.04            4.36
----------------------------------------------------------------------------------------------------------------

    For further information regarding the aforementioned cost and 
benefit estimates, please reference the FRE that NHTSA placed in the 
docket.

VIII. Regulatory Notices and Analyses

Executive Order (E.O.) 12866 (Regulatory Planning and Review), E.O. 
13563, and DOT Regulatory Policies and Procedures

    We have considered the impacts of this final rule under Executive 
Orders 12866 and 13563, and the Department of Transportation's 
administrative rulemaking procedures. This final rule has been 
determined to be nonsignificant under E.O. 12866 and was not reviewed 
by OMB. We have discussed comments to the PRE and summarized the 
estimated costs, benefits, and cost-effectiveness of this final rule in 
the above section of this preamble, and in the FRE. NHTSA estimates 
that this final rule will save approximately 1.14 and 0.9 equivalent 
lives annually discounted at 3 percent and 7 percent, respectively. The 
total cost of the final rule, including material and fuel costs, is 
estimated to be $7.69 million discounted at 3 percent and $6.54 million 
discounted at 7 percent. The net cost per equivalent lives saved is 
$6.77 million and $7.25 million discounted at 3 percent and 7 percent, 
respectively. NHTSA's FRE fully discusses the estimated costs, 
benefits, and other impacts of this rule.
    Consistent with E.O. 13563, NHTSA is amending FMVSS Nos. 223 and 
224 because of retrospectively analyzing the effectiveness of the 
standards. NHTSA realized the merits of CMVSS No. 223 in addressing the 
same safety need that is the subject of FMVSS Nos. 223 and 224 and 
undertook this rulemaking to adopt upgraded strength and other 
requirements of CMVSS No. 223.

Regulatory Flexibility Act

    Pursuant to the Regulatory Flexibility Act (5 U.S.C. 601 et seq., 
as amended by the Small Business Regulatory Enforcement Fairness Act 
(SBREFA) of 1996), whenever an agency is required to publish a notice 
of proposed rulemaking or final rule, it must prepare and make 
available for public comment a regulatory flexibility analysis that 
describes the effect of the rule on small entities (i.e., small 
business, small organizations, and small governmental jurisdictions), 
unless the head of an agency certifies the rule will not have a 
significant economic impact on a substantial number of small entities. 
Agencies must also provide a statement of the factual basis for this 
certification.
    I certify that this rule will not have a significant economic 
impact on a substantial number of small entities. NHTSA estimates there 
are 354 manufacturers of trailers in the U.S., 331 of which are small 
businesses. The impacts of this final rule on small trailer 
manufacturers would not be significant. This rule will make changes to 
the strength requirements applying to rear impact guards but will not 
affect the method by which small trailer manufacturers can certify 
compliance with FMVSS Nos. 223 and 224.
    FMVSS No. 223, an equipment standard, specifies strength and energy 
absorption requirements in quasi-static force tests of rear impact 
guards sold for installation on new trailers and semitrailers. FMVSS 
No. 224, a vehicle standard, requires new trailers and semitrailers 
with a GVWR of 4,536 kg (10,000 lb) or more to be equipped with a rear 
impact guard meeting FMVSS No. 223. NHTSA established the two-standard 
approach to provide underride protection in a manner that imposes 
reasonable compliance burdens on small trailer manufacturers.
    Under FMVSS No. 223, the guard may be tested for compliance while 
mounted to a test fixture or to a complete trailer. FMVSS No. 224 
requires that the guard be mounted on the trailer or semitrailer in 
accordance with the instructions provided with the guard by the guard 
manufacturer. Under this approach, a small manufacturer that produces 
relatively few trailers can certify its trailers to FMVSS No. 224 
without feeling compelled to undertake destructive testing of what 
could be a substantial portion of its production. The two-standard 
approach was devised to provide small manufacturers a

[[Page 42365]]

practicable and reasonable means of meeting the safety need served by a 
rear impact guard requirement. This final rule does not change the 
method of certifying compliance to the rear impact guard requirements 
of FMVSS Nos. 223 and 224.

National Environmental Policy Act

    NHTSA has analyzed this final rule for the purposes of the National 
Environmental Policy Act and determined that it will not have any 
significant impact on the quality of the human environment.

Executive Order 13132 (Federalism)

    NHTSA has examined this final rule pursuant to Executive Order 
13132 (64 FR 43255, August 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 rulemaking would not have sufficient federalism implications 
to warrant consultation with State and local officials or the 
preparation of a federalism summary impact statement. The final rule 
will 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 preempt 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 chapter 301, 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 chapter 301. 49 U.S.C. 
30103(b)(1). It is this statutory command by Congress that preempts any 
non-identical State legislative and administrative law addressing the 
same aspect of performance.
    The express preemption provision described above is subject to a 
savings clause under which ``[c]ompliance 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 such 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 there being 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 Orders 13132 and 12988, NHTSA has considered 
whether this final 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 final rule and 
finds that this rule, like many NHTSA rules, prescribes only a minimum 
safety standard. As such, NHTSA does not intend that this final rule 
will preempt State tort law that would effectively impose a higher 
standard on motor vehicle manufacturers than that established by this 
rule. Establishment of a higher standard by means of State tort law 
would not conflict with the minimum standard in this final rule. 
Without any conflict, there could not be any implied preemption of a 
State common law tort cause of action.

Executive Order 12988 (Civil Justice Reform)

    When promulgating a regulation, Executive Order 12988 specifically 
requires that the agency must make every reasonable effort to ensure 
that the regulation, as appropriate: (1) Specifies in clear language 
the preemptive effect; (2) specifies in clear language the effect on 
existing Federal law or regulation, including all provisions repealed, 
circumscribed, displaced, impaired, or modified; (3) provides a clear 
legal standard for affected conduct rather than a general standard, 
while promoting simplification and burden reduction; (4) specifies in 
clear language the retroactive effect; (5) specifies whether 
administrative proceedings are to be required before parties may file 
suit in court; (6) explicitly or implicitly defines key terms; and (7) 
addresses other important issues affecting clarity and general 
draftsmanship of regulations.
    Pursuant to Executive Order 12988, NHTSA notes as follows: The 
preemptive effect of this final rule is discussed above in connection 
with Executive Order 13132. NHTSA notes further that there is no 
requirement that individuals submit a petition for reconsideration or 
pursue other administrative proceedings before they may file suit in 
court.

Paperwork Reduction Act

    Under the Paperwork Reduction Act of 1995 (PRA), 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. Before 
seeking OMB approval, Federal agencies must provide a 60-day public 
comment period and otherwise consult with members of the public and 
affected agencies concerning each collection of information 
requirement. There are no PRA requirements associated with this final 
rule.

National Technology Transfer and Advancement Act

    Under the National Technology Transfer and Advancement Act of 1995 
(NTIAA) (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., material specifications, test methods, sampling procedures, and 
business practices) that are developed or adopted by voluntary 
consensus standards bodies, such as the International Organization for 
Standardization (ISO) and the Society of Automotive Engineers (SAE). 
The NTTAA directs us to provide Congress, through OMB, explanations 
when we decide not to use available and applicable voluntary consensus 
standards.
    This final rule will adopt requirements of CMVSS No. 223. NHTSA's 
consideration of CMVSS No. 223 accords with the principles of NTTAA, in 
that NHTSA is considering

[[Page 42366]]

an established, proven standard, and has not had to expend significant 
agency resources on the same safety need addressed by CMVSS No. 223.

Unfunded Mandates Reform Act

    Section 202 of the Unfunded Mandates Reform Act of 1995 (UMRA), 
Public Law 104-4, requires Federal 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 
expenditure by State, local, or tribal governments, in the aggregate, 
or by the private sector, of more than $100 million annually (adjusted 
for inflation with base year of 1995). After analyzing the costs of 
this final rule, it will not result in expenditures by any of the 
aforementioned entities of over $100 million annually.

Executive Order 13609 (Promoting International Regulatory Cooperation)

    The policy statement in section 1 of Executive Order 13609 provides 
in part that the regulatory approaches taken by foreign governments may 
differ from those taken by U.S. regulatory agencies to address similar 
issues. The E.O. states that, in some cases, the differences between 
the regulatory approaches of U.S. agencies and those of their foreign 
counterparts might not be necessary and might impair the ability of 
American businesses to export and compete internationally. The E.O. 
states that, in meeting shared challenges involving health, safety, 
labor, security, environmental, 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 that international regulatory cooperation can also 
reduce, eliminate, or prevent unnecessary differences in regulatory 
requirements.
    This final rule adopts requirements of CMVSS No. 223 to upgrade 
FMVSS Nos. 223 and 224. NHTSA recognizes that these requirements are 
different from those in the European standard, ECE R.58, ``Rear 
underrun protective devices (RUPD); Vehicles with regard to the 
installation of an RUPD of an approved vehicle; Vehicles with regard to 
their rear underrun protection.'' \92\ R.58 specifies requirements that 
are similar to, but less stringent than, the current standards in FMVSS 
Nos. 223 and 224. R.58 specifies a quasi-static loading test of 25 kN 
at P1, 25 kN at P2, and 100 kN at P3. R.58 also does not specify any 
energy absorption requirements. NHTSA has decided to adopt the strength 
requirements of CMVSS No. 223 rather than ECE R.58 because the rear 
impact protection requirements for trailers in Canada are more 
stringent than that in Europe and more appropriate for the underride 
crashes experienced in the U.S. Passenger vehicles in the U.S. are 
required by FMVSS No. 208 to have frontal air bag protection and comply 
with a full frontal 56 km/h (35 mph) rigid barrier crash test by 
ensuring that the injury measures of crash test dummies restrained in 
front seating positions are within the allowable limits. CMVSS No. 223 
is designed to prevent PCI in full frontal 56 km/h (35 mph) crashes. 
Together, FMVSS No. 208 and FMVSS Nos. 223 and 224 will significantly 
reduce the harm resulting to occupants of passenger vehicles impacting 
the rear of trailers in crashes of up to 56 km/h (35 mph).
---------------------------------------------------------------------------

    \92\ Economic Commission of Europe (ECE) R.58, ``Rear underrun 
protective devices (RUPDs); Vehicles with regard to the installation 
of an RUPD of an approved type; Vehicles with regard to their rear 
underrun protection (RUP),'' February 2019, https://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2017/R058r3e.pdf.
---------------------------------------------------------------------------

Plain Language

    Executive Order 12866 require each agency to write all rules in 
plain language. Application of the principles of plain language 
includes consideration of the following questions:
     Has the agency 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 is 
not 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 the agency improve clarity by adding tables, lists, 
or diagrams?
     What else could the agency do to make this rulemaking 
easier to understand?
    If you have any responses to these questions, please send them to 
NHTSA.

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, including any personal information the 
commenter provides, to www.regulations.gov, as described in the system 
of records notice (DOT/ALL-14 FDMS), which can be reviewed at 
www.dot.gov/privacy.

Regulation Identifier Number

    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 hearing at the beginning of this document 
to find this action in the Unified Agenda.

List of Subjects in 49 CFR Part 571

    Motor vehicle safety, Motor vehicles, Reporting and recordkeeping 
requirements, Tires.

    In consideration of the foregoing, NHTSA amends 49 CFR part 571 as 
follows:

PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS

0
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.

0
2. Section 571.223 is amended by:
0
a. Revising S3;
0
b. Adding definitions of ``Ground clearance'' and ``Load path'' in 
alphabetical order in S4;
0
c. Revising S5.2, S5.5(c), S6 introductory text, S6.3, S6.4 
introductory text, S6.4(a) introductory text, and S6.4(b) introductory 
text;
0
d. Removing S6.4(c);
0
e. Revising S6.5 introductory text and S6.5(a);
0
f. Adding S6.5(c);
0
g. Revising S6.6 introductory text, S6.6(b), and S6.6(c);
0
f. Adding S6.7 through S6.9;
0
g. Revising Figures 1 and 2; and
0
h. Adding Figures 3 and 4.
    The revisions and additions read as follows:

Sec.  571.223  Standard No. 223; Rear impact guards

* * * * *
    S3. Application. This standard applies to rear impact guards for 
trailers and semitrailers subject to Federal Motor Vehicle Safety 
Standard No. 224, Rear Impact Protection (Sec.  571.224).
    S4. * * *
    Ground clearance means the vertical distance from the bottom edge 
of a horizontal member to the ground.
* * * * *
    Load path means a route of force transmission between the 
horizontal member and the chassis.
* * * * *
    S5.2 Strength and Energy Absorption. When tested under the

[[Page 42367]]

procedures of S6 of this section, each guard shall comply with the 
strength requirements of S5.2.1 of this section at each test location 
and the energy absorption requirements of S5.2.2 of this section when a 
distributed load is applied uniformly across the horizontal member, as 
specified in S6.8 of this section. However, a particular guard (i.e., 
test specimen) need not be tested at more than one location.
    S5.2.1 Guard Strength. The guard must resist the force levels 
specified in S5.2.1(a) through (c) of this section without deflecting 
by more than 125 mm and without eliminating any load path that existed 
before the test was initiated.
    (a) A force of 50,000 N applied in accordance with S6.6 of this 
section at test location P1 on either the left or the right side of the 
guard as defined in S6.4(a) of this section.
    (b) A force of 50,000 N applied in accordance with S6.6 of this 
section at test location P2 as defined in S6.4(b) of this section.
    (c) A uniform distributed force of at least 350,000 N applied 
across the horizontal member, as specified in S6.8 of this section and 
in accordance with S6.6 of this section.
    S5.2.2 Guard Energy Absorption.
    (a) A guard, other than a hydraulic guard or one installed on a 
tanker trailer, when subjected to a uniform distributed load applied in 
accordance with S6.6(c) of this section:
    (1) Shall absorb by plastic deformation at least 20,000 J of energy 
within the first 125 mm of deflection without eliminating any load path 
that existed before the test was initiated; and
    (2) Have a ground clearance not exceeding 560 mm, measured at each 
support to which the horizontal member is attached, as shown in Figure 
4 of this section, after completion of the load application.
    (b) A guard, other than a hydraulic guard or one installed on a 
tanker trailer, that demonstrates resistance to a uniform distributed 
load greater than 700,000 N applied in accordance with S6.6(b) of this 
section, need not meet the energy absorption requirements of S5.2.2(a) 
of this section but must have a ground clearance not exceeding 560 mm 
at each vertical support to which the horizontal member is attached 
after completion of the 700,000 N load application.
* * * * *
    S5.5 * * *
    (c) An explanation of the method of attaching the guard to the 
chassis of each vehicle make and model listed or to the design elements 
specified in the instructions or procedures. The principal aspects of 
vehicle chassis configuration that are necessary to the proper 
functioning of the guard shall be specified including the maximum 
allowable vertical distance between the bottom edge of the horizontal 
member of the guard and the ground to ensure post-test ground clearance 
requirements are met. If the chassis strength is inadequate for the 
guard design, the instructions or procedures shall specify methods for 
adequately reinforcing the vehicle chassis. Procedures for properly 
installing any guard attachment hardware shall be provided.
    S6. Guard Test Procedures. The procedures for determining 
compliance with S5.2 of this section are specified in S6.1 through S6.9 
of this section.
* * * * *
    S6.3 Point Load Force Application Device. The force application 
device employed in S6.6 of this section consists of a rectangular solid 
made of rigid steel. The steel solid is 203 mm in height, 203 mm in 
width, and 25 mm in thickness. The 203 mm by 203 mm face of the block 
is used as the contact surface for application of the forces specified 
in S5.2.1(a) and (b) of this section. Each edge of the contact surface 
of the block has a radius of curvature of 5 mm plus or minus 1 mm.
    S6.4 Point Load Test Locations. With the guard mounted to the rigid 
test fixture or to a complete trailer, determine the test locations P1 
and P2 in accordance with the procedure set forth in S6.4(a) and (b) of 
this section. See Figure 1 of this section.
    (a) Point Load Test location P1 is the point on the rearmost 
surface of the horizontal member of the guard that:
* * * * *
    (b) Point Load Test location P2 is the point on the rearmost 
surface of the horizontal member of the guard that:
* * * * *
    S6.5 Positioning of Force Application Device. Before applying any 
force to the guard, locate the force application device specified in 
S6.3 of this section for the point load test location and that 
specified in S6.7 of this section for the uniform distributed load test 
location, such that:
    (a) The center point of the contact surface of the force 
application device is aligned with and touching the guard test 
location, as defined by the specifications of S6.4 of this section for 
the point load test locations, and S6.8 of this section for the uniform 
distributed load test location.
* * * * *
    (c) If the guard is tested on a rigid test fixture, the vertical 
distance from the bottom edge of the horizontal member to the ground at 
the location of each support to which the horizontal member is 
attached, shall be measured.
    S6.6 Force Application. After the force application device has been 
positioned according to S6.5 of this section, at the point load test 
locations specified in S6.4 of this section or the uniform distributed 
load test location specified in S6.8 of this section, apply the loads 
specified in S5.2 of this section. Load application procedures are 
specified in S6.6(a) through (d) of this section.
* * * * *
    (b) If conducting a strength test to satisfy the requirement of 
S5.2.1 or S5.2.2(b) of this section, the force is applied until the 
forces specified in S5.2.1 or S5.2.2(b) of this section have been 
exceeded, or until the displacement of the force application device has 
reached at least 125 mm whichever occurs first.
    (c) If conducting a test to be used for the calculation of energy 
absorption levels to satisfy the requirement of S5.2.2(a) of this 
section, apply a uniform distributed force to the guard until 
displacement of the force application device, specified in S6.7 of this 
section, has reached 125 mm. For calculation of guard energy 
absorption, the value of force is recorded at least ten times per 25 mm 
of displacement of the contact surface of the loading device. Reduce 
the force until the guard no longer offers resistance to the force 
application device. Produce a force vs. deflection diagram of the type 
shown in Figure 2 of this section using this information. Determine the 
energy absorbed by the guard by calculating the shaded area bounded by 
the curve in the force vs. deflection diagram and the abscissa (X-
axis).
* * * * *
    S6.7 Uniform Distributed Load Force Application Device. The force 
application device to be employed in applying the uniform distributed 
load is to be unyielding, have a height of 203 mm, and have a width 
that exceeds the distance between the outside edges of the outermost 
supports to which the tested portion of the horizontal member is 
attached, as shown in Figure 3 of this section.
    S6.8 Uniform Distributed Load Test Location. With the guard mounted 
to the rigid test fixture or to a complete trailer, determine the test 
location in accordance with the following procedure. See Figure 3 of 
this section. Distributed Force Test location is the plane on the 
rearmost surface of the horizontal member of the guard that:

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    (a) Is centered in the longitudinal vertical plane passing through 
the center of the guard's horizontal member; and
    (b) Is centered 50 mm above the bottom of the guard.
    S6.9 Ground Clearance Measurement.
    (a) For the test device attached to a complete trailer as specified 
in S6.2 of this section, the ground clearance of the guard at the 
vertical supports to which the horizontal member is attached shall be 
measured after completion of the uniform distributed load test in 
accordance with S6.6(b) or S6.6(c) of this section.
    (b) For the test device attached to a rigid test fixture as 
specified in S6.2 of this section, the vertical distance from the 
ground to the bottom edge of the horizontal member at the vertical 
supports to which the horizontal member is attached shall be measured 
after completion of the uniform distributed load test in accordance 
with S6.6(b) or S6.6(c) of this section and subtracted from the 
corresponding ground clearance measured before the load application in 
accordance with S6.5(c) of this section. The difference in ground 
clearance before and after the load application is added to the 
allowable maximum vertical distance between the bottom edge of the 
horizontal member of the guard and the ground as specified in S5.5(c) 
of this section, to obtain the ground clearance after completion of the 
uniform distributed load test.
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0
3. Section 571.224 is amended by revising the second sentence in S3 and 
the definition of ``Rear extremity'' in S4 to read as follows:

Sec.  571.224  Standard No. 224; Rear impact protection.

* * * * *
    S3. Application. * * * The standard does not apply to pole 
trailers, pulpwood trailers, low chassis vehicles, road construction 
controlled horizontal discharge trailers, special purpose vehicles, 
wheels back vehicles, or temporary living quarters as defined in 49 CFR 
523.2. * * *
    S4. * * *
    Rear extremity means the rearmost point on a trailer that is above 
a horizontal plane located above the ground clearance and below a 
horizontal plane located 1,900 mm above the ground when the trailer is 
configured as specified in S5.1 of this

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section and when the trailer's cargo doors, tailgate and other 
permanent structures are positioned as they normally are when the 
trailer is in motion, with non-structural protrusions excluded from the 
determination of the rearmost point, such as:
    (1) Tail lamps;
    (2) Rubber bumpers;
    (3) Hinges and latches; and
    (4) Flexible aerodynamic devices capable of being folded to within 
305 mm from the transverse vertical plane tangent to the rear most 
surface of the horizontal member for vertical heights below 1,740 mm 
above ground and, when positioned as they normally are when the trailer 
is in motion, are located forward of the transverse plane that is 
tangent to the rear bottom edge of the horizontal member and 
intersecting a point located 1,210 mm rearward of the horizontal member 
and 1,740 mm above the ground.
* * * * *

    Issued under authority delegated in 49 CFR 1.95 and 501.5.
Steven S. Cliff,
Administrator.
[FR Doc. 2022-14330 Filed 7-14-22; 8:45 am]
BILLING CODE 4910-59-P