[Federal Register Volume 80, Number 241 (Wednesday, December 16, 2015)]
[Proposed Rules]
[Pages 78417-78460]
[FR Doc No: 2015-31228]

Vol. 80

Wednesday,

No. 241

December 16, 2015

Part III

Department of Transportation

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National Highway Traffic Safety Administration

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49 CFR Part 571

Rear Impact Guards, Rear Impact Protection; Proposed Rule

Federal Register / Vol. 80 , No. 241 / Wednesday, December 16, 2015 /
Proposed Rules

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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. NHTSA-2015-0118]
RIN 2127-AL58

Rear Impact Guards, Rear Impact Protection

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

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This NPRM proposes to upgrade the Federal motor vehicle safety
standards that address rear underride protection in crashes into
trailers and semitrailers. NHTSA is proposing to adopt requirements of
Transport Canada's standard for underride 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 kilometers per hour (km/h) (35 miles per
hour (mph)). NHTSA is issuing this NPRM in response to a petition for
rulemaking from the Insurance Institute for Highway Safety (IIHS), and
from Ms. Marianne Karth and the Truck Safety Coalition (TSC). This is
the second of two documents issued in response to the Karth/TSC
petition. Earlier, NHTSA published an advanced notice of proposed
rulemaking requesting comment on strategies pertaining to underride
protection afforded by single unit trucks.

DATES: You should submit your comments early enough to ensure that the
docket receives them not later than February 16, 2016.

ADDRESSES: You may submit comments to the docket number identified in
the heading of this document by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the online instructions for submitting
comments.
     Mail: Docket Management Facility, M-30, U.S. Department of
Transportation, West Building, Ground Floor, Rm. W12-140, 1200 New
Jersey Avenue SE., Washington, DC 20590.
     Hand Delivery or Courier: West Building Ground Floor, Room
W12-140, 1200 New Jersey Avenue SE., between 9 a.m. and 5 p.m. Eastern
Time, Monday through Friday, except Federal holidays.
     Fax:<PHONE_NUMBER>.
    Regardless of how you submit your comments, please mention the
docket number of this document. You may also call the Docket at 202-
366-9324.
    Instructions: For detailed instructions on submitting comments and
additional information on the rulemaking process, see the Public
Participation heading of the Supplementary Information section of this
document. Note that all comments received will be posted without change
to http://www.regulations.gov, including any personal information
provided.
    Privacy Act: Please see the Privacy Act heading under Rulemaking
Analyses and Notices.

FOR FURTHER INFORMATION CONTACT: For technical issues, you may contact
Robert Mazurowski, Office of Crashworthiness Standards (telephone: 202-
366-1012) (fax:<PHONE_NUMBER>). For legal issues, you may contact
Deirdre Fujita, Office of Chief Counsel (telephone:<PHONE_NUMBER>) (fax:
202-366-3820). The address for these officials is: National Highway
Traffic Safety Administration, U.S. Department of Transportation, 1200
New Jersey Avenue SE., West Building, Washington, DC 20590.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Executive Summary
II. Overview of Existing Standards
III. IIHS Petition for Rulemaking
IV. Overview of Proposed Changes
V. Specific Aspects of the Proposal To Upgrade the Standards
    a. Strength and Energy Absorption Requirements
    b. Ground Clearance
    c. Types of Heavy Vehicles Excluded From FMVSS No. 224
    d. Require Attachment Hardware To Remain Intact
    e. Testing on a Trailer Rather Than a Fixture
    f. Moving P1 More Outboard
VI. Definition of ``Rear Extremity'' To Accommodate Aerodynamic
Devices on Trailers
VII. Cost and Benefits Analysis
VIII. Proposed Lead Time
IX. Regulatory Notices and Analyses
X. Public Participation
XI. Appendix A to Preamble: 2013 NHTSA/UMTRI Study
XII. Appendix B to Preamble: Summary of IIHS's Evaluation of Rear
Impact Guards

I. Executive Summary

Introduction

    This NPRM proposes to upgrade Federal Motor Vehicle Safety Standard
(FMVSS) No. 223, ``Rear impact guards,'' and FMVSS No. 224, ``Rear
impact protection,'' which together address rear underride protection
in crashes into trailers and semitrailers. NHTSA is proposing to adopt
requirements of the Canada Motor Vehicle Safety Standard (CMVSS) for
underride guards (CMVSS No. 223, ``Rear impact guards,'') that became
effective in 2007. The CMVSS No. 223 requirements are intended to
provide 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). As
the current requirements in FMVSS Nos. 223 and 224 were developed with
the intent of providing underride crash protection to occupants of
compact and subcompact passenger cars in impacts up to 48 km/h (30 mph)
into the rear of trailers, 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 FMVSS Nos. 223 and 224.
    This NPRM also proposes to adopt Transport Canada's definition of
``rear extremity'' to define where on a trailer aerodynamic fairings
are to be located to avoid posing a safety hazard in rear underride
crashes.
    Rear underride crashes are those in which the front end of a
vehicle impacts the rear of a generally larger vehicle, and slides
under the rear-impacted vehicle. Underride may occur to some extent in
collisions in which a small passenger vehicle crashes into the rear end
of a large trailer or semi-trailer because the bed and chassis of the
impacted vehicle is higher than the hood of the passenger vehicle. In
excessive underride crashes, there is ``passenger compartment
intrusion'' (PCI) as the passenger vehicle underrides so far that the
rear end of the struck vehicle collides with and enters the passenger
compartment of the striking passenger vehicle. PCI can result in severe
injuries and fatalities to occupants contacting the rear end of the
struck vehicle. An underride guard prevents PCI when it engages the
striking end of the smaller vehicle and stops the vehicle from sliding
too far under the struck vehicle's bed and chassis.
    The occupant crash protection features built into today's passenger
vehicles are able to provide high levels of occupant protection in 56
km/h (35 mph) frontal crashes.\1\ If guards were

made stronger to remain in place and prevent PCI in crashes of
severities of up to 56 km/h (35 mph), the impacting vehicle's occupant
protection technologies could absorb enough of the crash forces
resulting from the impact to significantly reduce the risk of fatality
and serious injury to the occupants of the colliding vehicle.
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    \1\ When FMVSS Nos. 223 and 224 were promulgated, FMVSS No. 208,
``Occupant crash protection,'' required all passenger cars to comply
to a full frontal 48 km/h (30 mph) rigid barrier crash test by
ensuring that the injury measures of crash test dummies positioned
in the front seating positions were within the allowable limits. In
2000, NHTSA amended FMVSS No. 208 to provide improved frontal crash
protection for all occupants by means that include advanced air bag
technology. The upgraded standard requires passenger cars to 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. In
addition, passenger vehicles are tested in frontal crash tests in
NHTSA's New Car Assessment Program (NCAP) at crash speeds of 56 km/h
(35 mph) and perform very well providing frontal crash occupant
protection.
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Origins of This Rulemaking

    NHTSA's interest in this rulemaking originated from the findings of
a 2009 NHTSA study \2\ to evaluate why fatalities were still occurring
in frontal crashes despite high rates of seat belt use and the presence
of air bags and other advanced safety features. NHTSA reviewed cases of
frontal crash fatalities to belted drivers and/or right-front
passengers in model year (MY) 2000 or newer vehicles in the
Crashworthiness Data System of the National Automotive Sampling System
(NASS-CDS) through calendar year 2007. Among the 122 fatalities
examined in this review, 49 (40 percent) were in exceedingly severe
crashes that were not survivable, 29 (24 percent) were in oblique or
corner impact crashes where there was low engagement of the striking
vehicle's structural members (a factor which would have resulted in the
striking vehicle absorbing more of the crash energy), and 17 (14
percent) were underrides into single unit trucks (SUTs) \3\ and
trailers (14 were rear underride and 3 were side underride).\4\ In
survivable frontal crashes of newer vehicle models resulting in
fatalities to belted vehicle occupants, rear underrides into large SUTs
and trailers were the second highest cause of fatality.
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    \2\ Kahane, et al. ``Fatalities in Frontal Crashes Despite Seat
Belts and Air Bags--Review of All CDS Cases--Model and Calendar
Years 2000-2007--122 Fatalities,'' September 2009, DOT-HS-811102.
    \3\ SUTs are trucks with a gross vehicle weight rating (GVWR)
greater than 4,536 kilograms (kg) (10,000 pounds (lb)) with no
trailer. They are primarily straight trucks, in which the engine,
cab, drive train, and cargo area are mounted on one chassis.
    \4\ In addition, 15 (12 percent) were fatalities to vulnerable
occupants (occupants 75 years and older), 4 (3.3 percent) were
narrow object impacts, and 8 (6.6 percent) were other types of
impact conditions.
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    In 2010, NHTSA published the results of a study, analyzing several
data sources, to determine the effectiveness of trailer rear impact
guards compliant with FMVSS Nos. 223 and 224 in preventing fatalities
and serious injuries.\5\ The agency's analysis of the Fatality Analysis
Reporting System (FARS) could not establish a nationwide downward trend
in fatalities to passenger vehicle occupants in impacts with the rear
of trailers subsequent to the implementation of FMVSS Nos. 223 and 224.
While supplemental data collected in Florida and North Carolina showed
decreases in fatalities and serious injuries, the observed decrease in
fatalities in these two States was not statistically significant,
possibly due to small sample sizes of the data.
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    \5\ Allen, Kirk, ``The Effectiveness of Underride Guards for
Heavy Trailers,'' October 2010, DOT HS 811 375. http://www-nrd.nhtsa.dot.gov/Pubs/811375.pdf. Last accessed on March 25, 2015.
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    Following these two studies, NHTSA undertook research to examine
the agency's underride protection requirements, highlighting this
program as a significant one in the ``NHTSA Vehicle Safety and Fuel
Economy Rulemaking and Research Priority Plan 2011-2013 (March 2011).''
    One of the resulting research projects began in 2010, as NHTSA
initiated research with the University of Michigan Transportation
Research Institute (UMTRI) to gather 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 its Trucks Involved in Fatal Accidents (TIFA)
survey for the years 2008 and 2009.6 7 These data enabled
NHTSA to obtain national estimates of rear impact crashes into heavy
vehicles that resulted in PCI. We discuss details of the study in
Appendix A of this preamble.
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    \6\ Analysis of Rear Underride in Fatal Truck Crashes, 2008, DOT
HS 811 652, August 2012, infra.
    \7\ 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.
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    More information was obtained in 2011 from IIHS, which petitioned
NHTSA to upgrade FMVSS Nos. 223 and 224 to improve the strength and
energy-absorbing capabilities of rear impact guards.\8\ IIHS based its
petition on a detailed review of rear impacts into trucks and trailers
from DOT's Large Truck Crash Causation Study (LTCCS) 9 10
and from an initial test series IIHS conducted of 56 km/h (35 mph)
passenger car-to-trailer rear impact crashes.\11\ Subsequently, IIHS
conducted follow on testing of 8 trailer models manufactured in 2012
and 2013 that were equipped with rear impact guards compliant with
CMVSS No. 223. NHTSA obtained test data of the initial test series and
the follow on testing of trailers. We summarize the IIHS petition and
test data below in this preamble and in detail in Appendix B.\12\ IIHS
suggests that trailers with rear impact guards compliant with CMVSS No.
223 are superior to those compliant with FMVSS No. 224 in mitigating
PCI of the striking passenger car. NHTSA has evaluated the data and has
agreed with IIHS on that point. Accordingly, we grant the petition and
issue this NPRM in response.
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    \8\ A copy of the petition is in the docket for this NPRM.
    \9\ LTCCS is based on a 3-year data collection project by NHTSA
and FMCSA and is the first-ever national study to attempt to
determine the critical events and associated factors that contribute
to serious large truck crashes. http://ai.fmcsa.dot.gov/ltccs/default.asp, last accessed on March 10, 2015.
    \10\ Brumbelow, M.L. and Blanar, L., ``Evaluation of US Rear
Underride Guard Regulation for Large Trucks Using Real-World
Crashes,'' Proceedings of the 54th Stapp Car Crash Conference, 119-
131, 2010, Warrendale, PA, SAE International.
    \11\ A discussion of the tests can be found in Brumbelow, M.L.,
``Crash Test Performance of Large Truck Rear Impact Guards,'' 22nd
International Conference on the Enhanced Safety of Vehicles (ESV),
2011. http://www-nrd.nhtsa.dot.gov/pdf/esv/esv22/22ESV-000074.pdf.
    \12\ In addition, copies of test reports from the program have
been placed in NHTSA's general reference docket for rear impact
protection, NHTSA-2015-0014.
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    In addition, this NPRM responds to a petition for rulemaking from
Mrs. Marianne Karth and the Truck Safety Coalition (TSC) (Karth/TSC
petition), requesting that NHTSA require underride guards on SUTs and
other vehicles not currently required by the FMVSSs to have guards, and
improve the standards' requirements for all guards. On July 10, 2014,
NHTSA granted the Karth/TSC petition and announced \13\ that NHTSA
would be pursuing possible rulemaking through: (a) An ANPRM pertaining
to rear impact guards for SUTs and other safety strategies not
currently required for those vehicles; \14\ and (b) an NPRM (which is
today's NPRM) to upgrade FMVSS Nos. 223 and 224.
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    \13\ 79 FR 39362.
    \14\ In July 2015 (80 FR 43663) (Docket No. NHTSA-2015-0070),
NHTSA published the ANPRM relating to SUTs. The ANPRM requests
comment on NHTSA's estimated cost and benefits of expanding FMVSS
Nos. 223 and 224, to require CMVSS No. 223 guards on SUTs, and of
amending FMVSS No. 108, ``Lamps, reflective devices, and associated
equipment,'' to require the type of retroreflective material on the
rear and sides of SUTs that is now required to be placed on the rear
and sides of trailers to improve the conspicuity of the vehicles to
other motorists. NHTSA will be following up on issues presented on
SUTs in an action separate from today's NPRM.

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    This NPRM also accords with an April 3, 2014, recommendation from
the National Transportation Safety Board (NTSB) regarding tractor-
trailer safety (H-14-004). NTSB recommends that NHTSA revise FMVSS Nos.
223 and 224 to ensure that newly manufactured trailers over 4,536
kilograms (kg) (10,000 pounds (lb)) gross vehicle weight rating (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 makes favorable
reference to IIHS's petition for rulemaking and the testing IIHS
conducted. We have carefully considered H-14-004 and have issued this
NPRM in response.

Impacts of the Rulemaking

    Based on information from the Truck Trailer Manufacturers
Association (TTMA),\15\ NHTSA estimates that 93 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 one life
and three serious injuries would be saved annually by requiring all
applicable trailers to be equipped with CMVSS No. 223 compliant guards.
The undiscounted equivalent lives saved are 1.3 per year.
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    \15\ TTMA Joint Industry/Government Meeting on July 24, 2014,
Embassy Suites Hotel, Alexandria, VA.
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    The average incremental cost of equipping CMVSS No. 223 compliant
rear impact guards on an applicable new trailer is about $229 and the
corresponding average incremental weight increase is 49 lb. The annual
average incremental material and fuel cost of requiring all applicable
new trailers in the fleet with CMVSS No. 223 guards is $13 million.
    Table 1 below presents the net cost and net benefits estimates for
requiring CMVSS No. 223 compliant rear impact guards on all applicable
new trailers in the fleet. The net cost per equivalent lives saved in
2013 dollars is $9.1 million and $9.5 million discounted at 3 percent
and 7 percent, respectively. The net benefit of this proposal in 2013
dollars is $0.59 million and $0.13 million discounted at 3 percent and
7 percent, respectively.

                 Table 1--Benefit and Cost, Net Cost per Equivalent Lives Saved, and Net Benefit
                               [All monetized values are in million 2013 dollars]
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                                                            Undiscounted       3% Discount        7% Discount
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Societal Economic Benefits (a).........................              $1.72              $1.52              $1.35
Total Safety Benefits (b)..............................             $14.13             $12.37             $10.89
Total Equivalent Lives Saved (c).......................               1.29               1.13               0.99
Total annual material + fuel Cost (d)..................             $12.98             $11.77             $10.76
Net Cost (e) = (d)-(a).................................             $11.26             $10.25              $9.40
Net Cost per Equivalent Lives Saved = (e)/(c)..........              $8.71              $9.07              $9.47
Net Benefit = (b)-(d)..................................              $1.15              $0.59              $0.13
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II. Overview of Existing Standards

FMVSSs

    FMVSS Nos. 223 and 224 were established in 1998 to reduce the risk
of PCI by upgrading then-existing rear impact guards to make them
stronger but energy-absorbing as well. 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.\16\ NHTSA established the two-standard approach to provide
underride protection in a manner that imposes reasonable compliance
burdens on small trailer manufacturers.\17\
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    \16\ Excluded from FMVSS No. 224 are pole trailers, logging
trailers, low chassis trailers (trailers where the ground clearance
of the chassis is no more than 560 mm (22 inches)), wheels back
trailers (trailers with rearmost point of rear wheels within 305 mm
(12 inches) of the rear extremity of the trailer), and special
purpose trailers (trailers with equipment in the rear and those
intended for certain special operations). The exclusions are based
on practical problems with meeting the standard or an absence of a
need to meet the standard due to, e.g., vehicle configuration.
    \17\ There are a significant number of 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 practicable and reasonable means of meeting the
safety need served by an underride guard requirement.
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    Briefly summarized, the requirements of FMVSS No. 223 relevant to
this NPRM are as follows. FMVSS No. 223 requires the guard to meet the
strength requirements of the standard at certain specified test
locations, and the energy absorption requirements of the standard at
location ``P3.'' (See Figure 1 below for a depiction of P3 and the
other test locations (P1 and P2) on the guard.) Test location P1 is at
a distance of 3/8th of the width of the horizontal member on either
side of the centerline 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 of FMVSS No. 223) 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 the 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, as illustrated in Figure 2 of the
standard. 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 of the standard, and the energy
absorbed by the guard is determined by calculating the shaded area
bounded by the curve in the diagram.
[GRAPHIC] [TIFF OMITTED] TP16DE15.016

    FMVSS 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 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.

CMVSS

    Transport Canada's upgraded CMVSS No. 223, ``Rear impact guards,''
was issued in 2005 and became effective in 2007.\18\ Given that
passenger car models manufactured on or after 2005 in Canada are
required to provide adequate occupant protection to restrained
occupants in 56 km/h (35 mph) full frontal rigid barrier crashes,
Transport Canada requires rear impact guards to provide sufficient
strength and energy absorption to prevent PCI of compact and subcompact
passenger cars impacting the rear of trailers at 56 km/h (35 mph).\19\
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    \18\ Canada Gazette Part II, Vol. 138, No. 20, 2004-10-06.
    \19\ Boucher, D. and Davis, D., ``A Discussion on Rear Underride
Protection in Canada,'' Informal Document, 127th WP.29, 25-28 June
2002, http://www.unece.org/fileadmin/DAM/trans/doc/2002/wp29/TRANS-WP29-127-inf05e.pdf.
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    CMVSS No. 223 applies to trailers and semitrailers and specifies
quasi-static loading tests similar to those in FMVSS No. 223. However,
CMVSS No. 223 replaces the 100,000 N quasi-static point load test at
the P3 location in FMVSS No. 223 with a 350,000 N uniform distributed
load test on the horizontal member.\20\ The guard is required to
withstand this load and absorb at least 20,000 J of energy within 125
mm of deflection, and have a ground clearance before and after the test
not exceeding 560 mm (22 inches). Optionally, manufacturers may choose
to forgo the energy absorption requirement if the guard can resist a
uniform distributed load of more than 700,000 N, but would need to
ensure that the ground clearance does not exceed 560 mm (22 inches)
after the uniform distributed load test. Similar to FMVSS No. 223,
CMVSS No. 223 permits testing the rear impact guard when attached, per
manufacturer's instructions, to a rigid test fixture or to a complete
trailer. Through extensive testing,\21\ Transport Canada demonstrated
that these requirements would ensure that compact and subcompact
passenger cars would not have PCI when rear-ending a CMVSS No. 223
compliant trailer at 56 km/h (35 mph).
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    \20\ The load is applied uniformly across the horizontal member
by a uniform load application structure with length that exceeds the
distance between the outside edges of the vertical support of the
horizontal member and which is centered on the horizontal member of
the guard.
    \21\ 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.
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    CMVSS No. 223 also has similar geometric specifications for rear
impact guards as FMVSS No. 224.
    Table 2 presents a general comparison of rear impact protection
requirements in the U.S. and Canada.

 Table 2--Comparison of Rear Impact Protection Requirements in the U.S.
                               and Canada
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          Requirement                   U.S.                Canada
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Applicable standards...........  FMVSS No. 223/224.  CMVSS No. 223.
Applicable vehicles............  Trailers..........  Trailers.
Ground clearance...............  560 mm measured     560 mm measured
                                  before test.        before and after
                                                      energy absorption
                                                      test (or after the
                                                      uniform
                                                      distributed load
                                                      test for guards
                                                      with strength
                                                      exceeding 700,000
                                                      N.).
Longitudinal distance from rear  305 mm............  305 mm.
 extremity.
Lateral distance from side of    100 mm............  100 mm.
 vehicle.
Point load at P1 (outer edge of  50 kN.............  50 kN.
 guard).
Point load at P2 (center of      50 kN.............  50 kN.
 guard).
Point load at P3 (at the guard   100 kN with no
 supports).                       more than 125 mm
                                  displacement,
                                  5,650 J energy
                                  absorption within
                                  125 mm
                                  displacement.
Distributed load across width    ..................  350 kN with no more
 of the guard.                                        than 125 mm
                                                      displacement and
                                                      20,000 J energy
                                                      absorption within
                                                      125 mm
                                                      displacement; or
                                                      700 kN with no
                                                      more than 125 mm
                                                      displacement.
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III. IIHS Petition for Rulemaking \22\
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    \22\ IIHS conducted more testing after the initial test program
discussed in its petition. NHTSA discusses IIHS's test program in
Appendix B of this preamble.
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    In 2011, IIHS petitioned NHTSA to upgrade FMVSS No. 223 and 224
``to require underride guards that are strong enough to [allow] the
energy absorbing structures of passenger vehicles to deform and provide
protection to their occupants.''
    IIHS conducted crash tests in which a model year (MY) 2010
Chevrolet Malibu (a midsize sedan) impacted the rear of various
trailers equipped with rear impact guards (full overlap of the rear
impact guard with the front end of the sedan) at 56 km/h (35 mph).\23\
(``Overlap'' refers to the portion of the striking passenger vehicle's
width overlapping the underride guard.) A 50th percentile male Hybrid
III dummy (HIII 50M) was in each of the front outboard seating
positions of the Malibu. IIHS evaluated trailers manufactured by
Hyundai, Vanguard, and Wabash. According to the petition, all three
trailer/guard designs easily passed FMVSS No. 223's quasi-static tests
at P1 and P3 locations, while the Vanguard and Wabash trailers/guards
also met the more stringent P3 requirements of CMVSS No. 223.
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    \23\ See Brumbelow, M.L., ``Crash Test Performance of Large
Truck Rear Impact Guards,'' 22nd International Conference on the
Enhanced Safety of Vehicles (ESV), 2011. http://www-nrd.nhtsa.dot.gov/pdf/esv/esv22/22ESV-000074.pdf.
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    The Hyundai guard, which only met FMVSS No. 223, resulted in
``catastrophic'' underride of the Malibu (``complete loss of the front
occupant survival space'') in the full-overlap test.
    In contrast, the Wabash guard (built to CMVSS No. 223 requirements)
``performed well in the full-width and 50 percent overlap conditions,
providing much greater protection against underride than the other two
guards.'' \24\ That is, the rear impact guard on the Wabash trailer,
certified to meet FMVSS No. 223 and CMVSS No. 223 requirements,
prevented PCI in the 56 km/h (35 mph) crash tests, while the Hyundai
guard (certified only to FMVSS No. 223) did not. The Wabash trailer/
guard design prevented PCI in both the full-width and the more
demanding 50 percent overlap tests.
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    \24\ In the 30 percent overlap test, the end of the guard bent
forward and allowed underride of the Malibu.
---------------------------------------------------------------------------

    The Vanguard trailer rear impact guard, certified to FMVSS No. 223
and to CMVSS No. 223, resulted in ``moderate'' \25\ and ``severe''
underride (``intrusion extending into the occupant compartment'') in 50
percent overlap tests. IIHS believes that the problem with the Vanguard
was that the guard is deemed to have met FMVSS No. 223 and CMVSS No.
223 even though the attachment bolts sheared or pulled away from the
guard during the quasi-static test. The petitioner suggests ``the
regulations should include a stipulation that all attachment hardware
must remain intact for the duration of the test or until reaching a
force threshold that is much higher than that required for the guard
itself.''
---------------------------------------------------------------------------

    \25\ IIHS did not define ``moderate'' underride.
---------------------------------------------------------------------------

    Table 3 summarizes the results of the initial six 56 km/h (35 mph)
crash tests. In the first test of the 2007 Hyundai guard, the guard was
ripped from the trailer's rear cross member early in the crash,
allowing the Malibu to underride the trailer almost to the B-pillar.
The heads of both dummies were struck by the hood of the Malibu as it
deformed against the rear surface of the trailer. In contrast, under
the same test conditions, the main horizontal member of the 2011 Wabash
guard bent forward in the center but remained attached to the vertical
support members, which showed no signs of separating from the trailer
chassis.

             Table 3--IIHS's Table of Its Front-Into-Trailer Rear Crash Tests; 2010 Chevolet Malibu
----------------------------------------------------------------------------------------------------------------
                                                               Guard ground
           Trailer              Speed (km/  Malibu's overlap    clearance          Guard           Underride
                                    h)         with guard     (centimeters)     performance
----------------------------------------------------------------------------------------------------------------
2007 Hyundai.................           56  Full-width......          47.6   Attachments       Catastrophic.
                                                                              failed.
2007 Vanguard................           40  50%.............          42.2   Attachments       Moderate.
                                                                              failed.
2007 Vanguard................           56  50%.............          42.7   Attachments       Severe.
                                                                              failed.
2011 Wabash..................           56  Full-width......          44.5   Good............  None.

2011 Wabash..................           56  50%.............          44.3   End bent forward  None.
2011 Wabash..................           56  30%.............          45.3   End bent forward  Catastrophic.
----------------------------------------------------------------------------------------------------------------

    In its petition, IIHS requests that NHTSA:
     Increase the strength requirements for rear impact guards
(at least to the levels that are currently required in Canada);
     Evaluate whether ground clearance of rear impact guards
can be further reduced;
     Reduce the number of heavy vehicles (trucks and trailers)
exempted from requiring rear impact guards;
     Require attachment hardware to remain intact during the
quasi-static tests;
     Require rear impact guards to be certified while attached
to the trailer for which it is designed; and
     Move the P1 location \26\ for the 50,000 N point load
quasi-static test more outboard ``to improve offset crash protection.''
---------------------------------------------------------------------------

    \26\ See Figure 1 of this preamble for the location of P1,
supra.
---------------------------------------------------------------------------

IV. Overview of Proposed Changes

    This NPRM proposes the following changes to FMVSS Nos. 223 and
224.\27\
---------------------------------------------------------------------------

    \27\ In addition, a few housekeeping amendments are proposed.
NHTSA would 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 (see 61 FR at 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). Typographical errors would also be corrected.
---------------------------------------------------------------------------

1. Performance Requirements

    NHTSA has reviewed CMVSS No. 223 and the information provided by
IIHS and agrees that CMVSS No. 223's performance requirements for
underride guards appear practicable, needed for safety, and
objective.\28\ Accordingly, NHTSA proposes that the current loading and
performance requirements of FMVSS No. 223 be replaced with the
specifications in CMVSS No. 223. Specifically:
---------------------------------------------------------------------------

    \28\ See National Traffic and Motor Vehicle Safety Act, 49
U.S.C. 30111(a).
---------------------------------------------------------------------------

     Rear impact guards (except as noted below) would be
required to resist a uniform distributed load of 350,000 N without
deflecting more than 125 mm and while absorbing at least 20,000 J of
energy by plastic deformation within the first 125 mm of deflection;
     Alternatively, rear impact guards may resist a minimum
uniform distributed load of 700,000 N without deflecting 125 mm.
     In accordance with CMVSS No. 223, we propose 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.
     NHTSA tentatively agrees with IIHS that FMVSS No. 223
should require that any portion of the rear impact guard and
attachments not separate from their mounting structure after completion
of the uniform distributed loading test and the energy absorption test.

2. Definition of ``rear extremity'' \29\
---------------------------------------------------------------------------

    \29\ This proposal would also further harmonize FMVSS No. 224
with CMVSS No. 223.
---------------------------------------------------------------------------

    We propose to replace the current definition of ``rear extremity''
in FMVSS No. 224 with that specified in CMVSS No. 223. The change is
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 underride 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 underride guard.

V. Specific Aspects of the Proposal To Upgrade the Standards

    Although NHTSA has granted the IIHS and Karth/TSC petitions, not
all aspects of the petitions have been granted. Specific aspects of the
petitions are discussed below. To the extent NHTSA disagrees with
suggested changes to FMVSS Nos. 223 and 224 in the petitions, NHTSA
denies the requested change.

a. Strength and Energy Absorption Requirements

    Since submitting the petition in 2011, IIHS conducted crash tests
with 8 trailer models that were designed to comply with CMVSS No. 223
(see Appendix B of this preamble). As discussed in Appendix B, the
dynamic crash tests conducted by IIHS showed that all 8 trailer models
that were designed to comply with CMVSS No. 223 were capable of
preventing PCI when struck by a mid-sized sedan at 56 km/h (35 mph) and
full overlap. Furthermore, 7 of the 8 guards were capable of preventing
PCI when struck by a mid-sized sedan at 56 km/h (35 mph) and 50 percent
overlap. These data suggest that upgrading the FMVSS No. 223 strength
and energy absorption requirements to that of the CMVSS No. 223
requirements would improve guard performance in crashes involving full
and 50 percent overlap scenarios.
Agency Decision
    NHTSA proposes to harmonize FMVSS No. 223's test and performance
requirement at the P3 location to that specified in CMVSS No. 223. Our
decision is based on the testing conducted by IIHS and that by
Transport Canada, which show that the Canadian compliant guards are
able to prevent PCI in 56 km/h light (35 mph) vehicle impacts into the
rear of trailers with 100 percent and 50 percent overlap with the
guard.
    The quasi-static point load test at the P3 location would be
replaced by a uniform distributed load test of 350,000 N. The force
application device for the uniform distributed load test would be
rigid, with a height of 203 mm and a width that exceeds the distance
between the outside edges of the outermost load-bearing supports to
which the horizontal member is attached. The load would be applied
using this load application device, in a similar manner to that
currently specified in FMVSS

No. 223. The performance requirements would require the rear impact
guard to 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,\30\ and have a ground clearance not exceeding 560 mm after
completion of the test.
---------------------------------------------------------------------------

    \30\ Canada believes that the energy absorption requirement
helps ensure that the guard will not sever from the trailer chassis
when an equivalent load is applied. Canada Gazette Part II, Vol.
138, No. 20, 2004-10-06, p. 1335.
---------------------------------------------------------------------------

    CMVSS No. 223 permits an option that a rear impact guard does not
have to meet energy absorption requirements if it is able to resist
700,000 N of force using the distributed load application device
without deflecting more than 125 mm. For guards that can withstand
700,000 N in the uniform distributed load test, the guard is required
to have a ground clearance of 560 mm after the uniform distributed load
test. Transport Canada states that it permitted this option based on
rigid barrier crash test results suggesting that a resistance to a
uniform load of at least 700,000 N would help ensure that the rear
impact guard will stay in place in an impact with a passenger car at
impact speeds of 56 km/h (35 mph) or more.\31\ Canada's view is that,
given that modern day passenger vehicles are able to protect occupants
in rigid barrier tests of up to 56 km/h (35 mph), a rear impact guard
that is strong enough to resist loads greater than 700,000 N would not
pose any additional injury to occupants at crash speeds of up to 56 km/
h (35mph). NHTSA is proposing to include this optional test in FMVSS
No. 223, but the agency does not believe guards are or will likely be
manufactured to this test. We seek comment on the need for including
the test in FMVSS No. 223.
---------------------------------------------------------------------------

    \31\ Id., p. 1349.
---------------------------------------------------------------------------

    CMVSS No. 223 also permits testing with half of the rear impact
guard (for symmetric guards) by applying a 175,000 N distributed load
along the length of half of the horizontal member (at the P3 location).
The rear impact guard is required to resist this load by deflecting no
more than 125 mm, and must absorb at least 10,000 J of energy within
125 mm of guard deflection. At the end of the energy absorption test,
the guard must have a ground clearance not exceeding 560 mm. Transport
Canada permitted this testing option to reduce costs associated with
testing, as manufacturers would be able to use existing testing
equipment to demonstrate compliance.32 33
---------------------------------------------------------------------------

    \32\ In 2005, guard manufacturers did not have the equipment and
loading apparatus to apply a distributed force of 350,000 N required
in the full guard test. Therefore, Transport Canada permits testing
with half of the guard with the option of applying a point load of
175,000 N at the P2 location. This option permits the manufacturers
to utilize then-existing equipment used for certifying FMVSS No. 223
rear impact guards.
    \33\ Transport Canada noted that a half guard test could
potentially be more stringent than a full guard test, but provided
no data to support this statement.
---------------------------------------------------------------------------

    NHTSA is not inclined to include this testing option in FMVSS No.
223. According to the data from 6 trailer manufacturers presented in
Table B-3 of Appendix B of this preamble, only one manufacturer
conducted the test using half the rear impact guard. We believe that
most trailer and rear impact guard manufacturers will not avail
themselves of this option, as they are now capable of testing with the
uniform distributed load applied to the complete guard. Additionally,
testing the full guard may be more beneficial to safety, as such a test
is more representative of the guard's performance in the field than
testing the guard cut in half. Therefore, the agency is not including
this option of testing with half of the rear impact guard in the
proposed regulatory text. We seek comment on whether this option should
be included in FMVSS No. 223.

b. Ground Clearance

    FMVSS No. 224 and CMVSS No. 223 require the bottom edge of the
horizontal member of the rear impact guard of the trailer to be no more
than 560 mm (22 inches) above the ground when the trailer is unloaded
and on level ground. IIHS requests that NHTSA evaluate whether the
ground clearance of rear impact guards can be reduced. The Karth/TSC
petition suggests that NHTSA require rear impact guards on trailers and
semitrailers be mounted 406 mm (16 inches) from the ground.\34\
---------------------------------------------------------------------------

    \34\ The agency interprets this request to mean that the ground
clearance of rear impact guards (vertical distance of the bottom of
the horizontal member from ground surface) on trailers and semi-
trailers be less than or equal to 406 mm.
---------------------------------------------------------------------------

Agency Decision
    NHTSA has considered the petitions and is generally denying the
request to lower the ground clearance requirement.
    The issue of appropriate rear impact guard ground clearance
involves balancing the ability of the guard to provide crashworthiness
protection with the operational restrictions associated with lower
guard heights. This issue was discussed in detail in the 1996 final
rule establishing FMVSS Nos. 223 and 224.\35\ At that time, the agency
analyzed public comments, vehicle geometry, heavy vehicle operations,
and crash test data and concluded that requiring a guard ground
clearance lower than 560 mm (22 inches) would cause an undue burden on
the industry. The agency was concerned that ground clearance lower than
560 mm (22 inches) would not only cause interference in intermodal
operations but also increase the probability that the guard would
scrape or snag during normal vehicle operations and be damaged as a
result.
---------------------------------------------------------------------------

    \35\ 61 FR 2004.
---------------------------------------------------------------------------

    For the 1996 final rule, NHTSA conducted a survey of engine block
heights and front end profiles of a sample of 40 vehicles and found
that the top of the engine block for these vehicles was between 660 and
790 mm (26 and 31 inches, respectively), with an average height of 711
mm (28 inches). The agency's crash tests indicated that rear impact
guards with ground clearances of 560 mm (22 inches) that met FMVSS No.
223 prevented PCI in light vehicles. During these tests, the impacting
cars had their front ends depressed to simulate the lowering that would
be experienced during heavy braking, to simulate a ``worst case
scenario'' with regard to guard height. Even in these conditions, the
rear impact guard engaged the structure (engine block) of each car,
resulting in air bag deployment and low injury measures on the dummies
in the front row. Accordingly, the agency decided in the 1996 final
rule to specify a ground clearance requirement of 560 mm (22 inches).
    Since the 1996 final rule, Transport Canada issued upgraded rear
impact guard tests and performance requirements that are intended to
prevent PCI in light vehicles at speeds up to 56 km/h (35 mph).
According to CMVSS No. 223, 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). Transport Canada
crash tests showed that rear impact guards with an initial ground
clearance of 560 mm that were designed to meet the strength, energy
absorption, and ground clearance requirements after the test were able
to prevent PCI in small passenger cars impacting the guard at 56 km/h
(35 mph).\36\ Thus, in response to commenters that suggested further
lowering of the guard ground clearance, Transport Canada stated that
while it agrees that the ground clearance of rear impact guards is an
important factor to preventing PCI, its crash tests of passenger cars
into rear impact guards

of different heights found that sufficient strength of the guard and a
560 mm (22 inch) ground clearance after the test were more important
factors in preventing PCI than a reduced initial ground clearance and
no post-test ground clearance requirement.\37\
---------------------------------------------------------------------------

    \36\ Boucher, D., Davis, D.T., ``Trailer Underride Protection--A
Canadian perspective,'' SAE technical paper 2000-01-3522, Society of
Automotive Engineers, 400 Commonwealth Dr., Warrendale, PA 15096-
0001.
    \37\ Canada Gazette Part II, Vol. 138, No. 20 SOR/DORS/2004-195.
---------------------------------------------------------------------------

    NHTSA concurs with Transport Canada's position on maintaining the
maximum allowable ground clearance of rear impact guards at 560 mm (22
inches). Because the upgrades to FMVSS Nos. 223 and 224 will require
substantially increased strength of rear impact guards and require 560
mm (22 inches) maximum ground clearance of the guards before and after
the energy absorption test, the agency believes reducing the ground
clearance of trailer rear impact guards from 560 mm (22 inches) to a
lower level is not needed.
    The maximum required ground clearance of 560 mm (22 inches) is
sufficiently low to engage the engine block of an impacting passenger
vehicle. NHTSA gathered data on the vertical height of passenger
vehicle bumpers and the top of the engine block from the ground on 50
vehicles crash-tested in 2013 under the agency's New Car Assessment
Program, as shown in Table 4. NHTSA chose the engine block height as a
suitable metric to represent a major structural element of the striking
vehicle that would engage the rear impact guard to mitigate PCI. These
light vehicles consisted of hatchbacks, sedans, coupes, minivans,
station wagons, utility vehicles, and extended cab pickups.
    The average height of the top of the engine block was 889 mm (35
inches) with a standard deviation of 102 mm (4.0 inches), and a range
of 739 mm (29.1 inches) to 1300 mm (51.2 inches). The lowest average
height of the top of the engine block was a 5-door hatchback with a
height of 804 mm (31.7 inches).\38\
---------------------------------------------------------------------------

    \38\ It is noteworthy that the top of the engine block is higher
in the MY 2013 vehicles than in the vehicles surveyed by NHTSA in
1993, which had showed an average top of engine block height of 711
mm (28 inches).
    \39\ From Safercar.gov at http://www.safercar.gov/Vehicle+Shoppers/5-Star+Safety+Ratings/1990-2010+Vehicles.

                Table 4--Engine Block Vertical Height From Ground Level in MY 2013 Vehicles \39\
----------------------------------------------------------------------------------------------------------------
                                                                                Average
                                                                                Percent of       height of
                          Vehicle type                               Quantity       population     engine block
                                                                                sampled        top (mm)
----------------------------------------------------------------------------------------------------------------
Five Door Hatchback.............................................               5              10             804
Four Door Sedan.................................................              19              38             862
Two Door Coupe..................................................               4               8             848
Minivan.........................................................               1               2             822
Station Wagon...................................................               2               4             853
Utility Vehicle.................................................              17              34             924
Extended Cab Pickup.............................................               2               4            1235
----------------------------------------------------------------------------------------------------------------

    NHTSA also does not believe that the ground clearance of the guard
needs to be reduced because fleet data suggest that where possible,
trailer manufacturers are voluntarily installing rear impact guards
with ground clearances under 560 mm (22 inches).
    NHTSA evaluated the ground clearance of rear impact guards in the
current trailer fleet by analyzing the supplemental data on the rear
geometry of trailers that UMTRI collected as part of 2008 and 2009 TIFA
survey.\40\ Guard ground clearance was reported for trailers that had
rear impact guards in the combined TIFA data for 2008 and 2009. The
mean, median, mode, and standard deviation of the ground clearance is
shown for rear impact guards on trailers (Table 5). The data indicate
that the mean ground clearance of rear impact guards on trailers in the
current fleet is 536 mm (21.1 inches), lower than the maximum allowable
ground clearance of 560 mm (22 inches). Further, an evaluation of
trailers manufactured in 1998 and later in the 2008-2009 TIFA data
files from UMTRI showed that the average ground clearance of rear
impact guards for newer (MY 1998+) trailer models was 457 mm (18
inches).
---------------------------------------------------------------------------

    \40\ 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.

                                          Table 5--Rear Impact Guard Ground Clearance From the 2013 UMTRI Study
                                                   [Supplemental data in 2008 and 2009 TIFA datafiles]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                        Maximum
                                                       allowable                                                                             Standard
                Truck configuration                      ground             N             Mean mm         Median mm         Mode mm       deviation  mm
                                                     clearance  mm                        (inches)         (inches)         (inches)         (inches)
                                                        (inches)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Trailer...........................................        560 (22)             3380       536 (21.1)         508 (20)         610 (24)        107 (4.2)
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The agency also conducted an informal survey of trailers at a weigh
station by the southbound lanes of I-81 near Stephen City, Virginia in
August 2012. The sample consisted of 47 trailers (van and flatbed) that
were directed to the inspection lot after passing through the weigh
scales. Thirty of the trailers had guards and the ground clearance of
the rear impact guards on these trailers ranged from 376 mm to 546 mm
(14.8 inches to 21.5 inches) with an average value of 472 mm (18.6
inches).
    Another reason not to reduce the current ground clearance
requirement of 560 mm is because NHTSA is proposing to adopt the CMVSS
No. 223 requirement that the rear impact guard must maintain the 560 mm
(22 inches) of ground clearance after the energy absorption uniform
distributed load test. It is possible that to meet the post-test ground
clearance requirements, the rear

impact guards will be installed with ground clearance lower than the
required 560 mm. For trailers involved in IIHS testing, the average
ground clearance of the guards that were certified to CMVSS No. 223 was
443 mm.
    NHTSA is not proposing to reduce the maximum allowable ground
clearance of rear impact guards also because NHTSA continues to be
concerned that a lower guard ground clearance requirement may interfere
with functionality of some of the vehicles. For example, in intermodal
operations, some trailers are driven into ships on ramps instead of
being crane loaded and some trailers need to drive up sloping driveways
during normal operations. Some trailers may have the rear axle further
forward to improve maneuverability of the trailer. NHTSA believes that,
for such trailers, rear impact guards that are lower than 560 mm (22
inches) may scrape and snag with the ground and get damaged.

c. Types of Heavy Vehicles Excluded From FMVSS No. 224

    IIHS requests that NHTSA evaluate whether FMVSS No. 224 can be
applied to more vehicles. IIHS states that more than half of the truck
units in the LTCCS cases studied by IIHS were excluded from FMVSS No.
224 requirements. IIHS stated that wheels back trailers and SUTs were
most of the excluded vehicles. The Karth/TSC petition requests that
NHTSA improve the rear impact protection provided by SUTs, a vehicle
class currently excluded from FMVSS No. 224. FMVSS No. 224 does not
apply to pole trailers, pulpwood trailers, wheels back vehicles, low
chassis vehicles, road construction controlled horizontal discharger
trailers,\41\ special purpose vehicles,\42\ or temporary living
quarters as defined in 49 CFR 529.2.\43\
---------------------------------------------------------------------------

    \41\ A road construction controlled horizontal discharge trailer
is a trailer or semitrailer that is equipped with a mechanical drive
and a conveyor to deliver asphalt and other road building materials
for road construction operations.
    \42\ Special purpose vehicle is a trailer or semitrailer that
has work performing equipment that resides in or moves through any
portion of the area that is designated for the rear impact guard.
Typically, trailers with equipment in the rear, such as lift gages,
are categorized as special purpose vehicles and are excluded from
the application of FMVSS No. 224.
    \43\ In addition, certain cargo tankers certified to carry
hazardous materials with a bumper or device in the area where the
horizontal member of a guard would be are excluded from having to
comply with the energy absorption requirement of FMVSS No. 224.
---------------------------------------------------------------------------

    The issue of exclusions from FMVSS No. 224 was discussed in detail
in the January 24, 1996 final rule and in subsequent final rules. Pole
and pulpwood trailers lack structure in the rear for attaching rear
impact guards and carry loads likely to substantially overhang the rear
of the trailer. This attribute of pole and pulpwood trailers thereby
negates the value of rear impact guards and consequently were excluded
from FMVSS No. 224 requirements. Wheels back vehicles were excluded
because the agency's testing indicated that the rear wheels of wheels
back trailers were able to prevent PCI into the impacting passenger car
and also were adequate for managing the energy in such a crash.
    Trailers with equipment in the rear, such as a lift gate, were
excluded from FMVSS No. 224 because of the complexities associated with
the installation of rear impact guards on these trailers, and because
rear impact guards could interfere with the operation of some lift
gates. There are practical problems to installing rear impact guards on
trailers with equipment in the rear if the equipment resides at the
location where the guard would be installed or if the guard interferes
with the operation of the equipment. Thus, NHTSA excluded trailers with
equipment in the rear which reside in or moves through any portion of
the space designated for a rear impact guard.
Agency Decision \44\
---------------------------------------------------------------------------

    \44\ The ANPRM that was published prior to this NPRM discusses
issues relating to applying FMVSS No. 224 to SUTs. Those issues will
not be discussed in this NPRM.
---------------------------------------------------------------------------

    To evaluate whether the exclusions in FMVSS No. 224 should be
rescinded, the agency analyzed the supplemental data on rear geometry
of trailers that UMTRI collected as part of 2008 and 2009 TIFA
survey.\45\ UMTRI collected specific data on the rear extremity of
trailers and determined whether a rear impact guard was required, and
if not required, what type of exclusion criterion was met. UMTRI also
collected detailed information on fatal vehicle crashes into the rear
of trailers and the extent of underride in these crashes.
---------------------------------------------------------------------------

    \45\ 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.
---------------------------------------------------------------------------

    For the combined 2008 and 2009 TIFA data (all fatal crashes
involving trucks in 2008 and 2009), UMTRI estimated that 66.4 percent
of trailers require rear impact guards per FMVSS No. 224 (see Table 6).
Among the 33.6 percent of trailers not requiring rear impact guards per
FMVSS No. 224, 5.4 percent were types such as pole and logging
trailers, 26.4 percent were wheels back trailers, 0.5 percent were low
chassis trailers, and 1.2 percent had equipment in the rear.

              Table 6--Rear Impact Guard Status per FMVSS No. 224 for Trailers; TIFA 2008 and 2009
----------------------------------------------------------------------------------------------------------------
                                                                       Guard not required
                                              ------------------------------------------------------------------
                                     Guard                                                Wheels back
                                   required      Excluded     Low chassis   Wheels back      + low     Equipment
                                                   type                                     chassis     in rear
----------------------------------------------------------------------------------------------------------------
Trailer........................        66.4%          5.4%          0.5%         26.4%          0.1%    1.2%
----------------------------------------------------------------------------------------------------------------

    As shown in Table 7, among 217 light vehicle fatal crashes into the
rear of trailers that occur annually, 115 are into trailers with
guards, 15 are into excluded trailers (equipment in rear, low chassis,
pole, pulpwood trailers), 44 are into wheels back trailers, and 43 are
into other trailer types. Among 90 fatal light vehicle impact into the
rear of trailers that result in PCI, 62 are into trailers with guards,
4 are into excluded trailers (equipment in rear, low chassis, pole,
pulpwood trailers), 7 are into wheels back trailers, and 17 involve
other truck/trailer types.

 Table 7--Annual Fatal Light Vehicle Impacts Into the Rear of Trailers by Trailer Configuration and Whether PCI
                                                    Occurred
----------------------------------------------------------------------------------------------------------------
                                  Fatal light vehicle crashes     Fatal light vehicle crashes     Percentage of
                                   into the rear of trailers    into the rear of trailers with     fatal light
                               --------------------------------               PCI                vehicle crashes
     Trailer configuration                                     -------------------------------- into the rear of
                                    Number          Percent                                         trailers
                                                                    Number          Percent     resulting in PCI
----------------------------------------------------------------------------------------------------------------
Trailer+guard.................             115              53              62              69                54
Trailer Excluded..............              15               7               4               4                27
Wheelsback....................              44              20               7               8                16
Other unknown.................              43              20              17              19                40
                               ---------------------------------------------------------------------------------
    Total.....................             217  ..............              90  ..............                41
----------------------------------------------------------------------------------------------------------------

    While 20 percent of fatal light vehicle impacts into the rear of
trailers are wheels back trailers, they only represent 8 percent of
those fatal crashes with PCI into the rear of trucks and trailers.
Additionally, only 16 percent of fatal light vehicle impacts into
wheels back trailers resulted in PCI, while 54 percent of fatal light
vehicle impacts into trailers with guards resulted in PCI. Excluded
trailers (equipment in rear, pole, pulpwood, and low chassis trailers)
only represent 4 percent of fatal light vehicle crashes into the rear
of trailers with PCI. These statistics suggest that the exclusion of
pole, logging, low chassis, and wheels back trailers and trailers with
equipment in rear from FMVSS No. 224 requirements may not have
significant safety consequence.
    To better understand the circumstances resulting in PCI and
fatality in light vehicle impacts into the rear of wheels back
trailers, NHTSA reviewed the available details of all fatal light
vehicle impacts into the rear of wheels back trailers that resulted in
PCI in the 2009 TIFA data files, as supplemented with trailer and crash
information. UMTRI defined PCI as vehicle front end deformation
extending up to and beyond the windshield. The results of the review
are presented in Table 8. The data shows that there were 6 light
vehicle fatal crashes into the rear of wheels back trailers resulting
in PCI in 2009. Of these, 4 impacts were at crash speeds greater than
80 km/h (50 mph), which are exceedingly severe.
    The relative crash speeds were not known in the other two crashes.
One was an impact of a Ford pickup which, with its high ride height
construction, was not likely to underride the trailer. A review of this
crash suggests that high crash speeds may have been the cause of PCI
(defined by UMTRI as the deformation of the vehicle's front end
extending up to and beyond the windshield) in the Ford pickup rather
than underride of the pickup into the rear of a trailer. The other
crash was a 1990 Buick Electra, a large sedan, impacting the rear of a
wheels back van trailer. The Electra was traveling in a 55 mph speed
zone and so may have also been in a high speed crash.
    This analysis suggests that the available data support the
exclusion of wheels back trailers in FMVSS No. 224. The analysis of the
2009 TIFA data for light vehicle crashes into the rear of wheels back
trailers indicates 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. Therefore, we do not believe that a
rear impact guard would have prevented these fatalities. The agency is
not proposing to extend the applicability of FMVSS No. 224 to wheels
back trailers.

[GRAPHIC] [TIFF OMITTED] TP16DE15.017

    NHTSA conducted a similar analysis of 2009 TIFA data files of all
fatal light vehicle crashes into the rear of pole, logging trailers and
with trailers with equipment in the rear. Low chassis, pole, and
pulpwood trailers and trailers with equipment in the rear account for 3
percent of fatal light vehicle impacts into the rear of trailers with
resulting PCI. Annually there are 4 light vehicle impacts with PCI into
the rear of these excluded vehicles.
    Detailed analysis of light vehicle crashes into the rear of these
excluded vehicles which resulted in PCI of the light vehicle suggest
that all these crashes were very severe and that a CMVSS compliant rear
impact guard, if present, would not have prevented the fatalities.
Additionally, installing rear impact guards on these excluded vehicles
is not necessarily feasible or practicable due to the geometry of the
rear extremity. Given all the above, the agency is not proposing to
remove the exclusion of low chassis, pole, pulpwood trailers, and
trailers with equipment in the rear, from FMVSS No. 224.

d. Require Attachment Hardware To Remain Intact

    Currently FMVSS No. 223 specifies strength requirements for the
guard in terms of the forces that the guard must withstand to prevent
PCI and the energy it must absorb to reduce injury to occupants of the
impacting vehicle. It does not specify performance requirements
relating to the attachment hardware itself of the rear impact guard,
i.e., that the guard's attachments must remain attached, etc. IIHS
requests that FMVSS No. 223 require that attachment hardware of the
rear impact guard remain intact throughout the quasi-static tests.
    IIHS suggests that its data demonstrate that simply increasing the
overall peak force requirements of FMVSS No. 223 would be insufficient
to improve the performance of rear impact guards. IIHS notes that, in
its tests, the 2007 Hyundai and the 2007 Vanguard trailer rear impact
guards met the quasi-static loads test requirements at the P3

location \46\ by substantial margins, despite having attachment bolts
that sheared or pulled away from the guard during the test. IIHS states
that similar failures of the rear impact guard attachments were also
observed in IIHS's 56 km/h (35 mph) crash tests of a MY 2010 Chevrolet
Malibu into the rear of the 2007 Hyundai and Vanguard trailers and
which resulted in PCI of the Malibu. IIHS states that, in contrast, the
2011 Wabash trailer rear impact guard did not experience any attachment
failures during the quasi-static test at the P3 location and performed
well in the 56 km/h (35 mph) crash test with the Chevrolet Malibu with
no PCI of the Malibu. IIHS states that to encourage intelligent guard
designs, FMVSS Nos. 223 and 224 should include a stipulation that all
attachment hardware must remain intact for the duration of the test or
until reaching a force threshold that is much higher than that required
for the guard itself.
---------------------------------------------------------------------------

    \46\ The 2007 Hyundai rear impact guard was certified and tested
to the FMVSS No. 223 load test at the P3 location and the 2007
Vanguard rear impact guard was certified and tested to both the
FMVSS No. 223 and CMVSS No. 223 load tests at the P3 location. When
displaced to 125 mm, as required in the energy absorption test, IIHS
found that the rear impact guard attachments failed. Such failure
was not considered a failure to comply with the standards, however.
---------------------------------------------------------------------------

    IIHS provides further information on this issue in a 2011 paper
\47\ in which it describes the attachment hardware for the rear impact
guards of the 2007 Hyundai, 2007 Vanguard, and the 2011 Wabash trailers
that it tested. The 2007 Hyundai guard that was only certified to FMVSS
No. 223 requirements, did not have any forward attachments points to
the trailer side rails or structure, and the vertical supports of the
guard were directly bolted to the lower rear cross-members of the
trailer. The 2007 Vanguard rear impact guard that complied with CMVSS
No. 223 requirements in addition to that of FMVSS No. 223, had diagonal
gussets attached to forward portions of the trailer chassis using bolts
that would be loaded in shear in a rear impact. The 2011 Wabash rear
impact guard that was certified to CMVSS No. 223 in addition to FMVSS
No. 223, had diagonal gussets attached to forward portions of the
trailer chassis using bolts that transfer loads from the guard to the
chassis through overlapping steel plates.
---------------------------------------------------------------------------

    \47\ Brumbelow, M.L., ``Crash Test Performance of Large Truck
Rear Underride Guards,'' Paper No. 11-0074. 22nd International
Technical Conference on the Enhanced Safety of Vehicles, Washington
DC, 2011. http://www-esv.nhtsa.dot.gov/Proceedings/22/isv7/main.htm.
Last accessed on March 15, 2015.
---------------------------------------------------------------------------

    In the quasi-static load test at the P3 location of the rear impact
guards, for the Hyundai guard, the vertical support member slowly
pulled out from the bolts attaching it to the fixture. The peak load
achieved by the 2007 Vanguard guard was 257,000 N, after which the
attachment bolts of the Vanguard guard began to shear after 50 mm of
guard displacement, causing the load to drop below 100,000 N. On the
other hand, the attachments of the Wabash guard remained intact
throughout the test and the vertical member buckled near its
attachment.
    In the 56 km/h (35 mph) full overlap crash test of the Chevrolet
Malibu with full overlap into the rear of the 2007 Hyundai trailer, the
attachment bolts ripped from the trailer's rear cross-member resulting
in PCI of the Malibu. In the crash test into the rear of the 2007 and
the 2013 Vanguard trailer at 50 percent overlap with the guard, the
attachments bolts sheared and the right half of the guard completely
detached from the trailer resulting in PCI of the Malibu.
Agency Decision
    NHTSA sees merit in IIHS's request for requiring the attachment
hardware to remain intact in the quasi-static load tests, and is thus
granting the request.
    The agency tentatively concludes that the IIHS data indicate that a
requirement that ensures the integrity of the guard attachments would
reduce the likelihood of failure of the anchorages or attachments in
real world crashes in crashes up to 56 km/h (35 mph). The IIHS testing
showed that the Wabash rear impact guard that exhibited no attachment
failure and deformed plastically during the quasi-static load tests,
performed well in the 56 km/h (35 mph) crash test with full overlap and
50 percent overlap of the Chevrolet Malibu. Therefore, to maximize the
performance potential of the rear impact guard, the agency is proposing
to require that any portion of the guard and the guard attachments not
completely separate from its mounting structure after completion of the
quasi-static uniform distributed load test. The agency reviewed its
compliance tests conducted in the past five years and found that no
portion of the rear impact guards and their attachments completely
separated from the mounting structure.\48\
---------------------------------------------------------------------------

    \48\ The agency did not test the rear impact guards of the 2007
Hyundai, 2007 Vanguard, or the 2013 Vanguard trailers.
---------------------------------------------------------------------------

    We are interpreting ``any portion of the guard and the guard
attachment completely separating from it 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. We 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.'' We seek comment on this proposed performance criterion
and whether its objectivity can be improved by, e.g., specifying the
percentage of fasteners or welds that remain intact during the test.

e. Testing on a Trailer Rather Than a Fixture

    Both FMVSS No. 223 and CMVSS No. 223 provide the option of testing
the rear impact guard when attached to a rigid test fixture or when
attached to a complete trailer. IIHS states that, to ensure the
compliance tests correspond to on-road underride protection, rear
impact guards should not be certified separately from the trailers to
which they will be attached. IIHS states that several of its crash
tests of a 2010 Chevrolet Malibu into the rear of trailers produced
deformation to various portions of the trailer, and that this suggests
that the total resistance of the guard-attachment-trailer system is
lower than that of a guard alone when tested on a rigid fixture. IIHS
states that ideally, FMVSS No. 223 should require guards to be
certified while attached to complete trailers, and that at a minimum,
guards should be tested while attached to sections of the trailer rear
that include all the major structural components and that are
constrained such that the load paths near the guard are not changed.
Agency Decision
    NHTSA is denying the request to remove the option of testing guards
on a rigid test fixture. Both FMVSS No. 223 and CMVSS No. 223 provide
the option of testing the rear impact guard when attached to a rigid
test fixture or when attached to a complete trailer. NHTSA believes the
rigid test fixture and complete trailer tests are essentially
equivalent. In NHTSA rigid test fixture compliance tests, the rear
impact guards contain part of the trailer frame rails and/or cross
beams to which the rear impact guard is attached. When testing on a
trailer, the trailer chassis is secured so it behaves essentially as a
fixed object during the test.
    FMVSS No. 223 and CMVSS No. 223 specify that the guard be attached
to the test device (rigid test fixture or complete trailer) in
accordance with the instruction or procedures for guard attachment
provided by the manufacturer. The specification assists in ensuring
that the rear impact guard

is evaluated in representative real world-installed conditions.
    We do not agree with IIHS's conclusion that, when tested on a
trailer, the total resistance of the guard-attachment-trailer system is
lower than that of the guard alone on a rigid fixture due to
deformation of the trailer structure. We believe that in the crash
tests, the trailer structure along with the guard offered resistance to
the dynamic loads and that is why the trailer structure also deformed.
    We believe that testing a rear impact guard when attached to the
rigid structure could be more stringent than when testing the guard
while attached to the trailer. If the trailer structure is resisting a
portion of the load as noted by IIHS, testing a guard on a rigid
fixture may result in a more stringent test than testing it when
attached to the trailer. When the guard is attached to a rigid fixture,
it has to resist all the loads and absorb all the energy, whereas when
it is installed on a trailer, the designs could be such that the
trailer structure could resist a portion of the load.
    NHTSA is also denying the request because requiring that the guard
be tested when attached to the trailer would be a significant cost
burden to trailer manufacturers. Trailer manufacturers typically design
and fabricate their own guards in conjunction with the rest of the
vehicle. Trailer manufacturers typically test rear impact guards when
attached to components of the trailer such as the frame rails and/or
the cross member, similar to NHTSA's compliance testing program. Though
the trailer manufacturers have access to their trailers for testing, it
is expensive to conduct a full trailer test, which is a destructive
test, and so they do not conduct the FMVSS No. 223 specified quasi-
static tests when the guard is attached to the full trailer.
    Requiring that the guard be tested when attached to the trailer
would be an unnecessary and significant cost burden for the
manufacturers, especially for small trailer manufacturers with low
sales volumes. If those manufacturers were to test the guard on the
trailer, this testing would entail sacrificing what could be a large
part of their overall trailer production for such testing.
Additionally, NHTSA also acknowledges there are a few rear impact guard
manufacturers who are not trailer manufacturers (some of which are
small businesses), and a requirement that the guard be tested when
installed on the trailer could substantially and unnecessarily impact
these entities.
    For the reasons stated above, NHTSA believes it is beneficial to
retain the current option of testing rear impact guards when attached
either to a rigid test fixture or a trailer to ensure flexibility in
testing capability. The agency's position is consistent with CMVSS No.
223 and with the test methods used for verifying compliance to the
Canadian standard.

f. Moving P1 More Outboard

    FMVSS No. 223 and CMVSS No. 223 specify that the P1 test location
is at a distance from the centerline of the horizontal member of 3/8th
of the width of the horizontal member, the P2 test location is at the
centerline of the horizontal member, and the P3 test location is 355 mm
(14 inches) to 635 mm (25 inches) from the horizontal member centerline
(see Figure 1 of this preamble, supra).
    IIHS requests that NHTSA evaluate relocating the quasi-static point
load test at the P1 location further outboard toward the end
of the guard horizontal member. IIHS states that the crash tests of the
2010 Chevrolet Malibu into the rear of the 2011 Wabash trailer with
full, 50 percent, and 30 percent overlap of the Malibu front end show
that the CMVSS No. 223 certified guards prevented underride in the full
and 50 percent overlap crashes by transferring the crash loads to stiff
portions of the trailer chassis. IIHS suggests that, to extend the same
level of underride protection to 30 percent overlap crashes, the test
at the P1 location should be moved farther outboard, as well as
subjected to a higher force requirement. (IIHS did not specify a
specific location for P1 nor did it specify a specific force level for
the test.) IIHS believes that on many trailers, the strong side rails
would provide an acceptable location for attaching a guard to protect
against underride in small engagement crashes.
    The Karth/TSC petition requests that the agency improve the safety
of rear impact guards on trailers in low overlap crashes by specifying
the guard vertical supports be located 457 mm (18 inches) from the
``outer edges.'' (It is not clear from the petition whether the ``outer
edges'' refers to the outer edge of the rear impact guard horizontal
member or that of the trailer body. NHTSA assumes ``outer edges''
refers to the lateral edges of the trailer.) Figure 2 shows where we
believe the petition suggests placing the guard supports.
    The width of a typical trailer is 2,600 mm (102 inches) and so the
width of the horizontal member of the rear impact guard for the typical
trailer is 2,400 mm (94.5 inches). For such a guard, the location of
P1, P2 and P3, and the average location of the vertical attachments,
are shown in Figure 2.

[GRAPHIC] [TIFF OMITTED] TP16DE15.018

    In this configuration, P1 is 400 mm (16 inches) from the lateral
edge of the trailer and the centerline of the vertical support is 753
mm (30 inches) from the lateral edge of the trailer.
Agency Decision
    NHTSA is not proposing to move the P1 location farther outboard.
The P1 location is about 300 mm (12 inches) from the lateral edge for
typical rear impact guards. NHTSA is concerned that moving the P1
location would not benefit safety overall.
    First, NHTSA's analysis of field data found that underride crashes
of 30 percent or less appear to represent a small portion of the rear
underride fatality problem. The agency reviewed the UMTRI special study
of 2008 and 2009 TIFA data to evaluate the requested amendment. UMTRI
defined ``offset crashes'' as impacts with the outer one-third or less
of the rear plane of the truck or trailer. (For a 2,600 mm wide
trailer, one third of the trailer width is 867 mm from the lateral edge
of the trailer. As shown in Figure 2, the vertical members are
typically 753 mm from the lateral edge of the trailer.)
    The study found that most underride crashes into the rear of
trailers are not offset impacts. UMTRI found that 40 percent of light
vehicle impacts into the rear end of trucks and trailers in fatal
crashes met the UMTRI definition of ``offset crashes,'' \49\ and that
60 percent were non-offset impacts.\50\ Moreover, the non-offset
crashes appear to be more destructive (potentially harmful) than offset
crashes. UMTRI noted that only 38.7 percent of light vehicle offset
impacts into rear guards resulted in major damage to the guard, while
almost half of the light vehicle non-offset impacts into rear guards
resulted in major damage to the guard, including tearing it off. UMTRI
also found for trailers with rear impact guards, there was virtually no
difference in the percentage of light vehicle crashes with PCI in
offset crashes (53.3 percent) and non-offset crashes (51.9 percent) as
shown in Table 9.
---------------------------------------------------------------------------

    \49\ 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.
    \50\ 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.

 Table 9--Underride Extent in Light Vehicle Fatal Crashes Into the Rear of Trailers With Rear Impact Guards, by
                                    Whether the Impact Was ``Offset'' or Not
                                              [TIFA 2008 and 2009]
----------------------------------------------------------------------------------------------------------------
                                                     Underride Extent \51\  (percentage of light vehicle rear
                                                                      impacts into trailers)
                  Impact Type                   ----------------------------------------------------------------
                                                                            Less than
                                                      N           None       halfway      Halfway+   Windshield+
----------------------------------------------------------------------------------------------------------------
Offset.........................................          105         17.1         14.3         15.2         53.3
Non-Offset.....................................          135         18.5         14.1         15.6         51.9
----------------------------------------------------------------------------------------------------------------

    Given that the majority of fatal light vehicle crashes into the
rear of trucks and trailer were non-offset crashes, the percentage of
light vehicle crashes with major rear impact guard damage is greater in
non-offset crashes than in offset crashes, and that there was virtually
no difference in the percentage of light vehicle crashes with PCI in
offset crashes and in non-offset crashes, NHTSA believes that the
performance of rear impact guards in the fleet \52\ in non-offset
crashes should be enhanced before turning to the issue of improving the
performance of the guards in offset crashes.
---------------------------------------------------------------------------

    \51\ ``None'' means no underride, ``Less than halfway'' means
underride extent of less than halfway up the hood, ``Halfway+''
means underride extent at or more than halfway up the hood but short
of the base of the windshield and ``Windshield+'' means intrusion at
or beyond the base of the windshield. This is also considered PCI.
    \52\ The 2013 UMTRI study was conducted using 2008 and 2009 TIFA
data files. The rear impact guards of the 2008-2009 trailers fleet
were mainly FMVSS No. 223 certified and some (pre-1998 models) were
FMCSR 393.86(b) certified.
---------------------------------------------------------------------------

    IIHS conducted 56 km/h crash tests of the 2010 Chevrolet Malibu
into the rear of trailers with full, 50 percent, and 30 percent overlap
of the Malibu front end with the rear impact guard. (The width of the
Chevrolet Malibu is 1790 mm. Therefore, 50 percent overlap is 995
(=1790 x 0.5 +100 \53\) mm from the rear lateral edge of the trailer
and 30 percent overlap is 637 (=1790 x 0.3+100) mm from the rear
lateral edge of the trailer.) See Figure 3. Since the vertical supports
of a typical trailer are located 753 mm from the lateral edge of the
trailer, we calculate that the vertical supports are engaged in crashes
with 50 percent overlap of the Malibu but not in 30 percent overlap
crashes. The percentage of light vehicle rear impacts with only 30
percent overlap with the rear impact guard (with the Malibu this would
be 637 mm from the lateral edge of the trailer or 25 percent of the
rear of the trailer engaged) would likely be a small percentage of rear
impact crashes into trailers.\54\
---------------------------------------------------------------------------

    \53\ 100 mm is the maximum allowable distance between lateral
edge of the rear impact guard and the lateral edge of the trailer
per FMVSS No. 224.
    \54\ The UMTRI study of 2008-2009 TIFA data files indicated that
light vehicle offset crashes into the rear of trailers (about 867 mm
from the edge of a 2,600 mm width trailer engaged) is about 40
percent of all light vehicle crashes into the rear of trailers.
Therefore, crashes with 25 percent of the trailer (637 mm for a
2,600 mm width trailer) would represent a significantly lower
percentage of light vehicle crashes into the rear of trailers.

---------------------------------------------------------------------------

[GRAPHIC] [TIFF OMITTED] TP16DE15.019

    Second, we are concerned that moving the P1 location would not
benefit safety overall. A comparison of the rear impact guard
performance of the Manac trailer and the Wabash trailer in the IIHS
crash tests of the Malibu indicate that moving the vertical supports
towards the lateral edges of the trailer, as with the Manac guard, does
show improved performance in the 30 percent overlap crash in the IIHS
test. However, moving the supports may reduce the performance of rear
impact guards in preventing PCI in the more common 50 and 100 percent
overlap crashes at higher speeds.
    In the crash tests conducted by IIHS, the Manac rear impact guard
was able to prevent PCI in the Chevy Malibu in the 56 km/h (35 mph) 30
percent overlap condition. Manac attaches the main vertical supports
outside of the axle rails. It fastens the guard to a reinforced floor
section. Moving the vertical supports further outboard as requested by
the petitioners may improve rear impact protection in small overlap
crashes of light vehicles into the rear of trailers, but mounting the
vertical supports further outboard 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.
    The Manac rear impact guard prevented PCI in 56 km/h (35 mph) crash
tests with full overlap, 50 percent and 30 percent overlap of the
Malibu. However, the full overlap crash test results indicate 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 for crash speeds greater
than 56 km/h (35 mph). Since full and 50 percent overlap crashes are
more frequent than low overlap (30 percent or less) crashes, and since
most fatal light vehicle impacts into the rear of trailers are at
speeds greater than 56 km/h (35 mph), such guard designs may reduce
protection against PCI in higher speed full and 50 percent overlap
crashes. It has not been shown that protection in the 30 percent
overlap crashes can be provided without degrading protection in the 50
and 100 percent overlap crashes. NHTSA is not convinced that improved
protection in the less frequent 30 percent overlap crashes should come
at the cost of adequate protection in the more common 50 and 100
percent overlap crashes.
    In addition, the suggested amendment to move the vertical supports
more outboard may not be practical for different trailer types.
Typically, the vertical supports of rear impact guards are attached to
the longitudinal members of the trailer frame that have sufficient
strength to withstand loads transferred from the guard in the event of
a rear impact. Moving the vertical supports further outboard would
require changes to trailer designs so that in a

rear impact, the loads from the guard can be transferred to
substantially strong structural members of the trailer. Such changes in
trailer design may add weight to the trailer, reduce payload, and may
not be practicable for all trailer types.
    IIHS suggested moving the P1 test location further outboard or
increasing the load in the quasi-static test at P1. However, IIHS did
not provide specifics on this request. As shown in Figure 2, the P1
test location is about 300 mm (12 inches) from the edge of a typical
trailer rear impact guard. It is not clear how moving the P1 location
further outboard or increasing the load in the quasi-static test would
improve guard performance in 56 km/h 30 percent overlap crashes and
what impact that would have on crashes with a full or 50 percent
overlap.

VI. Definition of ``Rear Extremity'' To Accommodate Aerodynamic Devices
on Trailers

    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. Boat tails generally extend several feet
beyond the end of the trailer.\55\ Some boat tails protrude so far
rearward that they could strike the passenger compartment of a vehicle
that impacts the trailer from the rear, notwithstanding the presence of
an upgraded underride guard.
---------------------------------------------------------------------------

    \55\ The Federal Highway Administration's (FHWA's) regulation 23
CFR part 658, ``Truck size and weight, route designations,'' limits
the length, width, and weight of trailers for purposes of ensuring
the highways can safely and efficiently accommodate large vehicles.
23 CFR 658.16, ``Exclusions from length and width determinations,''
excludes aerodynamic devices that extend a maximum of 1,524 mm (5
feet) beyond the rear of the vehicle from either the measured length
or width of a trailer. (Also, among other things, the aerodynamic
devices must ``have neither the strength, rigidity nor mass to
damage a vehicle, or injure a passenger in a vehicle, that strikes a
trailer so equipped from the rear, and provided also that they do
not obscure tail lamps, turn signals, marker lamps, identification
lamps, or any other required safety devices, such as hazardous
materials placards or conspicuity markings. Id.) This regulation has
the effect of limiting aerodynamic devices to 1,524 mm (5 feet))
when deployed.
---------------------------------------------------------------------------

    Currently, there is some ambiguity in FMVSS No. 224 as to how boat
tails are covered under the standard. FMVSS No. 224 (S5.1.3) requires
rear impact guards to be located at a maximum distance of 305 mm (12
inches) forward of the ``rear extremity'' of the trailer. One question
is whether a boat tail on a new trailer constitutes the ``rear
extremity'' of the vehicle. If it constitutes the rear extremity of the
vehicle, the underride guard must be positioned no further than 305 mm
(12 inches) forward of the boat tail. Another question is if the
features and design of the aerodynamic device matter as to whether it
should be considered the rear extremity of the vehicle.
    We propose amending FMVSS No. 224 to answer those questions and
make clearer its regulation of trailers with boat tails. We are
proposing to achieve this by replacing the current definition of ``rear
extremity'' in FMVSS No. 224 with that specified in CMVSS No. 223. The
amendment would better ensure that boat tails are located within a
certain safe zone at the rear of the trailer, and have features that
are beneficial to crash protection.
    In 2008, CMVSS No. 223 had the same definition of ``rear
extremity'' as FMVSS No. 224, and Transport Canada had challenges
similar to ours regarding boat tails. Transport Canada contracted the
Centre for Surface Transportation Technology of the National Research
Council (NRC) in Canada to study the aerodynamic gains of boat tails
and determine which types of vehicles and what percentage of vehicles
on the Canadian roads would strike the boat tail before striking the
rear underride guard of trailers. NRC also examined the effect of snow,
ice, and debris accumulation by boat tails, as well as downstream
visibility.
    NRC conducted wind tunnel experiments with different lengths,
heights, and shapes of aerodynamic rear-mounted trailer panels (boat
tails) to assess their drag reduction capability. Collision risk
analysis with boat tails was conducted using dimensional data and
population data of motor vehicles registered in Canada. The NRC also
developed computational fluid dynamics models to evaluate visibility
and particulate accumulation.
    The NRC report was published in December 2010.\56\ The main
findings of the NRC study are as follows:
---------------------------------------------------------------------------

    \56\ ``Trailer Boat Tail Aerodynamic and Collision Study,
Technical Report,'' National Research Council, Canada, Project 54-
A3871, CSTT-HVC-TR-169, December 2010.
---------------------------------------------------------------------------

     Reduction in drag and fuel consumption: The boat tails
reduced aerodynamic drag by 7.6 to 11.8 percent when the vehicle is
operating at 65 mph. This corresponds to an estimated 4.7 to 7.3
percent reduction in fuel consumption.
     Length of boat tails: The most significant aerodynamic
drag reduction occurred for boat tail lengths from 0 to 2 feet. For
boat tails longer than 2 feet, there is further drag reduction, but
only incrementally. Boat tails longer than 4 feet offered minimal or no
additional reduction in drag compared to shorter boat tails.
     Height of boat tails: Boat tails were most effective if at
least 75 percent of the height of the trailer has full length boat
tails. For most trailers, this corresponds to having full length boat
tails at heights above 1,800 mm from the ground.
     Boat tail length and shape at lower heights: Although full
length side panel boat tails that extend the entire height of the
trailer offered the best reduction in drag, nearly the same level of
drag reduction could be achieved by less. However, it was found that
there should be at least some boat tail structure at the lower part of
the trailer, even if it is significantly shorter than the higher
section of the boat tail. The complete absence of boat tail structure
at the bottom of the trailer significantly reduced the effectiveness of
the boat tails.
     Boat tail bottom panel: The presence of the bottom panel
was found to be more critical than the length of the side panels for
drag reduction. As much as 20 percent of the aerodynamic drag reduction
was from the bottom panel.
     Visibility and particulate material: Both 2 feet and 4
feet boat tail lengths provided a significant improvement in reduced
turbulence downstream of the trailer. However, there was a risk of
particulate accumulation (snow and ice) on the bottom panel of boat
tails.
     Collision Risk:
    [cir] If 4 foot long boat tails are fitted to trailers along their
entire height, 33.6 percent of vehicles on Canadian roads would strike
the boat tail before striking the rear impact underride guard, however
many of these contacts with the boat tail could be to the grille/hood
rather than the windshield.
    [cir] In order to prevent at least 90 percent of the vehicles on
the roads from initial boat tail strikes, the full length boat tails
(1,219 mm (4 feet)) should be mounted on the trailer higher than 1,740
mm (68 inches) from the ground.
    [cir] There are boat tail configurations that provide up to a 9
percent reduction in aerodynamic drag and less than a 15% risk of
collision before striking the underride guard. These configurations
have shorter boat tail lengths (610 mm (2 feet)) at heights below 1,740
mm (68 inches) above ground.
    Following the completion of the NRC of Canada study, Transport
Canada undertook rulemaking to develop a clearance zone to allow
aerodynamic devices (boat tails) that, in a collision, would not reduce
safety for occupants of vehicles which may strike the rear of

a trailer.\57\ The regulation, finalized on August 8, 2011, modified
the definition of ``rear extremity'' of the trailer (which was similar
to that currently specified in FMVSS No. 224) to read as follows:
---------------------------------------------------------------------------

    \57\ Transport Canada consulted with NHTSA on its rulemaking
before it issued its proposal on a revised definition of rear
extremity of a trailer.

    ``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 subsection (7) and when the
trailer's cargo doors, tailgate and other permanent structures are
positioned as they normally are when the trailer is in motion.
However, nonstructural protrusions, including but not limited to the
following, are excluded from the determination of the rearmost
point:
    (a) tail lamps;
    (b) rubber bumpers;
    (c) hinges and latches; and
    (d) flexible aerodynamic devices that are capable of being
folded to within 305 mm from the transverse vertical plane tangent
to the rearmost surface of the horizontal member and that, while
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 that intersects a point
located 1,210 mm rearward of the rearmost surface of the horizontal
member and 1,740 mm above the ground.

    Based on this language, the permitted zone for boat tails at the
rear of trailers is as shown in Figure 4, below.\58\ The reference to
``subsection (7)'' in the Transport Canada regulation set forth above
means the trailer is resting on level ground, unloaded, with its full
capacity of fuel, its tires inflated and its air suspension, if so
equipped, pressurized in accordance with the manufacturer's
recommendations.
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    \58\ The maximum length of aerodynamic devices of 1,542 mm (5
feet), specified in 23 CFR 658.16, ``Exclusions from length and
width determinations,'' applies at heights above 1900 mm from ground
level, as shown in Figure 4.
[GRAPHIC] [TIFF OMITTED] TP16DE15.020

    NHTSA is proposing to revise the definition of rear extremity in
FMVSS No. 224 to adopt that of Transport Canada, so as to define a zone
in which aerodynamic devices (boat tails) may be placed where, in a
collision, they would not reduce the safety of occupants of vehicles
striking the rear of a trailer. The agency expects that there will be
an increased use of aerodynamic devices in the rear of trailers in the
coming years for fuel efficiency purposes. NHTSA intends this proposal
to address the installation of aerodynamic devices on trailers and to
harmonize with the requirements of Transport Canada. Comments are
requested on the proposed amendment.

VII. Cost and Benefits Analysis

    NHTSA has prepared a Preliminary Regulatory Evaluation (PRE) for
this NPRM and has placed a copy of the PRE in the docket.
    For estimating the benefits of requiring applicable trailers to be
equipped with CMVSS No. 223 certified guards, NHTSA estimated the
annual number of fatalities in light vehicle crashes with PCI into the
rear of trailers. NHTSA only considered fatal crashes with PCI for the
target population because the IIHS test data presented in Appendix A of
this preamble show that when PCI was prevented, the dummy injury
measures were significantly below the injury assessment reference
values of NHTSA's occupant crash protection standard, and are likely
similar to values in crashes into the rear of passenger vehicles. In
non-PCI crashes into the rear of trailers, the IIHS test data indicate
that the passenger vehicle's restraint system, when used, would
mitigate injury. Therefore, non-PCI crashes were not considered as part
of the target population for estimating benefits.
    Annually, there are 72 light vehicle occupant fatalities in crashes
into the rear of trailers with rear impact guards with PCI. About 26
percent of fatal light vehicle crashes into the rear of trailers is at
speeds 56 km/h (35 mph) or less. The agency estimates that 19
fatalities (=72 x 0.26) are in crashes with relative velocity of 56 km/
h (35 mph) or less. 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 or less because some crashes may involve low
overlap (30 percent or less) and some fatalities may be due to
circumstances other than underride (i.e. unrestrained status of
occupants, elderly and other vulnerable occupants). For the purpose of
this analysis, NHTSA assumed that the incremental

effectiveness of CMVSS No. 223 compliant guards over FMVSS No. 223
compliant guards in preventing fatalities in light vehicle impacts with
PCI into the rear of trailers with crash speeds less than 56 km/h is 50
percent. 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%).
    The target population of fatalities considered is representative of
fatalities occurring in light vehicle crashes into the rear of trailers
that result in PCI. As noted above, in estimating benefits, the agency
assumed that the upgraded rear impact guards would mitigate fatalities
and injuries in light vehicle impacts with PCI into the rear of
trailers at impact speeds up to 56 km/h (35 mph), since the
requirements of CMVSS No. 223 are intended to prevent PCI in impacts
with speeds up to 56 km/h (35 mph). We recognize, however, that
benefits may accrue from underride crashes at speeds higher than 56 km/
h (35 mph), if, e.g., a vehicle's guard exceeded the minimum
performance requirements of the FMVSS. NHTSA requests information that
would assist the agency in quantifying the possible benefits of CMVSS
No. 223 rear impact guards in crashes with speeds higher than 56 km/h
(35 mph).
    We note also that, while CMVSS No. 223 requirements are intended
for mitigating PCI in light vehicle rear impacts at speeds less than or
equal to 56 km/h (35 mph),\59\ CMVSS No. 223 certified rear impact
guards may not be able to mitigate all fatalities in such crashes
because some of the crashes may be low overlap (30 percent or less)
\60\ and because some fatalities are not as a result of PCI but are due
to other circumstances (e.g. unrestrained status of occupants, elderly
occupants) in which improved rear impact guards may not have prevented
the fatalities.
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    \59\ Transport Canada testing of minimally compliant CMVSS No.
223 rear impact guards indicated that such guards could prevent PCI
in light vehicle impacts with full overlap with the guard at crash
speeds up to 56 km/h (35 mph). See Boucher D., Davis D., ``Trailer
Underride Protection--A Canadian Perspective,'' SAE Paper No. 2000-
01-3522, Truck and Bus Meeting and Exposition, December 2000,
Society of Automotive Engineers.
    \60\ Table 13 shows that 8 of the 9 rear impact guards tested by
IIHS could not prevent PCI in a 56 km/h (35 mph) crash with 30
percent overlap of the Chevrolet Malibu.
---------------------------------------------------------------------------

    The agency estimates that 93 percent of new trailers are already
equipped with CMVSS No. 223 compliant guards. Assuming 13 percent
effectiveness of these guards in fatal crashes with PCI into the rear
of trailers, the agency estimates 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. The agency
also estimated that a total of 2.7 serious injuries would be prevented
annually with the proposed underride guard rule. The equivalent lives
saved were estimated to be 1.1 and 1 lives discounted at 3 percent and
7 percent, respectively.
    NHTSA conducted a study to develop cost and weight estimates for
rear impact guards on heavy trailers.\61\ In this study, the agency
estimated the cost and weight of FMCSR 393.86(b) compliant rear impact
guards, FMVSS No. 223 compliant rear impact guards, and CMVSS No. 223
compliant rear impact guards (Table 10). All costs are presented in
2013 dollars.
---------------------------------------------------------------------------

    \61\ Cost and weight analysis for rear impact guards on heavy
trucks, Docket No. NHTSA-2011-0066-0086, June 2013.
---------------------------------------------------------------------------

    In estimating the cost and weight of guards in this study, an
engineering analysis of the guard system for each trailer was
conducted, including material composition, manufacturing and
construction methods and processes, component size, and attachment
methods. However, the researchers did not take into account the
construction, costs, and weight changes in the trailer structure in
order to withstand loads from the stronger guards. A limitation of this
analysis is the fact that the authors did not evaluate the changes in
design of the rear beam, frame rails, and floor of the trailer when
replacing a rear impact guard compliant with FMCSR 393.86(b) with an
FMVSS No. 224 compliant guard and then to a CMVSS No. 223 compliant
guard.

                                    Table 10--Cost (2013 Dollars) and Weight of Different Types of Rear Impact Guards
--------------------------------------------------------------------------------------------------------------------------------------------------------
          Type of rear impact guard               Trailer model year/make       Guard assembly   Installation cost      Total cost        Weight (lb)
--------------------------------------------------------------------------------------------------------------------------------------------------------
FMCSR 393.86(b).............................  1993 Great Dane...............             $65.31             $41.92            $107.23                 78
FMVSS No. 224...............................  2001 Great Dane...............             153.22             109.75             262.86                172
                                              2012 Great Dane...............             191.17             153.25             344.05                193
CMVSS No. 223...............................  2012 Manac....................             302.05             248.74             550.08                307
                                              2012 Stoughton................             248.02             222.37             470.91                191
                                              2012 Wabash...................             447.05             155.21             601.84                243
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The average cost of a Canadian compliant rear impact guard is $492,
which is $229 more than an FMVSS No. 224 compliant guard. The
incremental cost of equipping CMVSS No. 223 compliant rear impact
guards on applicable new trailers (those that are subject to FMVSS No.
223) is $229. There are 243,873 trailers sold in 2013,\62\ among which
65 percent (see Appendix A to this preamble, Table A-1) are required to
be equipped with rear impact guards. Of those, 93 percent are 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 is approximately $2.5 million (= 243,873 x 0.65 x (1.0-
0.93) x $229).
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    \62\ http://trailer-bodybuilders.com/trailer-output/2014-trailer-production-figures-table.
---------------------------------------------------------------------------

    As shown in Table 10, upgrading from the FMVSS No. 224 compliant
guard to the CMVSS No. 223 compliant guard would add an average
incremental weight of 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 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 is $9.2 million and $8.2 million
discounted at 3 percent and 7 percent, respectively. Therefore the
total cost of the proposed rule, including material and fuel costs is
$11.77 million discounted at 3 percent and $10.76 million discounted at
7 percent (Table 11).

          Table 11--Cost of Proposed Rule With Average Increase in Weight, in Millions, in 2013 Dollars
----------------------------------------------------------------------------------------------------------------
                          Cost                              No-discount             3%                 7%
----------------------------------------------------------------------------------------------------------------
Material...............................................              $2.54              $2.54              $2.54
Fuel...................................................              10.44               9.23               8.22
                                                        --------------------------------------------------------
    Total..............................................              12.98              11.77              10.76
----------------------------------------------------------------------------------------------------------------

    The agency estimates that the net cost per equivalent lives saved
is $9.1 million and $9.5 million discounted at 3 percent and 7 percent,
respectively. A summary of the regulatory cost and net benefit of the
proposed rule at the 3 percent and 7 percent discount rates are
presented in Table 12. At 3 percent discount rate, the net benefit of
the proposed rule is $0.59 million. At 7 percent discount rate, the net
benefit of the proposed rule is $0.13 million.

                                        Table 12--Cost-Effectiveness and Net Benefits (2013 dollars), in Million
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Societal Econ.                        Total benefits
                         Discount                           Regulatory cost        savings          VSL* savings           \1\          Net benefits \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
3%.......................................................             $11.77              $1.52             $10.85             $12.37              $0.59
7%.......................................................              10.76               1.35               9.54              10.89               0.13
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Value of Statistical Life.
\1\ Total Benefit = Societal Economic Benefit + VSL Benefit.
\2\ Net Benefit = Total Benefit-Regulatory Cost.

    For further information regarding the aforementioned cost and
benefit estimates, please reference the preliminary regulatory
evaluation (PRE) that NHTSA prepared and placed in the Docket.\63\
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    \63\ The PRE discusses issues relating to the potential costs,
benefits, and other impacts of this regulatory action. The PRE is
available in the docket for this NPRM and may be obtained by
downloading it or by contacting Docket Management at the address or
telephone number provided at the beginning of this document.
---------------------------------------------------------------------------

    We have tentatively decided not to require used trailers be
retrofitted with CMVSS No. 223 compliant rear impact guards. Our
analysis indicates such a retrofitting requirement would be very costly
without sufficient safety benefits. The net benefit for a retrofitting
requirement was estimated to be -$402 million at 3 percent discount
rate and -$414 million at 7 percent discount rate. Details of the
analysis for a retrofitting requirement are provided in the PRE.

VIII. Proposed Lead Time

    NHTSA proposes a lead time of two years following date of
publication of a final rule. NHTSA provided a two year lead time when
FMVSS Nos. 223 and 224 were adopted. We note that 93 percent of
trailers already meet the requirements of CMVSS No. 223, so we
tentatively conclude that two years will provide sufficient time for
guard and trailer manufacturers to meet the requirements proposed
today. Comments are requested on whether the lead time is appropriate.

IX. Regulatory Notices and Analyses

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

    The agency has considered the impact of this rulemaking action
under E.O. 12866, E.O. 13563, and the Department of Transportation's
regulatory policies and procedures. This rulemaking was not reviewed by
the Office of Management and Budget under E.O. 12866, ``Regulatory
Planning and Review.'' The rulemaking action has also been determined
to be not significant under the Department's regulatory policies and
procedures. NHTSA's Preliminary Regulatory Evaluation fully discusses
the estimated costs, benefits and other impacts of this NPRM.
    As discussed in the PRE and summarized in the section above, the
annual incremental fleet cost of equipping all applicable trailers with
CMVSS No. 223 rear impact guards is estimated to be approximately $2.5
million (= 243,873 x 0.65 x (1.0-0.93) x $229). The agency estimates
that 93 percent of new trailers in the U.S. are already equipped with
CMVSS No. 223 compliant guards. The agency estimates that the
incremental effectiveness of CMVSS No. 223 guards over FMVSS No. 223
guards is 13 percent in preventing fatalities in light vehicle crashes
with PCI into the rear of trailers. The agency estimates that about
0.66 life (= 72 x (1-0.93) x 0.13) would be saved annually by requiring
all applicable trailers to be equipped with CMVSS No. 223 compliant
guards.\64\ The agency also estimated that a total of 2.7 serious
injuries would be prevented annually with the proposed underride guard
rule. The equivalent lives saved were estimated to be 1.1 and 1 lives
discounted at 3 percent and 7 percent, respectively. The agency
estimates that the net cost per equivalent lives saved is $9.1 million
and $9.5 million discounted at 3 percent and 7 percent, respectively.
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    \64\ CMVSS No. 223 compliant rear impact guards may mitigate the
severity of impact into the rear of trailers at speeds greater than
56 km/h (35 mph), but NHTSA is unable to quantify this possible
benefit at this time. We seek comment on this issue.
---------------------------------------------------------------------------

    Consistent with E.O. 13563, ``Improving Regulation and Regulatory
Review,'' NHTSA is proposing to amend FMVSS Nos. 223 and 224 as a
result 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 has
undertaken 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 businesses, small
organizations, and small governmental