
[Federal Register Volume 80, Number 241 (Wednesday, December 16, 2015)]
[Proposed Rules]
[Pages 78417-78460]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-31228]



[[Page 78417]]

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  

[[Page 78418]]


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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: (202) 493-2251.
    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: 202-493-2990). For legal issues, you may contact 
Deirdre Fujita, Office of Chief Counsel (telephone: 202-366-2992) (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

[[Page 78419]]

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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[[Page 78420]]

    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

[[Page 78421]]

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.

[[Page 78422]]



 Table 2--Comparison of Rear Impact Protection Requirements in the U.S.
                               and Canada
------------------------------------------------------------------------
          Requirement                   U.S.                Canada
------------------------------------------------------------------------
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.
------------------------------------------------------------------------

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

    \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.

[[Page 78423]]

 
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

[[Page 78424]]

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

[[Page 78425]]

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

[[Page 78426]]

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.

[[Page 78427]]



 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.

[[Page 78428]]

[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

[[Page 78429]]

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

[[Page 78430]]

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.

[[Page 78431]]

[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.

[[Page 78432]]



 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.

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

[[Page 78433]]

[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

[[Page 78434]]

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

[[Page 78435]]

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

    \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

[[Page 78436]]

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

    \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).
---------------------------------------------------------------------------

    \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).

[[Page 78437]]



          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\
---------------------------------------------------------------------------

    \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.
---------------------------------------------------------------------------

    \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

[[Page 78438]]

jurisdictions), unless the head of an agency certifies the rule will 
not have a significant economic impact on a substantial number of small 
entities. Agencies must also provide a statement of the factual basis 
for this certification.
    I certify that this proposed rule would not have a significant 
economic impact on a substantial number of small entities. NHTSA 
estimates there to be 354 manufacturers of trailers in the U.S., 331 of 
which are small businesses. The impacts of this proposed rule on small 
trailer manufacturers would not be significant. This NPRM proposes 
changes to the strength requirements applying to underride guards, but 
would not be amending the method by which small trailer manufacturers 
can certify compliance with FMVSS Nos. 223 and 224.
    FMVSS No. 223, an equipment standard, specifies strength and energy 
absorption requirements in quasi-static force tests of rear impact 
guards sold for installation on new trailers and semitrailers. FMVSS 
No. 224, a vehicle standard, requires new trailers and semitrailers 
with a GVWR of 4,536 kg (10,000 lb) or more to be equipped with a rear 
impact guard meeting FMVSS No. 223. NHTSA established the two-standard 
approach to provide underride protection in a manner that imposes 
reasonable compliance burdens on small trailer manufacturers.
    Under FMVSS No. 223, the guard may be tested for compliance while 
mounted to a test fixture or to a complete trailer. FMVSS No. 224 
requires that the guard be mounted on the trailer or semitrailer in 
accordance with the instructions provided with the guard by the guard 
manufacturer. Under this approach, a small manufacturer that produces 
relatively few trailers can certify its trailers to FMVSS No. 224 
without feeling compelled to undertake destructive testing of what 
could be a substantial portion of its production. The two-standard 
approach was devised to provide small manufacturers a practicable and 
reasonable means of meeting the safety need served by an underride 
guard requirement. This NPRM does not propose changing the method of 
certifying compliance to the underride guard requirements of FMVSS Nos. 
223 and 224.

National Environmental Policy Act

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

Executive Order 13132 (Federalism)

    NHTSA has examined today's proposed rule pursuant to Executive 
Order 13132 (64 FR 43255, August 10, 1999) and concluded that no 
additional consultation with States, local governments or their 
representatives is mandated beyond the rulemaking process. The agency 
has concluded that the rulemaking would not have sufficient federalism 
implications to warrant consultation with State and local officials or 
the preparation of a federalism summary impact statement. The proposed 
rule would not have ``substantial direct effects on the States, on the 
relationship between the national government and the States, or on the 
distribution of power and responsibilities among the various levels of 
government.''
    NHTSA rules can preempt in two ways. First, the National Traffic 
and Motor Vehicle Safety Act contains an express preemption provision: 
When a motor vehicle safety standard is in effect under this chapter, a 
State or a political subdivision of a State may prescribe or continue 
in effect a standard applicable to the same aspect of performance of a 
motor vehicle or motor vehicle equipment only if the standard is 
identical to the standard prescribed under this chapter. 49 U.S.C. 
Sec.  30103(b)(1). It is this statutory command by Congress that 
preempts any non-identical State legislative and administrative law 
addressing the same aspect of performance.
    The express preemption provision described above is subject to a 
savings clause under which ``[c]ompliance with a motor vehicle safety 
standard prescribed under this chapter does not exempt a person from 
liability at common law.'' 49 U.S.C. Sec.  30103(e) Pursuant to this 
provision, State common law tort causes of action against motor vehicle 
manufacturers that might otherwise be preempted by the express 
preemption provision are generally preserved. However, the Supreme 
Court has recognized the possibility, in some instances, of implied 
preemption of such State common law tort causes of action by virtue of 
NHTSA's rules, even if not expressly preempted. This second way that 
NHTSA rules can preempt is dependent upon there being an actual 
conflict between an FMVSS and the higher standard that would 
effectively be imposed on motor vehicle manufacturers if someone 
obtained a State common law tort judgment against the manufacturer, 
notwithstanding the manufacturer's compliance with the NHTSA standard. 
Because most NHTSA standards established by an FMVSS are minimum 
standards, a State common law tort cause of action that seeks to impose 
a higher standard on motor vehicle manufacturers will generally not be 
preempted. However, if and when such a conflict does exist--for 
example, when the standard at issue is both a minimum and a maximum 
standard--the State common law tort cause of action is impliedly 
preempted. See Geier v. American Honda Motor Co., 529 U.S. 861 (2000).
    Pursuant to Executive Order 13132 and 12988, NHTSA has considered 
whether this proposed rule could or should preempt State common law 
causes of action. The agency's ability to announce its conclusion 
regarding the preemptive effect of one of its rules reduces the 
likelihood that preemption will be an issue in any subsequent tort 
litigation. To this end, the agency has examined the nature (e.g., the 
language and structure of the regulatory text) and objectives of 
today's proposed rule and finds that this proposed rule, like many 
NHTSA rules, would prescribe only a minimum safety standard. As such, 
NHTSA does not intend that this proposed rule would preempt state tort 
law that would effectively impose a higher standard on motor vehicle 
manufacturers than that established by today's proposed rule. 
Establishment of a higher standard by means of State tort law would not 
conflict with the minimum standard proposed here. Without any conflict, 
there could not be any implied preemption of a State common law tort 
cause of action.

Civil Justice Reform

    With respect to the review of the promulgation of a new regulation, 
section 3(b) of Executive Order 12988, ``Civil Justice Reform'' (61 FR 
4729, February 7, 1996) requires that Executive agencies make every 
reasonable effort to ensure that the regulation: (1) Clearly specifies 
the preemptive effect; (2) clearly specifies the effect on existing 
Federal law or regulation; (3) provides a clear legal standard for 
affected conduct, while promoting simplification and burden reduction; 
(4) clearly specifies the retroactive effect, if any; (5) adequately 
defines key terms; and (6) addresses other important issues affecting 
clarity and general draftsmanship under any guidelines issued by the 
Attorney General. This document is consistent with that requirement.
    Pursuant to this Order, NHTSA notes as follows. The preemptive 
effect of this proposed rule is discussed above. NHTSA notes further 
that there is no requirement that individuals submit a

[[Page 78439]]

petition for reconsideration or pursue other administrative proceeding 
before they may file suit in court.

Paperwork Reduction Act (PRA)

    Under the Paperwork Reduction Act of 1995, a person is not required 
to respond to a collection of information by a Federal agency unless 
the collection displays a valid OMB control number. Before seeking OMB 
approval, Federal agencies must provide a 60-day public comment period 
and otherwise consult with members of the public and affected agencies 
concerning each collection of information requirement. There are no 
Paperwork Reduction Act requirements associated with this proposed 
rule.

National Technology Transfer and Advancement Act

    Under the National Technology Transfer and Advancement Act of 1995 
(NTTAA) (Pub. L. 104-113), all Federal agencies and departments shall 
use technical standards that are developed or adopted by voluntary 
consensus standards bodies, using such technical standards as a means 
to carry out policy objectives or activities determined by the agencies 
and departments. Voluntary consensus standards are technical standards 
(e.g., material specifications, test methods, sampling procedures, and 
business practices) that are developed or adopted by voluntary 
consensus standards bodies, such as the International Organization for 
Standardization (ISO) and the Society of Automotive Engineers (SAE). 
The NTTAA directs us to provide Congress, through OMB, explanations 
when we decide not to use available and applicable voluntary consensus 
standards.
    This NPRM proposes to adopt requirements of CMVSS No. 223, as 
discussed later in this section. NHTSA's consideration of CMVSS No. 223 
accords with the principles of NTTAA, in that NHTSA is considering an 
established, proven standard, and has not had to expend significant 
agency resources on the same safety need addressed by CMVSS No. 223.

Unfunded Mandates Reform Act

    Section 202 of the Unfunded Mandates Reform Act of 1995 (UMRA), 
Pub. L. 104-4, requires Federal agencies to prepare a written 
assessment of the costs, benefits, and other effects of proposed or 
final rules that include a Federal mandate likely to result in the 
expenditure by State, local, or tribal governments, in the aggregate, 
or by the private sector, of more than $100 million annually (adjusted 
for inflation with base year of 1995). Adjusting this amount by the 
implicit gross domestic product price deflator for the year 2013 
results in $142 million (106.733/75.324 = 1.42). This NPRM would not 
result in a cost of $142 million or more to either State, local, or 
tribal governments, in the aggregate, or the private sector. Thus, this 
NPRM is not subject to the requirements of sections 202 of the UMRA.

Executive Order 13609 (Promoting International Regulatory Cooperation)

    The policy statement in section 1 of E.O. 13609 provides, in part:
    The regulatory approaches taken by foreign governments may differ 
from those taken by U.S. regulatory agencies to address similar issues. 
In some cases, the differences between the regulatory approaches of 
U.S. agencies and those of their foreign counterparts might not be 
necessary and might impair the ability of American businesses to export 
and compete internationally. In meeting shared challenges involving 
health, safety, labor, security, environmental, and other issues, 
international regulatory cooperation can identify approaches that are 
at least as protective as those that are or would be adopted in the 
absence of such cooperation. International regulatory cooperation can 
also reduce, eliminate, or prevent unnecessary differences in 
regulatory requirements.
    This rulemaking is considering adopting requirements of CMVSS No. 
223 to upgrade FMVSS Nos. 223 and 224. In 2005, Transport Canada issued 
upgraded rear impact protection requirements for trailers and 
semitrailers. Given that passenger car models manufactured in 2005 and 
later 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). FMVSS No. 208 has similar occupant protection requirements as 
those applicable in Canada. NHTSA believes that the FMVSS Nos. 223 and 
224 requirements can be upgraded to that required by CMVSS No. 223's 
upgraded requirements for the same principles underlying the CMVSS No. 
223 upgrade.
    CMVSS No. 223, ``Rear impact guards,'' is applicable to trailers 
and semitrailers and has similar geometric specifications for rear 
impact guards as FMVSS No. 224. CMVSS No. 223 specifies quasi-static 
loading tests similar to those in FMVSS No. 223. However, CMVSS No. 223 
replaced 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.\65\ 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 after the test not exceeding 560 mm (22 
inches). 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. These requirements 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).
---------------------------------------------------------------------------

    \65\ 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.
---------------------------------------------------------------------------

    Table 13 presents a comparison of rear impact protection 
requirements for trailers in the U.S., Canada, and Europe.

      Table 13--Comparison of Rear Impact Protection Requirements for Trailers in U.S., Canada, and Europe
----------------------------------------------------------------------------------------------------------------
             Requirement                         U.S.                    Canada                   Europe
----------------------------------------------------------------------------------------------------------------
Applicable standards.................  FMVSS No. 223/224......  CMVSS No. 223..........  ECE R.58.
----------------------------------------------------------------------------------------------------------------
                                  Geometric requirements in unloaded condition
----------------------------------------------------------------------------------------------------------------
Ground clearance.....................  560 mm.................  560 mm.................  550 mm.
Longitudinal distance from rear        305 mm.................  305 mm.................
 extremity.

[[Page 78440]]

 
Lateral distance from side of vehicle  100 mm.................  100 mm.................  100 mm.
----------------------------------------------------------------------------------------------------------------
                                             Quasi-static load tests
----------------------------------------------------------------------------------------------------------------
Point load at P1 (outer edge of        50 kN..................  50 kN..................  25 kN.
 guard).
Point load at P2 (center of guard)...  50 kN..................  50 kN..................  25 kN.
Point load at P3 (at the guard         100 kN with no more                               100 kN with distance of
 supports).                             than 125 mm                                       rear impact guard from
                                        displacement, 5,650 J                             vehicle rear extremity
                                        energy absorption.                                of 400 mm after test.
Distributed load.....................                           350 kN with no more
                                                                 than 125 mm
                                                                 displacement and
                                                                 20,000 J energy
                                                                 absorption; guard
                                                                 ground clearance less
                                                                 than 560 mm after test.
----------------------------------------------------------------------------------------------------------------

    The European standard, ECE R.58, ``Rear underrun protective devices 
(RUPD); Vehicles with regard to the installation of an RUPD of an 
approved vehicle; Vehicles with regard to their rear underrun 
protection,'' specifies rear impact protection requirements for 
trailers weighing more than 3,500 kg (7,716 lb). The dimensional and 
strength requirements for rear impact guards in ECE R.58 are similar to 
but less stringent than those specified in FMVSS Nos. 223 and 224. ECE 
R.58 specifies that both during and after the quasi-static force 
application test, the horizontal distance between the rear of the rear 
impact guard and the rear extremity of the vehicle not be greater than 
400 mm. However, ECE R.58 does not specify any energy absorption 
requirements.
    NHTSA has decided to propose the strength requirements of CMVSS No. 
223 rather than ECE R.58 because the rear impact protection 
requirements for trailers in Canada are more stringent than that in 
Europe, and more appropriate for the underride crashes experienced in 
the U.S. Passenger vehicles in the U.S. are required by FMVSS No. 208 
to have frontal air bag protection and comply with a full frontal 56 
km/h (35 mph) rigid barrier crash test by ensuring that the injury 
measures of crash test dummies restrained in front seating positions 
are within the allowable limits. CMVSS No. 223 is designed to prevent 
PCI in full frontal 56 km/h (35 mph) crashes. Together, FMVSS No. 208 
and FMVSS Nos. 223 and 224 would significantly reduce the harm 
resulting to occupants of passenger vehicles impacting the rear of 
trailers in crashes of up to 56 km/h (35 mph).

Regulation Identifier Number

    The Department of Transportation assigns a regulation identifier 
number (RIN) to each regulatory action listed in the Unified Agenda of 
Federal Regulations. The Regulatory Information Service Center 
publishes the Unified Agenda in April and October of each year. You may 
use the RIN contained in the heading at the beginning of this document 
to find this action in the Unified Agenda.

Plain Language

    Executive Order 12866 requires each agency to write all rules in 
plain language. Application of the principles of plain language 
includes consideration of the following questions:
     Have we organized the material to suit the public's needs?
     Are the requirements in the rule clearly stated?
     Does the rule contain technical language or jargon that 
isn't clear?
     Would a different format (grouping and order of sections, 
use of headings, paragraphing) make the rule easier to understand?
     Would more (but shorter) sections be better?
     Could we improve clarity by adding tables, lists, or 
diagrams?
     What else could we do to make the rule easier to 
understand?
    If you have any responses to these questions, please write to us 
with your views.

Privacy Act

    In accordance with 5 U.S.C. 553(c), DOT solicits comments from the 
public to better inform its rulemaking process. DOT posts these 
comments, without edit, including any personal information the 
commenter provides, to www.regulations.gov, as described in the system 
of records notice (DOT/ALL-14 FDMS), which can be reviewed at 
www.dot.gov/privacy.

X. Public Participation

    In developing this proposal, we tried to address the concerns of 
all our stakeholders. Your comments will help us improve this proposed 
rule. We welcome your views on all aspects of this proposed rule, but 
request comments on specific issues throughout this document. Your 
comments will be most effective if you follow the suggestions below:
     Explain your views and reasoning as clearly as possible.
     Provide solid technical and cost data to support your 
views.
     If you estimate potential costs, explain how you arrived 
at the estimate.
     Tell us which parts of the proposal you support, as well 
as those with which you disagree.
     Provide specific examples to illustrate your concerns.
     Offer specific alternatives.
     Refer your comments to specific sections of the proposal, 
such as the units or page numbers of the preamble, or the regulatory 
sections.
     Be sure to include the name, date, and docket number with 
your comments.
    Your comments must be written and in English. To ensure that your 
comments are correctly filed in the docket, please include the docket 
number of this document in your comments.
    Your comments must not be more than 15 pages long (49 CFR Sec.  
553.21).

[[Page 78441]]

We established this limit to encourage you to write your primary 
comments in a concise fashion. However, you may attach necessary 
additional documents to your comments. There is no limit on the length 
of the attachments.
    Please submit your comments to the docket electronically by logging 
onto http://www.regulations.gov or by the means given in the ADDRESSES 
section at the beginning of this document.
    Please note that pursuant to the Data Quality Act, in order for 
substantive data to be relied upon and used by the agency, it must meet 
the information quality standards set forth in the OMB and DOT Data 
Quality Act guidelines. Accordingly, we encourage you to consult the 
guidelines in preparing your comments. OMB's guidelines may be accessed 
at http://www.whitehouse.gov/omb/fedreg/reproducible.html.

How do I submit confidential business information?

    If you wish to submit any information under a claim of 
confidentiality, you should submit three copies of your complete 
submission, including the information you claim to be confidential 
business information, to the Chief Counsel, NHTSA, at the address given 
above under FOR FURTHER INFORMATION CONTACT. In addition, you should 
submit a copy from which you have deleted the claimed confidential 
business information to the docket. When you send a comment containing 
information claimed to be confidential business information, you should 
include a cover letter setting forth the information specified in our 
confidential business information regulation. (49 CFR Part 512.)

Will the agency consider late comments?

    We will consider all comments that the docket receives before the 
close of business on the comment closing date indicated above under 
DATES. To the extent possible, we will also consider comments that the 
docket receives after that date. If the docket receives a comment too 
late for us to consider it in developing a final rule (assuming that 
one is issued), we will consider that comment as an informal suggestion 
for future rulemaking action.

How can I read the comments submitted by other people?

    You may read the comments received by the docket at the address 
given above under ADDRESSES. You may also see the comments on the 
Internet (http://regulations.gov).
    Please note that even after the comment closing date, we will 
continue to file relevant information in the docket as it becomes 
available. Further, some people may submit late comments. Accordingly, 
we recommend that you periodically check the docket for new material.
    Anyone is able to search the electronic form of all comments 
received into any of our dockets by the name of the individual 
submitting the comment (or signing the comment, if submitted on behalf 
of an association, business, labor union, etc.). You may review DOT's 
complete Privacy Act Statement in the Federal Register published on 
April 11, 2000 (Volume 65, Number 70; Pages 19477-78). See Privacy Act 
heading above under Rulemaking Analyses and Notices.

List of Subjects in 49 CFR Part 571

    Imports, Motor vehicle safety, Motor vehicles, Rubber and rubber 
products, Tires.

    In consideration of the foregoing, NHTSA proposes to amend 49 CFR 
part 571 as set forth below.

PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS

0
1. The authority citation for Part 571 continues to read as follows:

    Authority: 49 U.S.C. 322, 30111, 30115, 30117 and 30166; 
delegation of authority at 49 CFR 1.95.

0
2. Section 571.223 is amended by:
0
a. Revising S3;
0
b. Amending S4 by adding a definition of ``ground clearance,'' in 
alphabetical order;
0
c. Revising S5.2; S5.5(c); the introductory text of S6; the last 
sentence of S6.1; S6.3; the introductory texts of S6.4, S6.4(a), and 
S6.4(b);
0
d. Removing S6.4(c);
0
e. Revising S6.5 and S6.6;
0
f. Adding S6.7 through S6.9; and,
0
g. Revising Figures 1 and 2, and adding Figures 3 and 4.
    The added and amended text and figures read as follows:


Sec.  571.223  Standard No. 223; Rear impact guards.

* * * * *
    S3. Application. This standard applies to rear impact guards for 
trailers and semitrailers subject to Federal Motor Vehicle Safety 
Standard No. 224, Rear Impact Protection (Sec.  571.224).
    S4.
* * * * *
    Ground clearance means the vertical distance from the bottom edge 
of a horizontal member to the ground.
* * * * *
    S5.2 Strength and Energy Absorption. When tested under the 
procedures of S6 of this section, each guard shall comply with the 
strength requirements of S5.2.1 of this section at each test location, 
and the energy absorption requirements of S5.2.2 of this section when a 
distributed load is applied uniformly across the horizontal member as 
specified in S6.6 of this section. However, a particular guard (i.e., 
test specimen) need not be tested at more than one location.
    S5.2.1 Guard Strength. The guard must resist the force levels 
specified in S5.2.1 (a) through (c) of this section without deflecting 
by more than 125 mm and without complete separation of any portion of 
the guard and guard attachments from its mounting structure.
    (a) A force of 50,000 N applied in accordance with S6.8 at test 
location P1 on either the left or the right side of the guard, as 
defined in S6.4(a) of this section.
    (b) A force of 50,000 N applied in accordance with S6.8 at test 
location P2, as defined in S6.4(b) of this section.
    (c) A uniform distributed force of at least 350,000 N applied 
across the horizontal member, as specified in S6.6 and in accordance 
with S6.8.
S5.2.2 Guard Energy Absorption
    (a) A guard, other than a hydraulic guard or one installed on a 
tanker trailer, when subjected to a uniform distributed load applied in 
accordance with S6.8(c) of this section:
    (1) shall absorb by plastic deformation at least 20,000 J of energy 
within the first 125 mm of deflection without complete separation of 
any portion of the guard and guard attachments from its mounting 
structure; and
    (2) have a ground clearance not exceeding 560 mm, measured at each 
support to which the horizontal member is attached, as shown in Figure 
4, after completion of the load application.
    (b) A guard, other than a hydraulic guard or one installed on a 
tanker trailer, that demonstrates resistance to a uniform distributed 
load greater than 700,000 N applied in accordance with S6.8(b) of this 
section, need not meet the energy absorption requirements of S5.2.2(a) 
but must have a ground clearance not exceeding 560 mm at each vertical 
support to which the horizontal member is attached after completion of 
the 700,000 N load application.
* * * * *
    S5.5
* * * * *
    (c) An explanation of the method of attaching the guard to the 
chassis of each vehicle make and model listed or to the design elements 
specified in the instructions or procedures. The

[[Page 78442]]

principal aspects of vehicle chassis configuration that are necessary 
to the proper functioning of the guard shall be specified including the 
maximum allowable vertical distance between the bottom edge of the 
horizontal member of the guard and the ground to ensure post-test 
ground clearance requirements are met. If the chassis strength is 
inadequate for the guard design, the instructions or procedures shall 
specify methods for adequately reinforcing the vehicle chassis. 
Procedures for properly installing any guard attachment hardware shall 
be provided.
    S6. Guard Test Procedures. The procedures for determining 
compliance with S5.2 of this section are specified in S6.1 through S6.9 
of this section.
    S6.1 * * * The hydraulic units are compressed before the 
application of force to the guard in accordance with S6.8 of this 
section and maintained in this condition throughout the testing under 
S6.8 of this section.
* * * * *
    S6.3 Point Load Force Application Device. The force application 
device employed in S6.8 of this section consists of a rectangular solid 
made of rigid steel. The steel solid is 203 mm in height, 203 mm in 
width, and 25 mm in thickness. The 203 mm by 203 mm face of the block 
is used as the contact surface for application of the forces specified 
in S5.2.1 (a) and (b) of this section. Each edge of the contact surface 
of the block has a radius of curvature of 5 mm plus or minus 1 mm.
    S6.4 Point Load Test Locations. With the guard mounted to the rigid 
test fixture or to a complete trailer, determine the test locations P1 
and P2 in accordance with the procedure set forth in S6.4 (a) and (b) 
of this section. See Figure 1 of this section.
    (a) Point Load Test location P1 is the point on the rearmost 
surface of the horizontal member of the guard that:
* * * * *
    (b) Point Load Test location P2 is the point on the rearmost 
surface of the horizontal member of the guard that:
* * * * *
    S6.5 Uniform Distributed Load Force Application Device. The force 
application device to be employed in applying the uniform distributed 
load is to be unyielding, have a height of 203 mm, and have a width 
that exceeds the distance between the outside edges of the outermost 
supports to which the tested portion of the horizontal member is 
attached, as shown in Figure 2.
    S6.6 Uniform Distributed Load Test Location. With the guard mounted 
to the rigid test fixture or to a complete trailer, determine the test 
location in accordance with the following procedure. See Figure 2 of 
this section. Distributed Force Test location is the plane on the 
rearmost surface of the horizontal member of the guard that:
    (a) Is centered in the longitudinal vertical plane passing through 
the center of the guard's horizontal member; and
    (b) Is centered 50 mm above the bottom of the guard.
    S6.7 Positioning of Force Application Device. Before applying any 
force to the guard, locate the force application device specified in 
S6.3 for the point load test location and that specified in S6.5 for 
the uniform distributed load test location, such that:
    (a) The center point of the contact surface of the force 
application device is aligned with and touching the guard test 
location, as defined by the specifications of S6.4 of this section for 
the point load test locations, and S6.6 of this section for the uniform 
distributed load test location.
    (b) The longitudinal axis of the force application device passes 
through the test location and is perpendicular to the transverse 
vertical plane that is tangent to the rearmost surface of the guard's 
horizontal member.
    (c) If the guard is tested on a rigid test fixture, the vertical 
distance from the bottom edge of the horizontal member to the ground at 
the location of each support to which the horizontal member is 
attached, shall be measured.
    S6.8 Force Application. After the force application device has been 
positioned, according to S6.7 of this section, at the point load test 
locations specified in S6.4 of this section or the uniform distributed 
load test location specified in S6.6 of this section, apply the loads 
specified in S5.2 of this section. Load application procedures are 
specified in S6.8 (a) through (d) of this section.
    (a) Using the force application device, apply force to the guard in 
a forward direction such that the displacement rate of the force 
application device is the rate, plus or minus 10 percent, designated by 
the guard manufacturer within the range of 2.0 cm per minute to 9.0 cm 
per minute. If the guard manufacturer does not designate a rate, any 
rate within that range may be chosen.
    (b) If conducting a strength test to satisfy the requirement of 
S5.2.1 or S5.2.2(b) of this section, the force is applied until the 
forces specified in S5.2.1 or S5.2.2(b) of this section have been 
exceeded, or until the displacement of the force application device has 
reached at least 125 mm, whichever occurs first.
    (c) If conducting a test to be used for the calculation of energy 
absorption levels to satisfy the requirement of S5.2.2(a) of this 
section, apply a uniform distributed force to the guard until 
displacement of the force application device, specified in S6.5 of this 
section, has reached 125 mm. For calculation of guard energy 
absorption, the value of force is recorded at least ten times per 25 mm 
of displacement of the contact surface of the loading device. Reduce 
the force until the guard no longer offers resistance to the force 
application device. Produce a force vs. deflection diagram of the type 
shown in Figure 3 of this section using this information. Determine the 
energy absorbed by the guard by calculating the shaded area bounded by 
the curve in the force vs. deflection diagram and the abscissa (X-
axis).
    (d) During each force application, the force application device is 
guided so that it does not rotate. At all times during the application 
of force, the location of the longitudinal axis of the force 
application device remains constant.
S6.9 Ground Clearance Measurement
    (a) For the test device attached to a complete trailer as specified 
in S6.2, the ground clearance of the guard at the vertical supports to 
which the horizontal member is attached shall be measured after 
completion of the uniform distributed load test in accordance with 
S6.8(b) or S6.8(c) of this section.
    (b) For the test device attached to a rigid test fixture as 
specified in S6.2, the vertical distance from the ground to the bottom 
edge of the horizontal member at the vertical supports to which the 
horizontal member is attached shall be measured after completion of the 
uniform distributed load test in accordance with S6.8(b) or S6.8(c) of 
this section and subtracted from the corresponding ground clearance 
measured before the load application in accordance with S6.7(c). The 
difference in ground clearance before and after the load application is 
added to the allowable maximum vertical distance between the bottom 
edge of the horizontal member of the guard and the ground as specified 
in S5.5(c), to obtain the ground clearance after completion of the 
uniform distributed load test.
BILLING CODE 4910-59-P

[[Page 78443]]

[GRAPHIC] [TIFF OMITTED] TP16DE15.021


[[Page 78444]]


[GRAPHIC] [TIFF OMITTED] TP16DE15.022


[[Page 78445]]


[GRAPHIC] [TIFF OMITTED] TP16DE15.023


[[Page 78446]]


[GRAPHIC] [TIFF OMITTED] TP16DE15.024

BILLING CODE 4910-59-C
0
3. Section 571.224 is amended by:
0
a. Revising the second sentence in S3; and;
0
b. Revising the definition of ``Rear extremity'' in S4.
    The revised text reads as follows:


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

* * * * *
    S3. Application. * * * The standard does not apply to pole 
trailers, pulpwood trailers, low chassis vehicle, road construction 
controlled horizontal discharge trailers, special purpose vehicles, 
wheels back vehicles, or temporary living quarters as defined in 49 CFR 
529.2.
* * * * *
    Rear extremity means the rearmost point on a trailer that is above 
a horizontal plane located above the ground clearance and below a

[[Page 78447]]

horizontal plane located 1,900 mm above the ground when the trailer is 
configured as specified in S5.1 and when the trailer's cargo doors, 
tailgate and other permanent structures are positioned as they normally 
are when the trailer is in motion, with non-structural protrusions 
excluded from the determination of the rearmost point, such as:
    (a) Tail lamps,
    (b) Rubber bumpers,
    (c) Hinges and latches, and
    (d) Flexible aerodynamic devices capable of being folded to within 
305 mm from the transverse vertical plane tangent to the rear most 
surface of the horizontal member for vertical heights below 1,740 mm 
above ground and, 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 
intersecting a point located 1,210 mm rearward of the horizontal member 
and 1,740 mm above the ground.
* * * * *

XI. Appendix A to Preamble: 2013 NHTSA/UMTRI Study

    In 2009, the agency initiated an in-depth field analysis to obtain 
a greater understanding of the characteristics of underride events and 
factors contributing to such crashes. NHTSA sought this information to 
assess the need for and impacts of possible amendments to the FMVSSs to 
reduce severe passenger vehicle underride in truck/trailer rear end 
impacts.
    NHTSA published the first phase of the field analysis in 2012,\66\ 
and published the final report in March 2013. The reports analyze 2008-
2009 data collected as a supplement to UMTRI's TIFA survey.\67\ The 
TIFA survey contains data for all the trucks with a GVWR greater than 
4,536 kg (10,000 lb) (``medium and heavy trucks'') that were involved 
in fatal traffic crashes in the 50 U.S. States and the District of 
Columbia. TIFA data contains additional detail beyond the information 
contained in NHTSA's FARS.
---------------------------------------------------------------------------

    \66\ Analysis of Rear Underride in Fatal Truck Crashes, DOT HS 
811 652, August 2012. Also available at http://www.nhtsa.gov/Research/Crashworthiness/Truck%20Underride, last accessed on March 
6, 2015.
    \67\ 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. Also available at http://www.nhtsa.gov/Research/Crashworthiness/Truck%20Underride, last 
accessed on March 6, 2015.
---------------------------------------------------------------------------

    NHTSA contracted UMTRI to collect supplemental data for 2008 and 
2009 as part of the TIFA survey. The supplemental data included the 
rear geometry of the SUTs and trailers; type of equipment at the rear 
of the trailer, if any; whether a rear impact guard was present; the 
type of rear impact guard; and, the standards the guard was 
manufactured to meet. For SUTs and trailers involved in fatal rear 
impact crashes, additional information was collected on: the extent of 
underride; damage to the rear impact guard; estimated impact speeds; 
and whether the collision was offset or had fully engaged the guard.
    NHTSA derived average annual estimates from the 2008 and 2009 TIFA 
data files and the supplemental information collected in the 2013 UMTRI 
study. The agency's review of these files found that there are 3,762 
SUTs and trailers involved in fatal accidents annually, among which 
trailers accounted for 67 percent, SUTs for 29 percent, tractors alone 
for 1.5 percent, and unknown for the remaining 2.5 percent.\68\ About 
489 SUTs and trailers are struck in the rear in fatal crashes, 
constituting about 13 percent of all SUTs and trailers in fatal 
crashes. Among rear impacted SUTs and trailers in fatal crashes, 331 
(68 percent) are trailers, 151 (31 percent) are SUTs, and 7 (1 percent) 
are tractors alone.
---------------------------------------------------------------------------

    \68\ ``Bobtail'' and ``tractor/other'' configurations were 
combined into the ``tractors'' category and ``tractor/trailer'' and 
``straight trucks with trailer'' were combined into the ``trailers'' 
category.
---------------------------------------------------------------------------

Presence of Rear Impact Guard on Trailers and SUTs
    UMTRI evaluated 2008 and 2009 TIFA data regarding the rear geometry 
of all the trailers and SUTs involved in all fatal crashes (not just 
those rear-impacted) to assess whether the vehicle had to have a guard 
under FMVSS No. 224 (regarding trailers) or the Federal Motor Carrier 
Safety Administration's (FMCSA's) Federal Motor Carrier Safety 
Regulation (FMCSR) No. 393.86(b) (49 CFR 393.86(b), ``FMCSA 
393.86(b)'') (regarding SUTs).\69\ Based on this evaluation, UMTRI 
estimated that 65 percent of trailers had to have a rear impact guard 
per FMVSS No. 224 (Table A-1). Among the 35 percent of trailers that 
did not have a guard because they were excluded from FMVSS No. 224, 26 
percent were wheels back trailers,\70\ 2 percent were low chassis 
vehicles,\71\ 1 percent had equipment in the rear, and 6 percent were 
excluded vehicles because of type of cargo or operation. UMTRI 
estimated that although 38 percent of the SUTs involved in fatal 
crashes were required to have rear impact guards (based on the truck 
rear geometry according to FMCSR 393.86(b)), only 18 percent were 
equipped with them (Table A-1). It is likely that the remaining 20 
percent of the SUTs that were configured such that they would be 
subject to FMCSR 393.86(b) based on vehicle design, but that did not 
have a guard, were not used in interstate commerce. Among the 62 
percent of SUTs that were excluded from installing rear impact guards 
by the FMCSR, 27 percent were wheels back SUTs,\72\ 9 percent were low 
chassis SUTs,\73\ 2 percent were wheels back and low chassis SUTs, and 
16 percent had equipment in the rear that interfered with rear impact 
guard installation (see Table A-1).
---------------------------------------------------------------------------

    \69\ UMTRI only evaluated the rear geometry to determine whether 
a SUT's configuration qualified the vehicle as subject to FMCSR 
393.86(b). It did not determine how the truck was operated and 
whether it was used in interstate commerce.
    \70\ Wheels back trailers, defined in FMVSS No. 224, is a 
trailer or semitrailer whose rearmost axle is permanently fixed and 
is located such that the rearmost surface of tires is not more than 
305 mm forward of the rear extremity of the vehicle.
    \71\ Low chassis trailers are defined in FMVSS No. 224, and are 
trailer or semitrailer having a chassis that extends behind the 
rearmost point of the rearmost tires and a lower rear surface that 
meets the configuration (width, height, and location) requirements 
for an underride guard.
    \72\ Wheels back SUTs according to FMCSR 393.86(b) is where the 
rearmost axle is permanently fixed and is located such that the 
rearmost surface of the tires is not more than 610 mm forward of the 
rear extremity of the vehicle.
    \73\ Low chassis SUTs according FMCSR 393.86(b) is where the 
rearmost part of the vehicle includes the chassis and the vertical 
distance between the rear bottom edge of the chassis assembly and 
the ground is less than or equal to 762 mm (30 inches).

[[Page 78448]]



  Table A-1--Percentage of Trailers and SUTs by Their Rear Geometry and
Whether a Rear Impact Guard Was Required According to UMTRI's Evaluation
  of SUTs and Trailers Involved in Fatal Crashes in the 2008-2009 TIFA
                               Data Files
------------------------------------------------------------------------
                                      Percentage of      Percentage of
       Type of rear geometry             trailers             SUTs
------------------------------------------------------------------------
Rear Impact Guard Required
    Guard present.................                 65                 18
    Guard not present.............                  0                 20
Rear Impact Guard Not Required
    Excluded vehicle..............                  6                  8
    Wheels back vehicle...........                 26                 27
    Low chassis vehicle...........                  2                  9
    Wheels back and low chassis                     0                  2
     vehicle......................
    Equipment.....................                  1                 16
------------------------------------------------------------------------

    Since the data presented in Table A-1 takes into consideration all 
SUTs and trailers involved in all types of fatal crashes in 2008 and 
2009 (total of 2,159 trucks and 5,231 trailers), we make the assumption 
that the percentage of SUTs and trailers with and without rear impact 
guards in Table A-1 is representative of that in the SUT and trailer 
fleet.

Light Vehicle Fatal Crashes Into the Rear of Trailers and SUTs

    Among the types of vehicles that impacted the rear of trailers and 
SUTs, 73 percent were light vehicles,\74\ 18 percent were large trucks, 
7.4 percent were motorcycles, and 1.7 percent were other/unknown 
vehicle types. Since we do not expect trucks and buses to underride 
other trucks in rear impacts, the data presented henceforth only apply 
to light vehicles impacting the rear of trailers and SUTs.
---------------------------------------------------------------------------

    \74\ UMTRI categorized passenger cars, compact and large sport 
utility vehicles, minivans, large vans (e.g. Econoline and E150-
E350), compact pickups (e.g., S-10, Ranger), and large pickups (e.g 
Ford F100-350, Ram, Silverado) as light vehicles.
---------------------------------------------------------------------------

Underride Extent in Fatal Crashes of Light Vehicles Into the Rear of 
Trailers and SUTs

    In the UMTRI study of 2008 and 2009 TIFA data, survey respondents 
estimated the amount of underride in terms of the amount of the 
striking vehicle that went under the rear of the struck vehicle and/or 
the extent of deformation or intrusion of the vehicle. The categories 
were ``no underride,'' ``less than halfway up the hood,'' ``more than 
halfway but short of the base of the windshield,'' and ``at or beyond 
the base of the windshield.'' When the extent of underride is ``at or 
beyond the base of the windshield,'' there is PCI that could result in 
serious injury to occupants in the vehicle. Rear impacts into trailers 
and SUTs could result in some level of underride without PCI when the 
rear impact guard prevents the impacting vehicle from traveling too far 
under the heavy vehicle during impact. Such impacts into the rear of 
heavy vehicles without PCI may not pose additional crash risk to light 
vehicle occupants than that in crashes with another light vehicle at 
similar crash speeds.
    The data show that about 319 light vehicle fatal crashes into the 
rear of trailers and trucks occur annually. UMTRI determined that about 
36 percent (121) of light vehicle impacts into the rear of trailers and 
trucks resulted in PCI. Among fatal light vehicle impacts, the 
frequency of PCI was greatest for passenger cars and sport utility 
vehicles (SUVs) (40 and 41.5 percent, respectively) and lowest for 
large vans and large pickups (25 and 26 percent, respectively), as 
shown in Figure A-1 below. Since the extent of underride was also 
determined by the extent of deformation and intrusion of the vehicle, 
it was observed in a number of TIFA cases that large vans and large 
pickups did not actually underride the truck or trailer but sustained 
PCI because of the high speed of the crash and/or because of the very 
short front end of the vehicle.
---------------------------------------------------------------------------

    \75\ The extent of underride in this and subsequent figures and 
tables means the following: 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''; windshield+ means 
``extent of underride at or beyond the base of the windshield'' or 
PCI.

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

[[Page 78449]]

[GRAPHIC] [TIFF OMITTED] TP16DE15.025

    Fatal light vehicle crashes into the rear of trailers and trucks 
were further examined by the type of trailer and truck struck and 
whether a guard was required (according to FMVSS No. 224 for trailers 
and FMCSR 393.86(b) for SUTs) (Figure A-2 and Figure A-3).
    Among the 319 annual fatal light vehicle crashes into the rear of 
trailers and SUTs, 23 (7 percent) are into SUTs with guards, 79 (25 
percent) are into SUTs without guards, 115 (36 percent) are into 
trailers with guards, 44 (14 percent) into wheels back trailers, 15 (5 
percent) into exempt trailers (due to equipment in rear, type of 
operation, low bed), and 43 (13 percent) are other types of trucks 
(Figure A-2).
[GRAPHIC] [TIFF OMITTED] TP16DE15.026

    Among these light vehicle fatal crashes annually, 121 result in 
PCI, among which 62 (51 percent) occur in impacts with trailers with 
guards, 23 (19 percent) in impacts with SUTs without guards, 8 (7 
percent) in impacts with SUTs with guards, 7 (6 percent) in impacts 
with wheels back trailers, 4 (3 percent) with excluded trailers (by 
type of cargo or operation), and 17 (14

[[Page 78450]]

percent) in impacts with other truck/trailer type (Figure A-3).\76\
---------------------------------------------------------------------------

    \76\ Underride extent was determined for 303 light vehicles, 
about 95 percent of the 319 light vehicle impacts into the rear of 
trailers and trucks. Unknown underride extent was distributed among 
known underride levels.
[GRAPHIC] [TIFF OMITTED] TP16DE15.027

    It is noteworthy that trailers with guards represent 36 percent of 
annual light vehicle fatal rear impacts but represent 51 percent of 
annual light vehicle fatal rear impacts with PCI. On the other hand, 
SUTs (with and without guards) represent 32 percent of annual light 
vehicle fatal rear impacts but represent 26 percent of annual light 
vehicle fatal rear impacts with PCI. The field data suggest that there 
are more light vehicle fatal impacts into the rear of trailers than 
SUTs and a higher percentage of fatal light vehicle impacts into the 
rear of trailers involve PCI than those into the rear of SUTs.

Relative Speed of Light Vehicle Fatal Crashes Into the Rear of Trailers 
and SUTs

    Using information derived by reviewing police crash reports,\77\ 
UMTRI estimated the relative speed of fatal light vehicle crashes into 
the rear of SUTs and trailers. Relative velocity

[[Page 78451]]

was computed as the resultant of the difference in the trailer (truck) 
velocity and the striking vehicle velocity and could only be estimated 
for about 30 percent of light vehicle fatal crashes into the rear of 
trailers and SUTs. Most of the crashes (with known relative velocity) 
were at a very high relative velocity and many were not survivable. The 
mean relative velocity at impact into the rear of trailers and SUTs was 
estimated at 44 mph. Among fatal light vehicle impacts into the rear of 
trailers that resulted in PCI, 74 percent were with relative velocity 
greater than 56 km/h (35 mph) (Figure A-4). Among the remaining 26 
percent fatal light vehicle impacts into the rear of trailers, 21 
percent were trailers with guards and 5 percent were trailers excluded 
from FMVSS No. 224 requirements. Among fatal light vehicle impacts into 
the rear of SUTs that resulted in PCI, 70 percent were with relative 
velocity greater than 56 km/h (35 mph). Among the remaining 30 percent 
fatal light vehicle impacts into the rear of SUTs, 3 percent of the 
SUTs had rear impact guards, 10 percent of the SUTs could be required 
to have a guard based on rear geometry but did not have a guard, 3 
percent were excluded from requiring a guard (wheels back, low chassis 
vehicles), and 14 percent had equipment in the rear precluding rear 
impact guards.
---------------------------------------------------------------------------

    \77\ Information included police estimates of travel speed, 
crash narrative, crash diagram, and witness statements. The impact 
speed was estimated from the travel speed, skid distance, and an 
estimate of the coefficient of friction.
[GRAPHIC] [TIFF OMITTED] TP16DE15.028

Fatalities Associated With Light Vehicle Crashes Into the Rear of 
Trailers and SUTs

    There are about 362 light vehicle occupant fatalities annually due 
to impacts into the rear of trailers and SUTs. Of these fatalities, 191 
(53 percent) are in impacts with trailers, 104 (29 percent) are in 
impacts with SUTs, and 67 (18 percent) are impacts with an unknown 
truck type (Figure 5).
    Among the 191 light vehicle occupant fatalities resulting from 
impacts with the rear of trailers, 125 occurred in impacts with 
trailers with rear impact guards while the remaining 66 were in impacts 
to trailers without guards (trailers excluded from a requirement to 
have a rear impact guard). PCI was associated with 86 annual light 
vehicle occupant fatalities resulting from impacts into the rear of 
trailers; 72 of these fatalities were in impacts with trailers with 
rear impact guards and 14 with trailers without guards (see Figure A-
5).
    Among the 104 light vehicle occupant fatalities resulting from 
impacts with the rear of SUTs, 80 occurred in impacts with SUTs without 
rear impact guards while the remaining 24 were in impacts to SUTs with 
guards. PCI was associated with 33 annual light vehicle occupant 
fatalities resulting from impacts into the rear of SUTs; 25 of these 
fatalities were in impacts with SUTs without rear impact guards and 8 
with SUTs with guards (see Figure A-5).

[[Page 78452]]

[GRAPHIC] [TIFF OMITTED] TP16DE15.029

    Among light vehicle occupant fatalities in impacts into the rear of 
trailers and SUTs, approximately 60 percent were in vehicles with no 
underride, underride less than halfway or underride up to the hood 
without PCI. The agency found that in a number of TIFA cases reviewed, 
fatalities in non-PCI crashes into the rear of trailers and SUTs 
occurred due to occupants being unrestrained, other occupant 
characteristics (e.g. age), and other crash circumstances. 
Additionally, as shown in Figure A-4, 26 percent and 30 percent of 
light vehicle impacts with PCI into the rear of trailers and SUTs, 
respectively, had a relative velocity less than or equal to 56 km/h (35 
mph). Since currently manufactured light vehicles are subject to FMVSS 
No. 208 requirements that ensure adequate occupant crash protection to 
restrained occupants in a 56 km/h (35 mph) rigid barrier frontal crash 
test, some light vehicle occupant fatalities in impacts into the rear 
of SUTs and trailers at speeds less than or equal to 56 km/h (35 mph) 
that resulted in PCI may be preventable if intrusion into the passenger 
compartment were mitigated.\78\
---------------------------------------------------------------------------

    \78\ Some of the fatalities associated with PCI may also be due 
to unrestrained status of the occupant.
---------------------------------------------------------------------------

XII. Appendix B to Preamble: Summary of IIHS's Evaluation of Rear 
Impact Guards

    In 2010, IIHS completed a review of the Large Truck Crash Causation 
Study (LTCCS) \79\ database to evaluate fatal crashes of vehicles into 
the rear of heavy vehicles.\80\ IIHS reviewed 115 LTCCS

[[Page 78453]]

cases of vehicle underride into the rear of heavy vehicles and 
documented the presence and type of underride guard and performance of 
the guard in mitigating underride. Among the 115 cases reviewed, nearly 
half of the passenger vehicles had underride classified as severe or 
catastrophic. IIHS noted that for the cases involving trailers with 
rear impact guards, guard deformation or complete failure of the guard 
was frequent and commonly due to weak attachments, buckling of the 
trailer chassis, and bending of the lateral end of the guard under low 
overlap loading. IIHS stated that 57 percent of the heavy vehicles in 
the 115 LTCCS cases were excluded from FMVSS No. 224 requirements by 
the standard, among which a large proportion were wheels back vehicles 
and single unit trucks (SUTs) such as dump trucks. IIHS was not able to 
estimate the crash speeds in its review of the LTCCS cases.
---------------------------------------------------------------------------

    \79\ Supra.
    \80\ Brumbelow, M.L., 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-
31, 2010. Warrendale, PA, SAE International.
---------------------------------------------------------------------------

    Following the review, in 2011, IIHS conducted an initial round of 
crash tests in which the front of a model year (MY) 2010 Chevrolet 
Malibu (a midsize sedan) impacted the rear of trailers equipped with an 
underride guard.\81\ A 50th percentile male Hybrid III dummy (HIII 50M) 
was in each of the front outboard seating positions of the Malibu. 
Three trailer/guard designs (2007 Hyundai, 2007 Vanguard, and 2011 
Wabash trailers) were evaluated in various conditions. Each guard 
design was certified to FMVSS No. 223 requirements, and two (Vanguard 
and Wabash) also met the more stringent CMVSS No. 223 requirements. A 
2010 Chevrolet Malibu was first crashed into a trailer at 56 km/h (35 
mph) with full overlap (the overlap refers to the portion of the 
Malibu's width overlapping the underride guard). If the rear impact 
guard of a trailer model was successful in preventing passenger 
compartment intrusion in the full overlap crash test, a new Malibu was 
crashed into a new trailer of the same model with 50 percent overlap of 
the Malibu. If the rear impact guard was successful in preventing PCI 
in this case as well, a third test was performed with only 30 percent 
overlap of the Malibu.
---------------------------------------------------------------------------

    \81\ 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. Last accessed on April 2, 2015.
---------------------------------------------------------------------------

    The test results showed that the full overlap 56 km/h (35 mph) 
crash test of the Malibu with the guard of the Hyundai trailer (built 
to only FMVSS No. 223 requirements) resulted in catastrophic underride 
with PCI of the Chevrolet Malibu. The guard on the Vanguard trailer 
that complied with the upgraded CMVSS No. 223 rear impact guard 
requirements could not prevent PCI in a 56 km/h (35 mph) crash test 
with 50 percent overlap of the Malibu because the attachments of the 
guard to the trailer failed. The rear impact guard on the Wabash 
trailer, also certified to meet CMVSS No. 223 requirements, prevented 
PCI in 35 mph crash tests with full and 50 percent overlap of the 
Malibu, but could not prevent PCI in the crash test with 30 percent 
overlap.

Quasi-Static Load Testing of Rear Impact Guards

    To compare the static performance of the guards, IIHS conducted 
quasi-static load tests using a 203 mm square force application device 
(similar to that specified in FMVSS No. 223) at P1 and P3 locations of 
the horizontal member of the rear impact guards on the Hyundai, 
Vanguard and Wabash trailers. The load was applied at a rate of 1.3 mm/
sec until the force application device displaced 125 mm. Figure B-1 
below shows the force-displacement curves for all three guards in the 
quasi-static test at the P3 location.
    Deformation patterns of the underride guards varied substantially 
in the quasi-static tests. In the test at P3 location on the Hyundai 
guard, a peak force of 163,000 N was achieved and then the vertical 
support member of the Hyundai guard was pulled slowly from some of the 
bolts attaching it to the fixture, whereas the vertical member itself 
deformed only minimally. In the test at P3 of the Vanguard guard, the 
vertical member flexed for the first 50 mm of loading achieving a peak 
load of 257,000 N and then the attachment bolts began to shear, causing 
the measured force to drop below that measured for the Hyundai later in 
the test. The Wabash guard reached its peak force of 287,000 N 
earliest, and then the vertical member began buckling near its 
attachment to the horizontal member. As the buckling continued, the 
rear surface of the guard eventually bottomed out against the diagonal 
gusset, causing the load to increase again late in the test. The 
Hyundai rear impact guard absorbed 13,900 J of energy, the Vanguard 
guard absorbed 14,000 J of energy, and the Wabash guard absorbed 22,100 
J of energy in the P3 point-load tests.

[[Page 78454]]

[GRAPHIC] [TIFF OMITTED] TP16DE15.030

    Table B-1 summarizes the results of the initial five IIHS 56 km/h 
(35 mph) crash tests. In the first test, the 2007 Hyundai 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. 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 B-1--Results of IIHS Initial Round of 56 km/h Crash Tests of the 2010 Chevrolet Malibu Into the Rear of
                                                    Trailers
----------------------------------------------------------------------------------------------------------------
                                                                                                       Max.
                                                                                                  longitudinal A-
            Conditions                   Trailer         Guard performance        Underride           pillar
                                                                                                    deformation
                                                                                                       (cm)
----------------------------------------------------------------------------------------------------------------
100% overlap.....................  2007 Hyundai.......  Attachments failed.  Catastrophic.......              80
                                   2011 Wabash........  Good...............  None...............               0
50% overlap......................  2007 Vanguard......  Attachments failed.  Severe.............              27
                                   2011 Wabash........  End bent forward...  None...............               6
30% overlap......................  2011 Wabash........  End bent forward...  Catastrophic.......              87
----------------------------------------------------------------------------------------------------------------

    Table B-2 summarizes the peak injury measures \82\ of the HIII 50M 
dummies in the front seating positions of the Malibu. For comparison 
purposes, Table B-2 also presents the HIII 50M dummy injury measures in 
the full frontal 56 km/h rigid barrier crash test of the 2010 Chevrolet 
Malibu conducted as part of NHTSA's New Car Assessment Program (NCAP). 
Head injury measures recorded by the dummies in the tests with severe 
underride were much higher than those reported for the Malibu's NCAP 
rigid wall test at the same speed. Chest acceleration and deflection 
measures were generally higher in tests without PCI than those with 
PCI.\83\ The frontal air bag deployed in the 100, 50, and 30 percent 
overlap crash tests of the Malibu into the rear of the Wabash trailer. 
The driver and passenger injury measures in the Malibu full width crash 
test with the Wabash trailer (where the guard prevented PCI) was 
similar to the injury measures in the Malibu NCAP frontal crash test.
---------------------------------------------------------------------------

    \82\ HIII 50M dummy injury measures are those applicable to 
current model passenger vehicles as specified in FMVSS No. 208, see 
http://www.ecfr.gov/cgi-bin/text-idx?SID=77e2aab5d088f2e9b46d15606090f9b0&node=se49.6.571_1208&rgn=div8.
    \83\ When PCI was prevented by the rear impact guard, the 
accelerations on the vehicle are higher which results in higher 
chest injury measures.

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[[Page 78455]]

[GRAPHIC] [TIFF OMITTED] TP16DE15.031

    Following the preliminary crash tests in 2011, IIHS conducted 
similar crash tests of a 2010 Chevrolet Malibu sedan with eight 
additional 2012 and 2013 model year trailers from various 
manufacturers, including newly redesigned Hyundai and Vanguard models. 
All guards in this round of testing were not only certified as 
complying with FMVSS No. 223 but were also certified as complying with 
CMVSS No. 223.
    Table B-3 presents certification data from trailer manufacturers 
showing compliance with CMVSS No. 223. Only one trailer manufacturer 
utilized an option in CMVSS No. 223 to test using half the guard with a 
point load force application of 175,000 N at P3, while the other rear 
impact guards were certified with the uniform distributed quasi-static 
load application of 350,000 N on the full guard. All the rear impact 
guards tested also complied with the CMVSS requirement that the ground 
clearance of the guard after the test not exceed 560 mm.
[GRAPHIC] [TIFF OMITTED] TP16DE15.032

    The ground clearance of the bumper (vertical distance of the bottom 
of the bumper from the ground) of the 2010 Chevrolet Malibu is 403 mm 
and the vertical height of the bumper is 124 mm. Therefore, the Malibu 
bumper is located at a vertical height between 403 mm and 527 mm above 
the ground with its centerline located 465 mm above ground. The 
vertical height of the top of the engine block from the ground is 835 
mm. The ground clearance of the horizontal member of each rear impact 
guard ranged between 400 mm and 498 mm (Table B-4).

                Table B-4--Trailer Guard Ground Clearance
------------------------------------------------------------------------
                                                                 Guard
                                                                ground
                           Trailer                             clearance
                                                                 (mm)
------------------------------------------------------------------------
2011 Wabash.................................................         445
2012 Manac..................................................         498
2012 Stoughton..............................................         477
2013 Great Dane.............................................         400

[[Page 78456]]

 
2012-2013 Hyundai...........................................         409
2013 Strick.................................................         413
2013 Utility................................................         455
2013 Vanguard...............................................         452
------------------------------------------------------------------------

    Table B-5, Table B-6, and Table B-7 present the extent of 
underride, deformation of the Malibu, performance of the guard, and 
whether there was PCI in the 56 km/h (35 mph) frontal impact crash 
tests of the Malibu into the rear of trailers with full overlap, 50 
percent overlap, and 30 percent overlap of the Malibu, respectively.
    All the rear impact guards on the trailers that were compliant with 
CMVSS No. 223 were able to prevent passenger compartment intrusion in 
full overlap crashes. In the tests with 50 percent overlap of the 
Malibu, all the guards except the 2013 Vanguard was able to prevent 
PCI. The Vanguard rear impact guard failed at the attachments where the 
bolts sheared off during the crash resulting in PCI of the Malibu. All 
the rear impact guards tested except the 2012 Manac guard were not able 
to prevent PCI in the 30 percent offset crash tests of the Malibu.
[GRAPHIC] [TIFF OMITTED] TP16DE15.033


[[Page 78457]]


[GRAPHIC] [TIFF OMITTED] TP16DE15.034

    Table Table B-8 presents the injury measures of crash test dummies 
(HIII-50M) in the driver and front passenger seating positions in 56 
km/h (35 mph) crash tests conducted by IIHS with 100 percent overlap of 
the 2010 Malibu with rear impact guard.
    Table B-9 and Table B-10 present the injury measures for the HIII-
50M in the driver position in 56 km/h (35 mph) crash tests with 50 
percent and 30 percent overlap of the 2010 Malibu with the rear impact 
guard, respectively.
    The frontal air bags deployed in all the 100 percent and 50 percent 
overlap crash tests of the Malibu into the rear of 2011-2013 model year 
trailers. The air bag deployed in the 30 percent overlap crash tests of 
the Malibu into the rear of 2011-2013 model year trailers except for 
the tests into the rear of the 2012 Hyundai, 2013 Great Dane, and 2013 
Strick trailer. When the Malibu experienced PCI in a crash test, the 
dummy injury measures, specifically the head injury criterion (HIC) and 
the neck injury criterion (Nij) generally exceeded the allowable Injury 
Assessment Reference Values (IARV) of 700 and 1.0 set forth in FMVSS 
No. 208, respectively, regardless of whether the air bag deployed.\84\ 
When PCI was prevented by the rear impact guard, the accelerations on 
the vehicle are higher which results in higher chest deflection 
measures, although well within the allowable level, indicating higher 
acceleration loads on the dummy.
---------------------------------------------------------------------------

    \84\ Except in the neck injury measure (Nij = 0.65) in the 50 
percent overlap crash with the Vanguard trailer.

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

[[Page 78458]]

[GRAPHIC] [TIFF OMITTED] TP16DE15.035

Summary of the IIHS Test Data

    The test data, summarized in Table B-11 and Table B-12 below, show 
that trailer guards compliant with FMVSS No. 223 were unable to 
withstand an impact of the Malibu at 56 km/h (35 mph), which resulted 
in PCI. The tests also demonstrated that trailers that comply with the 
Canadian standard, CMVSS No. 223, were generally able to prevent PCI in 
56 km/h (35 mph) impacts of the Malibu with full and 50

[[Page 78459]]

percent overlap with the rear impact guard. However, seven of the eight 
rear impact guards compliant with the Canadian standard could not 
prevent PCI when only 30 percent of the Malibu front end engaged the 
rear impact guard.
    In a quasi-static test at P3 location of the Vanguard rear impact 
guard, the attachments bolts sheared but still enabled the vehicle to 
meet the load and energy absorption requirements of CMVSS No. 223. 
However, in the 56 km/h (35 mph) crash test with 50 percent overlap of 
the 2010 Malibu with the Vanguard trailer, the guard bolts sheared 
resulting in PCI of the Malibu. In the tests where there was no PCI of 
the Malibu, the injury measures of the restrained test dummies in the 
Malibu were below the injury threshold levels used by the FMVSSs. When 
PCI was prevented by the rear impact guard, generally higher chest 
injury measures resulted compared to when PCI occurred, but the values 
were well within the allowable limits.
    When the Malibu sustained PCI, the head and neck injury measures 
were generally greater than the allowable threshold levels indicating 
high risk of serious head and neck injuries, regardless of whether the 
air bag deployed. The IIHS tests showed that when PCI occurs, air bag 
deployment does not improve injury outcome.

  Table B-11--Occurrence of PCI in 35 MPH Crash Tests (Conducted by IIHS) of the 2010 Chevrolet Malibu Into the
                                                Rear of Trailers
----------------------------------------------------------------------------------------------------------------
          Trailer Model               Designed to         Full Width          50% overlap         30% overlap
----------------------------------------------------------------------------------------------------------------
2011 Wabash.....................  CMVSS No. 223.....  None..............  None..............  Yes.
2012 Manac......................  CMVSS No. 223.....  None..............  None..............  None.
2012 Stoughton..................  CMVSS No. 223.....  None..............  None..............  Yes.
2013 Great Dane.................  CMVSS No. 223.....  None..............  None..............  Yes.
2012-2013 Hyundai...............  CMVSS No. 223.....  None..............  None..............  Yes.
2013 Strick.....................  CMVSS No. 223.....  None..............  None..............  Yes.
2013 Utility....................  CMVSS No. 223.....  None..............  None..............  Yes.
2013 Vanguard...................  CMVSS No. 223.....  None..............  Yes *.............  N/A.
2007 Hyundai....................  FMVSS No. 224.....  Yes...............  N/A **............  N/A.
----------------------------------------------------------------------------------------------------------------
* The attachment of the guard to the trailer failed during impact.
** Since the guard was unable to withstand the loads in the first test, the second and third tests were not
  conducted.


[[Page 78460]]

[GRAPHIC] [TIFF OMITTED] TP16DE15.036


    Issued under authority delegated in 49 CFR 1.95.
Raymond R. Posten,
Associate Administrator for Rulemaking.
[FR Doc. 2015-31228 Filed 12-15-15; 8:45 am]
 BILLING CODE 4910-59-P


