[Federal Register: December 2, 2009 (Volume 74, Number 230)]
[Proposed Rules]
[Page 63179-63233]
[DOCID:fr02de09-13]

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

Part II

Department of Transportation

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

National Highway Traffic Safety Administration

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

49 CFR Parts 571 and 585

Federal Motor Vehicle Safety Standards, Ejection Mitigation; Phase-In
Reporting Requirements; Proposed Rule

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

DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Parts 571 and 585

[Docket No. NHTSA-2009-0183]
RIN 2127-AK23

Federal Motor Vehicle Safety Standards, Ejection Mitigation;
Phase-In Reporting Requirements

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

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: This notice of proposed rulemaking would establish a new
Federal Motor Vehicle Safety Standard (FMVSS) No. 226, to reduce the
partial and complete ejection of vehicle occupants through side windows
in crashes, particularly rollover crashes. The standard would apply to
the side windows next to the first three rows of seats in motor
vehicles with a gross vehicle weight rating (GVWR) of 4,536 kilogram
(kg) or less (10,000 pounds (lb) or less). To assess compliance, the
agency is proposing a test in which an impactor would be propelled from
inside a test vehicle toward the windows. The ejection mitigation
safety system would be required to prevent the impactor from moving
more than a specified distance beyond the plane of a window. To ensure
that the systems cover the entire opening of each window for the
duration of a rollover, each side window would be impacted at up to
four locations around its perimeter at two time intervals following
deployment.
    The agency anticipates that manufacturers would meet the standard
by modifying existing side impact air bag curtains, and possibly
supplementing them with advanced laminated glazing. The curtains would
be made larger so that they cover more of the window opening, made more
robust to remain inflated longer, and made to deploy in both side
impacts and in rollovers. In addition, they would be tethered or
otherwise designed to keep the impactor within the vehicle.
    This NPRM advances NHTSA's initiatives in rollover safety and also
responds to Section 10301 of the Safe, Accountable, Flexible, Efficient
Transportation Equity Act: A Legacy for Users (SAFETEA-LU). That
section directs NHTSA to initiate and complete rulemaking to reduce
complete and partial ejections of vehicle occupants from outboard
seating positions, considering various ejection mitigation systems.

DATES: You should submit your comments early enough to ensure that the
docket receives them not later than February 1, 2010.

ADDRESSES: You may submit comments (identified by the Docket ID Number
above) 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: U.S. Department of
Transportation, 1200 New Jersey Avenue, SE., West Building Ground
Floor, Room W12-140, Washington, DC 20590-0001.
     Hand Delivery or Courier: West Building Ground Floor, Room
W12-140, 1200 New Jersey Avenue, SE., between 9 a.m. and 5 p.m. ET,
Monday through Friday, except Federal holidays.
     Fax:<PHONE_NUMBER>
    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. Please see the Privacy Act heading below.
    Privacy Act: 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 (65 FR 19477-78).
    Docket: For access to the docket to read background documents or
comments received, go to http://www.regulations.gov or the street
address listed above. Follow the online instructions for accessing the
dockets.

FOR FURTHER INFORMATION CONTACT: For non-legal issues, you may contact
Mr. Louis Molino, NHTSA Office of Crashworthiness Standards, telephone
202-366-1740, fax<PHONE_NUMBER>. For legal issues, you may contact Ms.
Deirdre Fujita, NHTSA Office of Chief Counsel, telephone<PHONE_NUMBER>,
fax<PHONE_NUMBER>.
    You may send mail to these officials at the 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. Congressional Mandate
III. Safety Problem
IV. Proposed Solution
    a. Various Ejection Mitigation Systems Considered
    b. Full Window Opening Coverage Is Key
    1. Tests With 50th Percentile Adult Male and 5th Percentile
Adult Female Test Dummies
    2. Tests With 6-Year-Old Child Test Dummy Showed a Risk of
Ejection Through Openings Not Fully Covered
    3. Differences in Design Between the Two Inflatable Systems
    4. Insights
    c. Comparable Performance in Simulated Rollovers and Component-
Level Impact tests
    d. Advantages of a Component Test Over a Full Vehicle Dynamic
Test
    e. Existing Curtains Can Be Made More Effective
    1. Existing Curtains
    2. Component Tests of Real-World Curtains and Advanced Glazing
Systems Show That Improvements Could Be Made
    3. Use of Advanced Glazing With the Air Bag Curtain Resulted in
Reduced Displacement
    4. Field Performance of Ejection Mitigation Curtain Systems
V. Proposed Ejection Mitigation Requirements and Test Procedures
    a. Impactor Dimensions and Mass
    b. Displacement Limit (100 mm)
    c. Speed(s) and Time(s) at Which the Headform Would Impact the
Countermeasure.
    1. Ejections Can Occur Both Early and Late in the Rollover Event
    2. Speed at Which Occupants Impact or Move Through the Window
Opening
    3. Alternative Testing of Only One Target Position at Higher
Speed
    d. Locations Where the Device Would Impact the Ejection
Mitigation Countermeasure To Assess Efficacy
    1. Occupants are Mainly Ejected Through Side Windows
    2. The Requirements Would Apply to Side Windows Adjacent to
First Three Rows
    3. Four Targets Per Glazing Area
    4. Method for Determining Impactor Target Locations
    e. How Should the Window Glazing Be Positioned or Prepared in
the Test To Represent Real-World Circumstances?
    1. Window Position and Condition
    2. Window Pre-Breaking Specification and Method
    f. Test Procedure Tolerances
    g. Impactor Test Device Characteristics
    h. Readiness Indicator
VI. Other Considered Performance Aspects of an Ejection Mitigation
Standard
    a. Rollover Sensor
    1. Introduction
    2. Alternative Approaches
    b. Quasi-Static Loading in a Compliance Test

VII. To Which Vehicles Would The Proposed Standard Apply?
VIII. The Proposed Lead Time and Phase-In Schedules
IX. The Estimated Benefits and Costs of This Rulemaking
X. Rulemaking Analyses and Notices
XI. Public Participation

I. Executive Summary

    Addressing vehicle rollovers is one of NHTSA's highest safety
priorities. In 2002, the agency conducted an in-depth review of
rollovers and associated deaths and injuries and assessed how NHTSA and
the Federal Highway Administration (FHWA) could most effectively
improve safety in this area.\1\ The agency formulated strategies
involving improving vehicle performance and occupant behavior, and with
the FHWA taking the lead, improving roadway designs. Vehicle
performance strategies included crash avoidance and crashworthiness
programs, and included four wide-ranging initiatives to address the
rollover safety problem: Prevent crashes, prevent rollovers, prevent
ejections, and protect occupants who remain within the vehicle after a
crash. Projects aimed at protecting occupants remaining in the vehicle
during a rollover included improved roof crush resistance and
researching whether seat belts could be made more effective in
rollovers.
---------------------------------------------------------------------------

    \1\ The assessment was carried out by one of four Integrated
Project Teams (IPTs) formed within NHTSA, whose recommendations
culminated in the agency's priority plan, ``NHTSA Vehicle Safety
Rulemaking and Supporting Research: 2003-2006'' (68 FR 43972; July
18, 2003) http://www.nhtsa.dot.gov/cars/rules/rulings/PriorityPlan/
FinalVeh/Index.html. The IPT Report on Rollover was published in
June 2003 (68 FR 36534, Docket 14622).
---------------------------------------------------------------------------

    A major undertaking implementing the first two initiatives was
completed in 2007 when NHTSA published a new Federal Motor Vehicle
Safety Standard (FMVSS) No. 126 to require electronic stability control
(ESC) systems on passenger cars, multipurpose passenger vehicles,
trucks, and buses with a gross vehicle weight rating (GVWR) of 4,536 kg
(10,000 lb) or less (72 FR 17236, April 6, 2007, Docket 27662). ESC
systems use automatic computer-controlled braking of the individual
wheels of a vehicle to assist the driver in maintaining control in
critical driving situations in which the vehicle is beginning to lose
directional stability at the rear wheels (spin out) or directional
control at the front wheels (plow out). Because most loss-of-control
crashes culminate in the vehicle's leaving the roadway--an event that
significantly increases the probability of a rollover--preventing
single-vehicle loss-of-control crashes is the most effective way to
reduce deaths resulting from rollover crashes.\2\ The agency estimates
that when all vehicles (other than motorcycles) under 10,000 lb GVWR
have ESC systems, the number of deaths each year resulting from
rollover crashes would be reduced by 4,200 to 5,500. Currently, there
are over 10,000 such deaths each year.
---------------------------------------------------------------------------

    \2\ NHTSA estimates that the installation of ESC will reduce
single-vehicle crashes of passenger cars by 34 percent and single
vehicle crashes of sport utility vehicles (SUVs) by 59 percent.
NHTSA further estimates that ESC has the potential to prevent 71
percent of the passenger car rollovers and 84 percent of the SUV
rollovers that would otherwise occur in single-vehicle crashes.
NHTSA estimates that ESC would save 5,300 to 9,600 lives and prevent
156,000 to 238,000 injuries in all types of crashes annually once
all light vehicles on the road are equipped with ESC systems.
---------------------------------------------------------------------------

    While ESC systems will avoid many of the roadway departures that
lead to rollover, vehicle rollovers will continue to occur.\3\ Once a
rollover occurs, vehicle crashworthiness characteristics play a crucial
role in protecting the occupants. According to agency data, occupants
have a much better chance of surviving a crash if they are not ejected
from their vehicles. Among the promising technological innovations to
prevent occupant ejections are side curtain air bags and improved
glazing.
---------------------------------------------------------------------------

    \3\ The target population addressed by this rulemaking action is
discussed in detail in the Preliminary Regulatory Impact Analysis
(PRIA) for this NPRM, which has been placed in the docket for this
NPRM.
---------------------------------------------------------------------------

    Concurrent with the agency's work on ESC, NHTSA began work on the
third initiative on rollover safety, which addresses occupant ejections
through side windows in rollovers (``ejection mitigation''). Inroads on
this third initiative were realized in 2007 when the agency published a
final rule that incorporated a dynamic pole test into FMVSS No. 214,
``Side impact protection'' (49 CFR 571.214) (72 FR 51908; September 11,
2007, Docket No. NHTSA-29134; response to petitions for
reconsideration, 73 FR 32473, June 9, 2008, Docket No. NHTSA-2008-
0104).\4\ The pole test, applying to motor vehicles with a GVWR of
4,536 kg (10,000 lb) or less, requires vehicle manufacturers to provide
side impact protection for a wide range of occupant sizes and over a
broad range of seating positions. To meet the pole test, manufacturers
will install new technologies capable of improving head and thorax
protection in side crashes, i.e., side curtain air bags and torso side
air bags. We believe that these side curtain air bag systems can be
effectively modified to meet the occupant containment requirements of
this ejection mitigation initiative on rollover safety.
---------------------------------------------------------------------------

    \4\ On August 10, 2005, the ``Safe, Accountable, Flexible,
Efficient Transportation Equity Act: A Legacy for Users,'' (SAFETEA-
LU), Public Law 109-59 (Aug. 10, 2005; 119 Stat. 1144) was enacted,
to authorize funds for Federal-aid highways, highway safety
programs, and transit programs, and for other purposes. Section
10302(a) of SAFETEA-LU directed the Secretary to complete the FMVSS
No. 214 rulemaking by July 1, 2008. The September 11, 2007 final
rule completed the rulemaking specified in Sec.  10302(a).
---------------------------------------------------------------------------

    The ejection mitigation initiative was bolstered by the efforts of
vehicle manufacturers to install side impact air bags (SIABs) on a
voluntary basis. Immediately prior to the publication of the FMVSS No.
214 NPRM, the Alliance of Automobile Manufacturers (the Alliance), the
Association of International Automobile Manufacturers, and the
Insurance Institute for Highway Safety announced a voluntary commitment
to enhance occupant protection in front-to-side crashes, focusing on,
among other things, accelerating the installation of SIABs.\5\ The
industry's voluntary commitment to install side impact air bags
demonstrated the feasibility of installing side curtain air bags on a
near fleet-wide basis.
---------------------------------------------------------------------------

    \5\ See Docket NHTSA-2003-14623-13. Alliance and AIAM members
agreed to provide side impact head protection in at least 50 percent
of their new passenger car and light truck fleet by September 1,
2007, and in 100 percent of the vehicles by September 1, 2009.
---------------------------------------------------------------------------

    Today's NPRM begins a new stage in implementing ejection
mitigation. This document would establish a new FMVSS for ejection
mitigation (FMVSS No. 226), specifying occupant containment performance
requirements. It would apply to motor vehicles with GVWR of 4,536 kg
(10,000 lb) or less. The countermeasures most likely to be installed to
meet the performance requirements of this NPRM would be the FMVSS No.
214 side curtain air bags \6\ made larger to cover more of the window
opening, made more robust to remain inflated longer, enhanced to deploy
in side impacts and in rollovers, and made not only to cushion but also
made sufficiently strong to keep an occupant from being fully or
partially ejected through a side window. We have drafted the test
procedure of our proposal to accommodate the use of advanced laminated
glazing in fixed and

in possibly moveable windows in addition to or in lieu of the side
curtain air bag.
---------------------------------------------------------------------------

    \6\ In this document, this countermeasure is referred to as an
``ejection mitigation side curtain air bag,'' ``side curtain air
bag,'' ``air bag curtain,'' ``rollover curtain,'' or simply
``curtain.'' This countermeasure is designed to deploy in a rollover
crash and is distinct from strictly a ``side impact curtain,'' which
is designed predominately to protect occupants in side crashes and
meet the requirements of FMVSS No. 214. Notwithstanding this
nomenclature, it is anticipated that rollover curtains will mitigate
occupant ejections in side impacts as well as rollover crashes.
---------------------------------------------------------------------------

    The standard would use a guided impactor component test to assess
the ability of the countermeasure (e.g., a curtain system) to mitigate
ejections in different types of rollover and side impact crashes
involving different occupant kinematics. The test has been carefully
designed to represent the dynamic rollover event. The impact mass is
based on the mass imposed by a 50th percentile male's upper torso on
the window opening during an occupant ejection. The mass of the
impactor, 18 kilograms (kg) (40 lb), in combination with the impact
speed discussed below, has sufficient kinetic energy to assure that the
ejection mitigation countermeasure is able to protect a far-reaching
population of people in real world crashes. In the test, the linear
travel of the impactor beyond where the device contacts the inside of
the unbroken vehicle glazing must not exceed 100 millimeters. This
displacement limit serves to control the gap size between the
countermeasure and the window opening, thus reducing the potential for
both partial and complete ejection of an occupant.
    To evaluate the performance of the curtain to fully cover potential
ejection routes, the impactor would typically target four specific
locations per side window adjacent to the first three rows of the
vehicle. NHTSA has tentatively determined that impacting four targets
around the perimeter of the opening would assure that the window will
be covered by the curtain, while imposing a reasonable test burden.
Small windows would be tested with fewer targets.
    Computer modeling has shown that ejections can occur early and late
in the rollover event. The impactor would strike the targets at two
impact speeds and at two different points in time following side
curtain air bag deployment, to ensure that the curtains will retain the
occupant from the relatively early through the late stages of a
rollover. The first impact would be a 24 kilometer per hour (km/h) (15
miles per hour (mph)) impact, 1.5 seconds after deployment of the
curtain. The 1.5 second time delay is proposed because half of all
fatal complete ejections occurred in crashes with 5 or more quarter-
turns (\1/4\-turns), and film analysis of vehicles that rolled 5 or
more \1/4\-turns in staged rollover tests performed by the agency
showed the vehicles taking about 1.5 seconds to achieve one complete
vehicle revolution. The second impact would be at 16 km/h (10 mph), 6
seconds after deployment of the curtain. Film analysis of the staged
vehicle tests showed a maximum roll time of 5.5 seconds for a vehicle
that rolled 11\1/4\-turns. The test speeds are representative of the
occupant dynamics during the rollover events as well as side impacts.
The agency is considering the alternative of applying the 24 km/h (1.5
second delay) impact only to the target location that exhibited the
greatest displacement in the 16 km/h (6 second delay) impact.
    Under today's NPRM, vehicle manufacturers would have to provide
information to NHTSA upon request that describes the conditions under
which the ejection mitigation air bags will deploy. We do not believe
conditions need to be specified in the standard dictating when the
sensors should deploy; field data indicate that rollover sensors are
deploying when they should in the real world. We discuss our rationale
for this decision in more detail below. Comments are requested on this
issue.

II. Congressional Mandate

    Section 10301 of SAFETEA-LU required the Secretary to issue by
October 1, 2009, an ejection mitigation final rule reducing complete
and partial ejections of occupants from outboard seating positions.
Section 10301 of SAFETEA-LU amended Subchapter II of chapter 301 (the
National Traffic and Motor Vehicle Safety Act, 49 U.S.C. Chapter 301)
to add Sec.  30128. Paragraph (a) directs the Secretary to initiate
rulemaking proceedings, for the purpose of establishing rules or
standards that will reduce vehicle rollover crashes and mitigate deaths
and injuries associated with such crashes for motor vehicles with a
gross vehicle weight rating of not more than 10,000 pounds. Paragraph
(c) directs the Secretary to initiate a rulemaking proceeding to
establish performance standards to reduce complete and partial
ejections of vehicle occupants from outboard seating positions.
Paragraph (c) states that, in formulating the standards, the Secretary
shall consider various ejection mitigation systems, and that the
Secretary shall issue a final rule under this paragraph no later than
October 1, 2009. Paragraph (e) states that if the Secretary determines
that the subject final rule deadline cannot be met, the Secretary shall
notify and provide explanation to the Senate Committee on Commerce,
Science, and Transportation and the House of Representatives Committee
on Energy and Commerce of the delay. On September 24, 2009, the
Secretary provided appropriate notification to Congress that the final
rule will be delayed until January 31, 2011.

III. Safety Problem

    Rollover crashes are a significant and a particularly deadly safety
problem. As a crash type, rollovers are second only to frontal crashes
as a source of fatalities in light vehicles. According to 1998-2007
Fatal Analysis Reporting System (FARS) data, frontal crash fatalities
have averaged about 12,000 per year, while rollover fatalities have
averaged 10,400 per year. In 2007, 35 percent of all fatalities were in
rollover crashes. Since the early 1990s, the sport utility vehicle
(SUV) segment has provided an increasing proportion of rollover
fatalities. There were approximately 1,700 SUV rollover fatalities in
1998, and more than 2,800 in 2007. The last 10 years of data from the
National Automotive Sampling System (NASS) General Estimates System
(GES) indicate that an occupant in a rollover is 14 times more likely
to be killed than an occupant in a frontal crash.\7\
---------------------------------------------------------------------------

    \7\ The relative risk of fatality for each crash type can be
assessed by dividing the number of fatalities in each crash type by
the frequency of the crash type. The frequency of particular crash
types is determined by police traffic crash reports (PARs).
---------------------------------------------------------------------------

    Ejection is a major cause of death and injury in rollover crashes.
According to 1998-2007 FARS data, about half of the occupants killed in
rollovers were completely ejected from their vehicle. During this time
period, there were 338 fully ejected occupants killed for every 1,000
fully ejected occupants in rollover crashes, as compared to 14 of every
1,000 occupants not fully ejected occupants killed.\8\ Although the
majority of occupants exposed to rollover crashes are in vehicles that
roll two \1/4\-turns or less, the distribution of ejected occupants who
are seriously injured (maximum abbreviated injury scale (MAIS) 3+) or
killed is skewed towards rollovers with higher degrees of rotation.
According to NASS Crashworthiness Data System (CDS) data of occupants
exposed to a rollover crash from 1988 to 2005, half of all fatal
complete ejections occurred in crashes with five or more \1/4\-turns.
---------------------------------------------------------------------------

    \8\ The data combines partially-ejected and un-ejected occupants
together, because partial ejection is sometimes difficult to
determine and the PAR-generated FARS data may not be an accurate
representation of partially-ejected occupant fatalities.
---------------------------------------------------------------------------

    Annualized injury data from 1997 to 2005 NASS CDS and fatality
counts adjusted to 2005 FARS levels indicate that ejection through side
windows constitutes the greatest part of the ejection problem. There
were 6,174 fatalities, 5,271 MAIS 3-5 injuries, and 18,353 MAIS 1-2
injuries for occupants

ejected through side windows. These constitute 61 percent of all
ejected fatalities, 47 percent of MAIS 3-5 injuries, and 68 percent of
MAIS 1-2 injuries.
    This NPRM seeks to reduce complete and partial ejections of
occupants from outboard seating positions in crashes involving a
rollover or a side planar crash. The target population for this
rulemaking would not include the population addressed by the FMVSS No.
214 pole test rulemaking.\9\ The target population would also not
include persons benefited by the installation of ESC systems in
vehicles, based on an assumption that all model year 2011 vehicles
would be equipped with ESC. As adjusted, the target population for this
ejection mitigation rulemaking is 1,392 fatalities, 1,410 MAIS 3-5
injuries and 4,217 MAIS 1-2 injuries. This target population
constitutes 23% of fatally-injured occupants ejected through the side
window, 27% of MAIS 3-5 injured, and 23% of MAIS 1-2 injured side
window-ejected occupants.
---------------------------------------------------------------------------

    \9\ The Phase 1 FMVSS No. 214 rulemaking included reduction of
partial side window-ejected adult (13+ years) occupants in side
impacts, but did not include complete ejections. The Phase 1
rulemaking also excluded any impact where a rollover was the first
event. Crashes where a rollover was a subsequent event were
included, but only for partially-ejected fatalities. In addition,
benefits were only assumed for side impact crashes with [Delta]V
between 19.2 and 40.2 km/h (12 to 25 mph) and impact directions from
2 to 3 o'clock and 9 to 10 o'clock.
---------------------------------------------------------------------------

IV. Proposed Solution

a. Various Ejection Mitigation Systems Considered

    In formulating this NPRM, NHTSA considered various ejection
mitigation systems in accordance with Section 10301 of SAFETEA-LU. One
of the considered systems was advanced laminated side glazing, a
countermeasure thought in the 1990s to have potential for use in
ejection mitigation.\10\ In 2002, the agency terminated an advance
notice of proposed rulemaking on advanced glazing after observing that
advanced glazing appeared to increase the risk of neck injury by
producing higher neck shear loads and neck moments than impacts into
tempered side glazing (67 FR 41365, June 18, 2002). In addition, the
estimated incremental cost for installing ejection mitigation glazing
in front side windows ranged from over $800 million to over $1.3
billion, based on light vehicle annual sales of 17 million units in the
2005-2006 timeframe. Moreover, because side curtain air bags were
showing potential as an ejection mitigation countermeasure, NHTSA
redirected its research and rulemaking efforts toward developing
performance-based test procedures for an ejection mitigation
standard.\11\
---------------------------------------------------------------------------

    \10\ Ejection mitigation glazing systems have a multi-layer
construction with three primary layers. There is usually a plastic
laminate bonded between two pieces of glass.
    \11\ ``Ejection Mitigation Using Advanced Glazing, Final
Report,'' NHTSA, August 2001, DMS Docket 1782-22 (``advance glazing
final report'').
---------------------------------------------------------------------------

    As with all of the FMVSSs, this proposed ejection mitigation
standard would be performance-oriented, to provide manufacturers wide
flexibility and opportunity for design innovation in developing
countermeasures that could be used for ejection mitigation. We
anticipate that manufacturers would likely install ejection mitigation
side curtain air bags in response to this rulemaking, taking advantage
of the side impact curtains already in vehicles. However, advanced
glazing could have a role in complementing ejection mitigation curtain
systems. NHTSA tested several vehicles' ejection mitigation side
curtain air bags both with and without laminated glazing to the 18 kg
impactor performance test proposed in this NPRM. In the tests, the
glazing was pre-broken to simulate the likely condition of the glazing
in a rollover. Tests of vehicles with advanced glazing resulted in an
average 51 mm reduction in impactor displacement across target
locations.\12\ That is, optimum (least) displacement of the headform
resulted from use of both an ejection mitigation window curtain and
advanced glazing. To encourage manufacturers to enhance ejection
mitigation curtains with advanced glazing, this NPRM proposes to allow
windows of advanced laminated glazing to be in position, but pre-broken
to reproduce the state of glazing in an actual rollover crash. Although
the glazing is pre-broken, the laminate in combination with the
remaining integrity of the glazing acts as a barrier to ejection.
Details on the pre-breaking method are given later in this preamble. As
discussed later, the vast majority of side windows in real-world
rollover crashes are closed.\13\
---------------------------------------------------------------------------

    \12\ To accompany this NPRM, NHTSA prepared a technical analysis
that presents a detailed analysis of engineering studies, and other
information supporting the NPRM, such as the results of NHTSA's
impactor testing of OEM and prototype side window ejection
mitigation systems, ``Technical Analysis in Support of a Notice of
Proposed Rulemaking for Ejection Mitigation.'' We will refer to this
technical analysis from time to time in this preamble. A copy of the
technical analysis has been placed in the docket.
    \13\ For the target population of this rulemaking, the front row
window through which an occupant was ejected was closed or fixed
prior to the crash 69 percent of the time. However, we are concerned
that for those instances where manufacturers utilize advanced
(laminated) glazing in their design, when the window is partially or
fully down, there may be a reduction of occupant retention. As
discussed later in this preamble, comments are requested on
alternatives to the approach of allowing laminated windows to be in
place and pre-broken. One option would be to test with all movable
windows removed or rolled down, regardless of whether the window is
laminated.
---------------------------------------------------------------------------

    Comments are requested on whether manufacturers would use advanced
glazing or some other novel window design alone, without a window
curtain, to meet the ejection mitigation requirements throughout the
vehicle or at least for some windows (e.g., as the countermeasure to
protect against ejection from a small window). Pre-breaking the glazing
using the proposed methodology would substantially damage advanced
glazing and might foreclose its use to meet the proposed requirements.
NHTSA's (limited) test data, discussed below, indicate that various
combinations of ejection mitigation countermeasures do not have a high
potential for producing neck injury.\14\ Yet, in lateral impact tests
comparing unbroken advanced glazing alone to tempered glazing, the
agency found that in some tests the lateral neck shear forces were
higher for the advanced glazing.\15\ Given these data, comments are
requested on the potential for neck injury in the event that advanced
glazing alone were used to comply with the proposed standard.
---------------------------------------------------------------------------

    \14\ ``Status of NHTSA's Ejection Mitigation Research Program,''
Willke et al., 18th International Technical Conference on the
Enhanced Safety of Vehicles, paper number 342, June 2003.
    \15\ ``Ejection Mitigation Using Advanced Glazing, Final
Report,'' supra.
---------------------------------------------------------------------------

b. Full Window Opening Coverage Is Key

    NHTSA undertook several research programs using a dynamic rollover
fixture (DRF), which produced full-dummy ejection kinematics in an open
window condition, to assess the potential effectiveness of ejection
mitigation countermeasures in a rollover.\16\ These countermeasures

included several designs of inflatable curtain air bags, advanced
laminated glazing, and combinations of curtains and advanced glazing.
The results showed, however, that not all ejection mitigation air bag
curtains work the same way. Full window opening coverage is key to the
effectiveness of the curtain in preventing ejection.
---------------------------------------------------------------------------

    \16\ NHTSA developed the DRF to produce full-dummy ejection
kinematics in a less costly manner than full-scale testing. The DRF
models a lateral rollover crash of approximately one vehicle
revolution. The DRF rotates approximately one revolution and comes
to rest through the application of a pneumatic braking system on one
end of the pivot axle. It does not simulate lateral vehicle
accelerations often encountered in a rollover crash prior to
initiation of the rollover event. The DRF has a test buck fabricated
from a Chevrolet CK pickup cab. The cab was longitudinally divided
down the center from the firewall to the B-pillar. The left (driver)
side is rigidly attached to the test platform. The Chevrolet CK was
chosen so that the advanced glazing systems developed in the
previous ejection mitigation research could be evaluated in this
program. A seat back and cushion were made from Teflon material, to
minimize the shear forces on the dummy buttocks for more desired
loading on the window area by the dummy's head and upper torso.
---------------------------------------------------------------------------

1. Tests With 50th Percentile Adult Male and 5th Percentile Adult
Female Test Dummies
    In the first research program, experimental roof rail-mounted
inflatable devices developed by Simula Automotive Safety Devices
(Simula) and by TRW were evaluated on the DRF, along with an advanced
side glazing system.\17\ In the tests, unrestrained 50th percentile
male and 5th percentile female Hybrid III dummies, instrumented with 6
axis upper neck load cells and tri-axial accelerometers in the head,
were separately placed in the buck.\18\ The DRF rotation results in a
centripetal acceleration of the dummy that caused it to move outwards
towards the side door/window. In baseline tests of the unrestrained
dummies in the DRF with an open side window and no countermeasure, the
dummies were fully ejected. The ability of the countermeasure to
restrain the dummies was assessed and compared to that baseline test.
---------------------------------------------------------------------------

    \17\ ``Status of NHTSA's Ejection Mitigation Research Program,''
Willke et al., 18th International Technical Conference on the
Enhanced Safety of Vehicles, paper number 342, June 2003.
    \18\ Two dummy positions were used. The first was behind the
steering wheel. The second position was more inward, toward the
pivot axle, which generated higher contact velocities. Film analysis
was used to measure the dummy's relative head contact velocity with
the side window plane from these two seating positions. From the
first position, the impact speeds were 14 km/h (9 mph) for the 5th
percentile female dummy and 18 km/h (11 mph) for the 50th male. From
the second (inboard) position, the velocities were 31 km/h (19 mph)
for the 5th female and 29 km/h (18 mph) for the 50th male.
---------------------------------------------------------------------------

    In the tests of the experimental inflatable devices, the air bags
were pre-deployed and their inflation pressure was maintained
throughout the test by the use of an air reservoir tank mounted on the
platform.\19\ In the tests, the dummy's upper body loaded the
inflatable device, which limited the dummy's vertical movement toward
the roof and caused the pelvis to load the side door throughout the
roll, rather than to ride up the door. The inflatable devices contained
the torso, head, and neck of the dummy, so complete ejection did not
occur. However, both devices did allow partial ejection of the dummy's
shoulder and arm below the bags, between the inflatable devices and the
vehicle door.
---------------------------------------------------------------------------

    \19\ Since these were experimental systems, they were not
deployed through pyrotechnic or in-vehicle compressed gas, as might
be the case with production designs. The air pressure supplied by
the laboratory reservoir kept the systems fully inflated over the
test period.
---------------------------------------------------------------------------

    In the test of the advanced side glazing (laminated with door/
window frame modifications around the entire periphery to provide edge
capture), the glazing contained the dummies entirely inside the test
buck. The glazing was not pre-broken before the testing. There was some
flexing of the window frame when the dummies loaded the glazing, and
the 50th percentile male dummy's shoulder shattered the glass when the
dummy was located behind the steering wheel.
    In the test of the combined systems, the dummies remained entirely
inside the buck. Although the shoulder and arm escaped under the
inflatable devices, the advanced glazing prevented the partial ejection
seen in tests of the inflatable devices alone.
    In these tests, the ejection mitigation systems did not show a high
potential for producing head and neck injury. However, head and neck
loading were higher than the open window condition. The highest load
with respect to the Injury Assessment Reference Values (IARVs) was 82
percent for the neck compression for the 5th percentile female tested
with the Simula/laminate combination. The highest injury response for
the 50th percentile male dummy was 59 percent for the neck compression
with the TRW system alone. All HIC36 \20\ responses were
extremely low and ranged from 8 to 90, with the maximum occurring in an
open window test. Lateral shear and bending moment of the neck were
also measured, although there are no established IARVs. The maximum
lateral neck shear loads were 950 N (50th percentile male tested with
TRW system) and 1020 N (5th percentile female tested with laminate
only).
---------------------------------------------------------------------------

    \20\ HIC36 is the Head Injury Criterion computed over
a 36 msec duration. HIC36 =1000 represents an onset of
concussion and brain injury.
---------------------------------------------------------------------------

2. Tests With 6-Year-Old Child Test Dummy Showed a Risk of Ejection
Through Openings Not Fully Covered
    The second research program involved a series of tests on the DRF
using an unrestrained Hybrid III 6-year-old dummy. In previous tests
with the 50th percentile adult male and 5th percentile adult female
dummies, a gap formed between the inflatable devices and the window
sill (bottom of the window opening), which allowed partial ejection of
those dummies. The second program investigated whether the gap allowed
ejection of the 6-year-old child dummy.\21\
---------------------------------------------------------------------------

    \21\ ``NHTSA's Crashworthiness Rollover Research Program,''
Summers, S., et al., 19th International Technical Conference on the
Enhanced Safety of Vehicles, paper number 05-0279, 2005.
---------------------------------------------------------------------------

    In baseline testing with an open side window without activation of
an ejection mitigation countermeasure, the child dummy was fully
ejected. In tests of the two inflatable systems tested in the first
program (at the time of the second research program, the inflatable
device formerly developed by Simula was then developed by Zodiac
Automotive US (Zodiac)), the inflatable devices prevented full ejection
of the 6-year-old child dummy in upright-seated positions (no booster
seat was used). However, dummy loading on the systems produced gaps
that did allow an arm and/or hand to pass through in some tests.
Moreover, in a series of tests with the dummy lying in a prone position
(the dummy was placed on its back at the height of the bottom of the
window opening), representing a near worst-case ejection condition, the
dummy was completely ejected at positions near the bottom of the
inflatable devices (above the sill) with the TRW curtain, while the
Zodiac system contained the dummy inside the test buck in all testing.
Adding pre-broken advanced glazing with the TRW system managed to
contain the dummy inside the test buck in all tests.\22\
---------------------------------------------------------------------------

    \22\ Id.
---------------------------------------------------------------------------

3. Differences in Design Between the Two Inflatable Systems
    The two prototype inflatable devices tested had fundamentally
different designs. The Zodiac/Simula prototype system used an
inflatable tubular structure (ITS) \23\ tethered near the base of the A
and B-pillars that deployed a woven material over the window opening.
(The Zodiac system differed from the originally-tested Simula design in
that it had more window coverage. This was achieved by placing the ITS
tether locations lower on the pillars and adding additional woven
material.) The TRW prototype was more akin to a typical air bag curtain
and was fixed to the A- and B-pillar at its end points and along the
roof rail, but not tethered. The ITS differed from conventional air
bags in that it was not vented. We believe that the better performance
of the Zodiac prototype system compared to that of TRW, in the DRF
testing described above and in impactor test

results provided later in this preamble, was due to the greater window
coverage by the Zodiac prototype along the entire sill and A-pillar.
---------------------------------------------------------------------------

    \23\ ITS systems were originally introduced by BMW as a side
impact countermeasure.
---------------------------------------------------------------------------

4. Insights
    The DRF research provided the following insights into ejection
mitigation curtains:
     Inflatable devices prevented ejection of test dummies in
simulated rollover tests, but design differences accounted for
differences in performance;
     Gaps in the inflatable device's coverage of the window
opening at the sill and A-pillar allowed partial ejection of adult
dummies and full ejection of a 6-year-old child dummy;
     Adding pre-broken advanced glazing to an air bag system
enhanced the ability of the system to contain the dummy; and,
     To optimize ejection mitigation potential, a performance
test should ensure that the countermeasure has full coverage of the
window opening.

c. Comparable Performance in Simulated Rollovers and Component-Level
Impact Tests

    Because full-vehicle rollover crash tests can have an undesired
amount of variability in vehicle and occupant kinematics, in the
advanced glazing program NHTSA developed a component-level impact test
for assessing excursion and the risk of ejection. The component-level
test is basically the test proposed in this NPRM for ejection
mitigation.\24\ The test involves use of a guided linear impactor
designed to replicate the loading of a 50th percentile male occupant's
head and shoulder during ejection situations. The impactor \25\ is
described later in this preamble. There are many possible ways of
delivering the impactor to the target location on the ejection
mitigation countermeasure. The ejection mitigation test device \26\
used in agency research has a propulsion mechanism \27\ with a
pneumatic piston that pushes the shaft component of the impactor. The
shaft slides along a plastic (polyethylene) bearing. The impactor has
an 18 kg mass.
---------------------------------------------------------------------------

    \24\ ``Technical Analysis in Support of a Notice of Proposed
Rulemaking for Ejection Mitigation,'' supra.
    \25\ The ``ejection impactor'' is the moving mass that strikes
the ejection mitigation countermeasure. It consists of an ejection
headform attached to a shaft
    \26\ The ejection mitigation test device consists of an ejection
impactor and ejection propulsion mechanism.
    \27\ The ``ejection propulsion mechanism'' is the component that
propels the ejection impactor and constrains it to move along its
axis or shaft.
---------------------------------------------------------------------------

    The component-level test identified four impact locations to
evaluate a countermeasure's window coverage and retention capability.
Two of the positions were located at the extreme corners of the window/
frame and were located such that a 25 mm gap existed between the
outermost perimeter of the headform and window frame. A third position
was near the transition between the upper window frame edge and A-
pillar edge. The fourth position was at the longitudinal midpoint
between the third position and the position at the upper extreme corner
of the window/door frame, such that the lowest edge of the headform was
25 mm above the surface of the door at the bottom of the window
opening. At each impact location, different impact speeds and different
time delays between air bag deployment and impact were used. To
simulate ejection early in a rollover event and in a side impact, the
air bags were impacted 1\1/2\ seconds after air bag deployment, at 20
and 24 km/h. To simulate ejection late in a rollover event, the air
bags were impacted after a delay of 6 seconds at an impact speed of 16
km/h.
    The two inflatable systems tested in the above-described research
programs (the inflatable devices developed by Zodiac and by TRW) were
installed on a Chevrolet CK pickup cab and subjected to the component-
level impact test. The air bag systems were evaluated for allowable
excursion (impactor displacement) beyond the side window plane. The
tests also assessed the degree to which the component-level test was
able to replicate the findings of the DRF tests.
    The component-level tests mimicked the DRF tests by revealing the
same deficiencies in the side curtain air bags that were highlighted in
the dynamic test. The Zodiac system \28\ did not allow the impactor to
go beyond the plane of the window in the 16 km/h and 20 km/h tests. The
air bag allowed only 12 and 19 mm of excursion beyond the window plane
in the 24 km/h tests. In the 24 km/h tests of the TRW system, the
curtain was not able to stop the impactor before the limits of travel
were reached (about 180 mm beyond the plane for the vehicle window for
that test setup) at the position at the extreme forward corner of the
window sill. This is the position at which the TRW prototype system
allowed excessive excursion of the test dummies in the DRF dynamic
tests. In the DRF tests, the 6-year-old dummy was completely ejected
through that window area even when the prone dummy was aimed at the
position at the other extreme corner of the window. In other tests, the
TRW prototype system was able to stop the impactor before the impactor
reached its physical stops.
---------------------------------------------------------------------------

    \28\ Testing was restricted to the extreme corners of the window
due to limited availability of this system.
---------------------------------------------------------------------------

d. Advantages of a Component Test Over a Full Vehicle Dynamic Test

    The component test not only distinguishes between acceptable and
unacceptable performance in side curtain air bags, but has advantages
over a full vehicle dynamic test. The acceptable (or poor) performance
in the laboratory test correlated to the acceptable (or poor)
performance in the dynamic test. The component test was able to reveal
deficiencies in window coverage of ejection mitigation curtains that
resulted in partial or full ejections in dynamic conditions. NHTSA
tentatively believes that incorporating the component test into an
ejection mitigation standard would ensure that ejection mitigation
countermeasures provide sufficient coverage of the window opening for
as long in the crash event as the risk of ejection exists, which is a
key component contributing to the efficacy of the system.
    As noted earlier, rollover crash tests can have an undesirable
amount of variability in vehicle and occupant kinematics. In contrast,
the repeatability of the component test has been shown to be good.\29\
Moreover, there are many types of rollover crashes, and within each
crash type the vehicle speed and other parameters can vary widely. A
curb trip can be a very fast event with a relatively high lateral
acceleration. Soil and gravel trips have lower lateral accelerations
than a curb trip and lower initial roll rates. Fall-over rollovers are
the longest duration events, and it can be difficult to distinguish
between rollover and non-rollover events. Viano and Parenteau \30\
correlated eight different tests to six rollover definitions from NASS-
CDS.\31\ Their analysis indicated that the types of rollovers occurring
in the real-world varied significantly. Soil trip rollovers accounted
for more than 47 percent of the rollovers in the field, while less than
1 percent of real-world rollovers were

represented by the FMVSS No. 208 dolly test.
---------------------------------------------------------------------------

    \29\ ``NHTSA's Crashworthiness Rollover Research Program,''
supra.
    \30\ Viano D, Parenteau C. Rollover Crash Sensing and Safety
Overview. SAE 2004-01-0342.
    \31\ ``Technical Analysis in Support of a Notice of Proposed
Rulemaking for Ejection Mitigation,'' supra.
---------------------------------------------------------------------------

    Occupant kinematics will also vary with these crash types,
resulting in different probabilities of occupant contact on certain
areas of the side window opening with differing impact energies. A
single full vehicle rollover test could narrowly focus on only certain
types of rollover crashes occurring in the field.\32\ NHTSA is
concerned that a comprehensive assessment of ejection mitigation
countermeasures through full vehicle dynamic testing may only be
possible if it were to involve multiple crash scenarios. Such a suite
of tests imposes test burdens that could be assuaged by a component
test such as that proposed today. We also note that a comprehensive
suite of full-vehicle dynamic tests would likely involve many more
years of research, which would delay this rulemaking action and the
potential for incorporating these life-saving technologies. Such a
delay seems unwarranted since NHTSA believes the component test will be
an effective means of determining the acceptability of ejection
countermeasures. Whether it would be more or less effective than a yet-
to-be-defined suite of full vehicle tests remains an open question.
However, as explained above, the proposed test clearly has advantages
over a single full vehicle test.
---------------------------------------------------------------------------

    \32\ The agency has in the past performed dolly type dynamic
testing. The agency has not performed enough repeat tests of the
same vehicles to draw any conclusions about the repeatability of
these tests to determine occupant containment. However, regardless
of the level of repeatability of dummy kinematics, it still only
represents a part of the kinematics that would occur in the field.
---------------------------------------------------------------------------

e. Existing Curtains Can Be Made More Effective

1. Existing Curtains
    The availability of vehicles that offer inflatable side curtains
that deploy in a rollover has increased since they first became
available in 2002. In the middle of the 2002 model year (MY), Ford
introduced the first generation of side curtain air bags that were
designed to deploy in the event of a rollover crash. The rollover air
bag curtain system, marketed as a ``Safety Canopy,'' was introduced as
an option on the Explorer and Mercury Mountaineer.\33\ For the 2007 MY,
rollover sensors were available on approximately 95 models, with 75 of
these models being sport utility vehicles. The system is standard
equipment on 62 vehicles (65 percent) and optional on 33 vehicles (35
percent).
---------------------------------------------------------------------------

    \33\ http://media.ford.com/article_display.cfm?article_
id=6447.
---------------------------------------------------------------------------

    In addition to the presence of a rollover sensor, there are two
important design differences between air bag curtains designed for
rollover ejection mitigation and air bag curtains designed for side
impact protection. The first difference is longer inflation duration.
Rollover crashes with multiple full vehicle rotations can last many
seconds. Ford states that its Safety Canopy stays inflated for 6
seconds,\34\ while GM has been reported to state that its side curtain
air bags designed for rollover protection maintain 80 percent inflation
pressure for 5 seconds.\35\ Honda reportedly states that the side
curtains on the 2005 and later Honda Odyssey stay fully inflated for 3
seconds.\36\ (To our knowledge, Ford has not indicated what level of
inflation is maintained during the duration.) In contrast, side impact
air bag curtains designed for occupant protection in side crashes,
generally stay inflated for less than 0.1 seconds.
---------------------------------------------------------------------------

    \34\ Ibid.
    \35\ ``Who Benefits From Side and Head Airbags?'' (http://
www.edmunds.com/ownership/safety/articles/105563/article.html).
    \36\ http://www.autodeadline.com/
detail?source=Honda∣=HON2004083172678&mime=ASC.
---------------------------------------------------------------------------

    The second important air bag curtain design difference between
rollover and side impact protection is the size or coverage of the air
bag curtain. One of the most obvious trends in newer vehicles is the
increasing area of coverage for rollover curtains. Ford reportedly
stated that its rollover protection air bags cover between 66 and 80
percent of the first two rows of windows, and that it was expanding the
designs so they cover all three rows in all models.\37\ GM reportedly
stated that its curtains designed for rollover protection are larger
than non-rollover curtains.\38\
---------------------------------------------------------------------------

    \37\ Ibid.
    \38\ Who Benefits From Side and Head Airbags?'' (http://
www.edmunds.com/ownership/safety/articles/105563/article.html).
---------------------------------------------------------------------------

2. Component Tests of Real-World Curtains and Advanced Glazing Systems
Show That Improvements Could Be Made
    NHTSA has tested real-world side window air bag curtains and
advanced glazing \39\ according to the test procedure proposed in this
NPRM, except for some differences in the target
locations.40 41 In addition, prototype Zodiac and TRW
systems were installed on the GM CK pickup and the Lincoln Navigator.
In this section of the preamble, we provide test results for ejection
mitigation countermeasures installed as original equipment (OE) and as
prototypes, tested to the proposed requirements. One of the findings of
this test series was that none of the original equipment (OE) systems
met the proposed displacement limit when impacted at the target in the
forward lower corner of the front window (target A1, see Figure 1
below) at 24 km/h.\42\
---------------------------------------------------------------------------

    \39\ The laminates tested were marketed as theft protection and
not as a form of ejection mitigation.
    \40\ ``Status of NHTSA's Ejection Mitigation Research Program,''
supra.
    \41\ ``NHTSA Crashworthiness Rollover Research Program,'' supra.
    \42\ ``Technical Analysis in Support of a Notice of Proposed
Rulemaking for Ejection Mitigation,'' supra.
---------------------------------------------------------------------------

    The target locations shown in Figure 1 were determined by the
method proposed for this NPRM. With the exception of the Honda Odyssey,
for all tests of prototype systems and OE system through MY05, the
method for determining the target location was slightly different than
currently proposed. (We will refer to this method as the ``research
target method'' as opposed to the ``proposed target method.'') The MY05
Odyssey was tested by the proposed target method. As explained below,
the differences in target locations identified by the two methods are
small enough that data using the research target method can be
reasonably compared to the proposed target method.
    The difference in determining the target location had the most
effect on the location of A2, A3, B1 and B4. The resulting shift in
target location was a function of the window shape. The primary
difference in the research target method was that A3 was found by
bisecting the angle produced by the intersection of a line parallel to
the A-pillar and roof rail, which in the case of the window in Figure 1
would shift A3 rearward and upward. Since A2 is located horizontally
midway between A3 and A4 in both the research and proposed target
methods, A2 in the research target method would be rearward of the A2
position shown in Figure 1.
    The rear window data for prototype and OE system through MY05 is,
for the most part, limited to B1 and B4. Under the research target
method used to find the target locations, B1 was at the lower sill, in
the middle of the window and B4 was in the upper rear corner. Again,
under the research target method, B1 and B4 would likely be shifted
forward from the location shown in Figure 1. For the test of the Zodiac
prototype on the Navigator, extra targets were impacted. For only this
vehicle, Tables 1 through 3 of this preamble present an average

result from two impacts that were on either side of the proposed
targets B1 and B4.
[GRAPHIC] [TIFF OMITTED] TP02DE09.000

    The results of the testing are given in Tables 1 through 3. The
results are given in columns, by target location. These data are also
found in a color coded format in the Technical Analysis report
accompanying this NPRM. The target location key is shown in Figure 1 of
this preamble, supra. In general, for a particular vehicle and target
location, if multiple trials were run at a particular impact speed and
time delay, each of the displacement results is shown by separating the
table cell into two or three cells.
    Although the agency is proposing a 24 km/h impact test 1.5 seconds
after air bag deployment, research data was acquired at 20 km/h to
determine the sensitivity to impact speed. Several ejection mitigation
systems were not tested at 24 km/h at every target location because the
20 km/h results indicated displacements in excess of 100 mm at that
location. We assume the 24 km/h impact would also have exceeded 100 mm.
Where this occurred, the cell in Table 1 contains the 20 km/h
displacement value and is identified by an asterisk. Similarly, some
target locations were not tested at 20 km/h, but we assume that the
value that would have been obtained would be below 80 mm of
displacement because the 24 km/h impact was less than 80 mm. Where this
occurred, the cell in Table 2 contains the 24 km/h displacement value
and is identified by a double asterisk.
    Tables 1 through 3 show the results for vehicle front windows. For
all three sets of tests, A1 was the most challenging target and A4 was
the least challenging. For the 24 km/h test, the only system that did
not exceed the 100 mm criterion at A1 was the Zodiac prototype on the
CK pickup. At 20 km/h, the MY05 Infinity had one test result of 99 mm
and another of 106 mm at A1. For the 16 km/h impact at a 1.5 second
delay, two OE systems and two prototype systems had displacements
slightly more or less than 100 mm at A1. No displacement at A4 exceeded
76, 73 or 67 mm at 24, 20 and 16 km/h, respectively. Taken as a whole,
A2 and A3 showed similar results to each other for all three test
conditions in that neither was as consistently challenging to meet as
A1 nor as easily met as A4. The trends for severity by target location
are the same for the 16 km/h impacts at a 6 second delay.

               Table 1--Impactor Displacement--Front Row Window, 24 km/h Impact, 1.5 Second Delay
----------------------------------------------------------------------------------------------------------------
                                      Position A1         Position A2         Position A3         Position A4
----------------------------------------------------------------------------------------------------------------
03 Navigator....................  No Data...........  * 186 196*........  * 229.............  -22.
03 Navigator w/lam..............  No Data...........  35................  No Data...........  No Data.
04 Volvo XC90...................  * 163.............  193...............  130...............  18.
04 Volvo w/lam..................  * 102 * 151.......  44................  118...............  15.
05 Nissan Pathfinder............  * 181.............  161...............  * 240.............  76 76.
05 Toyota Highlander............  * 159 * 164.......  202...............  137...............  67.
05 Infinity FX35................  124...............  83 96 112.........  89 89 108.........  53.
05 Chevy Trailblazer............  138...............  168...............  159...............  No Data.
05 Chevy Trailblazer w/lam......  No Data...........  No Data...........  * 107 * 110.......  No Data.
05 Honda Odyssey................  No Cover..........  119...............  107...............  No Data.
06 Dodge Durango................  174...............  156...............  * 180.............  54.
06 Dodge Durango w/lam..........  No Data...........  * 101.............  No Data...........  No Data.
Zodiac Prot. on CK..............  12................  19................  No Data...........  No Data.
Zodiac Prot. on Navigator.......  150 143...........  54................  96 102............  21 24.
Zodiac Prot. on Nav. w/lam......  No Data...........  No Data...........  91 97.............  No Data.
TRW Prot. on CK.................  No Cover [dagger].  82 82 102.........  2 6...............  -13 -8.
TRW Prot. on CK w/lam...........  180 182...........  21................  -26 -26...........  -33 -25.
----------------------------------------------------------------------------------------------------------------
* Only tested at 20 km/h and displacement exceeded 100 mm.
[dagger] No countermeasure at this target location.

               Table 2--Impactor Displacement--Front Row Window, 20 km/h Impact, 1.5 Second Delay
----------------------------------------------------------------------------------------------------------------
                                      Position A1         Position A2         Position A3         Position A4
----------------------------------------------------------------------------------------------------------------
03 Navigator....................  No Data...........  186 196...........  229...............  -37.
03 Navigator w/theft lam........  No Data...........  6.................  No Data...........  No Data.
04 Volvo XC90...................  163...............  84 107............  107 131...........  -3.
04 Volvo w/theft lam............  102 151...........  27................  97................  ** 15.
05 Nissan Pathfinder............  181...............  133...............  240...............  58
05 Toyota Highlander............  159 164...........  113 150...........  106 113...........  73.
05 Infinity FX35................  99 106............  58................  70................  29.
05 Chevy Trailblazer............  112...............  121...............  127...............  No Data.
05 Chevy Trailblazer w/lam......  90................  80................  109...............  No Data.
05 Honda Odyssey................  No Cover [dagger].  96................  57................  -45.
06 Dodge Durango................  160...............  140...............  180...............  18.
06 Dodge Durango w/lam..........  No Data...........  101...............  No Data...........  No Data.
Zodiac Prot. on CK..............  -12...............  -9................  No Data...........  No Data.
Zodiac Prot. on Navigator.......  122...............  38................  76 81.............  -9 -0.9.
Zodiac Prot. on Nav. w/lam......  No Data...........  No Data...........  No Data...........  No Data.
TRW Prot. on CK.................  No Cover [dagger].  75................  -29...............  -52.
TRW Prot. on CK w/lam...........  104...............  0.................  -54...............  -60 -63.
----------------------------------------------------------------------------------------------------------------
** Only tested at 24 km/h and displacement was below 80 mm.
[dagger] No countermeasure at this target location.

                Table 3--Impactor Displacement--Front Row Window, 16 km/h Impact, 6 Second Delay
----------------------------------------------------------------------------------------------------------------
                                      Position A1         Position A2         Position A3         Position A4
----------------------------------------------------------------------------------------------------------------
03 Navigator....................  243...............  74................  211...............  -30.
03 Navigator w/theft lam........  157...............  -14...............  137...............  No Data.
04 Volvo XC90...................  154 167...........  52 93.............  78................  -22.
04 Volvo w/theft lam............  86 105............  26................  59................  No Data.
05 Nissan Pathfinder............  108 120...........  93 106............  188...............  37 46.
05 Toyota Highlander............  198...............  132...............  147...............  67.
05 Infinity FX35................  85................  21................  39................  9.
05 Chevy Trailblazer............  121...............  192...............  124...............  No Data.
05 Chevy Trailblazer w/lam......  No Data...........  102...............  No Data...........  No Data.
05 Honda Odyssey................  No Cover [dagger].  77................  47 90.............  -54.
06 Dodge Durango................  138...............  135...............  167...............  13.
06 Dodge Durango w/lam..........  No Data...........  No Data...........  142...............  No Data.
Zodiac Prot. on CK..............  0.................  0.................  No Data...........  No Data.
Zodiac Prot. on Navigator.......  135...............  49................  78 81.............  -0.2.
Zodiac Prot. on Nav. w/lam......  104...............  No Data...........  70................  No Data.
TRW Prot. on CK.................  No Cover [dagger].  99 97.............  -36...............  -41.
TRW Prot. On CK w/lam...........  80................  -3................  -44...............  -67.
----------------------------------------------------------------------------------------------------------------
[dagger] No countermeasure at this target location.

    The 2nd row window data in Tables 4 through 6 are much more
limited, with nearly all the data at B1 and B4. In general, these data
indicate target location B1 is more challenging than B4. The exception
to this is the Dodge Durango, which performed well at all 2nd row
targets. For the 24 km/h test at B1, three of the ejection mitigation
systems tested had displacements that did not exceed 100 mm. For the 20
and 16 km/h test at B1, a total of 3 systems did not exceed 100 mm. We
also expect that the Durango would not have exceeded 100 mm at 20 km/h,
since it did not exceed 100 mm at 24 km/h. At B4, three systems had
displacements that exceeded 100 mm. This was reduced to one system for
the 20 and 16 km/h impacts.
    Any cell listed as ``To Stops'' indicates a displacement of the
impactor to the point where the mechanical stops of the device keep it
from further movement. This occurred for the MY03 Navigator at B1 at 24
and 20 km/h. ``To stops'' is considered an infinite displacement and
indicates very little countermeasure coverage at this location.
    Table 7 shows very limited 3rd row window data for the Odyssey and
Durango at all test conditions. For this system C4 is much more
challenging than C1.\43\
---------------------------------------------------------------------------

    \43\ We are using C1 through C4 to denote the impact locations
for the 3rd row window. Third row target locations were found in the
same manner as 2nd row targets.

                          Table 4--Second Row Window, 24 km/h Impact, 1.5 Second Delay
----------------------------------------------------------------------------------------------------------------
                                      Position B1         Position B2         Position B3         Position B4
----------------------------------------------------------------------------------------------------------------
03 Navigator....................  To Stops..........  No Data...........  No Data...........  -40.
04 Volvo XC90...................  (20 km/h) \*\.....  No Data...........  No Data...........  69.
04 Volvo w/theft lam............  91/93.............  No Data...........  No Data...........  62.
05 Nissan Pathfinder............  161...............  No Data...........  No Data...........  128.

05 Toyota Highlander............  146...............  No Data...........  No Data...........  149.
05 Infinity FX35................  143...............  No Data...........  No Data...........  45.
05 Honda Odyssey................  71................  152...............  80................  193.
06 Dodge Durango................  76................  86................  91................  82.
Zodiac Prot. on Navigator.......  Avg. = 98.........  99................  No Data...........  Avg. = 104 (32 to
                                  (96 to 100)                                                  176) [Dagger].
                                   [Dagger]..
----------------------------------------------------------------------------------------------------------------
* Exceeded 100 mm at 20 km/h.
[Dagger] Combines data from two impact location closest to the defined target location.

                          Table 5--Second Row Window, 20 km/h Impact, 1.5 Second Delay
----------------------------------------------------------------------------------------------------------------
                                      Position B1         Position B2         Position B3         Position B4
----------------------------------------------------------------------------------------------------------------
03 Navigator....................  To Stops..........  No Data...........  No Data...........  -14.
04 Volvo XC90...................  183...............  No Data...........  No Data...........  (24 km/h) **.
04 Volvo w/theft lam............  94................  No Data...........  No Data...........  (24 km/h) **.
05 Nissan Pathfinder............  126/150...........  No Data...........  No Data...........  99.
05 Toyota Highlander............  107...............  No Data...........  No Data...........  102.
05 Infinity FX35................  79 94.............  No Data...........  No Data...........  21.
05 Honda Odyssey................  42................  134...............  34................  84.
06 Dodge Durango................  (24 km/h).........  No Data...........  No Data...........  No Data.
Zodiac Prot. on Navigator.......  Avg. = 70.........  70................  No Data...........  Avg. = 77 (9 to
                                  (67 to 72)                                                   144) [Dagger].
                                   [Dagger]..
----------------------------------------------------------------------------------------------------------------
[Dagger] Combines data from two impact location closest to the defined target location.
\**\ Below 80 mm at 24 km/h.

                           Table 6--Second Row Window, 16 km/h Impact, 6 Second Delay
----------------------------------------------------------------------------------------------------------------
                                      Position B1         Position B2         Position B3         Position B4
----------------------------------------------------------------------------------------------------------------
03 Navigator....................  126...............  No Data...........  No Data...........  -27.
04 Volvo XC90...................  189...............  No Data...........  No Data...........  29.
04 Volvo w/theft lam............  63................  No Data...........  No Data...........  9.
05 Nissan Pathfinder............  104...............  No Data...........  No Data...........  75.
05 Toyota Highlander............  138...............  No Data...........  No Data...........  107.
05 Infinity FX35................  61................  No Data...........  No Data...........  19.
05 Honda Odyssey................  12................  121...............  55................  28.
06 Dodge Durango................  3.................  36................  71................  18.
Zodiac Prot. on Navigator.......  Avg. = 81 (73 to    98................  No Data...........  Avg. = 67 (16 to
                                   89) [dagger].                                               117) [dagger].
----------------------------------------------------------------------------------------------------------------
[dagger] Combines data from two impact location closest to the defined target location.

                          Table 7--Third Row Window, All Impact Speeds and Time Delays
----------------------------------------------------------------------------------------------------------------
                                      Position C1         Position C2         Position C3         Position C4
----------------------------------------------------------------------------------------------------------------
24 km/h--1.5 s
    05 Honda Odyssey............  No Data...........  No Data...........  175...............  (20 km/h) *.
    06 Dodge Durango............  No Data...........  No Data...........  No Data...........  (20 km/h) *.
20 km/h--1.5 s
    05 Honda Odyssey............  58................  No Data...........  122...............  To Stops.
    06 Dodge Durango............  66................  No Data...........  No Data...........  283.
16 km/h--6 s
    05 Honda Odyssey............  44................  To Stops..........  80................  331.
    06 Dodge Durango............  52................  No Data...........  No Data...........  No Data.
----------------------------------------------------------------------------------------------------------------
* Exceeded 100 mm at 20 km/h.

    Summarized below are some very general trends for the displacement
data. These trends were based on limited data and were not analyzed for
statistical significance.
    Within target locations we found the following general trends:
     The 24 km/h--1.5 second delay test was the most
challenging test;
     The 20 km/h--1.5 second test was more consistently
challenging than the 16 km/h--6 second test;
     For the 24 km/h test, the only system that did not exceed
the 100 mm criterion at A1 was the Zodiac Prototype on the CK pickup.
    Comparing target locations we found the following general trends:
     In row one, A1 was the most consistently challenging
target and A4 was the least;
     In row two, target location B1 was more consistently
challenging than target B4;
     Data from the third row targets were too limited to
indicate any trends.

3. Use of advanced glazing with the air bag curtain resulted in reduced
displacement
    Several vehicles were tested both with and without laminated
glazing. A prototype glazing was used on the CK pickup. Tests where
advanced glazing was used resulted in a reduction in impactor
displacement. Table 8 shows the reduction in impactor displacement for
each of the vehicles. Not every target location was tested at each
impact speed. For all prototype and MY06 and older vehicles, the
glazing was pre-broken using a ball-peen hammer method discussed in the
Technical Analysis report accompanying this NPRM, while for MY07
vehicles, the glazing was broken using a 50 mm matrix hole punch
pattern. (The agency is proposing the latter method in this NPRM.)
    The largest displacement reduction was for the MY03 Navigator at
A2, impacted at 20 km/h--1.5 second delay. This location exhibited a
185 mm change in displacement (from 191 mm to 6 mm). The smallest
change in displacement was 3 mm (18 mm to 15 mm) for the MY04 XC90 at
A4, impacted at 24 km/h--1.5 second delay. For target positions with
multiple vehicle tests, the A2 position had the largest change in
displacement at each test speed. The average displacement reduction
across target locations and test types was 51 mm.

             Table 8--Reduction in Impactor Displacement Resulting From Pre-Broken Laminated Glazing
----------------------------------------------------------------------------------------------------------------
                                                    A1         A2         A3         A4         B1         B4
----------------------------------------------------------------------------------------------------------------
24 km/h, 1.5 sec.:
    04 Volvo XC90.............................  .........        149         12          3  .........          7
    Zodiac Prot. on Navigator.................  .........  .........          5  .........  .........  .........
    TRW Prot. on CK...........................  .........         68         30         19  .........  .........
    Average...................................  .........        108         16         11  .........  .........
20 km/h, 1.5 sec.:
    03 Navigator..............................  .........        185  .........  .........  .........  .........
    04 Volvo XC90.............................         37         69         22  .........         89  .........
    05 Trailblazer............................         22         41         19  .........  .........  .........
    06 Durango................................  .........         47  .........  .........  .........  .........
    TRW Prot. on CK...........................  .........         75         25         10  .........  .........
    Average...................................         29         83         22  .........  .........  .........
16 km/h, 6 sec.:
    03 Navigator..............................         86         88         74  .........  .........  .........
    04 Volvo XC90.............................         65         47         19  .........        126         20
    05 Trailblazer............................  .........         90  .........  .........  .........  .........
    06 Durango................................  .........  .........         25  .........  .........  .........
    07 Commander..............................  .........         91  .........  .........  .........  .........
    Zodiac Prot. on Navigator.................         31  .........         10  .........  .........  .........
    TRW Prot. on CK...........................  .........        101          8         26  .........  .........
    Average...................................         61         83         27  .........  .........  .........
----------------------------------------------------------------------------------------------------------------

4. Field Performance of Ejection Mitigation Curtain Systems
    To better understand the field performance of the current fleet
equipped with rollover systems, the agency evaluated available crash
data. A focus of this evaluation was the performance of the rollover
sensors and their ability to detect the rollover event and activate
deployment of the side curtain air bags. We also sought to understand
the occupant containment provided by the vehicle system. The available
data reviewed included a detailed analysis of a very limited number of
rollover crashes by NHTSA's Special Crash Investigation (SCI) division.
In all of the cases, the ejection countermeasure in the vehicle was an
air bag curtain which partially covered the first two window rows.
    The agency's SCI division analyzed seven real-world rollover
crashes of Ford vehicles where the subject vehicles contained a
rollover sensor and side curtain air bags. (Ford agreed to notify SCI
of the crashes.) The subject vehicles were Ford Expeditions, a Ford
Explorer, a Mercury Mountaineer, and a Volvo XC90. Table 9 gives
details about each case.
    In each case, the rollover sensor deployed the side curtain air
bag. Of the seven cases, there were a total of 19 occupants, 15 of whom
were properly restrained. All were in lap/shoulder belts, except one
child in a rear facing child restraint system (CRS). A single crash
(DS04-016) had all of the unrestrained occupants, serious injuries,
fatalities and ejections in this set of cases. Two of the four
unrestrained occupants were fully ejected from the vehicle, resulting
in one fatal and one serious injury. The fatality was a 4-month-old
infant, seated in the middle of the 2nd row. The ejection route was not
determined. The seriously injured occupant was an adult in the left 3rd
row, ejected through the uncovered right side 3rd row window. One non-
ejected, restrained occupant received a fatal cervical fracture
resulting from roof contact and another was seriously injured. The
injuries to the remaining occupants were ``none'' to ``minor.''

                                                                                Table 9--Ford SCI Rollover Cases
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Occupants                                                     Deploy
              Case                       Make              Model           MY   ------------------------------------------------------  \1/4\  -------------------------------------------------
                                                                                Row 1             Row 2              Row 3         Rot.        Angle         Time (ms)      Rate  (deg/s)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
CA02-059........................  Mercury..........  Mount............     2002  1R.............  1R...............  ................        1  17............  ..............  17 to 25.
CA04-010........................  Ford.............  Expl.............     2003  1R.............  .................  ................        1  43............  20............  75.
IN-02-010.......................  Ford.............  Exped............     2003  1R.............  .................  ................        2  45............  146...........  111.
2004-003-04009..................  Ford.............  Exped............     2003  1R.............  2R...............  ................        5  Yes...........  Unknown.......  Unknown.

DS04-016........................  Ford.............  Exped............     2003  2R.............  2R, 2NR [dagger].  1R, 2NR [dagger]        5  Yes...........  Unknown.......  Unknown.
DS04017.........................  Ford.............  Exped............     2004  1R.............  .................  ................       12  Yes...........  Unknown.......  Unknown.
2003-079-057....................  Volvo............  XC90.............     2003  1R.............  1R...............  ................        6  Yes...........  Unknown.......  Unknown.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
R = Restrained, NR = Not Restrained.
[dagger] One NR 2nd and 3rd row occupant ejected (total of 2 ejected).

V. Proposed Ejection Mitigation Requirements and Test Procedures

    As discussed above, NHTSA's research on rollover ejection found
that with partial window opening coverage by a curtain, occupants
initially contacting covered areas can slide to an opening and be
ejected. The agency is proposing a test that requires ejection
mitigation curtains to retain an impactor such that its displacement is
limited to a specified distance outside of the window. To assure full
window opening coverage through the duration of a rollover, the
proposed test procedure would require the first three rows of side
window openings to be impacted at up to four locations around the
perimeter of the opening at two time intervals.
    In this section, we discuss in detail the rationale for selection
of the impactor test parameters. The primary parameters that determine
the stringency of the test are: (a) The impactor dimensions and mass;
(b) the displacement limit; (c) impactor speed and time of impact; and
(d) target locations. We also discuss: (e) glazing issues; (f) test
procedure tolerances; (g) test device characteristics; and (h) a
proposal for a telltale requirement. See also ``Technical Analysis in
Support of a Notice of Proposed Rulemaking for Ejection Mitigation,''
supra.

a. Impactor Dimensions and Mass

    The component test involves use of a guided linear impactor
designed to replicate the loading of a 50th percentile male occupant's
head and upper torso during ejection situations. The portion of the
impactor that strikes the countermeasure is a featureless headform that
was originally designed for the upper interior head protection research
program (FMVSS No. 201).\44\ It averages the dimensional and inertial
characteristics of the frontal and lateral regions of the head into a
single headform. The headform is covered with an approximately 10 mm
thick dummy skin material whose outer surface dimensions are given in
Figure 2, below. The Technical Analysis report discusses other
dimensional attributes of the headform, such as the curvature of the
outer surface. There are many possible ways of delivering the impactor
to the target location on the ejection mitigation countermeasure. The
impactor used in agency research propels the shaft component of the
impactor with a pneumatic piston. The shaft slides along a plastic
(polyethylene) bearing. The impactor has an 18 kg mass.\45\
---------------------------------------------------------------------------

    \44\ ``Ejection Mitigation Using Advanced Glazings: A Status
Report,'' November 1995, Docket NHTSA-1996-1782-3; ``Ejection
Mitigation Using Advanced Glazings: Status Report II,'' August 1999,
Docket NHTSA-1996-1782-21; ``Ejection Mitigation Using Advanced
Glazings: Final Report,'' August 2001, Docket NHTSA-1996-1782-22.
    \45\ Since the proposed performance criterion for this ejection
mitigation standard is a linear displacement measure (a linear
displacement measure would correlate to the actual gap through which
an occupant can be ejected), a linear impactor appears to be a
suitable tool to dynamically measure displacement. The impactor can
be placed inside the vehicle for testing the ejection mitigation
curtains and glazing covering window openings.

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

[GRAPHIC] [TIFF OMITTED] TP02DE09.001

    The mass of the guided impactor was developed through pendulum
tests, side impact sled tests, and modeling conducted to determine the
mass imposed on the window opening by a 50th percentile adult male's
upper torso and head during an occupant ejection (``effective
mass'').\46\ Briefly, the pendulum impact tests were conducted on a
BioSID anthropomorphic test device (50th percentile adult male) to
measure effective mass of the head, shoulder, and upper torso. The
BioSID was chosen because it was originally configured for side impact,
unlike the Hybrid III dummy, and has a shoulder which the Side Impact
Dummy (49 CFR 572, subpart F) currently used for FMVSS No. 214, ``Side
impact protection,'' does not have. A linear impact pendulum weighing
23.4 kg (51.5 lb) was used to strike the head and shoulder of the dummy
laterally (perpendicular to the midsagittal plane) using two impact
speeds (9.7 and 12.9 km/h) and four impact surfaces. In addition to the
rigid impactor face, three types of padding were added to the impactor
face to increase the contact time, to replicate advanced glazing
impacts.
---------------------------------------------------------------------------

    \46\ ``Technical Analysis in Support of a Notice of Proposed
Rulemaking for Ejection Mitigation,'' supra.
---------------------------------------------------------------------------

    Effective mass was calculated by dividing the force time history
calculated from the pendulum accelerometers by the acceleration time
history from the dummy sensors. In general, higher speed impacts and
impacts with softer surfaces generated higher effective mass. Based on
these pendulum tests, a range for the effective mass of the head and
upper torso was estimated to be 16 to 27 kg.
    In the sled tests, we used a side impact sled buck with a load
plate representing a door and two load plates representing the glazing
to measure shoulder and head impacts with three different stiffness
foams. The purpose of these tests was to determine the effect lower
body loading would have on the combined head and upper torso effective
mass. Two impact conditions were simulated, one representative of a
rollover event and the second of a side impact event.
    In the rollover condition, the impact speed was 16.1 km/h and the
dummy was positioned leaning towards the door such that the head and
torso would contact the simulated glazing at the same time. This
leaning position was intended to be more representative of an
occupant's attitude in a rollover. For the test designed to be more
representative of a side impact condition, the dummy was seated upright
and the impact speed was 24 km/h. The effective mass of the head and
upper torso calculated for the 16.1 km/h impact condition showed a
quick rise to about 18 kg by about 5 ms, followed by an increase to
about 40 kg at about 30 ms. The effective mass for the 24 km/h impact
condition showed an initial artificially high value or spike prior to 5
ms because of a lag between the force measured in the load plates and
the acceleration measured at the upper spine. This spike was also seen
in the some pendulum shoulder impacts. The effective mass settled to
about 9 kg at about 10 ms, with a slow rise to about 18 to 20 kg at
about 25 to 30 ms. Looking at the results, we determined that early in
each event, when the impacting mass is traveling near the pre-impact
velocity, the energy levels of a 9 kg mass traveling at 24 km/h [9 kg x
(6.67 m/s)\2\/2 = 200 Nm] and an 18 kg mass traveling at 16 km/h [18 kg
x (4.47 m/s)\2\/2 = 180 Nm] were roughly the same. In consideration of
the similarity of energy results for the sled testing at two impact
speeds, we deferred to the 18 kg effective mass since the test
condition more closely represented a rollover. In addition, the 18 kg
value was within the range of the pendulum impactor results discussed
above, which showed an effective mass range between 16 and 27 kg.

    The final part of the analysis involved computer modeling of an 18
kg impactor and 50th percentile Hybrid III dummy impacting simulated
glazing (foam). The comparison found that the total energy transferred
by the 18 kg impactor was within the range of the total energy
transferred by the entire dummy. For a 16.1 km/h dummy model impact
with the foam, the effective mass that came in contact with the foam
was between 12.5 kg and 27 kg.
    We note that the 18 kg proposed mass is consistent with that used
by General Motors (GM) in 16.2 km/h (4.5 m/s) tests of ejection
mitigation curtains.\47\ GM based this value on test results from 52
full vehicle rollover tests that estimated the effective mass of
occupant contact with the first row side window area. Forty-six percent
of the tests were less than a \1/4\-turn, 27 percent were one \1/4\-
turn and 27 percent were two \1/4\-turns. (Twenty of the rollovers were
curb trip; 18 were soil trip; 11 were fall-over, and 3 were corkscrew.)
The tests used two 50th percentile male Hybrid III dummies in the front
seats. In half of the tests, the dummies were belted and in half they
were not. A membrane was placed over the window area to prevent
ejections, and tri-axial load cells were incorporated into the membrane
at the corners of the window opening. The effective mass was calculated
using the resultant loading on the dummy head by the window membrane,
along with resultant head and chest accelerations.
---------------------------------------------------------------------------

    \47\ O'Brian-Mitchell, Bridget M., Lange, Robert C., ``Ejection
Mitigation in Rollover Events--Component Test Development,'' SAE
2007-01-0374.
---------------------------------------------------------------------------

    For a subset of tests the effective mass was calculated using the
impulse and momentum principle represented by:

[int] Fdt = m[Delta]v

Where:

F = membrane contact force
m = effective mass
[Delta]v = change in occupant velocity

    Results were similar for tests employing both methods. The
estimated effective mass for most belted tests was about 5 kg and all
were less than 10 kg. The majority of belted tests had effective masses
which were a combination of both the near and far side occupants. The
effective mass for the unbelted occupants ranged from 5 to 85 kg.
However, we note there was a 40 kg effective mass for a single unbelted
occupant contact. Energy levels calculated by using effective mass and
peak head velocity were all below 182.25 Nm. This is the amount of
energy imparted in GM's internal impactor testing (18 kg impactor and a
16.2 km/h (4.5 m/s) velocity).

Request for Comments on the Impactor

    In summary, the impactor mass was based on the determination of an
effective mass calculated through both pendulum and sled test impacts.
Sled tests designed to represent both side impacts and rollover impacts
gave similar energies and two equivalent mass estimates. The 18 kg
equivalent mass was seen during the test intended to be more
representative of a rollover event. This was also the equivalent mass
calculated from pendulum impact into the dummy shoulder. Thus, the 18
kg equivalent mass is considered a reasonable representation of an
occupant's head and a portion of the torso. An equivalent mass more
representative of just the head would be substantially smaller and an
equivalent mass accounting for more torso and lower body mass would be
substantially more. The 18 kg mass is well within the effective mass GM
estimates from vehicle rollover tests, and is consistent with the
impactor that GM uses to evaluate side curtains. Comments are requested
on the 18 kg mass for the linear impactor headform.

b. Displacement Limit (100 mm)

    We are proposing that the linear travel of the impactor headform
must be limited to 100 mm from the inside of the tested vehicle's
glazing as measured with the glazing in an unbroken state. The 100 mm
boundary would be first determined with the original glazing ``in
position'' (up) and unbroken. Then, for the test, the original glazing
would be either: (a) In position but pre-broken; or (b) removed
altogether, at the manufacturer's option.
    The window-breaking procedure will damage but not destroy advanced
(laminated) glazing, while it will obliterate tempered glazing. For
vehicles with advanced glazing, the damaged glazing would be permitted
to be in position under option (a), above. Tempered glazing will
disintegrate when subjected to the window-breaking procedure, so under
option (b), above, manufacturers may remove or completely retract the
window since it would be destroyed in the pre-breaking procedure and
would have no effect on the ejection mitigation results. When tested
with the original glazing in position but pre-broken or with the
glazing removed, the linear travel of the impactor headform must not
exceed the 100 mm limit. If a side curtain air bag is present, and we
anticipate that most, if not all, vehicles will have an ejection
mitigation curtain, the curtain would be deployed.
    In the test, the ejection mitigation countermeasure must prevent
the headform from exceeding the 100 mm limit. The principle underlying
the 100 mm displacement limit is to ensure that the countermeasure
(curtain) does not allow gaps or openings to form through which
occupants can be ejected. In the component test results, targets that
had displacements of less than 100 mm did not eject the dummy in
dynamic testing. As discussed previously in this preamble, the TRW and
Zodiac prototype ejection mitigation countermeasures were tested on a
CK pickup to the proposed impactor test procedure.\48\ The TRW
prototype had no coverage at position A1 (front window forward lower
position), so the displacement in the impactor test was unlimited for
all impact speeds and time delays (displacements well over 100 mm at
position A1). These systems were later tested on the DRF with the 50th
percentile male, 5th percentile female and 6-year-old dummies in
upright seating positions, and a prone 6-year-old dummy aimed at
approximately the target positions A1 and A2 (front window rear lower
position). When tested on the DRF, the arms of the upright dummies
flailed out of the window opening up to the shoulder at the sill (A1
and A2) and the prone 6-year-old dummy was completely ejected at A1.
---------------------------------------------------------------------------

    \48\ There were only some slight variations in target locations.
---------------------------------------------------------------------------

    It is noted, however, that dummy ejection did not occur all the
time at targets that had displacements of over 100 mm. When tested with
pre-broken laminated glazing, at position A1 the TRW system had a 181
mm of displacement at the 24 km/h (1.5 second delay) test and 104 mm of
displacement in the 20 km/h (1.5 second delay) test, but did not eject
either the prone or seated dummies in DRF tests. Nonetheless, the
component and DRF testing indicate that there is an increased
likelihood that a gap could be formed between the curtain and the
window opening through which an occupant could be ejected if the
displacement were over 100 mm in the headform test. In addition, a 100-
mm limit would also help guard against the countermeasure being overly
pliable or elastic so as to allow excessive excursion of an occupant's
head and shoulders outside of the confines of the vehicle even in the
absence of a gap.
    A 100-mm performance limit is used in several regulations relating
to occupant retention. In FMVSS No. 217, ``Bus emergency exits and
window retention and release'' (49 CFR 571.217),

bus manufacturers are required to ensure that each piece of glazing and
each piece of window frame be retained by its surrounding structure in
a manner that prevents the formation of any opening large enough to
admit the passage of a 100-mm diameter sphere under a specified force.
The purpose of the requirement is to minimize the likelihood of
occupants being thrown from the vehicle. This value is also used in
FMVSS No. 206, ``Door locks and door retention components'' (49 CFR
571.206; as amended 69 FR 75020). In FMVSS No. 206, the door is loaded
with 18,000 N and the space between the interior of the door and the
exterior of the door frame must be less than 100 mm. In addition, NHTSA
also considered that a value of approximately 100 mm is used by the
International Code Council (ICC) in developing building codes used to
construct residential and commercial buildings.\49\ The ICC 2006
International Building Code and 2006 International Residential Code
require guards to be placed around areas such as open-sided walking
areas, stairs, ramps, balconies and landings. The guards must not allow
passage of a sphere 4 inches (102 mm) in diameter up to a height of 34
inches (864 mm). The ICC explains in the Commentary accompanying the
Codes that the 4-inch spacing was chosen after considering information
showing that the 4-inch opening will prevent nearly all children 1 year
in age or older from falling through the guard.
---------------------------------------------------------------------------

    \49\ The ICC is a nonprofit membership association that works on
developing a single set of comprehensive and coordinated national
model construction codes. http://www.iccsafe.org/news/about/.
---------------------------------------------------------------------------

Request for Comments on the Displacement Limit

    NHTSA requests comment on the linear displacement limit of 100 mm
as an appropriate value. We note that GM developed a test procedure
that also uses a 100 mm displacement limit,\50\ but the zero
displacement plane is defined in a slightly different way. GM places a
plane tangent to the exterior of the side of the vehicle at the target
location and defines the displacement perpendicular to this excursion
plane. Thus, the allowable GM displacement would be approximately 100/
cos([thetas]) mm if other aspects of the test were identical to those
of today's NPRM, with [thetas] being the angle with the vertical of the
exterior plane. If [thetas] were 20 degrees, the GM limit would be
approximately 106 mm, which allows slightly more displacement than the
100 mm proposal. The GM method also results in a slightly different
allowable final displacement position than the proposed method because
of the separation between the flat excursion plane and the inside
surface of the window at the target location.\51\ We do not know how
that difference affects the final allowable displacement of the
headform.
---------------------------------------------------------------------------

    \50\ O'Brian-Mitchell, Bridget M., Lange, Robert C., ``Ejection
Mitigation in Rollover Events--Component Test Development,'' SAE
2007-01-0374.
    \51\ GM explained that their justification for the 100 mm
displacement limit is that it represents half the height of the 50th
percentile male Hybrid III head.
---------------------------------------------------------------------------

    The agency further notes that an advantage to the displacement
limit is that the linear displacement of the headform can be measured
in a practicable and relatively straightforward manner, unlike a real-
time dynamic measurement of a gap during an impact. The latter would
likely involve complex and multiple imaging systems. Comments are
requested on this issue.

c. Speed(s) and Time(s) at Which the Headform Would Impact the
Countermeasure

    As will be discussed in this section, there appears to be a need
for a relatively high speed impact shortly after countermeasure
deployment and a lower speed impact late in the deployment. The two
time delays correspond to relatively early and late times in a rollover
event.\52\ The first impact would be at 24 km/h, and at 1.5 seconds
after countermeasure deployment (1.5 second time delay). The second
impact would be a 16 km/h impact initiated 6 seconds after deployment.
---------------------------------------------------------------------------

    \52\ Each impact would take place on a test specimen (e.g., a
curtain) that was not previously subject to an impact test.
---------------------------------------------------------------------------

    We are proposing and requesting comments on two alternatives
regarding the testing of the four target locations for each window
opening (see subsection 4, below). Only one of the alternatives would
be selected for the final rule. The first proposal would subject all
four target locations to both the 16 km/h (6 second time delay) and the
24 km/h (1.5 second time delay) impacts (which would amount to eight
impacts per window). The second proposal would be to apply the 16 km/h
(6 second time delay) test on all four target locations but just apply
the 24 km/h (1.5 second time delay) test to the location that had the
greatest displacement in the 16 km/h (6 second time delay) test (which
would amount to five impacts per window). The second approach would
reduce the costs and burdens of the impact tests per vehicle.
1. Ejections Can Occur Both Early and Late in the Rollover Event
    Two impacts are proposed because ejections can occur both early and
late in the rollover event. In the advanced glazing program, NHTSA
performed a series of simulations to recreate three NASS-investigated
rollover crashes with ejected occupants.\53\ The vehicles were a MY
1991 Toyota pickup, a MY 1986 Toyota Corolla and a MY 1985 Volkswagen
Jetta.\54\ Vehicle handling simulation software \55\ reconstructed the
vehicle motion up to the point where the vehicle started to roll. The
linear and angular velocity at the end of the vehicle handling
simulation was then used as input to a MADYMO \56\ lumped parameter
model of the vehicle to compute its complete rollover motion. The
motion of the vehicle obtained from the MADYMO vehicle model was used
as input to a MADYMO occupant simulation. Head and torso velocities of
a Hybrid III 50th percentile male driver dummy were calculated for the
three rollover simulations.
---------------------------------------------------------------------------

    \53\ ``Ejection Mitigation Using Advanced Glazings: A Status
Report,'' November 1995, Docket NHTSA-1996-1782-3. Pg. 6-1.
    \54\ The circumstances of the Toyota pickup rollover were that
the vehicle was traveling at 96 km/h and went into a sharp turn and
yaw, which resulted in a rollover. In the case of the Corolla, it
was also traveling 96 km/h on a gravel road. The vehicle went out of
control and left the road, resulting in roll initiation. The
Volkswagen was traveling at 88 km/h when the driver fell asleep and
the vehicle left the road. It struck a rock embankment and rolled
over.
    \55\ VDANL software user's manual V2.34, STI, 1992.
    \56\ MADYMO user's manual V5.1, TNO, 1994.
---------------------------------------------------------------------------

    Table 10 shows the simulation resultant head velocity through the
open window at the time of ejection. As indicated in the table, the
occupant of the pickup was ejected early (1st \1/4\-turn for Toyota
truck) while the occupants of the other vehicles were ejected late
(last \1/4\-turn for Corolla and Jetta) in the rollover event.

                        Table 10--Head and Torso Velocities of a Hybrid III 50th Percentile Male Dummy in 3 Rollover Simulations
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       \1/4\ Turns at
              Vehicle                 Vehicle \1/4\       complete             Restraint use         Head to opening   Head to glazing  Torso to glazing
                                          turns           ejection                                       (km/h)            (km/h)            (km/h)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Toyota PU.........................                12  ................  Yes.......................                20                20                 7
                                    ................                 1  No........................                 5                20                16
Toyota Corolla (86)...............                 6  ................  Yes.......................                15                15                11
                                    ................                 6  No........................                13                13                10
Volkswagen Jetta (85).............                 4  ................  Yes.......................                14                14                10
                                    ................                 4  No........................                22                18                16
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The agency has also considered other data indicating that very
early occupant contact with the window area is possible in rollover
crashes. Table 11 gives information on 30 rollover tests the agency
performed from the mid-1980s to the mid-1990s. This data set included
Rollover Test Device (RTD) tests, FMVSS No. 208 dolly tests, guardrail
tests and pole tests.\57\ A film analysis of dummy motion within the
vehicles showed that, excluding a pole impact test, occupant contact
with the window opening and surrounding area first occurred between
0.16 and 0.88 seconds after the event began.\58\ We note, however, that
the majority of these dummies were belted, which means they would be
most representative of potential partial ejections. In addition, where
the time of window breaking is known, most of these first contacts
occurred prior to the window breaking due to roof contact.
---------------------------------------------------------------------------

    \57\ These tests were done as part of a research program
evaluating full scale dynamic rollover test methods, occupant
kinematics, and vehicle responses. The RTD tests were similar to the
FMVSS No. 208 dolly test except that the vehicle was initially 4
feet off of the ground instead of 9 inches, and hydraulic cylinders
were used to push the vehicle from the cart and produce an initial
roll rate. The guardrail tests used a guardrail as a ramp to
initiate a vehicle roll. The pole tests rolled a vehicle into a
pole. Twenty-four of these were RTD tests on passenger cars, pickups
and vans (the RTD testing was not geared towards ejection testing
since all of the test dummies were belted), and four were FMVSS No.
208 dolly tests on Ford Explorers. The test films are available at
the National Crash Analysis Center (NCAC) at George Washington
University (http://www.ncac.gwu.edu).
    \58\ ``Evaluation of Full Vehicle Rollover Films,'' 2008, Docket
NHTSA-2006-26467.

                                               Table 11--NHTSA Full Vehicle Rollover Testing Film Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Tilt                Vehicle                Total
      Test No.               Make                  Model             MY           Test type          angle    Roll axis  speed (km/   \1/4\-      time
                                                                                (deg.)     (deg.)       h)       Turns      (sec)
--------------------------------------------------------------------------------------------------------------------------------------------------------
878................  Honda...............  Accord..............         84  RTD..................         41         45       33.8          2       1.29
888................  Chevrolet...........  Celebrity...........         82  RTD..................         41         45       37.0          4       3.58
920................  Dodge...............  Omni................         79  RTD..................         41         45       37.0          2       0.96
939................  Mercury.............  Zephyr..............         82  RTD..................         41         60       37.0          2       2.08
1255...............  Ford................  Bronco..............         88  RTD..................         30         45       37.0          2       1.17
1266...............  Dodge...............  Caravan.............         88  RTD..................         30         45       48.3          1       0.50
1267...............  Chevrolet...........  Pickup..............         88  RTD..................         30         45       48.3          4       2.58
1274...............  Nissan..............  Pickup..............         88  RTD..................         30         45       48.3          6       3.76
1289...............  Nissan..............  Pickup..............         89  RTD..................         30         45       48.3          2       0.83
1391...............  Dodge...............  Caravan.............         89  RTD..................         30         45       48.3          8       5.08
1392...............  Ford................  Bronco..............         89  RTD..................         30          0       48.3          8       3.60
1393...............  Nissan..............  Pickup..............         89  RTD..................         30          0       48.3          4       2.35
1394...............  Nissan..............  Pickup..............         89  RTD..................         30          0       48.3          4       1.33
1395...............  Pontiac.............  Grand Am............         89  RTD..................         30          0       48.3          2       1.54
1471...............  Dodge...............  Colt................         89  RTD..................         30         90       48.3          2       0.99
1520...............  Ford................  Ranger..............         88  RTD..................         30          0       48.3          2       0.75
1521...............  Dodge...............  Ram.................         88  RTD..................         30          0       48.3          4       1.42
1530...............  Dodge...............  Caravan.............         88  Guardrail............        N/A        N/A       96.6          1        N/A
1531...............  Nissan..............  Pickup..............         88  Guardrail............        N/A        N/A       96.6          4        N/A
1546...............  Plymouth............  Reliant.............         81  RTD..................         41         45       33.8          6       3.00
1851...............  Volvo...............  240.................         91  RTD..................         30          0       48.3          6       2.50
1852...............  Volvo...............  740.................         91  RTD..................         30          0       48.3          8       3.00
1925...............  Nissan..............  Pickup..............         90  RTD..................         30          0       48.3          8       3.04
1929...............  Nissan..............  Pickup..............         90  RTD..................         30          0       48.3          6       2.25
2141...............  Nissan..............  Pickup..............         90  RTD..................         30          0       48.3          8       4.25
2270...............  Nissan..............  Pickup..............         89  RTD..................         30          0       48.3          8       3.50
2514...............  Ford................  Explorer............         94  208..................         23          0       48.3         11       5.50
2553...............  Ford................  Explorer............         93  208..................         23          0       48.3         10        N/A
3012...............  Ford................  Explorer............         94  208..................         23          0       48.3         11        N/A
3635...............  Ford................  Explorer............         94  208..................         23          0       48.3         12      5.17
Analysis of 5+ \1/4\-turn Tests
Average..........................................................................................  .........  .........       47.2        8.3        3.7
Maximum..........................................................................................  .........  .........       96.6         12        5.5
Average + 2 standard deviations..................................................................  .........  .........       55.2       12.3        5.8
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The agency is proposing that the ejection mitigation countermeasure
be first tested at 1.5 seconds after deployment of the ejection
countermeasure. As indicated earlier in this preamble, more than half
of the

complete ejection fatalities occur when the vehicle rolls 5+ \1/4\-
turns. As shown in Table 11, restricting the analysis to the tests with
5+ \1/4\-turns, the average amount of time to complete 1 full vehicle
revolution (4\1/4\-turns) was 1.62 seconds with a standard deviation of
0.31 seconds. Thus, the 1.5 second represents a period of time in which
one full vehicle revolution occurs in a high-energy rollover event. We
also note that at 1.5 seconds into the rollover, roof contact would
likely have occurred, leading to window breaking. Thus, as discussed at
section V(e) of this preamble, we are proposing to pre-break the
glazing prior to this test.
    Additional rationale comes from data obtained from the advanced
glazing program (see Table 12, infra). In that program, NHTSA tested
vehicles on the DRF with 5th percentile adult female and 50th
percentile adult male test dummies (near and far side).\59\ Video
analysis of dummy head impact velocities with the glazing showed that
for the 5th percentile female far side occupant, the time to glazing
impact after the DRF began rotating was between 1.3 and 1.8 seconds,
which was in the range of two to three \1/4\-turns of rotation. The
peak impact speed was 31 km/h. Table 12 shows the estimated velocities
for the near and far side dummies.
---------------------------------------------------------------------------

    \59\ Duffy, S., ``Test Procedure for Evaluating Ejection
Mitigation Systems,'' 2002 SAE Government/Industry Meeting.

                                          Table 12--DRF Testing Results
----------------------------------------------------------------------------------------------------------------
                                                                Impact speed  (km/h)      Far side
                                                             --------------------------    impact      Far side
                            Dummy                                                           time     impact  \1/
                                                               Near side     Far side      (sec.)      4\ turns
----------------------------------------------------------------------------------------------------------------
5th Female..................................................           14           31      1.3-1.8          2-3
50th Male...................................................           18           29  ...........  ...........
----------------------------------------------------------------------------------------------------------------

    The agency is also proposing that ejection mitigation
countermeasures be tested towards the end of a rollover. Data indicate
that occupants could impact the window opening as late as 6 seconds
after initiation of a rollover involving 5+ \1/4\-turns. The last three
rows of Table 11, supra, show the average and maximum number of \1/4\-
turns and the total time of rollovers involving 5+ \1/4\-turns.\60\
This set of data contains 14 tests (highlighted in table). The average
and maximum number of \1/4\-turns are 8.3 and 12, respectively. The
average plus two standard deviations is 12.3 turns. Thus, 12.3 \1/4\-
turns is the 98th percentile value for this subset of data. The average
and maximum times to complete the entire rollover event were 3.7 and
5.5 seconds, respectively. The 98th percentile value was 5.8 seconds,
which is not much different than the maximum time for the entire data
set, which was 5.5 seconds.
---------------------------------------------------------------------------

    \60\ As earlier, more than half of the complete ejection
fatalities occur when the vehicle rolls 5+ \1/4\-turns.
---------------------------------------------------------------------------

    Other information we considered also supported a 6-second impact
time. The data set provided in Table 11, supra, showed the vehicle with
the longest rollover time (5.5 seconds) in the FMVSS No. 208 dolly test
rolled eleven \1/4\-turns. NASS-CDS shows that rollovers with eleven
\1/4\-turns account for about 90% of rollovers with fatal complete
ejection, i.e., 10% of rollovers with fatal complete ejections have
more than eleven \1/4\-turns. This does not mean that rollover crashes
with eleven \1/4\-turns only take 5-6 seconds. Five to six seconds may
be a conservative assumption for this many \1/4\-turns for some types
of rollover. The FMVSS No. 208 dolly test has a very quick rollover
initiation (high initial roll rate); the beginning of the rollover is
well defined. However, the test only represents about 1% of field
crashes.\61\ The vast majority of field cases are soil and curb trip
crashes. Soil trips involve high lateral deceleration in combination
with low initial roll rates. Ideally, the curtain air bag should deploy
in this early phase when the roll rate is still low but the occupant is
moving towards the window due to the lateral deceleration. The rollover
has a slow initiation, leading to a need for longer inflation.
Therefore, some rollover crashes with less than eleven \1/4\-turns may
have 5-6 second roll times. A factor that the agency also considered in
determining the time delay for the lower speed impact was the
practicability of curtains staying inflated for this length of time.
Ford stated that its ``Safety Canopy'' system stays inflated for six
seconds.\62\ GM has reportedly stated that its side curtain air bags
designed for rollover protection maintain 80 percent inflation pressure
for 5 seconds.\63\
---------------------------------------------------------------------------

    \61\ Viano, supra.
    \62\ http://media.ford.com/article_display.cfm?article_id=6447
    \63\ ``Who Benefits From Side and Head Airbags?'' (http://
www.edmunds.com/ownership/safety/articles/105563/article.html).
---------------------------------------------------------------------------

2. Speed at Which Occupants Impact or Move Through the Window Opening
    This NPRM proposes that the impactor should strike the window
opening countermeasure at a speed of 24 km/h (after a 1.5 second time
delay after deployment of the countermeasure) and at 16 km/h (after a 6
second delay). The 24 and 16 km/h values are based on several analyses,
discussed below, of speeds at which occupants impact or move through
the window opening, including analysis of accident data, computer
simulations and test films of rollover crashes.\64\ In addition, the
agency notes that the 24 km/h impact speed is consistent with the
impact speed of FMVSS No. 201, ``Occupant protection in interior
impact'' (49 CFR 571.201). FMVSS No. 201 uses a free-motion headform
with a 4.6 kg mass to strike vehicle upper interior locations including
areas around side window openings. The impact speed for these tests is
24 km/h.\65\
---------------------------------------------------------------------------

    \64\ It is noted that the DRF test data presented above that
showed far side occupant velocities of approximately 30 km/h (Duffy,
``Test Procedure for Evaluating Ejection Mitigation Systems'') also
support the proposed test speeds.
    \65\ The 24 km/h speed was chosen in part because it is the
average speed at which the onset of AIS 2 and AIS 3 injuries are
likely to occur.
---------------------------------------------------------------------------

Accident Data

    In the analysis of accident data, the agency investigated side
impact accident data to determine the [Delta]V of the crashes in which
near side impact occupants were completely ejected. This data is
depicted in Figure 3, which shows the cumulative percentage of near
side impact occupants completely ejected, by impact [Delta]V. This
graph represents 15,062 occupant ejections weighted from 704 NASS
ejection cases. The range of the [Delta]V was 2 to 55 km/h. With regard
to the proposed impact test speeds of 16 and 24 km/h, 47.6 percent of
the near side impact occupants were completely ejected at [Delta]Vs at
or below 16 km/h, while 65.5 percent of the

occupants were ejected at [Delta]Vs at or below 24 km/h.
[GRAPHIC] [TIFF OMITTED] TP02DE09.002

Computer Simulations

    NHTSA analyzed MADYMO simulations of the real-world rollovers of
the Toyota pickup, Toyota Corolla and Volkswagen Jetta, supra. As shown
in Table 10, supra, the computed resultant maximum head and torso
velocities at contact with the intact glazing for the unejected
occupant indicated a maximum head speed into the window openings of 22
km/h. The maximum head velocity was 22 km/h for the Jetta unrestrained