\126\ The commenter did not define the meaning of ``up and
out.'' Based on the context of the Alliance's use of the ``up and
out'' terminology, we assume that the term means that occupants
would be ejected near their longitudinal vehicle location at the
time of the rollover.
---------------------------------------------------------------------------

    We are also declining the Alliance request to modify the target
locations for rear windows such that they are the reverse of that
proposed in the NPRM for rear windows. In Figure 13 below, illustrating
the suggested Alliance targeting, it is shown that the Alliance
procedure targeting can provide a large gap for daylight openings with
a forward rake. It is our experience that, to the extent that the rear
windows have a rake, this rake is forward. For rear window openings,
matching the front window pattern creates a large gap of coverage, as
shown in Figure 13. Further, the Alliance methodology crowds the
targets closer together, raising the potential for forcing the
elimination of targets based on the target reduction methodology. We
are not aware of any reason why it is important to have consistency
between the protocol used in the front and rear windows. Accordingly,
we are denying the Alliance and Batzer and Ziejewski requests.

[GRAPHIC] [TIFF OMITTED] TR19JA11.019

iii. Reorienting the Targets
    The Alliance, Hyundai, AORC, TRW, NTEA and Pilkington were all
opposed to reorienting the impactor headform.\127\ The Alliance stated
that ``[if a daylight opening is such that the headform cannot fit with
25 mm clearance when oriented with a vertical long axis, then NHTSA's
goal to reduce the risk of head and upper torso ejection has already
been achieved by the architectural characteristics of the vehicle,
particularly when combined with belt usage.''
---------------------------------------------------------------------------

    \127\ This is the same as saying they did not want to rotate the
targets, because the impactor headform orientation is aligned with
the target orientation.
---------------------------------------------------------------------------

    Hyundai stated that they ``found that the side daylight opening of
some vehicles with high belt-lines \128\ could not fit the outline of
the impactor headform within the 25 millimeter offset line of the
window opening.'' \129\ Nonetheless, Hyundai opposed the rotation of
the headform by 90 degrees for windows with small vertical dimensions
where no targets will fit with the typical impactor orientations. It
stated ``these windows are unlikely exit portals.'' TRW believed that
``revising the orientation of the headform for certain window shapes,
while not doing so for others, does not appear to be based on any real
world rationale.'' The Alliance, AORC and TRW raised testing concerns
related to reorienting the impactor. The Alliance stated: ``Arbitrary
deviations from [the NPRM] approach introduce unnecessary setup
variation and also increase the complexity of the impactor design.''
---------------------------------------------------------------------------

    \128\ The beltline of a vehicle is a term used in vehicle design
and styling referring to the nominally horizontal imaginary line
below the side glazing of a vehicle, which separates the glazing
area from the lower body.
    \129\ NHTSA-2009-0183-0044, p. 6.
---------------------------------------------------------------------------

    The agency has decided that the final rule will allow the
reorientation of the targets and the associated reorientation of the
impactor headform, under specific conditions. We believe that, all
things being equal, the size of an uncovered side window has some
correlation to the risk of ejection. A gap in coverage of a small
window could be an ejection portal, just as it could be for a large
window. If the test procedure in the final rule does not allow for
rotation of the headform, it could allow large gaps in the window
coverage that could provide an ejection portal.
    We examined two issues in investigating whether the headform should
be reoriented. The first issue involved reviewing the number and
location of impact targets for vehicles with relatively long and narrow
side daylight openings (high beltline vehicles) under the NPRM
targeting procedure. The second issue involved the pluses and minuses
of systematically rotating the target outline in small increments in
order to fit a single target in a window opening that would otherwise
not accommodate a target.
    In an April 15, 2010 meeting with NHTSA, Ford showed the impact
locations for many of their current and future vehicles.\130\ One of
the vehicles was a MY 2010 Ford Taurus. In Table 40, we have summarized
the number of impact targets in each daylight opening for many of the
Ford vehicles, as provided by Ford.
---------------------------------------------------------------------------

    \130\ Docket No. NHTSA-2009-0183-47.1

     Table 40--Number of Targets per Daylight Opening for Ford Models, According to the NPRM Test Procedure
----------------------------------------------------------------------------------------------------------------
               MY                        Model                Type            Row 1        Row 2        Row 3
----------------------------------------------------------------------------------------------------------------
2010............................  Taurus.............  PC................            1            1           NA
2010............................  Lincoln MKS........  PC................            2            2           NA
2010............................  Lincoln MKT........  SUV...............            2            4           NA
2010............................  F150 Crew Cab......  PU................            4            4           NA
2010............................  F150 Super Cab.....  PU................            4            2           NA
2010............................  F150 Regular Cab...  PU................            4           NA           NA
2010............................  Flex...............  SUV...............            4            4            4
2010............................  Mustang............  PC................            3            0           NA
2011............................  Fiesta.............  PC................            3            2           NA
2012............................  Focus..............  PC................            2            2           NA
2012............................  Future SUV.........  SUV...............            3            3           NA
                                  Next Gen. Full Size  Van...............            4            4            4
                                   Van.
----------------------------------------------------------------------------------------------------------------

    This table indicates that, without target rotation, more than half
[\7/12\] of the vehicles on the list would have fewer than four targets
in the row 1 windows. Similarly, for the second row windows, seven of
11 would have fewer

than four targets. This level of target reduction is much greater than
we have seen in our research testing. There are several potential
reasons for this emerging picture. First, manufacturers initially
focused their introduction of rollover curtains on SUVs and pickups,
which typically have larger windows. Second, the trend towards higher
beltlines has reduced the height of windows.
    The question then becomes, how extensive is the window opening
coverage for windows with fewer than four vertically oriented targets?
To help answer this question we also examined a partial side view of a
MY 2010 Chevrolet Camaro. This view is shown in the technical report
for this final rule. In Figure 14 below, we drew the outline of the
daylight opening and the associated 25 mm offset line for illustration
purposes. (These are approximations given the resolution of the image
and given that we did not know the dimensions of the flexible gasket
material around the opening. Also, we could not determine the exact
outline at the forward lower corner because the view was obscured by
the outside mirror. However, to the extent this drawing differs from
the actual image of the vehicle, the differences would not be
significant for the purposes of discussion in this section.)
    If the targeting procedure defined in the NPRM is followed, the
four initial target locations (primary and secondary targets) are as
shown in the top graphic in Figure 14. (The procedure is explained in
detail in the NPRM at 74 FR at 63205-63211.) Under the NPRM procedure,
if the horizontal distance between target centers is less than 135 mm
and the vertical distance between target centers is less than 170 mm,
the targets are considered to be significantly overlapping and are
eliminated. At the end of the process, only a single target would
remain. See middle graphic of Figure 14(b). The forward edge of this
target is 464 mm from the forward edge of the daylight opening outline,
which would leave a large opening forward of the target untested.
Occupant ejection could occur through that opening. Further, if the
daylight opening were less than 1 mm smaller (a vertical dimension of
less than 276.1 mm), under the NPRM procedure, there would be no
targets in the window opening.
    If we perform the same targeting procedure as defined in the NPRM
except with a horizontally-oriented target outline (the long axis
oriented horizontally), the result is the four targets shown in the
bottom graphic of Figure 14. The forward edge of the most forward
target was 173 mm from the forward edge of the daylight opening.

[GRAPHIC] [TIFF OMITTED] TR19JA11.020

    It appears that, if the target outline were to be kept only
vertical, there would be an artifact in the test that could result in
the exclusion of entire or large parts of some window openings from
being tested, while not excluding a window that differed only by a few
millimeters in dimension. For a long narrow window, the number of
targets can jump from zero to four with an increase in vertical
dimension of the window opening of only about 15 mm. If a long, narrow
window had a vertical dimension of 277 mm, the NPRM procedure would
result in no targets on the window opening. If the window vertical
dimension were increased by only 5 percent, from 277 mm to 290 mm,
under the NPRM procedure the targets would go from zero to four.
    Figure 15 shows the result of the NPRM's targeting process with the
vertical dimension of the daylight opening increased by 3 percent (from
277 mm to 285 mm). The four initial vertical target locations are shown
in the top graphic. The target elimination process results in the two
middle targets being removed but under the target reconstitution
process a target is reconstituted between them; the final number of
vertical targets is three, as shown in the middle graphic of the
figure. The forward edge of the most forward target is 348 mm from the
forward edge of the daylight opening, which is a substantial area. If
we perform the targeting procedure with a horizontally oriented target
outline, the four targets shown in the bottom graphic of Figure 15
result. The forward edge of the most forward target is 159 mm from the
forward edge of the daylight opening.
BILLING CODE 4910-59-P

[GRAPHIC] [TIFF OMITTED] TR19JA11.021

    Figure 16 compares the horizontal coverage (dimension from leading
edge of most forward target to the trailing edge of the most rearward
target) of the daylight opening using the vertical and horizontal
target outlines. The vertical targets show a great deal of sensitivity
to the height of the daylight opening as opposed to the horizontal
targets, which are very insensitive to opening height.

[GRAPHIC] [TIFF OMITTED] TR19JA11.022

    The second issue we explored involved the pluses and minuses of
systematically rotating the target outline in small increments in order
to fit a single target in a window opening that would otherwise not
accommodate a target. Figure 17 depicts a daylight opening that is too
small to fit a vertically oriented target outline within the offset
line. Under the NPRM targeting procedure, such a daylight opening would
not be impacted. However, rotating the target in increments of 5
degrees, from the initial vertical orientation, we find that the target
outline will fit at an angle of 45 degrees.
[GRAPHIC] [TIFF OMITTED] TR19JA11.023

    We disagree with the Hyundai comment that suggested that, if there
are no vertically oriented targets that can fit in a window under the
NPRM procedure, it is unlikely to be a portal for ejection. We have no
data that supports the view that occupants maintain a vertical
orientation when ejected through a window in a rollover. Given the
chaotic nature of rollovers, we do not expect this to be the case. We
know of no convincing reason why the target should not be rotated at
the window opening, given that a simple and small rotation will enable
us to test a countermeasure in a satisfactory manner and ensure that
the ejection mitigation device fully covers the window opening.
    If we specified that the targets may be reoriented (rotated) in a
systematic manner, we could eliminate an artifact in the proposed
procedure. In the section above, we saw that for a long

narrow window, the number of targets can jump from zero to four with an
increase in vertical dimension of the window opening of about 15 mm.
This is not desirable that a daylight opening would go from zero to 4
targets when the vertical dimension of the opening is above or below
276.1 mm. These artifacts of the combination of the window opening
geometry and the orientation of the impactor under the NPRM are
unacceptable, given that the standard would not assess the ability of
the countermeasure installed at the window opening to prevent partial
or complete ejections.
    Contrary to the Alliance comments that rotating the headform is an
``[a]bitrary deviation'' of the test procedure, the agency believes
that, for certain situations, to leave the headform in the vertical
orientation would result in arbitrary results, not consistent with the
need for daylight opening coverage. Similarly, we disagree with the TRW
comment that implied that target reorientation needlessly complicates
the test procedure. Rotating the target outlines would add little if
any complexity to the standard. To the extent the procedure is more
complicated, the need is justified.
    Accordingly, the agency has decided that this final rule will allow
the reorientation of the targets and the associated reorientation of
the impactor headform, under specific conditions. The conditions are
discussed below.
    From the examples shown in the technical analysis above, any
situation where fewer than four vertical targets can be placed in the
daylight opening would allow for unacceptably large gaps in coverage.
As shown in Figure 15, supra, the 3 vertically-oriented targets had 279
mm less horizontal window coverage than did the 4 horizontally oriented
targets and the forwardmost horizontal target was 189 mm more forward
than the vertical target.
    Yet, the agency has chosen not to change the orientation of the
impactor from vertical to horizontal when the same number of targets
can be placed in the daylight opening in either orientation. This is so
even though in some cases, it is possible that the horizontal targets
provide more horizontal coverage of the window opening. There are
several reasons for this decision.
    First, regardless of target orientation, if the same number of
targets can be placed within the window opening then the area being
impacted in both cases would be essentially the same. For example,
looking at Figure 18 below, the target outlines impact approximately
the same amount of area in the window opening. What differs is the
distribution of the targets within the opening, which is solely a
function of the opening shape. The horizontal targets cover more of the
window opening towards the bottom of the A-pillar and the vertical
targets more fully cover more of the remaining areas of the window.
[GRAPHIC] [TIFF OMITTED] TR19JA11.024

    Second, the bulk of our test data to date and the test data
submitted by comments are with the impactor in the vertical
orientation. This includes data that indicates that the proposed
requirements are practicable. Without more test data with a horizontal
orientation, we are reluctant to change the impactor orientation for
all window openings. Notwithstanding that most of our testing was done
with the impactor in the vertical orientation, when the number of
targets is fewer because the target is oriented vertically, we believe
that the importance of fuller window opening coverage outweighs all
other considerations.
    Third, there are window openings that would otherwise not
accommodate a target unless the target outline is rotated to some
oblique angle. See Figure 17. We find it objectionable not to specify
that the impactor may be rotated.
    We find no reasonable argument that would compel us not to allow
rotation of the impactor beyond the vertical or horizontal
configurations given that this might result in such a window not being
covered by any countermeasure. To say that an occupant's head or some
other body part cannot reorient itself during the rollover event,
including the head or body part of a belted occupant, is not logical.
    The conditions for the rotation of the targets and impactor
headform by 90 degrees to a horizontal orientation are specified in the
final rule regulatory text at S<IP_ADDRESS> and S5.6.2, respectively. The
conditions for the incremental 5 degree rotation of the targets and
impactor headform are specified in final rule regulatory text S<IP_ADDRESS>
and S5.6.3, respectively. The 5 degree increment reorientation is about
the y axis of the target and achieved by rotating the target's positive
z axis toward the vehicle's positive x axis.\131\ At each increment of
rotation, an attempt is made to fit the target within the offset line
of the side daylight opening. At the first increment of rotation where
the target will fit, the target is placed such that its center is as
close as possible to the geometric center of the side daylight opening.
---------------------------------------------------------------------------

    \131\ Looking at the left side of the vehicle from the outside,
the rotation is counterclockwise and looking at the right side of
the vehicle, the rotation is clockwise.
---------------------------------------------------------------------------

iv. Suppose Even by Rotating the Headform the Vehicle Has No Target
Locations
    AIAM and VSC requested that the regulatory text expressly state
that vehicles without any target locations are excluded from the
standard. Hyundai suggested that any window not having targets
according to the proposed requirement should be excluded.
Agency Response
    We have added text to S4.2 of the standard to state that if a side
daylight opening contains no target locations, the impact test is not
performed on that opening.
    The vehicle is not excluded from FMVSS No. 226, however. There are
a number of requirements in section S4.2 of the standard that apply to
vehicles that have an ejection mitigation countermeasure that deploys
in the event of a rollover. Paragraph S4.2.2 requires the vehicles to
have a monitoring system with a readiness indicator meeting certain
specifications. Paragraph S4.2.3 requires the vehicle owner's manual to
have written information about the ejection mitigation system and the
readiness indicator. Paragraph S4.2.4 requires the manufacturer of the
vehicle to make available to the agency, upon request, certain
information about the rollover sensor system. Vehicles that have an
ejection mitigation countermeasure that deploys in the event of a
rollover are subject to these requirements even if side daylight
openings contain no target locations. Since the vehicle is subject to
FMVSS No. 226, the vehicle may be counted as a vehicle that meets the
ejection mitigation requirements of the standard for phase-in and
advanced credit purposes.
v. Decision Not To Test Target of Greatest Displacement
    Vehicle manufacturers were supportive of a method to reduce the
number of tests. However, not all supported the alternative presented
in the NPRM to test at the 24 km/h impact speed at only the target
location with the greatest displacement during the 16 km/h impact.
Hyundai stated that ``no significant additional information would be
gained by testing all of the lesser displacement locations.'' The
Alliance alternatively suggested a single impact speed and time delay
for all target locations (16 km/h with a 3.4 second delay). The
Alliance opined that ``[d]eployment of side curtain airbags is highly
dependent on placement of garnish trim and performance of attachments
in the vehicle body. If a subsequent test needs to be performed [on]
one side of a vehicle after an airbag is deployed, a new airbag and new
garnish trim will have to be installed.'' \132\ They mentioned that
this reinstallation may not be representative of factory installation.
In addition, it alleges that attachment points may wear or deform after
multiple tests.
---------------------------------------------------------------------------

    \132\ NHTSA-2009-0183-0029, p. 30.
---------------------------------------------------------------------------

    AIAM stated that ``[t]here would be no reduction in test burden
unless the agency were to require manufacturers to identify which
impact location had the largest displacement in their low speed
certification testing, so that the agency could perform its high speed
test at the same location. Otherwise, the manufacturer could be
required to conduct high speed tests at all impactor locations, to
assure that it has test data for the same location that the agency
tests.''
    Air bag suppliers were mixed in their responses on this topic. TRW
recommended ``keeping all four impact tests at both impact speeds. This
is because NHTSA testing could identify a different `worst point' than
is identified by the OEM in their tests. Therefore, vehicle
manufacturers would likely need to test more extensively than NHTSA.
Thus while the compliance testing burden may be slightly lowered,
testing at the manufacturer [sic] will probably not be diminished
significantly.'' Takata suggested the alternative of testing all target
locations at the 24 km/h-1.5 second test, then performing the 16 km/h-6
second test only at the location experiencing the greatest displacement
in the first series. Takata believed that ``it is important to test all
the locations at the high energy level to ensure structural integrity
of the countermeasure device. This approach identifies a robust design
and also reduces the number of tests.''
Agency Response
    After considering the comments, we have determined that the final
rule will require that all target locations be impacted at the higher
and lower impact velocities rather than just impacting one target
location at the higher speed test. This adopts the regulatory text
option presented in proposed S5.5(2A) (except, as discussed earlier in
this preamble, the higher speed will be 20 km/h rather than 24 km/h).
    We found the comments from AIAM, TRW, and Takata to be informative
and persuasive. We agree with AIAM and TRW that there is unlikely to be
a significant reduction of test burden to the industry by only
requiring a 1.5 second-high speed test at the location that yields the
greatest displacement at the 6 second-low speed test. This is because
our ejection mitigation side air curtain test data indicates that there
is typically no clear distinction between the displacements of several
of the target points in a vehicle window

opening. There sometimes is no clear distinction that a certain target
is the ``weakest,'' showing the most displacement in the 16 km/h-6
second test. Agency testing of production vehicles set forth earlier in
this preamble indicates that the weakest target location is not obvious
across data from the 24 km/h-1.5 second test, 20 km/h-1.5 second test,
or the 16 km/h-6 second test. Based on limited data from our new
impactor, we found that there is less difference in displacement
between the 20 km/h-1.5 second and 16 km/h-6 second tests. (See rank of
the displacement by target location for the second row testing of the
MY 2008 Highlander, Tables 10-18, supra.) Thus, vehicle manufacturers
might not be assured from their data which target location will be the
weakest in a NHTSA test. Accordingly, they may end up testing all of
the targets to all of the impact speeds.
    We also agree with Takata's comments that all target locations must
be tested at the higher impact speed to assure that the testing
determines the robustness of the designs. However, not only must the
robustness of design be assessed at the top impact speed of 20 km/h,
performance at 6 seconds must also be determined. The agency can only
assure this by impacting all locations at 16 km/h with a 6 second
delay.
    AORC suggested that the standard could specify that manufacturers
will pronounce to us which target point should be tested at the higher
speed. We do not agree with the logic of binding the agency to only
impact target locations deemed by the manufacturer to have the greatest
displacement in the 16 km/h test. Such an approach would be an
unacceptable limitation of the agency's ability to independently
determine how to test a vehicle.
    We also did not find compelling the comments expressed by the
Alliance. We have already discussed and rejected the commenter's
suggestion that FMVSS No. 226 should have only a single impact speed
and time delay for all target locations (16 km/h with a 3.4 second
delay).
    With regard to the commenter's suggestion that there should be only
one 16 km/h test due to wear and tear on and effect of trim components
on testing, we decline this suggestion also. There was no showing that
issues related to trim components justify reducing the tests to a
single impact speed. Moreover, the Alliance's concerns about trim
components appear inconsistent with Nissan's comment. Nissan indicated
that it would like the final rule to allow testing on an untrimmed
``cut body'' and that the headliner would not be expected to affect
performance of the side curtain air bag system. This indicates to us
the possibility that trim components generally might not have a
significant effect on curtain performance. The Alliance's comments
about trim components are not substantiated and do not justify reducing
the number of tests to one.
    This final rule does reduce a test burden on manufacturers of
vehicles that use only non-movable (fixed) glazing as the ejection
mitigation countermeasure to meet FMVSS No. 226, without use of a
deployable ejection mitigation countermeasure. We have written the
standard to apply only the 20 km/h-1.5 second test to the daylight
opening with the non-movable glazing, and not the 16 km/h-6 second
test. If the displacement limit can be met at the window opening in the
20 km/h-1.5 second test, we will not subject the window opening to the
16 km/h-6 second test. This is because the 20 km/h test would be
redundant. If the displacement limit is met in the high speed test, we
believe the limit will be met in the low speed test.
vi. Reconstitution of Targets
    The Alliance disagreed with the proposed method to add back a
target (reconstitution). It believed that ``[t]he combination of FMVSS
214 and FMVSS 226 requirements renders testing at any point and `target
reconstitution' unnecessary and redundant to provide enhanced side
curtain coverage.''
Agency Response
    We disagree with the Alliance's position that target reconstitution
is unnecessary and redundant. A large space between two impact
locations in a daylight opening is not consistent with our desire for
full window coverage. Reconstituting (adding back) a target back
between two distantly-spaced targets helps to meet our goal. We note
that both the Ford and GM internal ejection test procedures have an
impact location at the geometric center of the window. For many window
shapes assessed under the procedures of this final rule, the target at
the center of the window would be close to the location that would be
covered by the middle target reconstituted. Thus, the Ford and GM
procedures appear to recognize the merits of testing for full window
coverage.

f. Glazing Issues

    The NPRM proposed to allow movable windows made from advanced
glazing to be in position (up and closed) for the compliance test, but
pre-broken by a specified test procedure to simulate the breakage of
glazing during a rollover. Tempered (non-advanced) glazing shatters
when broken, so for tempered glazing, we proposed that we would conduct
the glazing breaking procedure and shatter the glazing, remove the
glazing, or retract the glazing, at the manufacturer's option.
1. Positioning the Glazing
    The NPRM discussed the pros and cons of advanced glazing for
ejection mitigation. Advanced glazing may enhance the performance of
current air bag curtain designs. Vehicles tested by NHTSA showed an
average displacement reduction across target locations and test types
of 51 mm.\133\ However, the updated target population data show that 31
percent of front seat ejections and 28 percent of all target population
ejections are through windows that were partially or fully open prior
to the crash. Further, the agency was concerned that in the real world,
advanced glazing would not be as effective as an ejection
countermeasure due to vehicle structural deformation and the effects of
inertial loading of the window mass.
---------------------------------------------------------------------------

    \133\ We stated in the NPRM that we believed that incorporation
of advanced glazing for ejection mitigation would be relatively
expensive compared to the implementation of air bags. The PRIA
showed that the proposed requirements would add about $33 per light
vehicle at a total cost of $568 million for the full curtain
countermeasure. A partial curtain plus advanced glazing would have
an incremental and total cost of $88 and $1,494 million,
respectively.
---------------------------------------------------------------------------

    The NPRM requested comments on several alternatives, including the
alternative of testing all movable windows removed or retracted,
regardless of whether the window is laminated or tempered; fixed
laminated windows would be permitted to be kept in place, but pre-
broken.
Comments
    Commenters were divided in their views of how Standard No. 226
should test vehicles that have advanced glazing covering a side
daylight opening.
    Vehicle manufacturers and air bag suppliers did not support testing
with advanced glazing in place. Ford stated that ``[s]ide glazing
retention, regardless of construction-type (e.g., laminated or
tempered), in real-world rollover crashes is random and
unpredictable.'' Ford stated that side glazing retention ``is dependent
on the unique characteristics of that particular crash (e.g., number of
quarter turns, vehicle roll rate and deceleration, objects contacted,
occupant loading, vehicle deformations, etc.).'' The commenter

referred to an SAE paper from Kramer, et al.\134\ in which the authors
stated ``there is information from the field (FARS and other individual
collisions) that document ejections through laminated side glass.''
Ford recommended \135\ that--
---------------------------------------------------------------------------

    \134\ Kramer et al. ``A Comparative Study of Automotive Side
Window Occupant Containment Characteristics for Tempered and
Laminated Glass,'' SAE Paper 2006-01-1492.
    \135\ NHTSA-2009-0183-0020, p. 4.

the eventual requirements of FMVSS 226 be focused on rollover
activated side curtain technology, with consideration of the
associated capabilities of this technology, because these devices
are designed to deploy regardless of side glazing status in a
rollover (e.g., retained, up, down or partially open) or
---------------------------------------------------------------------------
construction of the glazing.

    Honda had a similar view, stating that ``a vehicle with movable
windows, being operated with a laminated glazing even partially open,
could result in the window falling out of the window frame due to body
deformation resulting from the crash or subsequent ground contact
during a rollover event.'' It stated that because the pre-breaking
procedure allows the window to be in the full up position it ``may not
fully simulate real world conditions.'' Honda suggested that all
testing should be done with the windows ``removed or retracted prior to
the impact test instead of allowing pre-breaking for movable windows.''
For fixed laminated windows, the commenter said that ``the concerns
mentioned above would not apply and pre-breaking would be a suitable
method of simulating real world conditions * * *.''
    AORC and TRW expressed concerns about testing glazing with the
window up. They suggested that the agency could test without any
glazing present, but either increase the amount of allowable excursion,
or reduce the energy level (i.e. reduce the impactor velocity) for
impact locations which have advanced glazing, to reflect the enhanced
performance expected if the advanced glazing were present.
    In contrast, glazing suppliers stated that all testing should be
performed with the advanced glazing in place because they believed that
the NPRM provided strong support of advanced glazing in reducing
impactor displacement.
    Consumer groups overall supported the use of advanced glazing. IIHS
described roof crush and side impact testing it did on several vehicles
with front row laminated glazing. IIHS stated that all the laminated
glazing remained intact within the window frame. IIHS suggested NHTSA
provide an incentive to vehicle manufacturers to use advanced glazing,
such as by testing all vehicles without the glazing in place but allow
a higher displacement for vehicles equipped with laminated glazing. In
contrast, Advocates suggested NHTSA should test with both air curtains
and advanced glazing and require a much reduced displacement limit.
Public Citizen wanted the final rule to specifically disallow the use
of advanced glazing on a vehicle unless it was in combination with side
curtain air bags. Public Citizen stated there is a lack of evidence
that laminated glazing will perform well enough on its own.
Agency Response
    This final rule does not allow the use of movable glazing as the
sole means of meeting the displacement limit of the standard (i.e.,
movable glazing is not permitted to be used without a side curtain air
bag). It also specifies that if a vehicle has movable advanced glazing,
the 16 km/h-6 second test will be performed with the glazing retracted
or removed from the daylight opening. Our decision is based on the
following factors.
    First, field data already evidence an incongruity between the
glazing countermeasure and the foreseeable use of it by the public. The
updated target population data show that 31 percent of front seat
ejections and 28 percent of all target population ejections are through
windows that were partially or fully open prior to the crash. We have
no small concerns about a countermeasure that can be easily, totally
and most likely unknowingly counteracted by motorists by the simple and
everyday act of opening a window. As crash data show, many in the
target population already operate their vehicles in a manner that
negates the efficacy of the countermeasure. Any benefits accruing from
advanced glazing will not be achieved if the window were partially or
fully down.
    Second, in contrast to IIHS's roof crush and side impact laboratory
test findings, the field data of real-world performance of advanced
glazing are showing that even when movable advanced glazing is
initially up, such glazing may not be present as an effective
countermeasure beyond the initial phase of a rollover. Rollovers are
one of the most severe and unpredictable vehicle crash events. Based on
an analysis of field data and the comments on the NPRM, we are not
confident at this time that movable advanced glazing used alone,
without an ejection mitigation side air curtain to supplement it, will
be a viable countermeasure throughout a rollover crash. The following
illustrates some real world examples of the un-predictable nature of
advanced glazing in rollovers.
    In NASS CDS case 2001-43-190, a MY 2000 Audi A8 experienced a left
leading, four quarter-turn rollover.\136\ This vehicle did not have
side curtain air bags. The unbelted driver was completely ejected
through the sunroof. The belted front passenger was not ejected. The
technical report accompanying this final rule shows the interior views
of the passenger and driver sides of the vehicle, respectively. The
passenger side laminated glazing has completely detached from the first
and second row windows. However, the first and second row driver side
windows are in place. The first row driver side window was coded as
being partially open prior the crash. It remained so after the crash,
although it was extensively damaged. The second row driver side window
was in place and undamaged.
---------------------------------------------------------------------------

    \136\ Although the NASS coding indicates that the first 2 rows
of side windows were tempered glass, we determined this to be
incorrect from the photographic evidence.
---------------------------------------------------------------------------

    In SCI case CA09063 (RODSS 7242), a MY 2003 Lincoln Aviator with
laminated glass in the driver's side window sustained a head-on
collision followed by a three quarter-turn rollover. This vehicle had
rollover deployable curtain air bags, but they did not deploy. The
driver and right front passenger were belted. There were no ejections.
Both laminated driver and front row passenger windows detached from the
window opening.
    In SCI Case CA10006 (RODSS 8289), a MY 2003 Lincoln Aviator
experienced an eight quarter-turn rollover. This vehicle had rollover
deployable curtain air bags, which deployed. The driver and right front
passenger were belted. The belted driver was killed due to partial
ejection of her head. Both laminated driver and front row passenger
windows vacated the window opening. The passenger side window glazing
is shown in the foreground of a photograph of the scene, completely
detached from the vehicle.
    In these examples, it is not possible from the visual evidence to
determine when in the rollover event the advanced glazing detached from
the window opening, nor the cause(s) of the separation. In all except
one of the cases there was a belted occupant adjacent to the window
that detached from its opening. In these cases, occupant interaction
may have been a factor. The rear passenger side window of the Audi did
not have an adjacent occupant, so

occupant contact was not likely the cause of the window vacating the
opening. Other potential causes are structural deformation and inertial
forces due to impact or vehicle rotation.
    We found compelling the Ford and Honda comments discussing the
potential for advanced glazing to detach from the window opening in
real-world rollovers. We agree with Ford that the retention of advanced
glazing, particularly movable glazing, can be a function of the random
and unpredictable nature of rollovers. We also believe there is merit
to the Honda contentions that movable advanced glazing could vacate the
window frame due to vehicle body deformation resulting from crash
dynamics or ground contact, even when the window is partially up, and
that the pre-breaking procedure performed in a full-up position may not
fully simulate these conditions. We found their comments to be
consistent with the information presented above, which shows examples
of field performance of advanced glazing (specifically laminated
glazing) in several rollover and combination crashes (rollover in
combination with planar impacts). Particularly interesting is the Audi
A8 rollover, where the glazing on one side of the vehicle vacated, but
the windows on the other side did not.
    Ejection is a major cause of death and injury in rollover crashes.
As stated in our discussion of the safety need for this rulemaking,
according to 2000-2009 FARS data, about half of the occupants killed in
rollovers were completely ejected from their vehicle. A double-pair
comparison from the last ten years of FARS data show that avoiding
complete ejection is associated with a 64 percent decrease in the risk
of death. The ejection countermeasures that should be installed in
response to this final rule are those which have been shown to perform
well in keeping occupants in the vehicle in rollover crashes. We are
unable, at this time, to assert our confidence in the ability of
advanced glazing to retain occupants throughout a multiple quarter-turn
rollover when used alone in movable window applications.
    We have learned from the comments about ways to improve FMVSS No.
226's ability to distinguish between countermeasures. We saw that the
test procedure should be enhanced to ensure that the vehicle will
provide ejection mitigation protection throughout a multiple quarter-
turn real-world rollover. The proposed impactor test of ejection
countermeasures is appropriate and worthwhile, but we have learned that
to better replicate real-world conditions, it is imperative to remove
any kind of glazing on a movable window when preparing for the 16 km/h-
6 second test. Since there is a reasonable possibility that the movable
window glazing will vacate the vehicle in the later stages of the
crash, by removing the glazing in the test we better replicate the
real-world condition. Removing such glazing, and expressly stating in
the standard that vehicles are not allowed to use movable glazing as
the sole means of complying with the standard, assure that movable
advanced glazing will be used with an ejection mitigation side curtain
air bag or other deployable safety system. These provisions assure that
the movable glazing will have to be supplemented by a side curtain air
bag or other countermeasure, thus assuring a minimal level of safety in
the event the window is partially or fully rolled down or vacates the
window opening due to the dynamics of the crash.
    It is possible that there could be modifications to the designs of
the window frame that may improve the ability of movable advanced
glazing to remain within the window opening during a rollover.\137\
However, the agency currently does not have the information to make
this determination. We assume that this is what the AORC meant when it
stated that a single integrity test for laminated glazing could be
established to verify retention. Unfortunately, we did not learn of
these potential test parameters from the comments.
---------------------------------------------------------------------------

    \137\ The agency researched such window frame modifications
during the research into advanced glazing as a standalone ejection
mitigation countermeasure. ``Ejection Mitigation Using Advanced
Glazings: A Status Report,'' November 1995, DOT DMS NHTSA-1996-1782-
3, pp. 4-7 to 4-10. Results indicated that adequate retention was
maintained in the area of encapsulation, but that the unsupported
(nonencapsulated) top edge was subject to large deflections. (pg. 7-
29).
---------------------------------------------------------------------------

    Some glazing manufacturers indicated that the problem of the open
window could be mitigated by newer vehicle safety technology that rolls
windows up prior to a crash. It is our understanding that at least some
of these systems are initiated when the ESC is activated.\138\ ESC
would activate in only a portion of the rollover events that make up
our target population, i.e., most likely single vehicle rollover
crashes. The remainder would not be covered. Moreover, the
effectiveness, cost and practicability of an automatic roll up system
in achieving the benefits of ejection mitigation throughout a multiple
quarter-turn rollover has not been demonstrated.
---------------------------------------------------------------------------

    \138\ Mercedes offers this feature and calls it Pre-Safe.
---------------------------------------------------------------------------

    Accordingly, for the 16 km/h-6 second test, if a vehicle has
movable advanced glazing as all or part of the ejection countermeasure,
the test will be performed with the glazing retracted or removed from
the daylight opening. Based on the 28 percent of the target population
ejected through windows open prior to the crash and uncertainties about
the field performance of the current movable advanced glazing, we
cannot agree to the request that all impact testing be performed with
the movable advanced glazing in place.
    If the advanced glazing is fixed in place, we will not remove it in
the 16 km/h-6 second test. It is reasonable to assume that glazing
permanently fixed in the up position will be up when the vehicle is on
the road. We will pre-break the fixed glazing, to replicate the state
of the glazing during the stages of a rollover event, but we will not
remove it. Likewise, if the glazing is fixed, we will pre-break it but
will not remove it in the 20 km/h-1.5 second test. Thus, it remains
technically possible under the standard to have fixed advanced glazing
as the standalone countermeasure. This provides an incentive to
manufacturers to use advanced glazing.
    Movable advanced glazing will not be removed in the 20 km/h-1.5
second test. This test will be performed with the advanced glazing in
place, but the glazing will be pre-broken to replicate the state of the
glazing at the outset of a rollover event. Although advanced glazing
could vacate the opening late in the crash event after many quarter-
turns, we have more confidence that advanced glazing will not be
dislodged early in the rollover event represented by the 20 km/h-1.5
second test. This is because vehicle structural deformation and
inertial effects resulting from ground contacts contributing to glazing
being dislodge will be cumulative, i.e., increase as the rollover event
continues.
    IIHS's tests also showed that the advanced glazing on some of the
vehicles it tested remained within the frame in roof crush and side
impact testing. Allowing movable advanced glazing to be in position in
the high speed (20 km/h-1.5 second) test will provide an incentive to
vehicle manufacturers to use advanced glazing to meet the standard's
requirements or enhance ejection mitigation performance of side
curtains.
    We decline the suggestions to provide an incentive for advanced
glazing by increasing or decreasing the allowable displacement of 100
mm. TRW and AORC suggested increasing the allowed

displacement, or decreasing the impact speed, at places on the window
opening that had advanced glazing. We cannot agree to lessen the
severity of the test for advanced glazing as this would reduce the
protection of the motorists, particularly those who may have the window
partially or fully rolled down. Advocates suggested decreasing the
displacement limit below 100 mm for combined advanced glazing plus
curtain air bag. As explained earlier in this preamble, the 100 mm
limit strikes the appropriate balance between stringency and
practicability.
    Advocates also stated that vehicle structural deformation will
reduce the effectiveness of the curtain air bags and advanced glazing
will increase roof strength.\139\ It presented no data to substantiate
these claims. NHTSA is not aware of a technical or engineering basis
for the view that side curtain air bag performance will be reduced by
structural deformation.
---------------------------------------------------------------------------

    \139\ The relevance of the Advocates comment about advanced
glazing increasing roof strength is not clear to us. In the May 12,
2009, FMVSS No. 216 final rule, the agency stated that we had
investigated the contribution of tempered side windows to roof
strength and found that it had limited effect (74 FR 22371). We have
no reason to believe that there would not be similar results from
advanced laminates.
---------------------------------------------------------------------------

    Our concerns about the performance of advanced glazing also extend
to the deformation of the window opening. Because of its mass, advanced
glazing will be much more susceptible to inertial loading from vehicle
rotation and vehicle ground contact than will curtain air bags. That
was the point of our statement in the NPRM (74 FR at 63213) about
advanced glazing having greater mass compared to an air bag curtain. In
response to comments from some glazing suppliers, we did not mean to
imply that laminates had a weight penalty when compared to tempered
glazing.
2. Window Pre-Breaking Specification and Method
    We have determined that there is a safety need to have a glazing
breaking procedure applied to both the interior and exterior sides of
the glazing. We are slightly modifying the proposed procedure, to adopt
use of a 75 mm offset pattern to reduce the glazing preparation time.
NPRM
    In the NPRM, we proposed specifications and a method that called
for punching holes in the glazing in a 50 mm horizontal and vertical
matrix (``50 mm matrix'') on both sides of the glazing. A spring-loaded
automatic center punch was to be used to make the holes. The punch has
approximately a 5 mm diameter before coming to a point. The spring on
the punch was adjusted such that 150 N 25 N of force \140\
was required for activation. The details of the procedure were
described in the NPRM. When punching a hole, we placed a 100 mm by 100
mm piece of plywood on the opposite side of the glazing as a reaction
surface against the punch. In testing glazing that will disintegrate
under the procedure (e.g., tempered glazing), the vehicle manufacturer
could opt to remove or completely retract the tempered glazing and
thereby bypass the window breaking process.
---------------------------------------------------------------------------

    \140\ This force level worked well for the samples of advanced
glazing tested by the agency.
---------------------------------------------------------------------------

    We also noted that we would be continuing research into window pre-
breaking methods, specifically, a variation of the 50 mm matrix hole
punch method where the holes on either side of the glass are offset by
25 mm. Initial indications at the time of the NPRM were that this
variation exhibits the potentially positive attribute of lessening the
chances of penetrating the inner membrane between the glass layers. 74
FR at 63215.
Comments
    The Alliance said that use of different punches and punch settings
can produce differing amounts of penetration and potential damage to
the plastic laminate. The commenter also believed that the tolerance
for the punch activation force is too large (17% of nominal value), and
that the ``rigid'' backing material needs to be specified, as does the
pressure/force applied to the backing material. The AORC supported
offsetting the breaking pattern by 25 millimeters from the inside to
the outside of the window, to reduce the potential that a punch
impacting the same point from both sides of the window would produce a
hole through the laminate. Guardian, EPGAA and Solutia believed that
the 50 mm pre-breakage procedure was excessive and not consistent with
real-world conditions, particularly breakage of the interior side of
the glazing. Guardian commented that at a minimum the pre-breaking
procedure be altered to offset the punch locations on either side of
the glazing. Exatec asked about the suitability of the procedure for
non-glass advanced glazing material.
Agency Response
    We disagree with the comments from the vehicle manufacturers and
air bag suppliers that the proposed pre-breaking procedure was too time
consuming, onerous, or impractical. Nonetheless, the procedure we adopt
today calls for less than half the number of punched holes, reducing
the glazing preparation time.
    We have performed well over 100 tests with advanced laminated
glazing using various methods of pre-breaking. About 30 of these tests
have been performed using a 50 mm matrix. We estimate that it takes our
laboratory technicians about 30 minutes to mark the 50 mm grid pattern
and punch all the holes for a relatively large front row side window.
The time it takes to mark the holes per glazing pane can be
significantly shortened by laying an unmarked pane on top of an already
marked pane. If a subsequent test is to be performed (as might be the
case during research and development) and the door trim is installed,
it takes approximately 20 to 60 minutes to replace the glazing. Often
this is done in parallel with preparations for other aspects of the
test, so the overall test time is not affected appreciably. This
procedure is not difficult or onerous to conduct.\141\
---------------------------------------------------------------------------

    \141\ When testing with tempered glass, if the glass pane does
not move completely out of the window opening into the door, it must
be removed by opening the door trim. This glass pane removal takes
about 20 to 60 minutes as well, due to the removal and
reinstallation of door trim.
---------------------------------------------------------------------------

    Nor is the procedure gratuitous. To the contrary, the pre-breakage
procedure is crucial to ensuring that advanced glazing will perform as
intended in the field. Advanced glazing is weakened when pre-broken;
the more breakage of the glazing, generally the more displacement of
the impactor. See Table 23 of the NPRM, 74 FR at 63215. The pre-
breakage procedure is intended to condition the glazing to mimic the
degree of breakage that is occurring in the field. Crash information
and the results of impact testing corroborate the necessity of the
proposed procedure.
    In the technical report accompanying this final rule, we have
images from several rollover crashes. The first was a MY 2000 Audi A8
that underwent four quarter-turns. The second was a MY 2003 Lincoln
Aviator that was exposed to a frontal impact followed by a three
quarter-turn rollover. The last vehicle was also a 2003 Aviator that
experienced an eight quarter-turn rollover. The technical report also
shows a close-up of the driver side window laminated glazing of the
Aviator that rolled eight quarter-turns. In all of the cases, the crash
scene photographs show the degree to which both sides of the glazing
have been disintegrated, especially for those laminates that have
vacated the window

opening. This finding that advanced glazing experienced severe damage
to both inside and outside surfaces and detached from the vehicle
supports our belief that pre-breaking the advanced laminate should be
aggressive. The technical report also has a view of the driver's
advanced glazing in a 2000 Audi A8 from NASS case 2001-43-190. The
glazing remained in the window. Some areas appear more highly damaged
than others.
    Accordingly, we are adopting the glazing breaking procedure, with
slight changes that reduce the number of punched holes.
    In the NPRM preamble (74 FR at 63215), we stated that that the
agency was contemplating using a method for glazing pre-breaking that
takes the 50 mm matrix and offsets the holes horizontally on each side
of the glazing by 25 mm. Initial indications were that this variation
exhibits the potentially positive attribute of lessening the chances of
penetrating the inner membrane between the glass layers. Our research
since the NPRM has been focused on this and another alternative offset
method. This alternative uses a 75 mm by 75 mm hole punch pattern on
both sides of the glazing. However, the matrix on the inside of the
glazing is offset by 37.5 mm [75 mm/2] horizontally. A 75 mm matrix
pattern is used to reduce the number of breakage points from the 50 mm
matrix, and as stated before, the offset reduces the chances of
completely penetrating the material sandwiched between the glazing
layers. The technical report provides a schematic of the 50 and 75 mm
offset patterns.
    Our new results are consistent with our previous results. See the
technical report for this final rule. We found that the method of pre-
breaking the laminated window has a discernable effect on the test
results. We compared the 50 mm offset pattern to the 75 mm offset
pattern. When these treatments were able to be compared statistically,
there were no significant differences between the 50 and 75 mm offset
hole punch pattern as it relates to impactor displacement. Moreover,
given that finding and the finding that the 75 mm offset has less than
half the number of punched holes, reducing the glazing preparation
time, this final rule adopts the use of the 75 mm offset pattern.
    In response to Exatec, the final rule will clarify that it is only
necessary to attempt to make the holes in the glazing and to not
actually succeed. However, we will not change the procedure to stop
after the first row is attempted. We have no firm basis at this time to
treat one type of advanced glazing any differently than another. It is
conceivable that the punches might not break the material, but could
produce stress concentrations that weaken it.
    Finally, we decline all but one of the Alliance's requests because
we do not believe that the procedure is not repeatable or reproducible
and no information to the contrary was provided by the commenter. We
believe that the tolerances and values for center punch angle,
activation force and punch tip diameter are sufficient. We will
specifically call out the material for the 100 mm x 100 mm reaction
surface, rather than simply indicate that it should be rigid. The final
rule will specify the use of plywood with a minimum thickness of 18 mm
(standard \3/4\ inch), which is the material we used during our
testing. Although we believe any sufficiently rigid material will
adequately perform this function, for simplicity we will specify
plywood.

g. Test Procedure Tolerances

    The proposed regulatory text had tolerances on various test
parameters of the proposed test procedure. For example, the proposed
text specified that the target outline must be aligned within 1 degree of the vehicle longitudinal plane when determining the
proper target location. Tolerances were selected such that they would
not affect the test results, yet not be so small as to be unusable. In
some instances, we based tolerances on those of other FMVSSs because
those tolerances have been practicable and useful. For example, the
tolerance on the impactor alignment with the vehicle lateral axis was
based on a similar linear impactor tolerance in S5.2.5(c) of FMVSS No.
202a, ``Head Restraints.'' Tolerance selection was based on test
experience and engineering judgment. Comments were requested on whether
the tolerances assure an objective, repeatable and practical test
procedure.
Comments
    1. The Alliance ``requested that impactor specification be updated
to clarify that the long axis of the impactor headform is to maintain a
vertical orientation throughout the full stroke of the impact event.
This approach is recommended in an effort to maximize repeatability and
reproducibility of test results.'' The Alliance stated that they had
observed some impactors that constrain this motion and others that do
not.
Agency Response
    We agree with the request. The headform should not be able to
freely rotate during the impact test. Both our original and new test
devices have a specific mechanism to constrain them from rotation about
their axis of travel. Thus, we have added a specification that the
ejection impactor is inspected after the test, to make sure that it is
still within the  1 degree tolerance required at launch.
    2. TRW and AORC expressed concern about the  0.1 second
tolerance on the impact times of 1.5 and 6 seconds. They suggested a
tolerance of  0.05 seconds to reduce the amount of test
variability due to air bag pressure changes. The AORC also would like
the agency to clarify the time delay such that it would be the period
of time the ``unimpeded impactor would arrive at the target location.''
Agency Response
    We are declining these requests. To answer the questions, it is
important to keep in mind that under the test procedures, the impactor
is to strike the countermeasure at the specified speeds and time
delays.
    The target location is found by projecting the daylight opening on
a vehicle vertical longitudinal plane and then projecting the target
onto that plane. There are an infinite number of parallel vertical
longitudinal planes, or alternatively, the vertical longitudinal plane
can be thought of as having any lateral location. Assembling all the
planes, each with a projection of the target, creates a three
dimensional projection of the target, which crosses the vehicle
laterally. Or, in other words, imagine the 2 dimensional target being
translated along the transverse vehicle axis, creating a path the
impactor headform should be setup to travel along.
    If the countermeasure is an air bag, it is deployed, and the
ejection impactor is to strike the countermeasure (air bag) at the
impact target location, at the specified speed and time delay. The
trigger for the time delay is the activation of the countermeasure. For
a curtain air bag, that would be the time at which the deployment is
activated. The speed and time of impact of the impactor are measured at
contact with the countermeasure (air bag) and must both be within the
specified tolerances. To make it clear that it is the countermeasure
that must be contacted at the specified time intervals, we have added
text to S5.5(a).
    Since the agency anticipates that its tests will involve testing
side curtain air bags, we need to account for the effect of the air bag
on the impactor's timing. The calibration testing of our new impactor
indicates that the impactor would meet the timing tolerance

reduction recommended by commenters if the target were at a static
location. However, although our experience has been that curtain air
bags deploy in a very consistent and repeatable manner, the fact is
they are not static. Also, we determine contact time on a curtain
through video analysis. All in all, because of the variables and
calculations needed to establish contact time with the countermeasure,
we believe it is more reasonable to maintain the  0.1
second impact time tolerance.
    3. The AORC suggests the procedure specify that contact with the
countermeasure occurs when the impactor is beyond the influence of the
propulsion system.
Agency Response
    We agree and have modified S5.5 of the regulatory text by adding a
statement that the specified ejection impactor velocities must be
achieved after propulsion has ceased.
    4. Honda asked if the agency has any intention of specifying the
interval between each impact test. It also stated that the impactor
speed might decrease after propulsion, so it requested that ``NHTSA
clarify the position (by time) that the impact speed should be
measured.'' Honda also asked how contact with the countermeasure is
determined, and requested that we clearly state the speed and
displacement measurement methods. Honda further requested that NHTSA
provide the accuracy, sampling time, and filtering of each sensor.
Agency Response
    We do not agree with the suggestion to specify an interval between
multiple tests. We do not know of a reason to rest the equipment
between tests. We have no reason to believe that the amount of time
between tests would have any effect on the test results.
    As explained above in answering TRW and AORC, the speed and time of
impact are measured at contact with the countermeasure and must both be
within the specified tolerances. We have made these measurements during
our research testing, in several ways. As indicated above, one method
we have used to determine time of contact within a resolution of about
5 ms is video analysis. Another method is to know prior to the test the
approximate location of the impactor stroke where contact will occur.
In either case, the velocity versus time output of the ejection
impactor can then be used to determine if the contact time and velocity
parameters were met.
    There is no need to provide in the standard a specification for
velocity and displacement measurement. There are multiple ways of
measuring impactor displacement and velocity. The output of
displacement-based instruments such as Linear Variable Differential
Transformers (LVDTs) or string potentiometers can be used directly for
displacement or differentiated to give velocity. Accelerometer output
can be integrated once for velocity and twice for displacement. A
light-based speed trap can be used for velocity measurement as well.
The agency has used all of these methods. We believe it would be
counterproductive to specify a single method in the regulatory text in
that this may limit our flexibility in conducting compliance testing.
We note also that we found that our new impactor loses very little
speed over large ranges of stroke. If the speed is correctly set, it is
not difficult to meet the 0.5 km/h speed tolerance.

h. Impactor Test Device Characteristics

    The agency proposed certain characteristics that the impactor
should be calibrated to meet in order to enhance the repeatability of
the test, i.e., to increase the likelihood that the headform will be
delivered to the countermeasure and interact with it in a repeatable
manner. One was a 20 mm limit on static deflection when the impactor is
loaded by a 27 kg mass. There were two specifications to limit the
amount of energy the impactor may lose due to friction. The proposal
specified that the ejection impactor must not lose more than 10 and 15
percent of the 24 and 16 km/h impact velocity, respectively, in 300 mm
of unobstructed dynamic travel. Second, it must not require more than
an average of 570 N of force to push the impactor rearward with a 27 kg
mass attached to it. Finally, we required that impactor be able to
deliver the center of the headform through a theoretical cylindrical
shape.
    The agency stated that the research test device used to develop the
proposal had not been optimized for compliance test purposes (74 FR at
63216, footnote 81.). Thus, we stated our belief that tighter
tolerances on the calibration characteristics could be attained with an
optimized design. Id. Nonetheless, the agency's impactor was found to
meet the percentage velocity reduction, on an average basis.
Comments
    Honda asked that the agency indicate in the regulatory text where
the static deflection of the impactor headform should be measured. With
respect to the targeting accuracy requirement, Honda wanted to know
``if it is necessary to verify accuracy of the actual contact position
after each impact test, as long as the test device satisfies the
specifications.'' It stated that with testing of an air bag it would
not seem to be possible to verify whether the targeting accuracy was
achieved during the test. Also with respect to this targeting accuracy
requirement, it wished to have the agency specify a calibration method.
    TRW believed that the performance attributes of the impactor are
adequately covered by the AORC impactor specifications, as presented at
the 2009 SAE Government/Industry meeting. These specifications are
provided below in Table 41, for the convenience of the reader.
---------------------------------------------------------------------------

    \142\ Stein, Doug, ``Linear Impactor Performance Characteristics
for Ejection Mitigation Testing,'' SAE Government/Industry Meeting,
February 6, 2009, Washington DC. File Impactor--Charaterization.ppt,
available at http://www.aorc.org/coep.asp.

       Table 41--AORC Recommendations for Impactor Performance 142
------------------------------------------------------------------------
                                                          Preliminary
            Variable               Maximum variance     recommendation
------------------------------------------------------------------------
Velocity........................   0.75    0.25
                                   km/h.               km/h.
Deflection......................  >> 25 mm..........  < 10 mm.
Time Delay to Impact............  400 ms............  < 100 mm (or
                                                       redefine time to
                                                       contact).
Excursion Accuracy..............   4.6     2 mm.
                                   mm.
Dynamic Friction................  2.62..............  < 0.25.
Design Margin...................  - 20% (TYP).......  TBD.
------------------------------------------------------------------------

    The AORC commented that NHTSA should adopt similar specifications
for impactor performance as used by the agency in their solicitation
for a new impactor (Solicitation Number DTNH22-09-Q-00071).
    The highlights of that solicitation are provided in the bullets
below. An asterisk notes that the solicitation requirement matches the
AORC recommendation.
     The ejection mitigation impactor must be capable of
measuring the displacement of the moving impactor mechanism throughout
the entire stroke, with an accuracy of 2 mm.*
     The maximum radial deflection of the ejection mitigation
impactor must not exceed 10 mm.*
     When the ejection mitigation impactor assembly is used in
conjunction with the support frame, it must have a vertical radial
deflection of no more than 15 mm.
     The maximum dynamic coefficient of friction of the
ejection mitigation impactor must not exceed 0.25.*
     The moving impactor mechanism must be designed for use at
peak velocities between 15 km/h and 25 km/h, with a tolerance within
the range of 0.25 km/h; a range of 0.15 km/h or
less is preferred.*
     When used with an appropriate propulsion system, the time
from the signal to deploy the air curtain to the peak velocity of the
moving impactor mechanism (minus any pre-programmed delay time) must
not exceed 100 milliseconds for any velocity within the range of 15 km/
h to 25 km/h. These velocities must also be achieved prior to the
impactor making contact with deployed air curtains of current
production.*
     When the headform is fired at 24 km/h, point P must remain
within cylinder C from the position at which the moving impactor
mechanism achieves peak velocity to the position 100 millimeters beyond
the position of peak velocity. Point P is the geometric center of the
headform on the outer surface of the headform, and cylinder C is a 20-
millimeter diameter cylinder, centered on point P and parallel to the
headform's direction of motion.
Agency Response
    Many provisions of the impactor test device calibration have been
modified to make them consistent with some of the calibration
procedures suggested by AORC and others. The static deflection
provision has been changed from 20 mm under a 27 kg load, to 20 mm
under a 981 N force applied in four orthogonal directions, with the
device in a test-ready configuration. The final rule will require a
limit on the dynamic coefficient of 0.25, measured in four orientations
with the shaft loaded with a 100 kg mass. We believe this provision
will fulfill the requirement previously specified by the unobstructed
velocity test and obstructed push force tests.
    In response to Honda, we have added text to S7.2 in the final rule
to indicate that the movement of the ejection impactor targeting point
in the x-z plane (vehicle vertical-longitudinal plane) should be
measured. In other words, looking along the y axis (direction of
travel), the center of the headform face should not deflect more than
the specified value. We have also added additional detail to this
section to indicate that this static deflection test is to be performed
with the impactor attached to the propulsion mechanism, including any
support frame connecting it to the floor. In addition, the force is now
applied in four orthogonal directions, rather than just downward. This
is an acknowledgement that loading on the impactor can be in any
direction.
    Since the test is performed on the device in a test-ready
configuration, the allowable displacement is 20 mm rather than the 10
mm recommended by the AORC in Table 41. The 10 mm value would be more
appropriate for a test that excludes the supporting frame of the test
device, as did the AORC recommendation.
    There is no reason to specify the displacement measurement accuracy
for the impactor since we will use a method sufficiently accurate to
determine that the displacement limit has been exceeded or not. There
is also no reason to specify a minimum time from launch until the
impact speed is obtained; how long it takes the impactor is irrelevant
to the test as long as it arrives at the specified delay times of 1.5
0.1 seconds and 6.0 0.1 seconds.
    A very important impactor characteristic is dynamic friction. We
have indicated in S7.3 of the standard that the dynamic friction must
not exceed 0.25. This matches the AORC recommendation. In the technical
report for this final rule, we provided these dynamic friction
measurements for the agency's new impactor and how the agency
determined dynamic friction characteristics.
    We note that the dynamic friction test differs from the static
deflection test in that it need not be done on the support frame that
would connect to the impactor in a test-ready configuration. We believe
this is acceptable since it is not likely that the static deflection of
the entire frame will influence the dynamic friction determination. We
also think it is acceptable that the perpendicular loading for the
dynamic friction testing is achieved through gravity and rotation of
the impactor and bearings rather than by pulling in four orthogonal
directions, as is done in the static deflection tests. Practically
speaking, there is no other way to perform the test.
    We believe that this detailed dynamic friction test in S7.3 of the
standard will fulfill the purpose of the requirements previously
specified in the NPRM for unobstructed velocity (proposed S7.2.1) and
obstructed push force (proposed S7.2.2). We have reduced the maximum
allowable dynamic coefficient of friction of the test device by a
factor of 5 from 1.29 (NPRM) to 0.25 (final rule). In addition, S7.2.1
allowed as much as a 15 percent velocity loss over a range of impactor
stroke. Testing of the new impactor found about a 1 percent loss in
impactor speed over a stroke of more than 150 mm. Thus, we conclude
that proposed S7.2.1 can be removed with no negative effect on the test
procedure.
    We understood Honda's comments on the issue of targeting accuracy
(see S7.4 in the final rule) as seeking clarification as to when the
accuracy is to be determined, i.e., would the tester need to know that
for any particular impact test the ejection impactor targeting point
was within the required cylindrical targeting zone shown in Figure 16
of the NPRM. The answer to Honda's question is provided in S7 of the
standard, where it is stated: ``[t]he ability of a test device to meet
these specifications may be determined outside of the vehicle.'' That
is, it is necessary that the test device being used meet the
characteristics in S7, but these need not and cannot be determined
during the test. We cannot see that it would be feasible to perform
these calibration measurements during a vehicle test. Honda requested
the agency specify how often and/or when these calibration tests should
be done. We cannot make such a pronouncement in the regulatory text.
Frequency of calibration is a test device and due care-specific issue
and must be determined case by case.
    Honda also wanted to know how targeting accuracy would be measured
by the agency. On our new impactor, we made this determination through
analysis of high speed video. We found that the impactor met the
required accuracy. We can envision other measurement techniques that
utilize witness marks on stationary targets, or that make witness marks
on the headform.

i. Readiness Indicator

    NHTSA proposed a requirement for a monitoring system with a
readiness

indicator for ejection mitigation systems that deploy in a rollover,
such as that required for frontal air bags in S4.5.2 of FMVSS No. 208.
74 FR at 63218.
    No comments were received opposing the proposal. Accordingly, the
proposal is adopted for the reasons discussed in the NPRM.

j. Other Issues

1. Rollover Sensors
    The NPRM did not require vehicle manufacturers to provide a sensor
that deploys the ejection countermeasure in a rollover or side impact
crash, and did not dictate the performance of any supplied sensor. We
were concerned as to whether specifying performance features for the
sensor could satisfactorily capture the myriad of rollovers occurring
in the real-world. Moreover, we explained that ejection mitigation air
bag curtains are now being designed, developed, and implemented by
industry and are deploying satisfactorily in the field.
    We believed there would be no incentive for manufacturers to
provide an ejection mitigation side curtain designed to meet the
standard without providing the sensor to deploy it in a rollover crash.
In addition, under the proposed requirements of the standard,
manufacturers would be required to provide written information to
NHTSA, upon the agency's request, explaining the basic operational
characteristics of their rollover sensor system. We also proposed to
deploy the side curtain in our compliance testing only if the owner's
manual or other written material informs the owner that the vehicle is
equipped with an ejection mitigation countermeasure that deploys in the
event of a rollover.
    The NPRM also discussed alternatives considered by the agency to
the approach proposed, such as requiring that the rollover sensors be
provided as a piece of equipment and defining such a piece of
equipment, or specifying a test that would assure the presence of a
rollover sensor on the vehicle. Advantages and disadvantages of the
approaches were presented.
Comments
    Nearly all comments from vehicle manufacturers and air bag
suppliers supported the NPRM's not establishing specific rollover
sensor requirements or performance tests. The Alliance concurred with
the NPRM that sensors are performing well in the field. GM stated its
support for only deploying air bags ``during the compliance test that
have been identified in the owner's manual as rollover-enabled. This is
a practicable and reasonable approach.'' GM agreed that manufacturers
would have no incentive to misidentify an air bag system as rollover
capable. AIAM stated that manufacturers have their own test and
calibration processes for crash sensors, so adding any tests in the
final rule would only add complexity to manufacturers' test plans for
little or no benefit. AIAM believed that the definition of sensor
deployment requirements is vehicle specific due to the different nature
of such factors as mass distribution, center of gravity height and use
of stability systems. Therefore, AIAM believed that setting a generic
test requirement would not be feasible.
    On the other hand, Honda believed that ``some manner of performance
criteria may be necessary for rollover sensors required for deployment
of such countermeasures.'' The commenter encouraged NHTSA to establish
basic performance criteria ``consistent with other elements of the test
procedure for FMVSS No. 226, if possible.'' Honda suggested a
definition for ``rollover sensor'' and suggested that NHTSA ``establish
a minimum requirement for the system configuration.''
    Advocates and Public Citizen requested that the final rule place
requirements on sensors that would deploy the ejection countermeasures
rather than leave it to the discretion of the manufacturer. Advocates
believed that NHTSA should specify requirements for sensors to ensure
sustained inflation throughout the long event of a rollover with
multiple quarter-turns. Public Citizen recommended a dynamic test that
``would allow the agency to measure both the presence and the
performance of rollover sensors.''
    IIHS stated that while it understood the agency's reluctance to
specify performance requirements for sensors that may not capture the
scope of real-world rollover crash scenarios, NHTSA should continue
monitoring field data to determine the adequacy of the agency's
approach.
Agency Response
    This final rule adopts the approach of the NPRM and does not
specify direct rollover sensor specifications. The agency is not aware
of any repeatable rollover test that replicates the breadth of real-
world rollovers addressed by this rulemaking. Current dynamic tests,
such as the 208 Dolly test, do not allow the agency to determine how
well the sensor will perform in the field. The 208 Dolly test offers
little challenge to the sensor and, according to Viano and
Parenteau,\143\ represents a very small portion of rollover crashes.
See the NPRM, 74 FR at 63218, for additional discussion of dynamic
rollover testing.
---------------------------------------------------------------------------

    \143\ Viano D, Parenteau C., ``Rollover Crash Sensing and Safety
Overview,'' SAE 2004-01-0342.
---------------------------------------------------------------------------

    With respect to Honda's comment on specification of ``some manner
of performance criteria'' and/or a definition for ``rollover sensor,''
this concept is very similar to an option discussed in the NPRM
preamble (Equipment Definition Option) (74 FR at 63218). We indicated
in that analysis that this option was problematic for several reasons.
We stated that such an option has the--

limitation of having to definitively specify the item of equipment
it would be requiring, which might necessitate adopting and applying
an overly restricted view of what a deployable rollover is and
perhaps what it is not. For example, we can contemplate rollovers
that have such an extremely slow roll rate when it would not be
necessary or desirable for the countermeasure to deploy. That being
the case, a reasonable definition of a rollover sensor might include
a roll rate specification as a function of roll angle. Developing
such a definition requires vehicle roll angle versus rate data,
which are not readily available to NHTSA. Another potential drawback
of this option is that without a test or tests to assess compliance
with the definition, enforcement of the requirement could be
restricted. An approach for a compliance test could be for NHTSA to
remove the sensor from the vehicle and subject the sensor to a
performance test to assess whether a specified performance
requirement is achieved, but the agency has limited information at
this time on which to develop performance parameters or a compliance
test.

Id.

    As Honda's comments did not address the shortcomings of this
option, the agency continues to have concerns. We thus decline to
implement Honda's request in this final rule.
    In view of the determination to adopt the approach of the NPRM, and
after reviewing the comments, we conclude that it is critical that
written information be provided in the owner's manual that describes
how the ejection mitigation countermeasure deploys in the event of a
rollover (see regulatory text of S4.2.3(a) of this final rule) \144\
and how

system readiness is monitored (see S4.2.3(b)). It is also important
that the test procedure not deploy the ejection countermeasure if this
information is not provided (see S5.5(c)). We also adopt the
requirement that the final rule require manufacturers to provide more
detailed technical information to the agency upon request (see S4.2.4).
---------------------------------------------------------------------------

    \144\ Ford provided excerpts from the owner's manual of a
vehicle with a rollover curtain air bag, and asked if the
information would meet the requirements of S4.2.3(a), ``Written
information.'' (NHTSA-2009-0183-0047, p. 20.) Ford's excerpt stated
in part: ``The Safety Canopy system is designed to activate when the
vehicle sustains lateral deceleration sufficient to cause the side
crash sensor to close an electrical circuit that initiates Safety
Canopy inflation or when a certain likelihood of a rollover event is
detected by the rollover sensor.'' Our answer is yes.
---------------------------------------------------------------------------

    Field data on vehicles with rollover sensors continue to indicate
that curtains are deploying in rollovers when they should. Of the 21
RODSS cases, four NASS cases and 48 SCI cases believed to involve
vehicle rollover crashes and presumed to have rollover deployable
curtains, five were determined not to have deployed.
    We conducted an in-depth review of these five cases. Four of the
five cases had a significant frontal impact that preceded the rollover.
These impacts may have destroyed the vehicle battery and thus
eliminated the primary power source for deploying the rollover curtain.
There is also some question as to whether one of these vehicles was
definitely equipped with a rollover sensor, since the system was an
option on this vehicle. In one case, the vehicle's kinematics were very
complex and may have included some motion not typical of a lateral
rollover.
    After reviewing the five non-deployment cases, it was not apparent
to us that there was a problem with the rollover sensor that would have
been identified by a test for a sensor, such as the Equipment
Definition test or Presence test discussed in the NPRM (74 FR at
63218). We cannot make a finding that in these cases, the rollover
curtains' non-deployment was unrelated to the initial frontal impacts.
A presence test that only addressed whether the curtain will deploy,
that did not account for a significant initial frontal impact, might
not have made any difference on the deployment of these rollover
curtains.
    We have become interested, however, after reviewing the field data,
as to whether ejection mitigation systems could have a backup power
source, such as a capacitor, that can provide the power for curtain
deployment within some short time period after primary power is lost.
It is our understanding that generally vehicles currently have such
energy storage systems, but these systems may not have the ability to
deploy rollover curtains when the rollover is subsequent to a frontal
impact causing the loss of power. There were only a handful of cases on
hand. We would like to learn more about this issue.
    We are not ready to specify in this final rule some sort of
requirement related to the ability to deploy the curtain after loss of
primary power. For one thing, we believe that this issue is outside of
the scope of notice of the NPRM. Moreover, NHTSA would like to gain
more knowledge in this area. We would like to analyze the vehicle
kinematics that result when a frontal crash is followed by a rollover
to better understand the amount of time secondary power is, and should
be, available. Data available from event data recorders may provide a
starting point for the analysis of this issue. We have begun a review
of the EDR data available to the agency and will continue to monitor
data as it becomes available. We would like to find out if there is a
problem in the field and seek to know more about the amount of storage
time capacitors typically have vis-[agrave]-vis their ability to deploy
the curtain after power is lost.
2. Quasi-Static Loading
    We requested comments on the need for an additional test that would
impose quasi-static loading on the ejection countermeasure. Films of
occupant kinematics in vehicle rollover testing and in DRF testing
indicate that ejection mitigation countermeasures can be exposed to
quasi-static loading during a rollover, in addition to short-duration
impacts that the headform test replicates. Quasi-static loading can
occur when an occupant contacts the countermeasure and loads it
throughout or nearly throughout an entire rollover event.
Comments
    AIAM commented that in the absence of data demonstrating that
countermeasures designed to meet the proposed requirements are not
adequate to address quasi-static loading, there is no basis for
adopting such a test requirement at this time.
Agency Response
    We are not adopting a requirement at this time. Instead, we plan to
pursue some limited testing in the near term to see how an ejection
mitigation countermeasure that performs well to the requirements in the
final rule performs in a quasi-static test. At this time, there are no
data available to the agency. Therefore, we cannot determine the
consistency, or lack thereof, between quasi-static performance and
impact test performance.
3. Full Vehicle Test
    The NPRM explained the agency's position that the component test of
FMVSS No. 226 would not only distinguish 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.
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.
    The NPRM further noted that 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. 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
correlated eight different tests to six rollover definitions from NASS-
CDS. 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 208 Dolly test.
74 FR at 63185.
    The NPRM also discussed our belief that 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. Id. A single full vehicle rollover test
could narrowly focus on only certain types of rollover crashes
occurring in the field. We noted in the NPRM our concern 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 lessened by a component test. We also noted that a
comprehensive suite of full-vehicle dynamic tests would likely involve
many more years of research, which would delay the rulemaking

action and the potential for incorporating life-saving technologies.
The agency stated that such a delay appears unwarranted, given that
NHTSA believes the component test will be an effective means of
determining the acceptability of ejection countermeasures.
Comments
    AIAM agreed with the agency's view that a dynamic full vehicle test
should not be pursued at this time. The commenter concurred that it is
not clear how the agency could represent the wide range of rollover
crash scenarios with a single test mode, and that manufacturer
certification using a series of test modes would be unduly burdensome.
AIAM also stated, ``Making a dynamic rollover test adequately
repeatable for regulatory purposes would also be a very significant
challenge.'' AIAM supported continued research on developing a
practicable dynamic test approach that provides additional safety
benefits.
    In contrast, Batzer and Ziejewski recommended that in addition to
an impact test, NHTSA should ``mandate that all manufacturers perform
at least one FMVSS-208 style dolly rollover test.'' Advocates believed
that the FMVSS No. 226 impact test does not account for ``door-window
frame distortion that can occur in rollover crashes'' and that this
could result in reduced curtain air bag effectiveness. Public Citizen
also supported a whole vehicle dynamic test. Public Citizen stated that
further delays needed to develop a dynamic test would ``benefit
occupants in rollover crashes, if a dynamic rollover test resulted in a
better standard that was more representative of real world crash
conditions.'' The commenter also stated that the agency ``cannot simply
add up the sum of the target populations identified in each of its
rollover rulemakings and claim to have protected occupants.''
Agency Response
    For the reasons discussed in the NPRM, the final rule will not
contain a full vehicle dynamic test to evaluate ejection mitigation.
    We understand the appeal of a dynamic test for ejection mitigation
as well as all aspects of rollover protection, a complement of sorts to
frontal and side protection offered by the dynamic tests in FMVSS Nos.
208 and 214, respectively. As a matter of fact, the agency is currently
pursuing a research program looking at the development of a dynamic
test to address roof strength. In addition, the agency has been
pursuing laboratory research on restraint system (e.g., seat belt
system) optimization for rollover crashes.
    As it happens, however, a full vehicle dynamic test for rollover
crashworthiness systems is not available. An FMVSS No. 208 (frontal
impact) or No. 214 (side impact) test presents different challenges
than a rollover test. Frontal and side impacts, while deadly, are less
complex by comparison to a rollover crash. As explained in the NPRM,
rollover crash tests have a high degree of variability in vehicle and
occupant kinematics. There are many types of rollover crashes, and
within each crash type the vehicle speed, roll rate, roll axis and
other parameters can vary widely. In contrast, the critical parameters
for planar crashes can be captured by the direction of impact and
[Delta]V. It is a relatively simple matter to develop a test(s) (i.e.,
a vehicle into barrier or object into vehicle) that results in the
desired vehicle [Delta]V in the desired direction.
    Nor might a full vehicle dynamic test be available as an outgrowth
of the agency's roof crush and seat belt system research. The vehicle
kinematics involved in assessing enhanced protection of the occupant
within the vehicle (studied in the roof crush and belt system programs)
may be significantly different from those involved in mitigating the
risks of occupant ejection to belted and unbelted occupants. A dynamic
test that is appropriate for assessing roof crush and seat belt
performance may not necessarily provide the same kind of challenge to
ejection mitigation.
    It may or may not be suitable to have a single rollover test to
assess roof crush and seat belt performance. For ejection mitigation,
it is unlikely that a single rollover test would be sufficient to
address the many types of rollovers that occur in the field.\145\ We
would want the dynamic test to assure that an ejection mitigation
countermeasure constrains belted and unbelted occupants in all types of
rollover crashes. However, at this time there is no archetype rollover
crash that can be replicated in laboratory testing.\146\
---------------------------------------------------------------------------

    \145\ We have already discussed our determination that the 208
Dolly test is not suitable for ejection mitigation testing. See,
e.g., 74 FR at 63185. The 208 Dolly test represents less than 1
percent of real-world rollovers. Further, some recent experience
with the 208 Dolly test makes problematic its implementation as a
replacement for the impact test or an additional test. During recent
tests in our rollover restraints research program, we attempted to
subject a MY 2007 Ford Expedition to the 208 Dolly procedure.
However, two out of five attempts failed to initiate a roll of even
one quarter-turn. We acknowledge that the above was not a typical
result of 208 Dolly testing within the agency's experience, but it
does highlight testing issues.
    \146\ A full vehicle dynamic test would presumably involve the
use of anthropomorphic test devices (ATDs). There is some question
whether the currently available ATDs offer an acceptable level of
biofidelity with respect to occupant ejection. For example, the hip
articulation for the Hybrid III dummies is limited, which may alter
their ability to replicated real world occupant kinematics. An
appropriate ATD for use in the test would have to be explored.
---------------------------------------------------------------------------

    We stated in the NPRM preamble, ``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.'' 74 FR at
63186. We hope that in the future, a full vehicle dynamic test, or a
suite of tests, could be developed that is appropriate for use in FMVSS
No. 226. However, at this time, there is not a viable full vehicle
rollover test procedure to evaluate ejection mitigation. In response to
Public Citizen, we strongly disagree that a delay of this rulemaking to
develop a dynamic test would be justified. This final rule will save
over 370 lives a year. Each year delayed to develop what is now an
indefinable full vehicle test will have a substantial human cost.
    Public Citizen also commented that the agency ``cannot simply add
up the sum of the target populations identified in each of its rollover
rulemakings and claim to have protected occupants.'' The agency takes
great care when doing the benefits assessment to not double count lives
saved. If we assume a specific population is saved by one of our
standards, we do not count them again when determining the benefits for
another. In this way, our estimates are conservative.
4. Minor Clarifications to the Proposed Regulatory Text
    In preparing the final rule regulatory text, we made some changes
to make the text clearer and easier to understand. The changes were not
meant to alter the requirements of the proposal. Below we provide a
listing of the more noteworthy of these minor changes and a brief
rationale for the change.
    S3. Ejection Impactor--Deleted ``It consists of an ejection
headform attached to a shaft'' and moved it to S7.1. This was done
because this descriptive information is consistent with the type of
information provided in S7.1.
    S3. Ejection propulsion mechanism--Deleted ``specified in S7.2 of
this Standard No. 226.'' This was deleted because S7.2 (New S7.3) does
not really

provide information specific to the propulsion mechanism.
    S3. Target Outline--Eliminated the term ``target outline'' and
replace it with ``target'' throughout the regulatory text. This does
not result in any substantive change in the standard, since in the NPRM
these terms were defined to be interchangeable in the regulatory text.
    S3. Walk-in van--Deleted the second sentence indicating that the
seating position must be forward facing and edited the first sentence
to indicate the only seating position is the driver. This was done to
eliminate redundancy in the definition.
    S4.1.1--Added text to the first sentence referencing S8. This was
done to provide clarity and similarity with other standards.
    S5.1--The wording of the third sentence was modified to clarify
that the countermeasure was being struck at the defined target
locations.
    New S<IP_ADDRESS> (NPRM S5.2.1(a)), S5.5.5, S<IP_ADDRESS>--All occurrences of
``daylight opening'' were replaced with ``side daylight opening.''
    New S<IP_ADDRESS> (NPRM S5.2.1(a)), second sentences--Added the word
``projection'' after ``side daylight opening.''
    New S5.2.2(a) (NPRM S5.2)--Deleted ``and the x-z plane of the
target outline within 1 degree of a vehicle vertical
longitudinal plane.'' This was a redundant constraint. However, text
was added to indicate that the y axis of the target points outboard.
    New S<IP_ADDRESS> (NPRM S<IP_ADDRESS>)--Revisions were made to the structure
of this section to clarify the determination of primary targets.
    S5.5(a)--The sentence was modified to make it clear that it was the
countermeasure that must be impacted at the specified time.
    S5.5(a) and (b)--Replaced ``velocity'' with ``speed.''
    S6.1--Added text to clarify how the vehicle attitude is to be
adjusted.

k. Practicability

    NHTSA believed that meeting the proposed requirements as they
applied to the side windows at the first three rows was practicable.
There were a number of vehicles with side air bag curtains that cover
the windows adjacent to rows 1, 2, and 3, such as the 2005-2007 MY
Honda Odyssey, 2006 Mercury Monterey, 2007 Chevrolet Tahoe, and 2007
Ford Expedition.\147\ The agency also believed it was practicable to
produce vehicles that would meet the proposed performance requirements.
---------------------------------------------------------------------------

    \147\ Since that time the following vehicles with three rows of
coverage have been tested: MY 2007 Jeep Commander, MY 2008 Dodge
Caravan, MY 2008 Ford Taurus X, and MY 2008 Toyota Highlander.
---------------------------------------------------------------------------

    The NPRM had a proposed 24 km/h-1.5 second test, which has been
reduced in this final rule to 20 km/h-1.5 second. Some of the current
production vehicles tested during the development of the NPRM came
close to meeting the 100 mm displacement limit at all target locations
and impact speeds. The most challenging target location was A1, with A4
being the least challenging. For the 2nd row windows, the limited data
indicated target location B1 was more challenging than B4. Only two
vehicles were tested at the 3rd row. For these systems, C4 was more
challenging than C1.
    The agency stated that the primary parameters that determine the
stringency of the test were: (a) The impactor dimensions and mass; (b)
the displacement limit; (c) impactor speed and time of impact; and (d)
target locations. Comments focused on (c) above, specifically impactor
speed, to argue for reducing the stringency of the test based on
practicability grounds.
    We discussed in an earlier section of this preamble our decision to
reduce the impactor speed from 24 km/h-1.5 second (400 J) to 20 km/h-
1.5 second (278 J), based on a reanalysis of the research data used for
the NPRM. We believe this reduction in test velocity resolves many of
the comments, described below, that raised concerns about the
practicability of meeting a 24 km/h-1.5 second test. However, we wish
to address the concerns about practicability to explore any remaining
questions about the practicability of meeting a 20 km/h-1.5 second
requirement. Further, we would like to discuss issues relating to the
practicability and cost of meeting a 24 km/h-1.5 second requirement.
Comments
    All comments relating to practicability were submitted by vehicle
manufacturers. The comments were focused on side curtain air bags as
the sole countermeasure for the FMVSS No. 226 requirements. The
comments did not appear to dispute the potential of manufacturing side
curtain air bag systems that could meet the NPRM; rather they expressed
concerns with the potential negative trade-offs associated with such
systems for both side impact and OOP occupants.
    Honda referred to agency statements in the NPRM that indicated that
two methods of improving the ejection mitigation performance of curtain
air bags were to make them thicker and to increase their internal
pressure. Honda provided data on the relationship between internal
pressure and impactor displacement. Honda argued that increasing tank
pressure of an air bag design to meet the proposed requirements (to
produce less displacement of the impactor) results in notable increases
in Nij and neck compression measures. Honda believed that if 200 J is
set as the impact energy limit (17 km/h impact), ``the primary
objective of the side curtain airbag of occupant protection can be
balanced with the proposal for occupant ejection mitigation without
significant change to current side curtain airbag designs for some
vehicles.''
    VW also provided information showing the relationship between
impactor displacement and air bag pressure. It estimated that the
initial internal pressure would need ``to be increased 2-3 times
depending on the actual kinetic energy of the impactor and the NPRM's
required excursion limits.'' VW stated that ``the above mentioned
pressure increase for the ejection mitigation test will result in a
detuning of the airbag and in deterioration of the side crash test
results'' relevant to NCAP and IIHS consumer information programs. VW
believed there would be a reduction of overall fleet star ratings and a
reduction in occupant safety in conventional side crashes.
    The Alliance provided research performed by Toyota that the
Alliance believed ``illustrates the increased OOP risk associated with
the high impact energy (400 Joule impact) and limited excursion (100
mm) requirements proposed in the NPRM.'' In this research, two SUVs and
two passenger cars were tested to the 24 km/h-1.5 second impact test
and subsequently to OOP testing using the Technical Working Group (TWG)
Recommended Practice with an inboard facing 5th percentile adult female
dummy.\148\ When changes were made to the side curtain air bag systems
by increasing internal pressure and coverage to meet a 160 mm
displacement limit when tested at 24 km/h-1.5 seconds, the Alliance
reported that OOP values increased from approximately 80 percent of
IARVs to about 105 percent of IARVs.
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    \148\ The TWG Recommended Procedures were developed to evaluate
the risk of side air bags to children who are out-of-position.
Through a voluntary agreement with NHTSA, vehicle manufacturers
consented to meet the TWG. The agency requests the results of
testing through the Buying a Safer Car program and publishes the
data annually.

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Agency Response
    It appears from the comments that if the impact speed was 24 km/h,
some manufacturers would have to increase the air pressure in their
side curtain air bags to meet the requirement. We estimate that this
approach to meet a 24 km/h test would add $7.53 to the $31 incremental
cost of meeting a 20 km/h test. This added cost is for a larger
capacity inflator. Some manufacturers have commented that increasing
air bag pressure in current bags to meet a 24 km/h-1.5 second test
increases HIC values measured in a side impact test and IARVs measured
in OOP tests. If manufacturers were attempting to bring a curtain air
bag into compliance that was well outside of the 100 mm limit by only
increasing internal pressure, the air bag would likely become more
rigid. Whether those increased HIC values and IARVs in OOP tests from
increased air bag pressure pose an unreasonable safety risk has not
been shown, but so-called ``negative trade-offs'' concern the agency in
any rulemaking.
    New side curtain air bag designs appear to be evolving that show
promise in meeting the 100 mm limit of impactor displacement when
tested to a 24 km/h-1.5 second condition, without undesirably affecting
side impact and OOP test results.
    However, if these systems require significantly more air bag
volume, they may be more costly than a system that meets a 24 km/h
requirement by increased air pressure. We estimate that, for a vehicle
with an air bag system that uses higher volume and more material to
meet the 24 km/h requirement, $37.87 would be added to the $31
incremental cost of a system that meets a 20 km/h requirement.\149\
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    \149\ A curtain air bag with more volume will require more air
bag material and may also utilize an extra inflator if a single
inflator is not sufficient. An extra inflator adds significant cost
to a curtain air bag system.
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    Air bag supplier Takata met with the agency on July 28, 2009, to
discuss its effort at designing an ejection mitigation system to meet a
December 2006 NHTSA ejection mitigation research test procedure at a
displacement limit of 100 mm at 24 km/h-1.5 second impact.\150\ Takata
explained that it believed there were two potential ways of meeting the
requirement: By way of retaining a strong membrane over the window
opening, or by absorbing the impactor energy. For the first approach,
Takata stated that the strong membrane could be achieved by laminated
glazing or a high stiffness/pressure curtain. The second energy
absorption method could be achieved by air bags of increased volume or
air bags of a different shape to increase impactor stroke. Takata said
it chose this second approach, to develop an air bag of a different
shape.\151\
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    \150\ Docket NHTSA-2006-26467-0019.
    \151\ We note that Takata claimed that it achieved the necessary
performance by a change in shape, rather than an increase in
pressure or volume.
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    Takata stated that a new air bag design it has developed was
integrated into a sedan and tested to the 24 km/h-1.5 second and 16 km/
h-6 second impacts, and to TWG OOP requirements using both the 5th
percentile adult female and 6-year-old (6YO) child dummies. The
greatest displacement for the 24 km/h-1.5 second test was approximately
82 mm at A1. The greatest displacement at the 16 km/h-6 second test was
approximately 79 mm at B1. The air bag pressure at time of impact was
reported as 30 kPa.
    The results from the TWG testing are shown in Takata's docket
submission. The 5th percentile adult female results have a maximum
value of approximately 55 percent of the IARVs. For the 6YO child
dummy, no injury measure exceeded 20 percent of the IARVs.
    Takata determined that its new shape curtain could meet the 100 mm
displacement limit without advanced glazing with a sufficient
compliance margin in a sedan design. At the time of the presentation,
Takata indicated that it was working on increasing the compliance
margin for a sport utility vehicle (SUV) design and working with a
vehicle manufacturer to introduce the technology to the market.
    In its comment to the NPRM, the Alliance stated that NHTSA should
not interpret information about the performance of innovative side air
bag design concepts developed in an attempt to meet the NPRM to mean
that ``the requirements of the NPRM are practicable.'' \152\ The
Alliance claimed that the air bag supplier design evaluations have not
addressed the following areas: The ability of the air bags to be
deployed in time for a side impact and provide adequate side impact
protection; the ability to integrate these bags with FMVSS No. 201
countermeasures; the ability to function in a complete vehicle
environment; and the ability to implement this technology across
vehicle architectures.
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    \152\ NHTSA-2009-0183-0029, p. 20.
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    We understand that integrating a component into a full vehicle
design involves many factors. However, the Alliance did not provide a
convincing discussion as to why NHTSA should not consider a system such
as Takata's an indication of the practicability of meeting a 24 km/h-
1.5 second impact test.
    The Alliance and others questioned whether innovative systems could
be packaged in a vehicle to meet FMVSS No. 201 requirements. The
commenters did not explain how new ejection mitigation side air
curtains would pose unique design problems that would impede the
ability to certify to FMVSS No. 201, when current vehicles with
rollover side air curtains already are certified to that standard.
There was no showing that changes to the air curtains or to the
inflator will present insurmountable problems in packaging the
equipment to FMVSS No. 201. It also appears that Takata is now working
on implementing its system across vehicle architectures. Takata has
indicated that its new system has been successfully integrated into a
passenger car \153\ and is in the midst of SUV integration. Takata did
not provide cost data.
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    \153\ The Toyota data provided by the Alliance indicated that it
was more difficult to meet TWG guidelines in the passenger
environment than in SUVs.
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    The proposed 24 km/h-1.5 second impact has been reduced to 20 km/h-
1.5 second in this final rule after our reanalysis of the technical
basis for the energy requirement and our FRIA analysis showing a 20 km/
h requirement to be more cost effective. With this reduction in
impactor speed, vehicles will be able to meet the final rule's
requirements with fewer changes to existing designs. Data from agency
testing of production vehicles presented earlier in this preamble
demonstrate the practicability of the requirements of this final rule.
The MY 2007 Mazda CX9 was able to meet the performance tests in the
final rule (20 km/h), without modification. This vehicle had a 5-star
side impact rating in the 2007 NCAP program.
    We recognize that most side curtains will need design changes to
various degrees to meet the requirements of this final rule. As Takata
indicated in its 2009 meeting, there are several ways to possibly
improve performance in the ejection mitigation test. Manufacturers will
have to decide what suits their particular situation best.
Manufacturers could increase air bag internal pressure to make the air
bag stiffer and/or increase the volume to make the air bag thicker.
They could possibly change the air bag shape, such as Takata has done,
reducing the need for drastic changes in pressure and volume. They
might decide to use advanced glazing to

supplement ejection mitigation side air curtain performance in meeting
the 20 km/h-1.5 second test. In addition, the availability of lead time
and a phase-in schedule and advanced credits will provide manufacturers
time and flexibility to implement design changes to meet the standard.
    Lastly, the Alliance referred to data presented to NHTSA by Ford in
a September 10, 2008 meeting \154\ obtained by a load cell Ford placed
on the impactor shaft behind the headform. The Alliance believed that
``[p]reliminary testing has shown the need to further research energy
and excursion targets to ensure a `balanced approach' between excursion
and curtain stiffness (load cell measurement) in order to avoid
unintended consequences.'' In response, to our knowledge, no one has
established the biomechanical relevance of a uniaxial load measurement
on the shaft of an ejection impactor to occupant injury. Until and
unless such a relationship can be established, the agency has no
reasonable way to judge such data.
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    \154\ NHTSA-2006-26467-0016.
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l. Vehicle Applicability

    This standard applies to passenger cars, multipurpose passenger
vehicles (MPVs), trucks and buses with a GVWR of 4,536 kg (10,000 lb)
or less, except as noted in this section. Manufacturers are installing
or plan to install side impact air bag window curtains in many of these
vehicles. These side air bag window curtains are capable of meeting
FMVSS No. 214's pole test requirements, which apply to passenger cars,
MPVs, trucks and buses with GVWR of 4,536 kg or less. An FMVSS No. 214
air bag window curtain system can be augmented for use as an ejection
mitigation window curtain system.
1. Convertibles
    The NPRM tentatively determined that the standard should apply to
convertibles. We requested comments on the practicability of certifying
convertibles to the proposed performance test with door-mounted
ejection mitigation curtains and/or advanced glazing.
Comments
    All comments from vehicle manufacturers and air bag manufacturers
opposed the inclusion of convertibles in FMVSS No. 226 for
practicability reasons. Many stated that there was no technology that
would allow a convertible to meet the proposed requirements. The AIAM
explained that although convertibles can meet FMVSS No. 214's pole test
using a door-mounted upwardly deploying air bag, the inflated bag does
not have a door frame to which the curtain can be tethered to achieve
the lateral stiffness needed for ejection mitigation. Further, the
curtains need to be retained by the convertible top, which may not have
the same retention capability as the door trim of conventional
vehicles.
    The Alliance informed the agency that the agency was incorrect in
thinking that research from Porsche indicated the feasibility of a
door-mounted air bag system for ejection mitigation. The Alliance
explained that Porsche meant to describe a ``technologically neutral
solution'' for a coupe, ``which unlike a convertible, can be fitted
with framed windows.'' The Alliance stated that it believed that
``advanced glazing, with or without a door[hyphen]mounted airbag, does
not constitute a practicable compliance solution for convertibles.''
AORC stated that its members have been working on this technology but
have not yet verified performance relative to this specification.
    Comments from Pilkington and from Public Citizen supported
including convertibles in the applicability of the standard.
Agency Response
    We have decided that the standard will not apply to convertibles.
We found compelling the practicability concerns raised by vehicle
manufacturers and air bag suppliers related to the near-term technical
challenges involved with producing a compliant convertible.
    In NPRM preamble, we mentioned Porsche's development of door-
mounted curtains that would deploy upward toward the vehicle roof in a
rollover. Comments from the Alliance to the NPRM indicated that Porsche
was not developing this curtain for ejection mitigation of
convertibles, but rather for a coupe.
    We sought comments on the feasibility of a door-mounted upwardly-
deploying curtain for ejection mitigation of convertibles. Comments
from vehicle manufacturers and air bag suppliers indicated that current
air bag designs are not effective for ejection mitigation purposes in
vehicles without a window frame because the air bag cannot be tethered
at the leading edge of the curtain without a firm door frame to which
to attach. We concur that an ejection mitigation side curtain air bag
must be sturdily tethered in order to meet the displacement limits of
this final rule. At this time, convertibles lack the rigid door frame
or door pillar to which the ejection mitigation side curtain air bag
could be tethered. We agree that current ejection mitigation side
curtain air bag designs cannot be used on convertibles, and we are not
aware of information indicating the feasibility of developing designs
that could be used on convertibles in the foreseeable future.
    Advanced glazing will not be an available countermeasure for use in
convertibles to meet the standard. Honda and others stated that the
advanced glazing on a convertible door is likely to fall out in a
rollover crash due to the lack of roof structure and rigid structure
around the window opening. In our review of field data on advanced
glazing, we found sufficient evidence of glazing vacating the window
opening in real world rollover crashes that we decided not to allow
movable advanced glazing to be the sole countermeasure used to meet the
displacement limits of the standard. Also, movable glazing cannot be
present during the 16 km/h-6 second test. With these changes, the
glazing-only countermeasure is no longer viable for a movable window
opening. A convertible would have to pass the 16 km/h-6 second test
with just the door mounted ejection mitigation side curtain air bag. As
previously discussed, we do not believe it is practicable for
convertibles to meet the test with only an air bag at this time.
    In response to a comment from the Alliance, our reasons for
excluding convertibles from the standard are not based on FMVSS No.
216's exclusion of convertibles from roof crush resistance
requirements. However, we acknowledge that convertibles can pose unique
challenges related to the roof. As shown previously in this preamble,
there were 16 fatalities and 18 MAIS 3+ injuries due to ejections
through a convertible roof closed prior to the crash. For convertibles
where the roof was open, the fatalities and MAIS 3+ injuries were 31
and 84, respectively. This indicates that about half of the ejection
fatalities through the roof area occurred even when the roof was closed
before the crash. (These estimates are based on an extremely small
sample size.) These data reflect the problematic nature of convertible
ejection protection.
2. Original Roof Modified
    NHTSA proposed to exclude vehicles whose original roof was
replaced, raised or otherwise modified. A definition of ``modified
roof'' was adopted. No commenter opposed the proposal. NTEA commented
in support of it. This final rule adopts the proposed exclusion and
definition.

3. Multi-Stage Manufacture of Work Trucks
    NTEA asked that NHTSA exclude work trucks built in two or more
stages (``multi-stage vehicles'') from FMVSS No. 226. NTEA stated that
it expects that if ejection mitigation side curtain air bags are
installed by a chassis manufacturer to meet FMVSS No. 226, ``this
manner of compliance by the chassis manufacturers will result in
restrictive or non-existent pass-through compliance guidance for multi-
stage manufacturers of work trucks.'' The commenter believed that the
purchasers of these vehicles require an extensive variety of end
designs, ``including bulkheads and partitions to protect the driver
from loose cargo in the back of the vehicle,'' and that the design of
most vehicles will almost certainly affect the performance of the
chassis manufacturers' side curtain air bag systems. The commenter
believed that ``pass-through compliance will prohibit any completions
or alterations that could affect the vehicle's center of gravity thus
potentially affecting the sensor(s) that control side curtain bag
deployment. Also expected to be prohibited for pass-through compliance
would be any changes to the trim or headliner around any of the
regulated window space.'' \155\
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    \155\ NHTSA-2009-0183-0017, p. 3.
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    NHTSA is declining the request for a blanket exclusion of all work
trucks built in two or more stages from FMVSS No. 226. To provide
relief to multi-stage manufacturers and alterers, we have already
excluded vehicles whose original roof was removed, in part or in total,
by an alterer or final stage manufacturer. That exclusion addresses
designs that will specifically affect side curtain air bag coverage or
inflators for which pass-through guidance might not be available.
    A final-stage manufacturer can either stay within the incomplete
vehicle document (IVD) furnished by the incomplete vehicle manufacturer
(which are typically large vehicle manufacturers, such as GM or Ford),
or the final-stage manufacturer can work with incomplete vehicle
manufacturers to enable the final-stage manufacturer to certify to the
new standard.\156\ The final-stage manufacturer can also certify to the
standard using due care based on an assessment of the information
available to the manufacturer.
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    \156\ For a discussion of NHTSA's certification regulations for
final stage manufacturers, see 71 FR 28168, May 15, 2006, Docket No.
NHTSA-2006-24664, Response to petitions for reconsideration of a
final rule implementing regulations pertaining to multi-stage
vehicles and to altered vehicles. The Background section of that
document provides concepts and terminology relating to the
certification of multi-stage vehicles.
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    NTEA contended that work-performing vehicles should be excluded
from the standard because producing these vehicles may involve changing