occupant into the window opening. The maximum torso velocity was 16 km/
h, also for the unrestrained Jetta occupant.

Film Analyses of Full Vehicle Rollover Tests

    In the early 1990's the agency reviewed 23 of 28 full-scale
rollover tests performed in the 1970s-1990s to find any cases of
occupant to side glazing impact and to determine the contact
velocities. In seven of these tests, the occupant was observed striking
the side glazing with either the head or shoulder. As shown in Table
13, a film analysis was conducted to measure the velocity of the
impacts.\66\ The average impact velocity measured was 8.6 km/h. Maximum
and average head velocities were 17.0 km/h and 10.3 km/h, respectively.
Maximum and average shoulder velocities were 8 km/h and 6.3 km/h,
respectively.\67\
---------------------------------------------------------------------------

    \66\ The analysis is limited by the fact that a single camera
was used to determine the velocities.
    \67\ These measurements compare very closely to the measurements
reported in DOT HS476-PM-83-25. This report evaluated 48 FWHA
rollover tests involving passenger cars. In these tests, they found
six occupant/glazing impacts (5 head, 1 shoulder). An average impact
velocity of 10.9 km/h was measured. Maximum and average head
velocities were 17.8 km/h and 11.3 km/h, respectively. The only
measured shoulder velocities were 8 km/h and 8.7 km/h.

                                                     Table 13--Film Analysis of NHTSA Rollover Tests
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Vehicle      Occupant
          Test                      Make                  Model                Test type         test speed  impact speed      Contact point
                                                                                (km/h)        (km/h)
--------------------------------------------------------------------------------------------------------------------------------------------------------
878...............................  Honda................  84 Accord............  RTD..................         33.8          8.0   Shoulder.
No test .................  Dodge................  Aries................  Guardrail............         96.6         16.0   Head.
888...............................  Chevrolet............  82 Celebrity.........  RTD..................         37.0          6.5   Shoulder.
No test .................  Ford.................  Pinto................  Dolly................         27.4          2.5   Head.
No test .................  Dodge................  Reliant..............  RTD..................         33.8          4.5   Shoulder.
1520..............................  Ford.................  88 Ranger............  RTD..................         48.3          5.8   Head.
1522..............................  Nissan...............  88 Pickup............  Pole.................         48.3         17.0   Head.
Average...........................  .....................  .....................  .....................  ...........          8.61  ....................
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Based on the above information, the agency is proposing two impact
speeds and time delays. NHTSA requests comment on the appropriateness
of the impact speeds and of the time delay for both the high and low
speed impacts. If alternative impact speeds and/or time delays are
suggested, what are the rationale and data supporting that suggestion?
3. Alternative Testing of Only One Target Position at Higher Speed
    The agency proposes to subject all four target locations (per
window opening) to the 16 km/h (6 second time delay) impact, but
requests comments on whether to test all four target locations with a
24 km/h (1.5 second time delay) impact or just the location with the
greatest displacement in the 16 km/h impact. The latter approach would
reduce the test burden per window opening from eight targets to five.
Our analysis of available data shows that there appears to be a
correlation between the displacement results for the 24 km/h and the 16
km/h impacts, particularly for the target location with the greatest
displacement. That is, the weakest point in the countermeasure
(curtain) that allows the most displacement of the headform could be
the same for the 24 km/h impact as for the 16 km/h impact. If the
weakest point in the countermeasure is the same for each impact test,
it may be possible to reduce the number of tests for one of the impact
speeds to a single location. If a correlation exists, an approach the
agency could take would be to first determine the displacement at each
target location for the 16 km/h (6 second time delay) impact and rank
the displacement results from largest to smallest. The agency would
then subject only the target with the largest displacement to the 24
km/h (1.5 second delay) second impact. Under this scenario, if the
weakest target passes the 24 km/h test, it would be reasonable to
assume that the other targets would also have displacements under 100
mm in 24 km/h test. If the weakest target fails the 24 km/h test, the
vehicle would fail the requirements of the FMVSS proposed today and
there would not be a need to test the other targets.
    There are test data demonstrating that the target locations with
the most displacement at each test speed are generally the same, but
the data are limited. Table 14 shows the impactor displacement results
for the MY05 Infinity FX35 (front window), the Zodiac prototype on a
Navigator (front window), a TRW prototype on a CK (front window), the
MY06 Durango (second row window), and the MY05 Honda Odyssey (second
row window). Table 15 shows the displacement rank for each target
location and vehicle, from most displacement to least displacement.
    For the MY05 Infinity FX35, in the 24 km/h test, the largest and
smallest displacements are A1 and A4, respectively. For the 16 km/h
test of the Infinity, the ascending displacement ranking is A1, A3, A2
and A4. However, for the 24 km/h test, three trials were performed at
A2 and A3 and there is significant overlap in the displacement data.
The average displacement plus or minus one standard deviation is shown
in the table. In fact, there is no statistically significant difference
between the average results of 97 mm at A2 and 95 mm at A3. For the
Zodiac prototype data, the ranking of the displacement data at both
impact speeds is A1, A3, A2 and A4. For the TRW prototype, the ranking
is also identical at both speeds, but the ranking is A1, A2, A3 and A4,
which is different from the Zodiac. The target locations for the
Odyssey's largest and smallest displacements (A1 and A4, respectively)
are the same in the 16 km/h tests as for the 24 km/h impacts.
    For the second row window data, the MY06 Durango ranks the
displacement at both test speeds as B3, B2, B4 and B1, in ascending
order. However, at 24 km/h there is very little separating the
displacements at each location. The MY 05 Honda Odyssey has the
displacement ranking at the 24 km/h test of B4, B2, B3, and B1.
However, for the 16 km/h test the displacement ranking is B2, B3, B4
and B1.
    In general, this very limited data set shows a consistency in the
displacement results for each impact test speed, particularly for the
location of greatest displacement for the front window (A1). For the
second row window, the Dodge Durango had consistent results, but the
Honda Odyssey did not.
    We note that this alternative of performing a single 24 km/h impact
at the target that gives the largest displacement in the 16 km/h impact
has not been analyzed in the Preliminary Regulatory Impact Analysis
(PRIA). However, this does not mean there would be no difference in
cost or safety benefits. Rather, assessing this difference would
require sufficient data to determine the probability of having a 24 km/
h impact displacement greater than 100 mm at some location other than
the location of greatest displacement at 16 km/h. We do not have
sufficient data for such an assessment.
    Comments are requested on whether the 24 km/h impact should only be
conducted on the target location with largest displacement in the lower
speed test. If results for multiple targets at 16 km/h are within the
variance for the test, which target should be selected for the 24 km/h
test? The agency's supporting documents for this NPRM estimate the
likely test burdens associated with the two approaches. The agency
estimates that the restricted testing approach would reduce the number
of tests to determine full compliance by 38 percent, while reducing the
costs of testing by 8 percent. Please comment on the potential
advantages and disadvantages of each method and how the agency might
best balance both the safety and potential test burdens.

                   Table 14--Displacements for Vehicle Windows Where All Targets Were Impacted
                                                      [mm]
----------------------------------------------------------------------------------------------------------------
                                                    Position A1     Position A2     Position A3     Position A4
----------------------------------------------------------------------------------------------------------------
24 km/h--1.5 sec. Delay:
    05 Infinity FX35............................             124       97  14.5     minus> 11.0
    Zodiac Prot. On Navigator...................      147  4.9                      minus> 4.2      minus> 2.1
    TRW Prot. On CK w/lam.......................      181  1.4                      minus> 0.0      minus> 5.7
16 km/h--6 sec. Delay:
    05 Infinity FX35............................              85              21              39               9
    Zodiac Prot. On Navigator...................             135              49       80  2.1
    TRW Prot. On CK w/lam.......................              80              -3             -44             -67
----------------------------------------------------------------------------------------------------------------
                                                     Position B1     Position B2     Position B3     Position B4
----------------------------------------------------------------------------------------------------------------

24 km/h--1.5 sec. Delay:
05 Honda Odyssey................................       71  8.5
06 Dodge Durango................................              76              86              91              82
16 km/h--6 sec. Delay:
    05 Honda Odyssey............................              12      121  0.7
    06 Dodge Durango............................               3              36              71              18
----------------------------------------------------------------------------------------------------------------

  Table 15--Displacement Rank (From Left to Right, Most Displacement to
        Least Displacement), for Each Vehicle and Target Location
------------------------------------------------------------------------
                                    16 km/h--6 sec.    24 km/h--1.5 sec.
             Vehicle                     delay               delay
------------------------------------------------------------------------
05 Infinity FX35................  A1, A3, A2, A4....  A1, A2, A3, A4.
Zodiac Prot. on Navigator.......  A1, A3, A2, A4....  A1, A3, A2, A4.
TRW Prot. on CK w/lam...........  A1, A2, A3, A4....  A1, A2, A3, A4.
05 Honda Odyssey................  B2, B3, B4, B1....  B4, B2, B3, B1.
06 Dodge Durango................  B3, B2, B4, B1....  B3, B2, B4, B1.
------------------------------------------------------------------------

d. Locations Where the Device Would Impact the Ejection Mitigation
Countermeasure To Assess Efficacy

1. Occupants Are Mainly Ejected Through Side Windows
    NHTSA analyzed 1997 to 2005 NASS CDS data files to determine the
injury and fatality distribution by ejection routes.\68\ Table 16 shows
the MAIS 1-2, MAIS 3-5 and fatality distribution of ejected occupants
by eight potential ejection routes.\69\ Ejection through side windows
constitutes the greatest part of the ejection problem. There were
18,353 MAIS 1-2 injuries, 5,271 MAIS 3-5 injuries, and 6,174 fatalities
for occupants ejected through side windows. Table 17 gives the
percentage of the total at each injury level. The side window ejections
comprise 68 percent of all ejected MAIS 1-2 injuries, 47 percent of
MAIS 3-5 injuries, and 61 percent of all ejected fatalities. Because of
these data, NHTSA focused on the safety problem posed by side window
ejections.
---------------------------------------------------------------------------

    \68\ All crash types are included, but the counts are restricted
to ejected occupants that were injured. In addition, in NASS CDS the
ejection route for side windows is only explicitly coded for the
front (Row 1 Window) and rear (Row 2 Window). The third and higher
row side window ejections should be coded as ``other glazing.'' This
is because there are specific codes available for coding roof
glazing, windshield and backlight. However, when extracting NASS
cases of known ejections through ``other glazing,'' 17 unweighted
occupants were observed. A hard copy review of these cases showed
that 9 were known 3rd row side window ejections, but five cases were
miscoded. Four were actually backlight ejections and one was a
sunroof ejection. The known 3rd row ejections were recoded as ``Row
3 Window'' ejections.
    \69\ The ``Not Window'' category captures ejected occupants that
did not go through a glazing area. This might have been an open door
or an area of vehicle structure that was torn away during the crash.

 Table 16--Occupant Injury and Fatality Counts by Ejection Route in All
                               Crash Types
                 [Annualized 1997-2005 NASS, 2005 FARS]
------------------------------------------------------------------------
             Ejection route               MAIS 1-2   MAIS 3-5    Fatal
------------------------------------------------------------------------
Row 1 Window...........................     15,797      4,607      5,209
Row 2 Window...........................      2,533        621        906
Row 3 Window...........................         23         43         59
Windshield.............................      1,923      1,565      1,155
Backlight..............................      1,625      1,677        515
Sun Roof...............................      1,127        305        237
Other Window...........................          1         51          0
Not Window.............................      3,870      2,411      2,068
Subtotals:
    All Side Windows...................     18,353      5,271      6,174
                                        --------------------------------
        Total..........................     26,899     11,280     10,149
------------------------------------------------------------------------

 Table 17--Occupant Injury and Fatality Percentages by Ejection Route in
                             All Crash Types
                 [Annualized 1997-2005 NASS, 2005 FARS]
------------------------------------------------------------------------
                                     MAIS 1-2     MAIS 3-5      Fatal
          Ejection route            (percent)    (percent)    (percent)
------------------------------------------------------------------------
Row 1 Window.....................         58.7         40.8         51.3
Row 2 Window.....................          9.4          5.5          8.9
Row 3 Window.....................          0.1          0.4          0.6
Windshield.......................          7.1         13.9         11.4
Backlight........................          6.0         14.9          5.1

Sun Roof.........................          4.2          2.7          2.3
Other Window.....................          0.0          0.5          0.0
Not Window.......................         14.4         21.4         20.4
Subtotals:
    All Side Windows.............         68.2         46.7         60.8
                                  --------------------------------------
        Total....................        100.0        100.0        100.0
------------------------------------------------------------------------

2. The Requirements Would Apply to Side Windows Adjacent to First Three
Rows
    NHTSA evaluated crash data to assess which window, by row, the
above injured and killed occupants were ejected through. Table 18
provides the counts of the injured and killed side window ejected
occupants by the window row they were ejected through, ejection degree
(complete or partial) and restraint condition for the target population
of this rule. Table 19 shows the same data as a percentage of total
side window ejected fatalities, MAIS 3-5 and MAIS 1-2 injuries. The
first row (row 1) windows provide the ejection route for the most
injured and killed occupants. There were 2,459 fatalities and 2,243
MAIS 3-5 injuries that were unbelted and completely ejected through the
row 1 windows. The greatest number of fatally ejected occupants (3,671)
went through the row 1 window. This represents 83 percent of all side
window ejected fatalities. With regard to injuries, 3,735 (88 percent)
MAIS 3-5 and 11,016 (87 percent) MAIS 1-2 injured occupants went
through the row 1 windows. Ejection routes through row 1 and row 2
windows accounted for more than 99 percent of fatal and 98 percent of
MAIS 3-5 completely ejected and unbelted occupants. These data show a
compelling safety need to apply the ejection mitigation standard to row
1 and row 2 windows.

                      Table 18--Distribution of Target Population by Ejection Row and Injury Level by Ejection Degree and Belt Use
                                                         [Annualized 1997-2005 NASS, 2005 FARS]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Row 1                            Row 2                            Row 3
         Ejection degree                 Belted       --------------------------------------------------------------------------------------------------
                                                        MAIS 1-2   MAIS 3-5    Fatal     MAIS 1-2   MAIS 3-5    Fatal     MAIS 1-2   MAIS 3-5    Fatal
--------------------------------------------------------------------------------------------------------------------------------------------------------
Complete........................  Yes................         92         16         69         12         40          0          0         30          0
Complete........................  No.................      3,968      2,243      2,459      1,484        324        588         22          7         38
Partial.........................  Yes................      4,464      1,086        526         58         42         45          0          7          0
Partial.........................  No.................      2,492        391        617        119         64         53          0          0          0
                                                      --------------------------------------------------------------------------------------------------
    Total.......................  ...................     11,016      3,735      3,671      1,673        471        686         22         43         38
--------------------------------------------------------------------------------------------------------------------------------------------------------

 Table 19--Distribution of Target Population by Ejection Row and Injury Level by Ejection Degree and Belt Use, as a Percentage of Totals at Each Injury
                                                                          Level
                                                         [Annualized 1997-2005 NASS, 2005 FARS]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Row 1                            Row 2                            Row 3
                                                      --------------------------------------------------------------------------------------------------
         Ejection degree                 Belted         MAIS 1-2   MAIS 3-5    Fatal     MAIS 1-2   MAIS 3-5    Fatal     MAIS 1-2   MAIS 3-5    Fatal
                                                       (percent)  (percent)  (percent)  (percent)  (percent)  (percent)  (percent)  (percent)  (percent)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Complete........................  Yes................          1          0          2          0          1          0          0          1          0
Complete........................  No.................         31         53         56         12          8         13          0          0          1
Partial.........................  Yes................         35         26         12          0          1          1          0          0          0
Partial.........................  No.................         20          9         14          1          2          1          0          0          0
                                                      --------------------------------------------------------------------------------------------------
    Total.......................  ...................         87         88         84         13         11         16          0          1          1
--------------------------------------------------------------------------------------------------------------------------------------------------------

    We would also apply the standard to row 3 windows. All light
vehicle (GVWR 4,536 kg (10,000 lb) or less) rollover occupants in the
target population for this proposal were ejected through the windows of
the first 3 rows. Third and higher row windows are not specifically
coded as ejection routes in NASS, so the ``other'' window categories
were reviewed. These categories contained only a limited number of 3rd
row window ejections (about 1 percent of fatalities and MAIS 3-5
injuries). While the percentage of ejection through the third and
higher rows is small, this might be a reflection of the very few light
vehicles with more than three rows and the low occupancy in third and
higher rows. NHTSA is concerned that in a crash, an unbelted occupant
could be ejected from the 3rd row window opening. As discussed in
IV(b)(2) of this preamble, the agency has observed laboratory DRF tests
in which an unbelted dummy was initially prevented from ejection by a
side curtain, but was eventually ejected

when it slid to an opening in the curtain. Further, with substantial
numbers of 3-row vehicles used as passenger vehicles, applying the
standard to row 3 as well as rows 1 and 2 windows would be consistent
with the SAFETEA-LU mandate ``to establish performance standards to
reduce complete and partial ejections of vehicle occupants from
outboard seating positions.''
    In addition, it appears practicable for manufacturers to meet
ejection mitigation requirements applying to the row 3 windows. There
are a number of current OE air bag curtains that cover rows 1, 2 and 3
windows, such as the 2005-2007 MY Honda Odyssey, 2006 Mercury Monterey,
2007 Chevrolet Tahoe, and 2007 Ford Expedition.
    Less can be said about the practicability of air bag curtain
coverage beyond three rows of seating. Vehicles in this category are
primarily large vans with more than 10 seating positions and are in the
bus category. We do not believe that manufacturers have installed air
bag curtains that cover beyond the third row windows in vehicles that
have more than three rows. Thus, we would not apply the standard to
windows for row 4+.
    Out of concern to properly assess the cost impact of this
rulemaking, we are also proposing to limit the testable area of window
openings extending rearward past the designated seating positions of
the first three rows. This NPRM proposes that, for vehicles with 3
rows, for any side window opening that extends rearward of a 3rd row
forward-facing designated seating position (DSP), the rearward edge of
the testable side window opening would be bound by a transverse
vertical vehicle plane 600 mm (approximately 24 inches) behind the
seating reference point (SgRP) of the 3rd row DSP. If the 3rd row
designated seating position is adjustable to a non-forward facing
orientation, the target area extends to 600 mm behind the rearmost
portion of the seat when the seat is adjusted to the most rearward
position (with respect to the vehicle) and the seat cushion and seat
back are in the manufacturer's design position. So if a vehicle's third
row seat has both a forward and a rearward facing position, the
testable area would be determined as specified above. The final target
area would be the largest area as defined under either of these
conditions, i.e., (1) by the SgRP of the forward facing seat, or (2)
the most rearward part of the non-forward facing seat. This limitation
of testable area would also be applied to the 2nd row window in two-row
vehicles and 1st row window in one-row vehicles. The limitation would
primarily affect sport utility vehicles (SUVs) with two rows of seating
and side window areas adjacent to the rear cargo area. While it is not
impossible for unbelted occupants to be partially or completely ejected
through this area, we believe that ejection through a non-adjacent
opening more than 600 mm from the occupant's SgRP is less likely. We
note that FMVSS No. 201 has a similar exclusion in S6.3 that excludes
impact targets 600 mm rearward of the rearmost SgRP. We also note that
changes to the seating configuration for vehicles with removable or
stowable seats must be considered in the determination of the rearward
limit of the testable area. We propose that the seating configuration
that generates the largest testable area would be used.
    This NPRM proposes a definition of the term ``row,'' since the
proposed regulatory text frequently refers to the term in describing
the applicability of the ejection mitigation requirements. While the
definition of the term is generally understood, under the proposed
definition we would clarify that a single seat could constitute a
``row.'' The proposed definition of ``row'' would state: ``Row'' means
a set of one or more seats whose seat outline does not overlap with the
seat outline of any other set of seats, when all seats are to their
rearmost normal riding or driving position, when viewed from the
side.\70\
---------------------------------------------------------------------------

    \70\ Stated differently, the seats are adjusted such that their
design H-point coincides with seating reference point.
---------------------------------------------------------------------------

    In consideration of the above definition of ``row'' we believe it
is necessary to define ``seat outline.'' The proposed definition of
``seat outline'' would state: ``Seat outline'' means the outer limits
of a seat projected laterally onto a vertical longitudinal vehicle
plane.
    We believe that the definition is needed to address potential
questions about vehicles that appear in one seating configuration to
have 2 conventional rows of seating, but which have a seat or seats in
a row (e.g., the 2nd row) that are capable of being adjusted forward or
rearward independently from other seats in its row. For example,
suppose a seat in the 2nd row can move rearward such that it can occupy
a position occupied by a seat traditionally considered to be in the 3rd
row. NHTSA tentatively believes that a reasonable way of addressing
this issue is as follows. First, the vehicle seats must be adjusted
such that they are in the SgRP position. This places each seat in the
rearmost normal driving or riding position. The transition for a seat
being in one row as opposed to another is the overlapping of the side
view ``seat outline'' of the seats. Seats whose seat outlines overlap
are considered to be in the same row.
    To illustrate, Figure 4 shows the top and side view of a two row
vehicle, with two seats in the front row and three seats in the 2nd
row. All seats are assumed to be adjusted such that the design H-point
coincides with the SgRP. Figure 5 is another five-seat vehicle that has
a more rearward position for the 2nd row center seat than in Figure 4.
However, looking at the side view, there is still overlap between the
outline of the rear center seat and the outboard 2nd row seats. Thus,
by our proposed definitions this is still a two-row vehicle.
BILLING CODE 4910-59-P

[GRAPHIC] [TIFF OMITTED] TP02DE09.003

[GRAPHIC] [TIFF OMITTED] TP02DE09.004

BILLING CODE 4910-59-C
    Comments are requested on the practicability, cost and potential
benefit of extending application of the ejection mitigation
requirements to rows beyond the 3rd row. Please also comment on the
appropriateness and practicability of the 600 mm limitation, and on
whether the value should be increased or decreased. Comments are also
requested on the proposed definition of ``row'' and the implications of
the definition on other FMVSSs, e.g., FMVSS No. 225, ``Child restraint
anchorage systems.'' Standard No. 225 requires vehicles that have ``3
or more rows'' to have a child restraint anchorage system in the
``second row'' (S4.4(a)(1), 49 CFR 571.225).
3. Four Targets per Glazing Area
    NHTSA seeks to assure in a reasonable manner that any ejection

mitigation countermeasure provides the full coverage of potential
ejection routes. The cost and burden of testing increases as the number
of target locations increases, or as less specificity is provided in
the test procedures identifying the target location. The agency has
tentatively decided to limit the number of target locations per glazing
area to four. In examining current side window designs, four targets
appear sufficient to assure side window opening coverage for window
designs. The targets would be less than four if the window area is
small enough to create significant overlap in the target locations.
    As discussed earlier in this preamble at section IV(e), a
comparison of the results of the DRF tests and impactor tests indicated
that if key locations around the perimeter of the window opening were
not targeted, an opening could form through which an occupant could be
ejected in a rollover. Target A1 (see Figure 6 below, which is
replicated below for the convenience of the reader from Figure 1 of
this preamble) was the most challenging target in the component test,
while A4 was the least challenging. For the 24 km/h (1.5 second time
delay) test, the only system that did not exceed the 100 mm criterion
at A1 was the Zodiac Prototype on the CK pickup. The data indicate that
if target position A1 were not tested, an ejection mitigation curtain
could have displacements of less than 100 mm in the other tests, yet
have a hole large enough in a rollover to allow an occupant to be
ejected. No displacement at A4 exceeded 76, 73 or 67 mm at 24 km/h, 20
km/h and 16 km/h, respectively. Taken as a whole, A2 and A3 showed
similar results to each other for all three test conditions (24 km/h,
20 km/h, and 16 km/h impacts)) in that neither was as consistently
challenging to meet as A1 nor as easily met as A4. Thus, based upon
existing agency tests, passage of point A1 would tend to indicate a
satisfactory countermeasure, but some vehicles showed more displacement
at A3 than at A1.
[GRAPHIC] [TIFF OMITTED] TP02DE09.005

    The four targets are similar to those identified by GM in
developing that manufacturer's ejection mitigation side curtain air
bags. GM indicated that its test procedure targets the front side
window opening in three locations: the upper rear corner, the lower
front corner and the centroid of the window opening.\71\ The first two
target locations are very similar to the proposed target location A4
and A1 described in Figure 6 above. GM explained that it identified the
upper rear target as a test point because it represents the most
frequent impact position in rollover, and because it is at the edge of
the rearward seating position and assesses protection for taller
occupants. GM believes that the lower front corner test point evaluates
the curtain for the forward seating position, assesses the curtain's
performance with smaller occupants, and is the location at which the
trailing (far side) occupant contacted the window opening in rollover
tests. The centroid position represents the impact location with the
least boundary condition support. While NHTSA's proposed targets are
similar in location to GM's three targets, the agency tentatively
believes that using four targets is preferable to only three targets to
better assess how well the curtain covers the perimeter of the window
opening.
---------------------------------------------------------------------------

    \71\ O'Brian-Mitchell, Bridget M., Lange, Robert C., ``Ejection
Mitigation in Rollover Events--Component Test Development,'' SAE
2007-01-0374.
---------------------------------------------------------------------------

    Comments are requested on whether the FMVSS should specify that any
point of the ejection mitigation window curtain will be tested by
NHTSA, without limiting the number of target locations or specifying
precisely the locations of the targets. The advantage to such an
approach is that the agency would be allowed flexibility in choosing
where to impact the ejection mitigation curtain, and could choose the
location on the curtain that appeared to be the ``weakest,'' thereby
assuring that all portions of the curtain would limit head displacement
and not just the four target points identified in an FMVSS.
Manufacturers would have to ensure that the curtain passed the
performance limits at any point that NHTSA may select, which means that
all parts of the curtain would have to meet the requirements. Further,
it is possible that a sufficient assessment of countermeasure
effectiveness could be achieved with fewer than four tests per window
without decreasing the realized safety benefit.

What Is a ``Window Opening''?

    This NPRM proposes a specified procedure for identifying the four
targets of each window opening. The procedure is described in the next
section and in detail in the Technical Analysis. To objectively
describe ``window opening,'' this proposal would generally use the term
``daylight opening,'' as defined in FMVSS No. 201 for openings on the
side of the vehicle. The term is defined in FMVSS No. 201 as: ``the
locus of all points where a horizontal line, perpendicular to the
vehicle longitudinal centerline, is tangent to the periphery of the
opening. * * *'' There is a daylight opening for each separate piece of
glazing. For example, a single door may have multiple daylight openings
if there are

multiple pieces of glazing comprising the side window opening.\72\
---------------------------------------------------------------------------

    \72\ The proposed test procedure has a provision that provides
for fewer targets than four for small daylight openings.
---------------------------------------------------------------------------

    Note, however, there would be two differences between the proposed
definition and the FMVSS No. 201 definition of daylight opening. First,
the proposed definition would state that the above-referenced
horizontal line would not only be tangent to the periphery of the
opening, but would also include the area 50 mm inboard toward the
vehicle centerline from the window glazing interior surface. This
provision is intended to account for interior trim or other substantial
vehicle structure that might be in the vicinity of the daylight
opening, which could restrict the size of the opening through which an
occupant could be ejected.
    Second, we propose to exclude from the ``daylight opening''
definition any flexible gasket material or weather stripping used to
create a waterproof seal between the glazing and the vehicle interior.
The rationale for the exclusion is that the flexible material is
unlikely to impede occupant ejection through the opening. This results
in keeping the test area as large as possible. In the next paragraph,
we discuss a proposal that would specify a 25 mm offset from the
daylight opening in determining the testable area. If flexible gasket
material or weather stripping were not excluded from the daylight
opening definition, the testable area would be further reduced and the
impactor targets would be moved even further inward away from the
perimeter of the opening. Since we want to keep the target locations
close to the opening perimeter to assure full coverage of the ejection
mitigation curtain, we have tentatively decided to exclude the flexible
material from the daylight opening definition. Comments are requested
on the ``daylight opening'' definition.
    Although the determination of daylight opening is made with
flexible gasket material or weather stripping removed, we propose that
the gasket material be present for the impactor test. Our rationale for
having the material present is that conceivably, the material could
affect the test results in some situations, and that during real world
rollovers it is likely that the flexible gasket material or weather
stripping would be present. However, we do not have comparative data
between testing with and without the flexible gasket material or
weather stripping. Further, we recognize that if the gasket material is
removed to determine the daylight opening, specifying that the material
is present on the vehicle for the impactor test will necessitate an
extra step in the testing. Therefore, we request comments on whether
the impact test should be performed with or without the flexible gasket
material or weather stripping.
    In specifying how the four targets of a side window opening are
located, the test procedure would exclude a portion of the daylight
opening. Briefly stated, to identify the four targets, measurements
would be taken from a line offset 25 mm from the daylight opening
(depicted as the innermost outline of the daylight opening in Figure 6,
above). This is the line used to provide the tangent for the placement
of the two dimensional projection of the headform as viewed from the
lateral vehicle direction. The reason underlying the 25 mm offset for
the headform tangent relates to the potential imprecision of the linear
impactor. Although the impactor is guided, it is not possible to always
have it strike precisely where targeted. As will be discussed later, we
are proposing a 10 mm tolerance on the impact location as
well as 2 mm for locating the offset line and 2
mm for locating the target tangent to the offset line. Thus, a 25 mm
offset from the window daylight opening yields 11 mm of buffer to
assure that the impactor will not strike the window frame structure. If
the impactor were to strike the window frame structure, the impactor
could be at least partially restrained by the window frame structure
rather than by only the window curtain and/or other ejection
countermeasure.
    We are proposing that the location of the offset-line be made by
first projecting the daylight opening laterally onto a vehicle vertical
longitudinal plane. Then at each point on the projection, a tangent
line would be determined. Finally, a point would be located by moving
252 mm perpendicular to the point of tangency, in the
vehicle vertical longitudinal plane. The set of points determined in
this way would constitute the offset-line. Comments are requested on
the 25 mm offset value and the method used to determine its location.
Is there a simpler method to provide an offset from the daylight
opening that is sufficiently objective and repeatable?
4. Method for Determining Impactor Target Locations
    The agency developed a method for determining target locations with
the following goals in mind:
    (1) The test method has to be objective and repeatable so that
there would be no ambiguity as to the target locations and so different
testers would put the targets in the same locations;
    (2) The method has to result in the placement of targets that are
well distributed around the perimeter of the window opening to assure
full coverage of the opening by the ejection mitigation countermeasure;
and
    (3) The method has to be simple and straightforward and suitable
for varied window shapes of the vehicles to which the standard applies.
    NHTSA believes that the proposed test method meets these goals. The
test approach has three main parts. The first part specifies how
targets would be identified on front (between A- and B-pillars) and
rear windows (rearward of the B-pillar).\73\ The test method differs
slightly between front and rear windows to account for the distinct
shapes of the windows. Front windows typically have a large rearward
rake, while rear windows usually either have a forward rake due to the
inclination of the rear backlight area or are somewhat rectangular in
shape. For front windows, the lower-front and upper-rear portions of
the opening have acute angles. For rear windows, particularly the
second row in two-row vehicles and the third row in three-row vehicles,
the acute angles are on the upper-front and lower-rear part of the
opening. The lower acute angle locations are likely to be challenging
for any header-mounted air bag curtain and are, therefore, good
potential target locations (goal 2, above). These acute angles
also provide convenient target locations because there is no ambiguity
as to placement of the headform (goals 1 and 3). After
conducting this first part of the test approach, the four target
locations would be identified on most front and rear windows.
---------------------------------------------------------------------------

    \73\ The proposed method of determining target locations is
limited to side window openings. Thus, all front and rear window
locations discussed are on the sides of the vehicle. The front
window(s) are adjacent to the first vehicle seating row and the rear
window(s) are adjacent to second and third seating rows.
---------------------------------------------------------------------------

    The second part of the test procedure addresses what happens if,
after conducting the first part of the test approach, the four targets
substantially overlap each other, as would be the case involving
smaller than typical rear windows, such as ``sail panels'' that are
installed in the rear of larger rear windows of some vehicles. (These
windows are usually triangular in shape.) This part of the test
procedure specifies an objective means of eliminating some of the four
targets that overlap to avoid redundancy in testing, and describes
which targets would be eliminated or considered for elimination

and the order in which they would be considered (goals 1 and
2).
    The third and final part of the test procedure addresses what
happens if, after eliminating some targets pursuant to the second part
of the test procedure, too few targets remain to test a daylight
opening sufficiently. This part of the procedure involves the
reconstituting (adding back in) of targets if, after implementing the
second part of the procedure, there are too few targets remaining to
evaluate the ejection mitigation performance of a countermeasure (goal
3).

Part 1: Finding the Four Targets

    The first step in determining the four impactor target locations
would be to find the corners of the daylight opening. The target
locations are found by viewing the window from the lateral vehicle
direction (y-axis). The corner would be located by using the ``target
outline'' of the impactor face, which would be the x-z plane \74\
projection of the ejection headform face, as shown in Figure 2 of this
preamble. The target outline would be the projection of the impactor
face in a vehicle vertical longitudinal plane. A corner would be
defined as any location within the daylight opening where the impactor
target outline is tangent to the offset line (the offset line would be
25 millimeters inside the daylight opening) at two or more points.
Figure 7 shows target outlines placed in the corners of the side window
daylight opening for the front and rear windows of a two-row vehicle.
---------------------------------------------------------------------------

    \74\ The coordinate system convention is--
    x-axis: vehicle longitudinal axis;
    y-axis: vehicle lateral axis;
    z-axis: vehicle vertical axis.
    [GRAPHIC] [TIFF OMITTED] TP02DE09.006

    The next step in the target location process would be to locate the
geometric center \75\ of the daylight opening, and then to use the
geometric center to separate the opening into four quadrants, i.e.,
lower-front, lower-rear, upper-front and upper-rear. Next, we would
eliminate the target in certain quadrants. For the front window, we
would eliminate any target whose center is not within (inclusive of the
border between quadrants) the lower-front and upper-rear quadrants. For
all rear window openings, we would eliminate any target whose center is
not within the upper-front and lower-rear quadrants (inclusive of the
border). We would retain the front window lower front-most and rear
window lower rear-most target locations because they are likely to be
challenging for any header-mounted air bag curtain and are, therefore,
good potential target locations (goal 2, above). These
locations also have the advantage of presenting no ambiguity as to
placement of the headform (goals 1 and 3), as is also the goal
for the front window upper rear-most and rear window upper forward
target locations.
---------------------------------------------------------------------------

    \75\ The balance point of an object assuming uniform weight
distribution. Later in this section of this document we request
comments on an alternative to using the geometric center to separate
the window into quadrants.
---------------------------------------------------------------------------

    The remaining targets are called ``primary targets,'' and the
quadrants in which they are located are ``primary target quadrants.''
If there is more than one target left in a primary target quadrant, we
would maintain the lowest target in the lower quadrants and the highest
targets in the upper quadrants, to ensure that the extremes of the
ejection mitigation countermeasure would be tested. If there were no
target centers within those quadrants, we would use the target whose
center is closest to the quadrant. This process leaves the ``primary
targets'' shown in Figure 8.\76\
---------------------------------------------------------------------------

    \76\ Geometric center locations shown are for illustration
purposes only and may not reflect the actual location for the
daylight opening depicted.

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

[GRAPHIC] [TIFF OMITTED] TP02DE09.007

    The final step in the target location process would be to locate
the two additional targets (``secondary targets'') for each daylight
opening. The two targets would be positioned in reference to the
primary targets. To locate the two additional targets, we would measure
the horizontal distance between the centers of the primary targets.
These distances are shown as A and B for the front and rear windows in
Figure 9, respectively. In order to have targets spaced equally in the
fore-aft direction, vertical reference lines would be located at
horizontal distances A/3 and B/3 from the primary target locations. For
the front window area, a secondary target (the third target) would be
centered at a rearward horizontal distance A/3 from the lower-front
primary target and moved vertically upward until contact is made with
the offset line. Another secondary target (the fourth target) would be
centered at a forward horizontal distance A/3 from the upper-rear
primary target and moved vertically downward until contact is made with
the offset line.
[GRAPHIC] [TIFF OMITTED] TP02DE09.008

    For all other side windows, except the front, a secondary target
(the third target for these rear side windows) would be centered at a
rearward horizontal distance B/3 from the upper-front primary target
and moved vertically downward until contact is made with the offset
line. Another secondary target (the fourth for these side windows)
would be centered at a forward horizontal distance B/3 from the lower-
rear primary target and moved vertically upward until contact is made
with the offset line (see Figure 9).
    An example of the target identification procedure applied to a
daylight opening that is symmetric about the horizontal axis is
provided below in Figure 10. The opening has six corners \77\ and is a
rear window. Under

the targeting procedure, the targets located in the lower-front and
upper-rear quadrants are eliminated. Because of the symmetry, two of
the targets centers are located along the quadrant boundaries. Targets
located on a quadrant boundary as shown would be considered by the test
procedure to be in the upper-front and lower-rear quadrants, so these
targets would not be eliminated on the basis that they are not in the
upper-front and lower-rear quadrants. However, the targets would be
eliminated on the basis that they are not the uppermost and lowermost
targets in the upper-front and lower-rear quadrants, respectively. Two
primary targets remain as shown in Figure 10b after eliminating the
targets as specified; the primary targets are the upper target in the
upper-front quadrant and the lower target in the lower-rear quadrant.
Finally, the secondary targets are located as shown in Figure 10c.
---------------------------------------------------------------------------

    \77\ Note that although it may appear that there is only a
single point of contact for the middle targets in Figure 9a, due to
the relative curvature of the window and targets, there are two
points of contact.
[GRAPHIC] [TIFF OMITTED] TP02DE09.009

    Because of potential daylight opening shapes and sizes, the
possibility exists that, once targets are placed in the corners, no
target centers are located in one or both of the primary target
quadrants. If this occurs, the target whose center is closest to the
primary target quadrants is used. Figure 11 shows an example of this.
This is a representation of a rear window, so the primary quadrants are
at the upper-front and lower-rear. Note that there are three potential
primary targets located at the corners of the window opening. However,
only the lower primary quadrant has a target center located within its
boundary. The upper primary quadrant has no target center within its
boundary. In this example, the most forward target becomes the second
primary target because its center is closest to the boundary of the
upper primary quadrant. The procedure for locating the secondary
targets remains the same.
[GRAPHIC] [TIFF OMITTED] TP02DE09.010

    NHTSA requests comments on the proposed method for determining the
impactor target locations. Are there better alternatives than using the
geometric center of the daylight opening to determine the window
quadrants, such as dividing the overall length and height of the
daylight opening in half?

Would such a method be simpler and result in the same final target
locations?
    NHTSA also requests comment on the orientation of the target
outline. Occupant orientation when in contact with the ejection
mitigation system may vary; particularly for unbelted occupants. The
targeting procedure described above maintains the long axis of the
target outline aligned with the vehicle's vertical axis. Should the
targeting procedure instead be performed with the target outline's long
axis aligned with the vehicle's horizontal axis or some other
orientation? We have not studied the sensitivity of the impactor
displacement with the target outline orientation. Please provide data
on the effect of alternative impactor orientations.

Part 2: Allowing Fewer Than Four Targets for Small Windows

    The second part of the test procedure addresses what happens if,
after conducting the first part of the test approach, the four targets
substantially overlap each other, as would be the case involving
smaller than typical side rear windows, such as ``sail panels'' that
are installed in the rear of larger rear windows of some vehicles.
However, for some two-door passenger cars, these sail panels can be
large enough to be impacted. Since the impactor contact surface
represents the averaged dimensions of the side and face of a 50th
percentile head, a sail panel large enough to fit the impactor outline
within the offset line could be the location of a partial head
ejection.
    This part of the test procedure calls for eliminating some of the
four targets to avoid redundancy in testing, and describes which
targets would be eliminated or considered for elimination, and the
order in which they would be considered. This part involves measuring
the horizontal (x-axis) and vertical (z-axis) distances between target
centers. If the horizontal distance is less than 135 mm and the
vertical distance is less than 170 mm, the agency would eliminate a
target. Table 20 identifies which targets are compared, in priority
order. In each case, both the target centers must be closer than 135 mm
and 170 mm in the x and z directions, respectively, for a target to be
eliminated.

    Table 20--Priority List of Target Distances To Be Checked Against
                     Horizontal and Vertical Limits
------------------------------------------------------------------------
                                                   Eliminate this target
                                                     if horizontal and
                 Measure distance of these target   vertical  distances
      Step                    centers               are less than 135 mm
                                                        and 170 mm,
                                                       respectively *
------------------------------------------------------------------------
1..............  Upper Secondary to Lower          Upper Secondary.
                  Secondary.
2..............  Upper Primary to Upper or         Upper or Remaining
                  Remaining Secondary.              Secondary.
3..............  Lower Primary to Lower or         Lower or Remaining
                  Remaining Secondary.              Secondary.
4..............  Upper Primary to Lower Primary..  Upper Primary.
------------------------------------------------------------------------
* The target centers must be closer than 135 mm and 170 mm in the x and
  z directions, respectively.

    In step 1 of this procedure, we would determine the horizontal and
vertical distance between the centers of the secondary targets. If the
horizontal distance is less than 135 mm and the vertical distance is
less than 170 mm, we would eliminate the upper secondary target. If
only one distance is less than the specified value, we would not
eliminate the target. In either case, we would proceed to step 2.
    In step 2, we would measure the distance between the upper primary
target and the upper secondary target (if it survived step 1) or the
remaining secondary target. If the horizontal and vertical distances
are less than the specified values, the secondary target is eliminated.
If only one distance is less than the specified value, we would not
eliminate the target. In either case, we would proceed to step 3.
    In step 3, the process is repeated, except we would measure the
distance between the lower primary target and the lower secondary or to
the remaining secondary target. If the horizontal and vertical
distances are less than the specified values, the secondary target is
eliminated. If only one distance is less than the specified value, we
would not eliminate the target.
    In step 4, we would measure the distance between the upper primary
target and the lower primary target. If the horizontal and vertical
distances were less than the specified values, the upper primary target
would be eliminated. If only one distance is less than the specified
value, we would not eliminate the upper primary target.
    The Technical Analysis accompanying this NPRM provides examples of
the target comparison and elimination progression for illustration
purposes.
    The selection of the 135 mm and 170 mm dimensions is based on the
agency's engineering judgment as to what would be excessive overlap
between the targets, based on a small sample of window openings. The
agency determined that this spacing between targets would ensure a wide
and even distribution of targets across the ejection mitigation
countermeasure, which effectuates a thorough evaluation of the
countermeasure. Each value is approximately 75% of the maximum
dimension of the impactor in that direction (170/226 = 75% and 135/177
= 76%).
    The target elimination process proposed provides an objective and
repeatable means of limiting the overlap between targets while
maintaining coverage of the entire window opening. Thus, it is
consistent with all of the agency's stated goals for a targeting
procedure. The targets that are retained over those slated for
elimination in Table 20 (above), and deemed ``priority'' targets, are
important for the following reasons. NHTSA has given priority to the
primary targets over the secondary targets since the primary targets
assess the curtain at its extremes: at the foremost bottom portion of
the curtain and at the top aft of the curtain, for the case of a front
window, and the opposite corners in the case of a rear window. Further,
of the two primary targets, the lower primary target has priority over
the upper primary. This is because most ejection mitigation curtains
now deploy from the roof rail downward, and gaps through which
ejections may occur can form between the curtain and the window opening
more readily than at locations close to the air bag curtain housing
unit at the roof rail. Thus, if only the two primary targets remain
after the elimination process, the lower primary target is likely to be
the most demanding target in assessing the ability of the curtain to
retain occupant excursions. For these reasons, NHTSA tentatively
concludes that after the target elimination process is conducted, the
lower primary target should prevail.
    Finally, under the proposed test method, the long axis of the
target outline is aligned with the z-axis. Because of the 25 mm offset,
for window openings with a vertical

dimension of less than 276 mm (10.9 inches) no targets will fit in the
window opening. The agency is considering rotating the impactor outline
90 degrees and performing the same targeting methodology, in order to
fit a target(s) within the window opening.
    Comments are requested on the following issues:
     Please comment on the concept of impacting a window in at
least one location if it is large enough to fit a target outline within
the offset line. Is there a better method of determining if a window
opening is sufficiently large to be the site of a partial ejection, and
therefore, a reasonable location for impact?
     Comments are requested on the proposed method for reducing
the number of target locations for small windows. Specifically, are the
135 mm horizontal and 170 mm vertical limits reasonable?
     Please comment on a strategy of rotating the impactor
headform by 90 degrees in the event no targets fit in the window
opening when the impactor is oriented with a vertical long axis. If
this horizontal impactor orientation results in no target outlines
fitting within the window, should the impactor be allowed to be
oriented at any angle necessary to fit inside the opening?

Part 3: Reconstituting Targets To Get to Three

    If, after running the course of Parts 1 and 2 described above, the
window area drops from having four crowded targets to having only two
with a relatively substantial separation between them (more than 360
mm), we believe that a target should be reconstituted (added back)
between the two. This added target would be centered such that it
bisects a line connecting the centers of the two remaining targets. See
drawing on the right in Figure 12 for an illustrated example. In the
drawing, the total distance between the remaining targets was 429 mm;
the original two secondary targets have been replaced by single target
midway between the two primary targets.
    The limit for adding back a target is 360 mm of separation between
the remaining targets (see Figure 13). The 360 mm limit is based on
engineering judgment as to what would be too much gap between targets
and allow an ejection portal if the curtain was not sufficiently
inflated or taut. Please comment on the proposed method for adding
target locations if only two targets remain after the target reduction
scheme is followed. Is the 360 mm distance between the remaining
targets reasonable?
BILLING CODE 4910-59-P

[GRAPHIC] [TIFF OMITTED] TP02DE09.011

BILLING CODE 4910-59-C

Summary of Procedure Identifying Target Locations

    In summary, there are three main parts to the test procedure that
identifies the test target locations for each daylight opening. The
three parts are summarized below.

Part 1

     Find the corners of the window opening, then locate the
geometric center of the daylight opening. Separate the opening into
four quadrants, i.e., lower-front, lower-rear, upper-front and upper-
rear. Eliminate the target in certain quadrants, leaving two ``primary
targets.''
     Measure the horizontal distance between the centers of the
primary targets. Divide that distance into thirds. Identify the two
``secondary targets.''--For front windows, at the first \1/3\, place a
target and move it vertically upward until contact is made with the
offset line. At the second \1/3\, place a target and move it downward
until contact is made with the offset line.--For rear windows, do the
same, except that the first \1/3\ target is moved downward, and the
second \1/3\ target is moved upward.

Part 2

     Evaluate whether some of the four targets should be
eliminated because they excessively overlap. Determine whether target
centers are closer than 135 mm and 170 mm in the horizontal and
vertical directions, respectively.

Part 3

     If, after following the procedure given in part 2, there
are only two targets remaining, determine the absolute distance between
the centers of these targets. If this distance is at least 360 mm,
locate a target so that the center of its outline bisects a line
connecting the remaining targets.

e. How Should the Window Glazing Be Positioned or Prepared in the Test
To Represent Real-World Circumstances?

    We are proposing to allow windows to be in position (up and
closed), but pre-broken. We are proposing to allow windows to be in
position so as to not discourage the use of advanced glazing (laminated
glazing) in vehicles, since our testing has shown that advanced

glazing may enhance the performance of current air bag curtain designs.
Typically, advanced glazing has a multi-layer construction with three
primary layers: a plastic laminate bonded between two pieces of glass.
In the proposed test procedure, prior to running the headform impact
test, we would undertake a procedure on all glazing that entails pre-
breaking the glazing in a consistent fashion to simulate the breakage
of glazing during a rollover. With advanced glazing, the procedure
would likely result in the outside glass breaking without deforming the
laminate. With tempered (non-advanced) glazing, the procedure would
likely shatter the glazing into fragments, so manufacturers would be
given the option of: (a) Running the procedure and shattering the
glazing; or (b) having the glazing removed from the daylight opening,
or if the glazing completely retracts into the vehicle structure,
completely retracting the glazing, and simply bypassing the glazing-
breakage procedure.
1. Window Position and Condition
    The agency is proposing to have the windows in position (up and
closed) in the impact test because, for the target population of this
rulemaking, the front row window through which an occupant was ejected
was closed or fixed prior to the crash 69 percent of the time. Nearly
all of the closed or fixed front row ejection route windows (99
percent) were disintegrated after the crash. Table 21 shows these data
for three seating rows. For many vehicles, the rear seat window is
fixed. Our accident data show that the second and third row ejection
route windows were closed or fixed about 94 and 100 percent of the
time, respectively.\78\ Combining all of the data, the ejection route
windows were closed or fixed 72 percent of the time before the crash.
---------------------------------------------------------------------------

    \78\ The third row data is very limited. It is comprised of only
103 weighted ejections.

     Table 21--Pre- and Post-Impact Window Condition for Window Through Which the Occupants in the Ejection
                                    Mitigation Target Population Were Ejected
----------------------------------------------------------------------------------------------------------------
                                                            Window condition
                       -----------------------------------------------------------------------------------------
                                                                        Post-crash
    Window location                      -----------------------------------------------------------------------
                            Pre-crash       Disintegrated       In Place         No Glazing
                                              (percent)         (percent)         (percent)     Total  (percent)
----------------------------------------------------------------------------------------------------------------
Row 1.................  Closed or Fixed.                68                 1                 0                69
                        Open (Part. or                  11                17                 0                28
                         Fully).
                        No Glazing......                 0                 0                 3                 3
                                         -----------------------------------------------------------------------
                           Subtotal.....                79                18                 3               100
----------------------------------------------------------------------------------------------------------------
Row 2.................  Closed or Fixed.                71              * 23                 0                94
                        Open (Part. or                   0                 6                 0                 6
                         Fully).
                        No Glazing......                 0                 0                 0                 0
                                         -----------------------------------------------------------------------
                           Subtotal.....                71                29                 0               100
----------------------------------------------------------------------------------------------------------------
Row 3.................  Closed or Fixed.               100                 0                 0               100
                        Open (Part. or                   0                 0                 0                 0
                         Fully).
                        No Glazing......                 0                 0                 0                 0
                                         -----------------------------------------------------------------------
                           Subtotal.....               100                 0                 0               100
----------------------------------------------------------------------------------------------------------------
All...................  Closed of Fixed.                68                 4                 0                72
                        Open (Part. &                   10                16                 0                26
                         Fully.
                        No Glazing......                 0                 0                 2                 2
                                         -----------------------------------------------------------------------
                           Total........                78                20                 2               100
----------------------------------------------------------------------------------------------------------------
* This result seems to suggest that 23 percent of the target population ejected from the second row went through
  a closed window that remained in place after the crash. This is a physical impossibility and represents
  ambiguity in NASS. These data are derived from an unweighted count of 18 NASS occupants of the approximately
  1,200 occupants that make up the unweighted target population. The miscoding is likely a result of the fact
  that the NASS investigator has multiple side window ejection routes to properly code.

    Table 22 shows the result of expanding the data set to include all
vehicles exposed to a rollover crash, as opposed to just windows
through which occupants were ejected. The restriction on the data is
that an occupant needed to be seated next to the window opening. The
data is separated into front row and rear rows, inclusive of the third
row. It is comprised of 2.9 million weighted data points. We note that
only windows disintegrated from vehicle structural deformation have
been tabulated.\79\ This expanded data set shows a higher percentage
(86 percent) of front windows are closed or fixed prior to a rollover
than was the case for windows which were ejection routes. It also shows
that about half (47 percent (40 percent/86 percent)) of these closed or
fixed front row windows were disintegrated after the crash. For the
rear rows, the proportion of disintegrated windows, which were closed
prior to the rollover, drops to 22 percent (22 percent/98 percent).
---------------------------------------------------------------------------

    \79\ Windows disintegrated due to occupant contact would add
only about 0.5 percent to this data set.

 Table 22--Pre- and Post-Impact Window Condition for Vehicles Exposed to a Rollover With an Occupant Adjacent to
                                        the Window--1997 to 2004 NASS CDS
----------------------------------------------------------------------------------------------------------------
                                                                   Window condition
                                    ----------------------------------------------------------------------------
                                                                                Post-crash
          Window location                                  -----------------------------------------------------
                                           Pre-crash          Disintegrated       In place
                                                                (percent)         (percent)     Total  (percent)
----------------------------------------------------------------------------------------------------------------
Front..............................  Closed or Fixed......                40                46                86
                                     Open (Part. or Fully)                 3                11                14
                                                           -----------------------------------------------------
                                        Subtotal..........                43                57               100
----------------------------------------------------------------------------------------------------------------
Rear...............................  Closed or Fixed......                22                76                98
                                     Open (Part. or Fully)                 0                 2                 2
                                                           -----------------------------------------------------
                                        Subtotal..........                23                77               100
----------------------------------------------------------------------------------------------------------------
All................................  Closed or Fixed......                39                49                87
                                     Open (Part. & Fully..                 3                10                13
                                                           -----------------------------------------------------
                                        Total.............                41                59               100
----------------------------------------------------------------------------------------------------------------

Request for Comments on Glazing Position and Condition

    Although we believe that available data support a proposal allowing
windows to be in place and pre-broken prior to testing, we recognize
there are potential drawbacks to the proposal. On the issue of window
position, the most obvious of these drawbacks is for those instances
where manufacturers utilize advanced glazing in their design, when the
window is partially or fully down the vehicle may have degraded
occupant retention. This concern arises most frequently for first row
windows, which are nearly always retractable. The implication of the
data in Table 21 is that about 3 out of 10 occupants are ejected with
the front window when it is partially or fully open prior to the crash.
This becomes much less likely for the second and third rows.
    The agency is contemplating alternatives to the approach of
allowing windows to be in place and pre-broken. One option would be to
test with all movable windows removed or rolled down, regardless of
whether the window is laminated. Fixed laminated windows would continue
to be kept in place, but pre-broken. This would assure that the
ejection mitigation performance of vehicles with laminated windows is
equal to those without laminated windows, when the windows happen to be
rolled down. However, this would not provide an incentive to vehicle
manufacturers to install advanced glazing in movable windows.
    Another option would be to test the vehicle both with movable
laminated windows down and with them up and pre-broken. The arithmetic
or weighted average of the measurements could then be used to determine
compliance with the displacement limit. (One possible weighting would
represent the probability of windows up versus windows down.) We are
also considering placing some higher displacement limit on the window
down test for these systems that use both advanced glazing and an
ejection mitigation air bag curtain to provide protection. E.g., if we
were testing with the window down, we are considering permitting a
displacement of more than 100 mm.
    We request comments and ask for information relating to the
following questions:
     The agency has proposed allowing windows with advanced
laminated glazing to remain up, but pre-broken during impact testing.
We are also considering testing with all movable windows down or
removed, regardless of whether they are laminated. Finally, we
discussed requiring testing with laminated windows both up and down.
Please comment on the relative merits of these different options.
Please comment specifically on the effect these options will have on
overall benefits of the standard.
     The extent to which manufacturers will avail themselves of
advanced glazing to supplement air bag curtains is unknown. We are
aware that some manufacturers currently provide laminated glazing as a
theft prevention and noise reduction measure in more expensive
vehicles. We believe that incorporation of advanced glazing for
ejection mitigation will be relatively expensive compared to the
implementation of side curtain air bags. Our preliminary analysis shows
that the proposed requirements would add about $33 per light vehicle at
a total cost of $568 million for the full curtain countermeasure. To
what degree will manufacturers avail themselves of an advanced glazing
option? What would be the costs associated with advanced glazing alone
or in combination with side air bag curtains as opposed to the use of
side air bag curtains alone?
     Our data analysis shows that for the target population of
this proposal, about 30 percent of front windows will be rolled down
prior to the crash. We are aware that vehicle manufacturers are
researching and beginning to implement technology that senses an
impending crash and roll the windows up. Should a windows-up ejection
mitigation test option be restricted to only these vehicles?
     Advanced laminated glazing has considerably greater mass,
particularly as compared to an air bag curtain. The inertial effects
due to the mass of the advanced glazing and its retention by the
vehicle structure are not accounted for in the proposed test procedure.
To what extent might the advanced glazing mass degrade its real-world
performance? Should NHTSA account for this in some way in our testing?
If so, how?
2. Window Pre-Breaking Specification and Method
    We are proposing a breaking specification and method that calls for
punching holes in the glazing in a 50 mm horizontal and vertical matrix
(``50 mm matrix''). A spring-loaded automatic center punch would be
used to make the holes. The punch has approximately a 5 mm diameter
before coming to a point. The first step in the process is to mark the
surface of the

window glazing in a horizontal and vertical grid of points separated by
50 mm, with one point coincident with the geometric center of the
daylight opening (see Figure 14). The initial target point of the punch
would be the lowest and most forward mark made on the glazing. Holes
would be punched in the glazing starting with the inside surface of the
glazing, and starting with this initial lowest and most forward hole in
the pattern. We would continue punching holes 50 mm apart, moving
rearward on the vehicle. When the end of a row is reached, we would
move to the most forward hole in the next higher row, 50 mm from the
punched row. After completing the holes on the inside surface, we would
repeat the process on the outside surface at the same impact points as
the inside surface. These patterns are shown in Figure 14 below.
    When punching a hole, we would place a 100 mm by 100 mm piece of
plywood on the opposite side of the glazing as a reaction surface
against the punch. The spring on the punch would be adjusted such that
150 N  25 N of force \80\ would be required for activation.
The force has been designed so as to not penetrate the inner laminated
material. However, if a particular window were constructed such that
the inner laminated material is penetrated or damaged, the procedure
would not be halted or invalidated; the headform impact test would be
conducted at the conclusion of the glazing breakage procedure. If
punching a hole causes the glazing to disintegrate, as would likely
occur when testing tempered glazing, the procedure would be halted and
the headform impact test would be immediately conducted. (In the latter
situation, the vehicle manufacturer would have opted not to have
removed or completely retracted the tempered glazing and thereby bypass
the window breaking process.)
---------------------------------------------------------------------------

    \80\ This force level worked well for the samples of advanced
glazing tested by the agency.
[GRAPHIC] [TIFF OMITTED] TP02DE09.012

    In developing the proposed glazing breaking specification and
method, we considered and rejected a recommendation from an industry
group called the Enhanced Protective Glass Automotive Association
(EPGAA), which provided a test report entitled ``Laminated Glass Pre-
breakage Repeatability Testing,'' (see docket for this rulemaking). The
EPGAA evaluated whether different degrees of breakage affected
laminated glazing strength. Four different degrees of breakage were
tested and compared to glazing that had no breaks. The four were: 1
punched hole, 4 punched holes, 8 punched holes and completely pummeled
with a ball-peen hammer. The 4-hole punch pattern was made by first
locating the ejection headform contact point with the glazing at each
impact location for that window opening (see Figure 15). Each side of
the glass was punched with a spring activated center punch tool at each
contact location. The EPGAA recommended that NHTSA use the 4-hole punch
pattern, but NHTSA has tentatively decided to propose the 50 mm matrix
pattern rather than the 4-hole pattern, as explained below.

[GRAPHIC] [TIFF OMITTED] TP02DE09.013

    EPGAA's tests evaluated the strength of the glazing by using a ball
impact test prescribed in FMVSS No. 205 and the American National
Standards Institute (ANSI) in ``American National Standard, Safety Code
for Safety Glazing Materials for Glazing Motor Vehicles Operating on
Land Highways, ANSI Z26.1.'' In the ball impact test, a 2.2 kg steel
ball was dropped from 7.9 meters onto the glass, which was supported
from underneath. At this height, the ball struck the glass at 45 km/h.
A speed trap was used to measure the velocity of the ball after it
passed through the glass. The reduction in speed was used to calculate
the energy absorbed by the glass. This energy was converted to a mean
breaking height through a potential energy conversion. EPGAA found that
there was no statistical difference in the mean breaking height for the
glazing broken under the various methods. Thus, the EPGAA concluded
that the 4-hole pattern would be acceptable.
    NHTSA reviewed EPGAA's data but determined that the EPGAA test
results might not correlate with the ejection mitigation impactor test.
The proposed impactor test is much slower than the ANSI/SAE Z26.1 ball
impact test and the proposed impactor is much larger and massive. In
addition, for most vehicles, the impactor load would be distributed by
the air bag curtain. Finally, the glass is mounted differently in a
vehicle than on the test jig used in the EPGAA study. Given all these
differences, NHTSA performed follow-on testing to the EPGAA study,
using the proposed 18 kg impactor with the laminated glazing pre-broken
using the 4-hole pattern, as well as fully pummeled with a hammer. We
also used the 50 mm matrix pattern to attempt to recreate the more
fully broken pattern achieved by the fully-pummeled method in a more
managed and objective manner.
    In NHTSA's follow-on testing, we found that the breaking method for
the glazing resulted in very different breakage patterns (see Technical
Analysis) and in different displacement results. Table 23 shows the
limited test results to date. For all tests except the Durango at 16
km/h at position A3, the fully-pummeled glazing exhibited more impactor
displacement than either hole pattern. There was a statistically
significant difference (p = 0.024) between the 4-hole pattern and the
pummeled glazing. We have only one test using the 50 mm matrix pattern
on a MY07 Jeep Commander. For this vehicle, there is a 7 mm reduction
in displacement for the 50 mm matrix pattern and a 10 mm reduction for
the 4-hole pattern over the pummeled glazing.
    From the above data, we have tentatively concluded that the method
of pre-breaking the laminated window has a discernable effect on the
test results. Generally, the methods that result in more breakage also
result in less displacement reduction of the impactor, i.e., more
overall displacement in the proposed compliance test. Our decision for
this NPRM is to propose a method that results in more breakage than
less, to replicate more demanding scenarios involving breakage of the
advanced glazing. However, the most demanding method (pummeling the
glazing) was also the method that was the least controllable and the
most potentially difficult to repeat from laboratory to laboratory.
Accordingly, we have tentatively decided to adopt the 50 mm matrix hole
punching method, since it appears to be more controllable and
repeatable than pummeling the window with a hammer, and yet yields a
very extensive breakage pattern. Comments are requested on the method
of pre-breaking the glazing.
    The agency is continuing its research into window pre-breaking
methods. Specifically, we are looking into 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 are that this variation
exhibits the potentially positive attribute of lessening the chances of
penetrating the inner membrane between the glass layers. Comments are
requested on this issue.

                               Table 23--Impactor Displacement Data for Laminated Glazing Pre-Broken by Different Methods
--------------------------------------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------------------------------------
                              Test conditions                         Displacement (mm) vs. glass condition
--------------------------------------------------------------------------------------------------------------------------------------------------------
                     Vehicle                         Speed        Target             4-holes
                                                       (km/h)
                                                          Pummeled
                                                        50 mm matrix
--------------------------------------------------------------------------------------------------------------------------------------------------------
05 Trailblazer..................................           20           A2           62  ...........           80  ...........  ...........  ...........
05 Trailblazer..................................           20           A3           96           98          107          110  ...........  ...........
06 Durango......................................           20           A2           71  ...........          101  ...........  ...........  ...........
06 Durango......................................           16           A3          145  ...........          142  ...........  ...........  ...........
07 Commander....................................           16           A2           48  ...........           58  ...........           51  ...........
--------------------------------------------------------------------------------------------------------------------------------------------------------

Request for Comments

    Although testing by EPGAA showed no difference in the mean breaking
strength for laminated windows regardless of the method used to pre-
break them, ejection mitigation testing did show a significant
difference between a 4-hole pattern and pummeling with a ball-peen
hammer. The 50 mm matrix breaking method resulted in a very extensive
fracture pattern of the window. The 4-hole pattern did not.
Accordingly, we are proposing a 50 mm spacing breakage pattern through
the use of a spring-loaded center punch with a 5  2 mm
diameter prior to the tip, adjusted to an activation load of 150  25 N load.
    We request comments on the following issues.
     The agency has proposed allowing windows with advanced
laminated glazing to remain up, but pre-broken during impact testing.
(As noted earlier, we are also considering different alternatives,
including not having the windows up at all.) We have proposed a hole
punch pattern with a 50 mm matrix spacing to break the window. Please
comment on the appropriateness of the window breaking procedure.
Specifically, is the window condition representative of what would be
seen in the field as being caused by a crash prior to occupant
ejection? Is it necessary to fracture the glazing more extensively than
the proposed method? If so, what is the alternative method and its
basis?
     Is the spring loaded automatic center punch sufficiently
described by specifying an activation force of 150  25 N?
Is it necessary to specify the impact force generated when the spring
tension is released? If so, what procedure should be used to determine
the impact force? Is it sufficient to specify that the punch diameter
be 5  2 mm prior to the tip? Does there need to be a
specification regarding the sharpness of the tip? If so, what should
the specification account for?

f. Test Procedure Tolerances

    The proposed regulatory text for this ejection mitigation standard
has tolerances on various test parameters of the proposed test
procedure. For example, the proposed text specifies 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
have 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 is based on a similar
linear impactor tolerance in S5.2.5(c) of FMVSS No. 202a. Tolerance
selection has been based on test experience and engineering judgment.
Comments are requested on whether the tolerances assure an objective,
repeatable and practical test procedure.

g. Impactor Test Device Characteristics

    There are many possible ways of delivering the impactor to the
target location on the ejection mitigation countermeasure. As
previously discussed, the impactor used in agency research propels the
shaft component of the impactor with a pneumatic piston. The shaft
slides along a plastic (polyethylene) bearing (sleeve). This section
explores the need to specify characteristics of the impactor to
maximize the objectivity of the standard.
    We have tentatively determined that certain characteristics of the
impactor should be specified 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. A
specification we are considering in proposed S7.2 would limit the
amount of energy the impactor may lose due to friction. All guided
impactor designs will have some degree of velocity loss due to friction
on the impactor shaft. To enhance the objectivity of the test
procedure, we propose to specify 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 travel. The agency performed
five speed trials with the ejection mitigation test device used for the
agency's research.\81\ We found that the average and standard deviation
for the percentage velocity reduction was 8.2  1.9 percent
and 16.2  4.4 percent, for the 24 and 16 km/h impact
speeds, respectively; our research test device lost a higher percentage
of energy at the lower impact speed. Comments are requested on the need
for and merits of these proposed values. Should there be an upper and
lower limit on each value?
---------------------------------------------------------------------------

    \81\ This research test device has not been optimized for
compliance test purposes. Thus, we believe that tighter tolerance
can be attained with an optimized design.
---------------------------------------------------------------------------

    Another specification under consideration relates to assuring that
the projection of the impactor would not be unduly set off target when
it impacts a countermeasure. The ejection mitigation countermeasure
could impart off-axis loading on the impactor, i.e., the loading may
not just be in the direction of the impactor shaft. This off-axis
loading may affect the impactor in several ways. If the impactor shaft
and support mechanism is overly flexible, off-axis loading may allow
the impactor headform to deviate unduly from its intended target. We
have seen this in our testing when the headform strikes near the bottom
of the curtain. The curtain makes contact predominately on the upper
portion of the headform, which can cause a downward loading on the
impactor and a change in its intended path. This off-axis loading on
the headform may also allow the shaft bearing to be exposed to
additional loading and potentially increase the friction on the shaft.
    We are thus proposing specifications in S7.1.2 that would reduce
the effects of off-axis loading on the impactor device. First, we are
proposing to limit bending of the device in a static test. In the test,
the impactor would be extended 300 mm past the position where the test
impact velocity (24 or 16 km/h) is achieved. At that position, a 27 kg
mass would be attached to the back of the headform. We would require
that the headform's maximum vertical deflection, with the mass, must
not exceed 20 mm. Second, we are proposing that, with this 27 kg mass
attached, the average and standard deviation required to push the
impactor over a 200 mm distance at a velocity of 50 (13) mm
per second must not exceed 570 N and 30 N, respectively.
    Finally, in proposed S7.3 we set forth an additional way to assure
the impact test device delivers the headform to the required target
location on the side window opening. Briefly stated, this assessment
would determine the accuracy of the headform in hitting a determined
zone, similar to a pitcher in the game of baseball finding the strike
zone. The assessment would be conducted by establishing a zone within
which we would require the impactor to deliver the headform at test
speed. The following describes one objective method of determining the
``strike zone,'' to use the baseball analogy. Comments are requested on
whether other methods of determining the zone would be preferable and
what those methods should be.
    As shown in Figure 16, a zone could be established by first
determining the ``ejection impactor targeting point,'' the intersection
of the x- and y-axes on the outer surface of the headform. Next, the
location of first contact between the impactor and the ejection
mitigation countermeasure (e.g., ejection mitigation

air bag curtain) would be determined, based on the location of the
target outlines using the methodology in the compliance test specified
for identifying the target outlines. A 100 mm wide zone would be
determined by defining two vertical longitudinal planes that are 50 mm
on either side of the expected location of contact by the impactor with
the countermeasure. These longitudinal planes define a portion of the
strike zone. The other portion of the zone would be defined by locating
the axis normal to and passing through the target outline center. As
the impactor targeting point passes at test speed through the 100 mm
wide zone (as it passes ``over the plate,'' using the baseball
analogy), it must stay within  10 mm of the axis passing
through the center of the target outline center (continuing the
analogy, it must stay within the vertical zone bounded by the batter's
knees and chest). This assessment would not be conducted with an
ejection mitigation air bag curtain deployed, as the deployed curtain
could obstruct accurate measurement of the impactor location and the
effect of air bag interaction is assessed by the specification
previously discussed.
    Comments are requested on these proposals. We are considering
making this assessment of the impactor to assure that the impactor used
in the compliance test has the specified characteristics adopted by the
standard. If the impactor was able to meet the specifications during
the assessment, it would be assumed that the impactor has the
characteristics enabling it to meet the specifications and that it had
those characteristics during the compliance test of the countermeasure.
Are there any other or different characteristics of the ejection
impactor that should be specifically defined?
BILLING CODE 4910-59-P
[GRAPHIC] [TIFF OMITTED] TP02DE09.014

BILLING CODE 4910-59-C

h. Readiness Indicator

    NHTSA is proposing a requirement for a readiness 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. The indicator would monitor its own readiness and would
have to have a telltale clearly visible from the driver's designated
seating position. We would permit vehicle manufacturers to use the same
frontal air bag readiness indicator telltale currently used to meet
S4.5.2 of FMVSS No. 208. We also propose that manufacturer would have
to include in the vehicle owner's manual, or other written material
accompanying the vehicle, a list of the elements of the system being
monitored by the indicator, a discussion of the purpose and location of
the telltale and instructions to the consumer on the steps to take if
the telltale were illuminated. These proposals are intended to enhance
the longevity and dependability of the ejection mitigation system over
the life of the vehicle.

VI. Other Considered Performance Aspects of an Ejection Mitigation
Standard

 a. Rollover Sensor

1. Introduction
    NHTSA has tentatively decided that the regulatory text for this
NPRM will not specifically require a rollover sensor or specify
attributes that the sensor must meet. As explained earlier in this
preamble, deployable ejection mitigation countermeasures (ejection
mitigation air bag curtains) are now being designed, developed, and
implemented by industry and, SCI data suggest, are deploying
satisfactorily in the field. To optimize the performance of ejection
mitigation countermeasures at these early stages of development, we
have decided to proceed with an ejection mitigation rulemaking absent a
protocol for testing rollover sensors. Underlying our approach is that,
even without an explicit requirement to provide a rollover sensor,
manufacturers will provide sensor(s) with their ejection mitigation
curtains. We have accounted for the cost of rollover sensors in our
cost/benefit analysis for this rulemaking.
    Our assumption that manufacturers will provide rollover sensors is
based on several factors. First, as noted above, our SCI data for
lateral rollovers for vehicles currently in the field with side curtain
air bags intended for ejection mitigation show these systems have
deployed in rollover crashes. These data show that the installation of
rollover sensors is practicable and that the sensors are working in the
field. Second, this NPRM would require information in the owner's
manual or other written material accompanying the vehicle to describe
the ejection mitigation countermeasure that deploys in the event of a
rollover if the deployable countermeasure is provided. With customer
expectations at stake, there is virtually no incentive for
manufacturers to provide an ejection mitigation side curtain designed
to meet this NPRM without providing the sensor to deploy it in a
rollover crash. In addition, 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.
Finally, we would deploy the ejection mitigation side curtain in the
compliance test only if the owner's manual or other written material
accompanying the vehicle informs the owner that the vehicle is equipped
with an ejection mitigation countermeasure that deploys in the event of
a rollover. If the information is not present, we would perform the
headform test without deploying the ejection mitigation side curtain.
An example of this situation might be a vehicle that has a side curtain
primarily for side impact protection, but that uses advanced glazing to
meet the ejection mitigation requirements. In this case a rollover
sensor system would not be necessary. Thus, the written information
provided would not indicate that there is a deployable countermeasure
and the agency would not deploy the side curtain when testing this
vehicle.
    The agency acknowledges that the presence of a rollover sensor does
not guarantee optimal performance of the sensor in the field. However,
as noted earlier in this preamble and discussed further below, we are
concerned as to whether specifying performance features for the sensor
could satisfactorily capture the myriad of rollovers occurring in the
real-world.\82\ In addition, vehicle rollover crash attributes and
rollover sensing needs could change as ESC and other changes are
incorporated into vehicles. Rather than specify performance
requirements for the sensor that might address certain types of
rollover crashes and exclude others that should be addressed, this NPRM
provides manufacturers maximum design flexibility in developing sensors
that can achieve optimum performance in rollover crashes likely to be
encountered in the real world.
---------------------------------------------------------------------------

    \82\ Several types of rollover crashes are described by Viano
and Parenteau, ``Rollover Crash Sensing and Safety Overview,'' SAE
2004-01-0342, supra.
---------------------------------------------------------------------------

2. Alternative Approaches
    The agency considered alternative approaches on whether
requirements for a rollover sensor should be specified at this time.
These are discussed below and in the Technical Analysis for this NPRM.
    One option was to propose that the rollover sensors be provided as
a piece of equipment and define such a piece of equipment (Equipment
Definition Option). The Equipment Definition Option involves simply
having the FMVSS define the item of equipment (the rollover sensor) and
having the FMVSS require the installation of the item of equipment.
This option would assure a rollover sensor is present in the vehicle.
However, it 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.
    A second considered approach was to specify a test(s) that would
assure the presence of a rollover sensor on the vehicle (Presence Test
Option). A rollover test would be performed and the countermeasure
would or would not deploy. One option was to propose a test, with which
both the agency and industry have experience, which is certain to
deploy the countermeasure if a sensor were present and functioning. One
such test would be the FMVSS No. 208 dolly test. However, the use of
the FMVSS No. 208 dolly test as a rollover sensor test might be a
somewhat incomplete solution due to the variation in real world
rollover crashes. Even

with an indefinite development time period, there would be difficulties
in defining and developing any test(s), and in determining the real-
world relevance of the test procedure(s). The agency does not have
sufficient knowledge of any repeatable rollover test that merits
selection as the test that replicates the breadth of real-world
rollovers addressed by this rulemaking. Developing tests that assure
good sensor performance would require additional research, which would
delay the proposal and adoption of this FMVSS.
    The third approach we considered was a ``phase-plane zone'' option
suggested by the Automotive Occupant Restraints Council (AORC).\83\
This option basically requires the rollover sensor to deploy a
countermeasure if, prior to rolling more than 90 degrees about the
lateral axis, the vehicle roll angle versus rate curve exceeds a
threshold. The agency has no data to independently judge the AORC
deployment threshold against ideal field performance. Therefore, we
cannot assure that it represents the minimally acceptable performance.
This option only considers roll angle and roll rate as sensor inputs,
while AORC members indicated that many systems use other sensor inputs
and that future sensors may be integrated into and/or use information
from ESC systems. As discussed in the Technical Analysis for this NPRM,
we would need some time to develop the potential test parameters and
apparatuses for this approach.
---------------------------------------------------------------------------

    \83\ July 12, 2006 meeting between NHTSA and AORC (NHTSA-2006-
26467-11).
---------------------------------------------------------------------------

    NHTSA requests comments on the following issues:
     The agency has not included any regulatory requirements
for sensor(s) that will deploy ejection mitigation countermeasures
during a rollover. Comments are requested on the alternative approaches
considered by the agency. Are there other alternatives that the agency
has not considered? Are there particular performance attributes of a
sensor system and algorithm that this FMVSS should require of all
vehicles? Are there any particular sensor system performance tests that
should be conducted? How should the sensor system be tested, e.g., a
test of the system or equipment separate from the vehicle, a test of
the complete vehicle in a dynamic test, etc.? Please provide field
studies to support your arguments.
     Please comment on the AORC proposal for minimum sensor
performance and how the agency could test for such performance,
including specifics about test devices. Please discuss the
appropriateness of specifying the test parameters and leaving the
specific apparatus undefined.

b. Quasi-static Loading in a Compliance Test

    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. Once
an occupant contacts the ejection countermeasure, the occupant could
impose a centrifugal force on the countermeasure. That force depends
upon the rotational velocity, the radius from center of rotation to
contact point on the countermeasure, and the portion of occupant mass
loading the countermeasure.
    The value for each of these variables will be rollover and vehicle
specific. Assuming a roll rate of 250 deg./s (4.4 rad./s), a radius of
1.3 m and a mass equal to half the mass of a 50th percentile adult male
(37 kg), the force is equal to 931 N (209 lb).
     The agency has not studied how ejection countermeasures
perform when exposed to quasi-static loading, or whether the impact
test alone would adequately facilitate the manufacture of ejection
countermeasures that perform well when subjected to quasi-static
loading in a rollover. NHTSA requests comments on the need for an
additional test(s) that would impose quasi-static loading on the
ejection countermeasure. What would be an appropriate load value and
loading period? What would be an appropriate quasi-static test
procedure?

VII. To Which Vehicles Would the Proposed Standard Apply?

    We propose that this standard would apply to passenger cars,
multipurpose passenger vehicles, trucks and buses with a gross vehicle
weight rating (GVWR) of 4,536 kg (10,000 lb) or less. Those are the
vehicle classes to which the FMVSS No. 214 pole test applies. Comments
are requested on whether the standard should exclude the vehicle types
listed below, and whether other vehicle types not listed below should
also be excluded.
    Convertibles. NHTSA has tentatively determined that convertibles
should not be excluded from the applicability of the standard because
we believe there is potential benefit and because it is feasible to
build countermeasures into this type of vehicle. First, approximately
17% of the target population fatalities are in side impacts or side
impacts followed by a rollover. Even absent any roof structure, we
believe that side curtain air bags and/or advanced glazing may be
effective in reducing ejections in this side impact population and
perhaps, to a lesser degree, in the side impact followed by a rollover
population. We realize that occupants of convertibles in other rollover
crashes of two or more quarter-turns are extremely vulnerable due to
the lack of roof structure. This is particularly true if the
convertible top is down or hardtop is removed. However, survival space
may exist, particularly for convertibles with roll bars behind the
seats such in the Mini Cooper and Porsche Boxster. The version in the
Mini Cooper is recessed behind the rear seats and deploys in a
rollover. Although we have no firm data on the percentage of
convertibles driven with the top up, if they are and there is a roll
bar type structure, ejection mitigation countermeasures may be
effective.
    On the issue of feasibility, although these vehicles do not have a
permanent roof structure in which to house a roof-mounted ejection
mitigation curtain, Porsche has indicated to NHTSA that it is
developing a door-mounted curtain that would deploy upward toward the
vehicle roof in a rollover.\84\ Comments are requested on the
feasibility of installing door-mounted ejection mitigation curtains in
convertibles on a widespread basis, and if feasible, the costs and
benefits associated with door-mounted ejection mitigation curtains.
Please comment on the practicability of certifying convertibles to the
proposed performance test with door-mounted ejection mitigation
curtains and/or advanced glazing. Could advanced glazing alone be a
sufficient ejection mitigation countermeasure in convertibles? If it is
not practicable to meet the proposed requirements with any
countermeasures, please indicate how the proposed performance
requirement and test procedure could be adjusted to be more appropriate
for convertibles, such as by changes to the displacement limit, impact
velocity, target locations, etc.
---------------------------------------------------------------------------

    \84\ NHTSA-2006-26467-10.
---------------------------------------------------------------------------

    Vehicles that have had the original roof modified. If a vehicle
were altered or modified such that the original roof were replaced,
raised or otherwise modified, the original ejection mitigation window
curtain that was mounted in the header above the door would be affected
by such modification. NHTSA proposes excluding vehicles

with modified roofs from the standard, and adopting FMVSS No. 214's
definition of a ``modified roof.'' That standard defines ``modified
roof'' as ``the replacement roof on a motor vehicle whose original roof
has been removed, in part or in total.'' However, should vehicles with
door-mounted upward-deploying side curtain air bags installed as
original equipments be excluded from the ejection mitigation standard
if the vehicle's roof is later modified? There might not be a need to
exclude such vehicles from the ejection mitigation standard if the
door-mounted ejection mitigation countermeasure would not be
significantly affected by the modification to the vehicle's roof.
    Vehicles with a lowered floor. NHTSA does not think there is a need
to exclude from the standard vehicles that have had their floors
lowered by a final-stage manufacturer or alterer. It does not appear
that the ejection mitigation countermeasure would be significantly
affected by the modification, or that it would be overly difficult for
the manufacturer to certify the compliance of the vehicle. Comments are
requested on this issue.
    Vehicles that have no doors, or exclusively have doors that are
designed to be easily attached or removed so that the vehicle can be
operated without doors. Comments are requested on whether these
vehicles are still being manufactured in the U.S. Assuming the vehicles
are being manufactured, NHTSA proposes excluding the vehicles on
practicability grounds. Comments are requested on this issue.
    Walk-in vans. We propose excluding these vehicles on practicability
grounds.
    Police vehicles with security partitions. Considering that law
enforcement vehicles are more likely to be involved in risky driving
operations than other passenger vehicles, NHTSA would prefer that the
vehicles provide ejection mitigation countermeasures. However, security
partitions (e.g., prisoner partitions) are necessary for the safety and
security of the law enforcement officers, and they must be flush
against the sides of the vehicle to prevent a prisoner's hand or
article from intruding into the officer's compartment. We would like
information as to whether police vehicles with security partitions
should be excluded from the standard. Comments are requested on whether
innovative partition designs exist that would permit the side curtain
air bag to be deployed effectively without interference from a security
partition. Alternatively, is it feasible to incorporate separate
curtains for the front and rear passenger compartments? Is it feasible
to incorporate a window curtain for the front compartment and advanced
glazing for the rear compartment? Is it feasible to incorporate air bag
curtains that deploy upwards (e.g., as in the Volvo C70?) In addition,
would advanced glazing alone be sufficient in these vehicles to meet
the standard? The agency has tentatively decided not to exclude
vehicles with partitions generally, because it appears that a partition
other than a security (prisoner) partition could be made compatible
with a window air bag curtain by allowing a space between the daylight
opening and the partition edge. Comments are requested on these
tentative determinations.

VIII. The Proposed Lead Time and Phase-In Schedules

    Motor vehicle manufacturers will need lead time to develop and
install ejection mitigation countermeasures and rollover sensor
algorithms. Although inflatable side curtain air bags are being
developed in new vehicles to meet the September 11, 2007 final rule (as
amended June 9, 2008) incorporating a dynamic pole test in FMVSS No.
214, to meet the requirements proposed today these side curtains will
have to be made larger to cover more of the window opening, will have
to be made more robust to remain inflated longer, and will have to be
considerably enhanced (by tethering and other means) to retain vehicle
occupants within the vehicle. Moreover, rollover sensor algorithms will
be needed to deploy the ejection mitigation countermeasures in rollover
crashes, to augment the sensors needed to deploy the side curtains in
side impacts.\85\ Our tests of vehicles to the proposed ejection
mitigation requirements found that vehicle manufacturers are at
different stages with respect to designing inflatable ejection
mitigation side curtains that meet the proposed requirements. Vehicle
manufacturers also face unique manufacturing constraints and
challenges, e.g., each face differences in the technological advances
incorporated in their current air bag systems, differences in
engineering resources, and differences in the numbers and type of
vehicles for which ejection mitigation systems will need to be
incorporated. NHTSA believes that these differing situations can best
be accommodated by phasing in the ejection mitigation requirements
proposed today over a period of four years, and by allowing the use of
advance credits.
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    \85\ The FMVSS No. 214 final rule/response to petitions for
reconsideration acknowledged that current side air bag sensors will
have to be developed further to sense when it would be appropriate
to deploy in a crash situation involving impacts up to 32 km/h (20
mph). NHTSA provided manufacturers until September 1, 2014 to
develop these sensors. 73 FR 32473, June 9, 2008, Docket No. NHTSA-
2008-0104.
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    We also believe that the phase-in of the ejection mitigation
requirements should start after the date most vehicles will be
certified as meeting the FMVSS No. 214 side impact pole test
requirements.\86\ This is in recognition of the potential for a side
curtain system to meet both FMVSS No. 214 and the ejection mitigation
requirements and that meeting both sets of requirements will place
demands on manufacturers and air bag system suppliers to develop a
``new generation'' of side air bag curtains and sensors beyond those
installed to meet the FMVSS No. 214 test requirements. Taking into
account all available information, including but not limited to the
technologies that could be used to meet the proposed testing
requirements, the SAFETEA-LU provision that a final rule be issued by
October 1, 2009, and the relatively low percentage of the fleet that
has ejection mitigation countermeasures capable of meeting the proposed
requirements, the agency is proposing to phase-in the new ejection
mitigation requirements starting the first September 1 three years from
the date of publication of a final rule. Assuming that a final rule
would be issued in January 2011, NHTSA proposes that the phase-in would
be implemented in accordance with the following schedule:
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    \86\ The FMVSS No. 214 rule will be phased in and will apply to
80 percent of vehicles with a GVWR of 8,500 pounds or less
manufactured on or after September 1, 2013. Advance credits may be
used. All vehicles with a GVWR of 8,500 lb or less (except for
altered and multistage vehicles and vehicles produced by limited
line and small volume manufacturers) manufactured on or after
September 1, 2014 must meet the upgraded FMVSS No. 214 requirements
without use of advanced credits. All vehicles with GVWRs 8,500 to
10,000 lb (except for altered and multistage vehicles) manufactured
on or after September 1, 2015 must meet the upgraded FMVSS No. 214
pole test requirements. All altered and multistage vehicles
manufactured on or after September 1, 2016 must meet the upgraded
FMVSS No. 214 requirements.
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     20 percent of each manufacturer's vehicles manufactured
during the first production year beginning three years after
publication of a final rule (for illustration purposes, that effective
date would be September 1, 2014);
     40 percent of each manufacturer's vehicles manufactured
during the production year beginning, for illustration purposes,
September 1, 2015;
     75 percent of vehicles manufactured during the production
year beginning, for illustration, September 1, 2016;

     And all vehicles (without use of advanced credits)
manufactured on or after, for illustration, September 1, 2017.
    NHTSA believes that the proposed phase-in would best address a
number of issues. It would allow manufacturers to focus their resources
in an efficient manner. Data obtained from the agency's 2008 model year
New Car Assessment Program indicate that approximately 40 percent of
2008 model year vehicles are available with side air bags that are
designed to deploy in a rollover and stay inflated for a duration
longer than that needed to provide protection in a side impact not
involving a rollover. However, this does not mean that these vehicles
would be capable of complying with this NPRM. For example, the air bag
curtain may not have sufficient window coverage or stay inflated long
enough to meet the proposed requirements. Rather, these ejection
mitigation systems are designed to the manufacturers' internal design
criteria.
    The agency believes that it would not be possible for manufacturers
that produce large numbers of models of passenger cars and LTVs to
simultaneously design and install ejection mitigation air bags meeting
the proposed requirements in all of their vehicles at once.
Manufacturers have limited engineering resources, and will have been
using their resources to improve the performance of LTVs and passenger
cars in the dynamic pole test and the moving deformable barrier
vehicle-to-vehicle crash test of FMVSS No. 214. NHTSA seeks to provide
vehicle manufacturers sufficient opportunity to adopt the best designs
possible as quickly as possible. The agency tentatively concludes that
a 4-year phase-in beginning three full years after publication of a
final rule will provide the lead time needed while achieving the life-
saving benefits of the final rule in as expeditious a manner as
possible.
    NHTSA further believes that the proposed phase-in would not be
incompatible with the agency's efforts to upgrade FMVSS No. 216, ``Roof
crush resistance.'' The roof strength upgrade will mainly require
structural redesigns in the areas of the A- and B-pillars, side and
front header, and roof cross beams, particularly for heavier vehicles
that were not previously subject to the standard. Potential vehicle
modifications could include the incorporation of higher strength or
higher gauge steel, adding supporting materials in the pillars, and/or
reinforcing the roof-pillar joints. NHTSA believes that any structural
changes needed in response to the new roof crush resistance
requirements will have an inconsequential impact on the ability to
implement ejection mitigation countermeasures, such as rollover curtain
air bags. Possible ancillary changes could include the need to
accommodate larger air bag packaging and new curtain attachment points.
Nonetheless, the agency is considering overlapping the phase-ins of
both the roof crush resistance and ejection mitigation upgrades to
afford vehicle manufacturers the opportunity to make needed
modifications for compliance with both requirements at one time.
Ultimately, the improved roof strength provided by FMVSS No. 216, in
combination with the ejection mitigation countermeasures, will provide
comprehensive protection for vehicle occupants involved in rollover
crashes.
    We also propose to include provisions under which manufacturers can
earn credits towards meeting the applicable phase-in percentages if
they meet the new ejection mitigation requirements ahead of schedule.
In addition, as we have done with other standards, we are proposing a
separate alternative to address the special problems faced by limited
line and multistage manufacturers and alterers in complying with phase-
ins. A phase-in generally permits vehicle manufacturers flexibility
with respect to which vehicles they choose to initially redesign to
comply with new requirements. However, if a manufacturer produces a
very limited number of lines, a phase-in would not provide such
flexibility. NHTSA is accordingly proposing to permit ``limited line''
manufacturers that produce three or fewer carlines the option of
achieving full compliance when the phase-in is completed. Flexibility
would be allowed for vehicles manufactured in two or more stages and
altered vehicles from the phase-in requirements. These vehicles would
not be required to meet the phase-in schedule and would not have to
achieve full compliance until one year after the phase-in is completed.
Also, as with previous phase-ins, NHTSA is proposing reporting
requirements to accompany the phase-in.

IX. The Estimated Benefits and Costs of This Rulemaking

    We are placing in the docket a Preliminary Regulatory Impact
Analysis (PRIA) to accompany this NPRM.\87\ The PRIA analyzes the
potential impacts of the proposed ejection mitigation requirements. A
summary of the PRIA follows. Comments are requested on the
analyses.\88\
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    \87\ The PRIA may be obtained by contacting the docket at the
address or telephone number provided at the beginning of this
document.
    \88\ The analyses were based on information voluntarily
submitted by manufacturers at the end of 2006. Since that time,
various manufacturers have reported that product plans pertaining to
other rulemakings have changed due to changed economic
circumstances. Comments are requested on the estimates provided in
this section and in the PRIA.