ADB system switched from an upper beam to an adaptive beam in this
range. NHTSA believes this is acceptable because the left curve
scenarios generally test the ability of the ADB system to react and it
is reasonable to expect similar reactions on the left and right side.
The right curve test simply confirms the right side is performing
similarly by applying the oncoming glare limits to narrow angles on the
right side and providing greater flexibility at broader angles on the
right side of the vehicle.
f. Scenario 6: Oncoming Large Right Curve
    The NPRM proposed regulating glare on right curves with a radius of
335 m to 396 m at 50-55 mph from distances of 15 m to 220 m.

Comments
    As explained above regarding the medium right curve scenario,
Stanley ran simulations for right curves with a radius of 366 m and
commented that the oncoming glare limits were effectively more
stringent than the current Table XIX photometry on the right side of
the beam pattern. In addition, as noted earlier, commenters argued more
generally that the proposed glare limits were so stringent that
compliant lower beams would exceed them, and that there might not be
sufficient time for the ADB system to react to the stimulus lighting.
Agency Response
    This final rule modifies the proposal, similar to the modifications
for the medium right curve, in response to comments that current
compliant lower beams might not comply with the NPRM's glare limits at
all the proposed measurement distances. As explained earlier, this (in
conjunction with the requirement that areas of reduced intensity meet
the corresponding lower beam laboratory photometric requirements) means
that an area of reduced intensity, up to and including a full lower
beam, will meet the same level of safety (with respect to both
visibility and glare prevention) as current lower beams certified to
FMVSS No. 108. As NHTSA agrees with Stanley and other commenters that
the proposed scenario permitted less glare than presently required of a
lower beam on the right side of the beam pattern, NHTSA has narrowed
this angle not to go beyond 3 degrees right, to provide flexibility at
larger angles. The final rule therefore specifies testing on a right
curve with a radius of 335--400 m at distances of 15 m to 70 m, at the
proposed speeds of 50-55 mph.
    NHTSA believes that a lower beam that is FMVSS No. 108-compliant
and performs well on the IIHS test would generally be able to comply
with the glare limits in this scenario. The reasons for this are
analogous to the reasons given earlier for revising the measurement
distance in the medium right curve scenario. None of the IIHS data
submitted by SAE was for a right curve of this diameter. NHTSA tested
two lower beams on this scenario. See Figure 26. The Fusion lower beam
was within the glare limits at all specified distances, while the Volvo
lower beam exceeded the glare limits at distances from 60 m--70 m. This
is likely because, as explained earlier, the Table XIX photometry
requirements and the IIHS test have prompted some manufacturers to
provide greater light on the right side. NHTSA believes such systems
can comply with the requirements with minor modifications. This is also
consistent with what Stanley points out in its comment.

[GRAPHIC] [TIFF OMITTED] TR22FE22.024

    The agency also believes that the finalized requirements are within
the capabilities of existing ADB systems, for reasons analogous to
those provided for the medium right curve scenario above. The ADB NHTSA
system tested was within the glare limits in this scenario except at
distances greater than 60 m. See Figure 27. This is similar to the
results for the Volvo lower beam and, we believe, can be addressed with
minor system modifications. Agency test data also confirm that the most
closely analogous SAE test scenario (Fixture Position 3) does not
accurately replicate an actual right curve; the measured illuminance on
this scenario was significantly higher than in the analogous SAE
scenario. Thus, the data indicate again that the two test methods can
yield different results, and that the actual curve test is preferable
because it would be more evaluative of real-world performance.

[GRAPHIC] [TIFF OMITTED] TR22FE22.025

g. Scenario 7: Preceding Straight
    The NPRM proposed testing for preceding glare in a variety of
vehicle maneuvers, on both straight and curved roadway. It proposed
scenarios in which a stimulus vehicle preceded the test vehicle in the
same lane and in which the test vehicle overtakes the stimulus vehicle,
and vice versa. We proposed evaluating glare out to 119.9 m.
Comments
    SAE commented, with respect to NHTSA's statement in the NPRM that
the ECE ADB regulations require ADB cameras to be capable of sensing
vehicles out to 400 m, that this only applies to opposing vehicles
(headlamps), not preceding vehicles (rear lamps). For preceding
vehicles (i.e., tail/rear position lamps), the ECE requirement is
greater than 100 m. SAE also noted that ECE minimum photometric
requirements for a rear position lamp is 4 cd versus the 2 cd minimum
under FMVSS No. 108 for a taillamp. Thus, SAE stated, the ECE requires
a shorter detection distance (100 m in the ECE versus 120 m in the
NPRM) for a lamp whose absolute minimum intensity is two times that
required by FMVSS No. 108.
    Auto Innovators found that there were very few test failures in
this scenario (5 failures out of 109 valid test runs in its testing)
and therefore suggested eliminating it because it would provide no
additional benefit.
Agency Response
    The final rule scales back the proposal with respect to evaluating
preceding glare. The final rule does not include any passing or same-
lane scenarios because it utilizes stationary fixtures. The final rule
provides only for testing preceding glare with the fixture in the left
adjacent lane, on both a straight path (this ``preceding straight''
test scenario) and on a left curve path (Scenario 8).
    The final rule also shortens the measurement distance to 100 m. As
SAE suggested in its comment, the detection distance for ADB systems
differs for oncoming versus preceding traffic. It is much more
difficult for an ADB system to detect taillamps than headlamps, and the
difficulty increases with greater forward distances. This is mainly
due, as SAE notes, to the fact that headlamps are much brighter than
taillamps. The NPRM stated that it is reasonable to expect ADB systems
to detect oncoming vehicles at 220 m but did not mean to imply that
this also applies to preceding vehicles. The final rule harmonizes with
the ECE requirements in this respect.
    Agency test data indicate that current lower beams can comply with
this revised scenario. NHTSA tested two vehicle lower beams, both of
which performed well, with considerable margin. See Figures 28 and 29
below.

[GRAPHIC] [TIFF OMITTED] TR22FE22.026

    NHTSA's analysis also indicates that ADB systems can reasonably be
expected to comply with this scenario. As explained earlier for the
oncoming straight scenario, the preceding vehicle fixture--which is in
the same location as it is for the oncoming straight scenario--is
always within the ADB system's field of view, so that an ADB system
will have more than sufficient time to react to and shade the fixture.
NHTSA's test data bear this out. The Lexus ADB system performed well
with considerable margins in this scenario with all fixtures (passenger
car, truck, motorcycle). See Figure 30. On the SAE test run with the
preceding fixtures in Position 2 (the closest analog to this final rule
scenario), the ADB system passed with the car/truck fixtures, although
the margins were lower. See Figure 31.
[GRAPHIC] [TIFF OMITTED] TR22FE22.027

[GRAPHIC] [TIFF OMITTED] TR22FE22.028

h. Scenario 8: Preceding Medium Left Curve
    The NPRM included scenarios for testing preceding glare on short,
medium, and large right and left curves, in same-lane and passing
scenarios. It proposed evaluating glare from 15 m or 30 m (depending on
the scenario) out to 119.9 m. The agency did not receive any comments
specifically on the preceding curve scenarios.
    The final rule retains only one preceding curve scenario of those
proposed. This scenario evaluates preceding glare on a medium left
curve (with a radius from 210 m to 250 m) from 15 m to 100 m with the
fixture in the left adjacent lane.
    After considering the comments questioning the number and
complexity of the proposed test scenarios, NHTSA considered including
only a preceding vehicle straight path scenario, hypothesizing that it,
in addition to the full set of oncoming scenarios, would adequately
probe ADB system performance. NHTSA's testing, however, showed that ADB
systems encountered some difficulties preventing glare to preceding
vehicles on curves. The 2015 ADB Test Report concluded that left curve
same-direction maneuver scenarios in which the stimulus vehicle was
stationary were associated with high measured illuminance values.\139\
NHTSA's recent testing showed that the ADB system, while performing
adequately on oncoming left curve and preceding straight scenarios, had
trouble with a preceding left curve scenario for short and medium
curves, but handled the large curve well. See Figure 32.
---------------------------------------------------------------------------

    \139\ 2015 ADB Test Report, p. 173. See also pp. 114-123.

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

[GRAPHIC] [TIFF OMITTED] TR22FE22.029

[GRAPHIC] [TIFF OMITTED] TR22FE22.030

BILLING CODE 4910-59-C
    Accordingly, the final rule retains a preceding left curve scenario
to help ensure that ADB systems respond appropriately when encountering
preceding vehicles on curved roadways. NHTSA decided that one curve
test would suffice and has opted for the medium curve. The ADB system
we tested performed well on the large curve, and the short curvature
would be a difficult test for the manufacturers to meet. The final rule
does not add a right curve scenario for preceding vehicles because the
2015 study showed that ADB systems generally performed well on same-
direction right curve maneuvers.\140\ Further, because the final rule
truncates the measurement distances on right curves, preceding tests
for right curves would not test the system in any significant ways that
are not already covered by the other scenarios.\141\
---------------------------------------------------------------------------

    \140\ 2015 ADB Test Report, p. 173.
    \141\ For example, the Lexus has a late reaction (at 70 m) on
the preceding medium left curve. If the recognition system is
essentially symmetrical (i.e., the same for a right curve), the same
late recognition (70 m) on a preceding right curve would not result
in a failure, because the measurement distance for a right curve is
truncated to 50 m (Scenario 5). As is the case for the left curve,
the Lexus was under the right curve limits at distances less than 50
m.
---------------------------------------------------------------------------

    The results from the SAE test fixture position most analogous to
this final rule scenario (with the SAE fixture in Position 1) show that
the ADB system passed the test with the car/truck fixture with wide
margins. See Figure 33. Again, this contrasts with the results from the
final rule test scenario and suggests that the SAE test does not
sufficiently replicate a preceding situation on an actual curve.
i. Decision Not To Include Oncoming Short Right Curve Scenario
    The NPRM proposed evaluating illuminance on right curves with a
radius of 98 m to 116 m at distances of 15 m to 220 m.
Comments
    SAE and Stanley commented--parallel to their arguments for the
medium right curve--that contemporary lower beams would likely not
comply with this scenario. SAE provided a graph of illuminance data for
IIHS ``Good''-rated lower beams from about 0 m to 125 m on a 150 m
radius right curve. SAE stated that these data show that many of those
lower beams would not comply with the proposed glare limits at
distances greater than 30 m. Other commenters stated more generally
that the proposed glare limits were so stringent that even currently-
compliant lower beams would exceed them. Similarly, Stanley ran
simulations for a right curve with a radius of 107 m and asserted that
the glare limits were more stringent than the right-side intensities
currently permitted by the standard.
    As noted above under the small left curve scenario, several
commenters stated that curves of this size would require a camera field
of view beyond the capabilities of existing systems, and/or would not
allow a sufficient time for an ADB system to detect and react to the
stimulus.
    SAE also commented that upper beams at greater than 15 degrees left
or right are not as bright as lower beams straight ahead, and at an
angle of 40 degrees the light toward a stimulus vehicle driver is low,
further suggesting that requiring a camera field of view beyond 25
degrees is unnecessary.
Agency Response
    The final rule does not include a short right curve scenario
because NHTSA was persuaded by the comments.
    The reasons for this decision are similar to the reasons for
modifying the measurement distances for the medium and large right
curve scenarios. As explained earlier, NHTSA concluded that
contemporary lower beams--especially beams that score well on the IIHS
test--would likely not comply with the oncoming glare limits at
distances corresponding to horizontal angles greater than 3 degrees--
that is, on a 100 m right curve, distances greater than 30 m (the
distance at which the fixture would cross 3 degrees). This is
consistent with the IIHS data submitted by SAE, which shows that none
of the lower beams tested were within the oncoming glare limits between
60 and approximately 120 m, and most of the lower beams tested were not
within the oncoming glare limits from 30 m to 60

m. (From 15 m to 30 m, almost all the lower beams tested by IIHS were
within the glare limits.) As such, the agency has confidence that
including a small radius right curve scenario would have no positive
impact on safety relative to that provided by current lower beams in
this situation.
    Because, as explained above, the final rule specifies right curve
scenarios only for measurement distances corresponding to horizontal
angles to the left of 3R, this would leave only about 15 m of track
length (and 1 second of test time) for this scenario. NHTSA concluded
it was not useful to include such a short-duration scenario in the
final rule.
9. Other Test Parameters and Conditions
a. Radius of Curvature
    NHTSA proposed testing using a curved path scenario (both left and
right curves) with a variety of radii of curvature. The NPRM proposed
testing on a ``small'' curve with radii of curvature from 98 m--116 m
(320-380 ft); a ``medium'' curve with radii of curvature of 223 m-241 m
(730-790 ft); and a ``large'' curve, 335 m-396 m (1100-1300 ft). The
NPRM proposed that the curve on which testing is conducted be of a
constant radius within the range listed in the test matrix.
Comments
    Manufacturers requested clarification or modification of the
specifications and procedures related to the radius of curvature.
    The Alliance, Ford, and Toyota commented on measuring the radius of
curvature. Ford requested clarification on how to measure the radius of
curvature and all three commenters recommended following the IIHS
protocol and measuring the radius of curvature from the center of the
test vehicle's travel lane.
    Toyota suggested the final rule not specify a constant radius
because it is not practical and is rarely the case in real-world
situations.
    Honda, Toyota, and Auto Innovators requested clarification of the
direction of curvature (left or right).
    OICA, SAE, SMMT, and Auto Innovators commented that the proposed
road geometries do not exist at the proving grounds of many vehicle
manufacturers. Auto Innovators commented that its testing contractor
found that modifications to curvature radii were necessary to
accommodate performance of the specified test scenarios at its
facility, and that only the short-radius curve was within the NPRM
specification.
Agency Response
    NHTSA has made a variety of changes in the final rule in response
to these comments. With respect to measuring the radius of curvature,
the final rule adopts regulatory text to specify that the curve is of a
constant radius, as measured to the centerline of the path on which the
test vehicle travels, within the range specified in the test matrix. In
its latest testing, NHTSA used an inertial navigation system to follow
a pre-programmed path for the centerline of the vehicle to follow. This
was executed using a steering controller that followed the predefined
path.
    When conducting its compliance testing, the agency may choose any
radius within the range listed in the test matrix. The constant-radius
specification is intended to indicate that the agency does not intend
to test on compound curves (i.e., a curve with a non-constant radius of
curvature). Considering that the manufacturer must certify that the
vehicle will perform throughout the range of radii of curvature
specified in the test matrix, NHTSA does not expect dramatic
differences in results if the radius is not perfectly constant but
contains minor variations throughout the run. The final rule also
retains ranges for the radii of curvature, as opposed to a single
radius of curvature with a relatively narrow tolerance. NHTSA believes
the system should be able to function over at least these range of
radii because they are representative of real-world roadway geometry.
    NHTSA agrees with Honda and Toyota about clearly specifying the
direction of curvature and has done so in the regulatory text.
    With respect to the comment that the specified curves are not
available at testing facilities, NHTSA was able to test on the curves
specified in the final rule at the Transportation Research Center (TRC)
Vehicle Dynamics Area (VDA). This test facility is publicly available
to manufacturers.
    The final rule slightly modifies the specifications for the radii
of curvature for all curves. NHTSA converted the center of the proposed
range units from feet to meters and rounded the meter units.
b. Test Vehicle Speed and Acceleration
    The NPRM proposed, for each test scenario, a range of test vehicle
speeds that NHTSA could select. The values proposed for speed, radius
of curvature, and superelevation were consistent with a standard
formula used in road design specifying the relationship between these
parameters. The formula, referred to as the simplified curve formula,
is
[GRAPHIC] [TIFF OMITTED] TR22FE22.031

where f is the coefficient of friction, V is the vehicle speed, R is
the radius of curvature, and e is superelevation.\142\ The speeds
ranged from a high of 70 mph for the straight scenario to 25 mph for
the short-radius curve scenarios.
---------------------------------------------------------------------------

    \142\ See A Policy on Geometric Design of Highways and Streets.
American Association of State Highway and Transportation Officials.
Washington, DC (2011) (AASHTO Green Book), pp. 3-19 to 3-20.
---------------------------------------------------------------------------

    The NPRM proposed that for each test run, a speed conforming to the
ADB test matrix would be selected and that the test vehicle would
achieve this speed  0.45 m/s (1 mph) prior to reaching the
data measurement distance and maintain this speed with ``no sudden
acceleration or braking.''
Comments
    SAE, Toyota, and Honda recommended that, to simplify the test and
reduce variability, the final rule specify a specific vehicle speed and
tolerance for each scenario. Auto Innovators recommended that the
maximum test speed be reduced from 70 mph to 55 mph because camera
detection does not depend on vehicle speed; the majority of fatal
nighttime crashes on curves occur at speeds of 55 mph or less; and
certain vehicles (such as large trucks) would have difficulty reaching
the specified test speeds given the lengths of courses available at
test facilities. Toyota suggested providing a more specific
specification for acceleration.
Agency Response
    The final rule retains the speed ranges and tolerances proposed for
each scenario. The range of speeds reflects the real world (where
different drivers may take the same curve at different speeds) and
provides testing flexibility.

    The speeds set out in the final rule are generally higher than
specified in SAE J3069, which states that ``[t]he speed of the vehicle
for the full length of the 155 m test shall be above the ADB activation
threshold of the vehicle as specified by the manufacturer.'' \143\
NHTSA believes that testing at speeds only marginally higher than the
activation speed would not be representative of real-world driving,
especially on the types of roads and situations (e.g., outdriving lower
beam) in which ADB is most useful. The ADB systems NHTSA tested had
activation speeds ranging from 19 to 43 mph.\144\ Safety concerns
regarding glare, like many safety concerns, are also magnified at
higher speeds.
---------------------------------------------------------------------------

    \143\ <IP_ADDRESS>.
    \144\ 2015 ADB Test Report, p. 20.
---------------------------------------------------------------------------

    NHTSA disagrees with the suggestion that test speed does not impact
ADB system performance, as the higher the test speed, the quicker the
system must identify and shade the fixture. The proposal did not
specify test speeds greater than 55 mph on curves; speeds above this
were only proposed for straight-path scenarios. Regarding the concern
that vehicles such as large trucks may have difficulty attaining test
speeds in the distances available at track test facilities, the final
rule specifies test fixtures and not stimulus vehicles, which should
facilitate testing at the higher speeds. Further, the agency was able
to achieve the maximum test speed of 70 mph on two different sections
of the TRC facility for the straight scenario, using a class 8 truck
tractor in the loaded and unloaded condition on the skid pad and the
vehicle dynamics area (this is the surface that was used for all of the
research testing). While complete lamp testing was not conducted using
the class 8 truck tractor, the pitch and speed parameters were recorded
along the path to demonstrate that a valid test was possible. Given the
superiority of full-vehicle testing of ADB, the difficulties that a few
vehicles may have in executing the test procedure do not appear
insurmountable for heavy vehicles.
    Regarding Toyota's comment on the acceleration criteria, the
proposal did address acceleration beyond the specification that ``no
sudden acceleration or braking shall occur'' in that it also specified
a tolerance of +/- 0.45 m/s (1 mph) for the nominal test speed. This
tolerance is smaller than that used in the IIHS test procedure (3 km/h
(.83 m/s)). In NHTSA's testing, the test driver was able to
consistently maintain the speed within this tolerance. In addition, the
final rule includes a vehicle pitch allowance that constrains
acceleration in that if acceleration causes changes in vehicle pitch
exceeding 0.3 degrees compared to the average pitch, then the measured
illuminance at those points will not be considered in determining
compliance.
c. Headlamp Aim
    The proposed test procedures specified several aspects of test
vehicle preparation. This included that the headlamps would be aimed
and the ADB system adjusted according to the manufacturer's
instructions.
    FMVSS No. 108 requires that when a headlamp is installed on a motor
vehicle, it must be aimable.\145\ The standard specifies compliance
options for the aiming system. The principal options are vehicle
headlamp aiming devices (VHAD) and visual/optical aiming devices
(VOA).\146\
---------------------------------------------------------------------------

    \145\ S10.18.
    \146\ The standard specifies a third compliance option
(mechanical aim), which involves an externally-applied mechanical
device. This method is no longer in use and is not at issue in this
rulemaking.
---------------------------------------------------------------------------

    A VHAD is an item of equipment installed on the vehicle and
headlamp which is used for aiming the headlamp mechanically, such as
with a bubble vial on the headlamp housing which has a closely
specified geometric relationship to the headlamp beam's vertical
location. A similar mechanical reference marking system is used for
correct horizontal aim, essentially aligning the optical axis of the
headlamp housing or reflector to the vehicle's longitudinal axis.
    VOA involves either projecting the beam onto a vertical surface and
then adjusting the headlamp to an appropriate position as determined by
an observer (visual aim), or projecting the beam into an optical device
that is placed in front of the headlamp and then adjusting the headlamp
until the beam conforms to the appropriate parameters (optical aim).
VOA is used on most, if not all, vehicles currently sold in the U.S.
The standard requires a relatively sharp horizontal cutoff in the lower
beam pattern in order to aim the headlamps vertically. The standard
does not permit horizontal aiming on VOA headlamps unless the headlamp
is equipped with a horizontal VHAD.
Comments
    IIHS expressed concern that the NPRM allowed vehicle manufacturers
to provide headlamp re-aiming procedures and ADB adjustments prior to
testing, because for the systems to be effective in real-world driving,
they need to function without adjustment when the consumer purchases
the vehicle. IIHS explained that its headlighting system evaluations
are conducted without changing the factory aim of the headlamps. They
found that there is often a wide range of aim values between
manufacturers, between some vehicles of the same make and model, and
even between the left and right headlamp of the same vehicle,
indicating that ADB effectiveness will be reduced if there is no
incentive in the regulation for precise aiming at the factory. IIHS
noted that this is even more important for ADB than for traditional
headlighting systems since both the headlamps and the camera system
require accurate alignment. IIHS further stated that just as NHTSA
would not allow manufacturers to modify an air bag deployment algorithm
prior to conducting FMVSS No. 208 compliance crash tests, the agency
should not allow the ADB system to be modified to a condition that may
not exist on any other production vehicle. IIHS provided data on
factory aim variation for seven new vehicle models with VOR headlamps
showing that most had aim values that would have a substantial effect
on the measured visibility distances in the IIHS evaluation. IIHS
stated that this indicates that conducting headlamp evaluations or
compliance testing with re-aimed lamps is likely to reduce the real-
world relevance of the tests.
    Conversely, several commenters (Valeo, the Alliance, Volkswagen,
SAE, Koito, Global, Honda, Auto Innovators, and Ford) requested that
the final rule allow for horizontal aim adjustment on VOA ADB headlamps
without equipping them with a horizontal VHAD (as the standard
currently requires). The commenters highlighted the importance of
horizontal aiming for ADB systems and requested that the final rule
allow horizontal aim adjustment on VOA headlamps used in conjunction
with an ADB system. They stated that in order to maximize the
visibility benefits of ADB, the area of reduced intensity must be
minimized, which can only be accomplished using both horizontal and
vertical aiming. They commented that horizontal adjustment of the beam
is critical in placing the area of reduced intensity accurately over
the oncoming or preceding vehicles. If a horizontal aim access
allowance were not incorporated into the final rule, automakers would
be required to compensate for the expected horizontal vehicle variation
into the size of the area of reduced intensity, resulting in greatly
increasing this area, and lessening the additional light.
    The commenters noted that the standard prohibits horizontal aim on
a

VOA headlamp unless a VHAD is provided, and stated that VHADs are
unreliable, ineffective, lack the accuracy necessary for use with ADB
systems, and are essentially obsolete. SAE suggested that NHTSA modify
the current regulatory text in S10.18 and S14.2.5 to allow headlamps
with adaptive driving beams to be adjusted according to the
manufacturer's instructions.\147\ Auto Innovators commented that the
method to horizontally aim ADB headlamps varies depending on the
specific execution of the ADB system. Each involves an ADB-specific aim
calibration mode to be activated either by a dealer or consumer when
the vehicle is parked. This mode illuminates a horizontal aim feature
utilizing one or more of the ADB-illuminated elements which have a
sufficient vertical gradient that can be used for horizontal aim, just
as one does today with vertical aim. The dealer or consumer would use
this vertical gradient to properly calibrate the horizontal aim
following instructions specified in the service manual or owner's
manual.
---------------------------------------------------------------------------

    \147\ Ford noted that NHTSA has opined that horizontal aiming is
permitted with VOA headlamps provided it is disabled or made
inaccessible for consumers, but contended that this does not address
the potential need for re-adjustment should the ADB system need to
be aimed after sale to the consumer (for example, upon headlamp
replacement due to vehicle damage).
---------------------------------------------------------------------------

    Several of these commenters pointed out that the ECE and Canadian
requirements provide for horizontal aim with VOA headlamps and that
effectively requiring horizontal VHADs would drive hardware
disharmonization. Ford pointed out that SAE J3069 recognized the
necessity of horizontal aiming for ADB systems, and that Canada, in
adopting SAE J3069, specifically permitted horizontal aim.
    ALNA suggested applying tolerances for aiming the headlamps.
Agency Response
    The final rule follows the proposal and specifies that the
headlamps will be aimed and the ADB system adjusted according to the
manufacturer's instructions. In addition, the final rule provides that
the test vehicle will be loaded within +/- 5 kg of the total vehicle
weight during track testing prior to aiming the ADB headlamps. This is
intended to indicate that NHTSA will not change the loading of the
vehicle by more than 5 kg compared to what it is when the headlamps are
aimed. This means that NHTSA will not aim the headlamps when the
vehicle is at a lower weight compared to when the vehicle is fully
instrumented and occupied by a test driver (which changes the pitch of
the vehicle, and thus, the aim of the headlamps).
    NHTSA disagrees with IIHS and believes that manufacturers should be
permitted to specify aiming procedures prior to the compliance tests.
IIHS's suggestion is essentially that on-vehicle aim should be
regulated. Even if this approach may have merit, it is outside the
scope of this rulemaking, which extends the current requirements to ADB
systems. The proposed specification is also consistent with the
required laboratory testing, which involves aiming the headlamp prior
to testing. Conventional laboratory testing of headlamps has long
permitted aiming them prior to testing. This contributes to the
repeatability of the test and sets a consistent standard to which
headlamps must perform. This is important because the laboratory
photometric requirements are the basis for the current track-based test
procedure limits; if we were to consider practical limits that included
variations in aim introduced through the distribution chain, the limits
that are finalized might not be appropriate. In addition, as IIHS
notes, ADB systems rely on accurate alignment of the headlamps and
camera systems. Aiming the headlamps prior to the compliance test
limits aim variation and isolates ADB performance. This approach
ensures that the ADB compliance test will be performed with a
headlighting beam pattern that, as manufactured, at least meets a
minimum level of performance. The end customer or dealer can then aim
the headlamps to align the system appropriately.
    The agency agrees that successful implementation of ADB using
current technology requires the regulation to provide flexibility to
permit headlamps to be aimed horizontally once installed on the vehicle
to align the vehicle, camera, and headlamps. As explained below, while
NHTSA agrees with the commenters that ADB systems should be exempt from
several of the current requirements for horizontal VHADs, NHTSA does
not agree that ADB-equipped VOA headlamps should be completely exempt
from all the VHAD requirements.
    FMVSS No. 108 does not permit VOA headlamps to be visually aimed
with respect to horizontal aim. NHTSA explained the reason for this in
the 1997 final rule that permitted VOA aim headlamps.\148\ Because the
lower beam of a headlamp designed to conform to Standard No. 108 does
not have any visual cues for achieving correct horizontal aim when
aimed visually or optically, and because it is not possible to add such
visual features without damaging the beam pattern, horizontal aim
should be either fixed and nonadjustable, or have a horizontal VHAD.
The agency also noted that the negotiated rulemaking committee involved
in that 1997 negotiated rulemaking ``considered features for horizontal
visual/optical aiming but none were deemed sufficiently developed and
designed to be usable.'' \149\ Accordingly, that final rule did not
permit any horizontal movement of VOA headlamps, with the lamp
essentially being correctly aimed as installed, unless the headlamp was
equipped with a horizontal VHAD. The horizontal VHAD was included as a
compliance option (and required to be set to zero) as a means for
manufacturers to meet European requirements for both a horizontal and
vertical aim adjustment. For these reasons, in 1999 NHTSA denied a
petition for rulemaking to allow VOA headlamps to have a horizontal
adjuster system that does not have the required 2.5-degree horizontal
adjustment range or a VHAD indicator.\150\
---------------------------------------------------------------------------

    \148\ 62 FR 10710 (Mar. 10, 1997).
    \149\ Id., p. 10715.
    \150\ 66 FR 42985 (Aug. 16, 2001) (denial of rulemaking petition
from Federal-Mogul Lighting Products).
---------------------------------------------------------------------------

    Although VHADs are not widely (if ever) used, NHTSA is not
persuaded that a VHAD for horizontal aiming would not be feasible for
ADB-equipped headlamps. The commenters did not present any information
to show VHADs are necessarily incompatible with the aiming accuracy
necessary for ADB systems. While VHAD devices used prior to the
allowance of visual optical aiming in the U.S. may have been
inaccurate, these limitations are not driven by the requirements placed
on VHADs by the FMVSS.\151\ The minimum requirements in FMVSS No. 108
for horizontal VHADs provide a floor below which accuracy cannot drop,
but do not limit aiming accuracy.
---------------------------------------------------------------------------

    \151\ See S10.18.8.
---------------------------------------------------------------------------

    For example, the requirements in S<IP_ADDRESS>.2 that the VHAD include
references and scales relative to the longitudinal axis of the vehicle,
including a ``0'' mark and an equal number of graduations from the
``0'' mark, limit neither precision nor accuracy. The horizontal VHAD
need only be accurate enough to set at 0 in order to perform basic
photometry testing in the lab. Other measurement cues (including more
precise methods) may be used to more accurately aim the headlamps on
the vehicle for the purposes of ADB functionality. The

regulation does not restrict this but allows the flexibility to
customize such methods to accommodate any unique features present in
any beam.
    Even if NHTSA were to agree with the commenters that VHADs were not
optimal for ADB systems, the agency does not currently have, and the
commenters did not provide, a workable alternative. For example, SAE's
suggested amendments to S10.18 and S14.2.5 simply stated that ``if the
headlamp is equipped with ADB, and has horizontal aim, it shall be
adjusted according to the manufacturer's instructions.'' If the
commenters sought allowance of horizontal VOA aim for ADB systems, they
did not provide information on how this would work in practice. Unlike
the lower beam pattern in Europe, where the lower beam pattern has a
vertical cutoff component and uses VOA for horizontal aim, the U.S.
lower beam pattern has no such required cutoff or other cues--meaning
horizontal VOA in FMVSS No. 108 is not currently feasible.\152\ If the
beam pattern were to include cues that could be used to visually aim
the headlamps horizontally, such a procedure could be workable. Such
procedures, however, have not been developed for the United States
market for visual/optical horizontal aim of the headlamps, and they
would need to include, among other things, a cut-off requirement
analogous to the current requirements for the horizontal cutoff for the
lower beam.\153\ In addition, such requirements would limit the
flexibility of beam pattern design currently permitted by the standard.
This could limit the potential for innovative safety solutions
generally afforded by this final rule. On the other hand, if the
commenters referred to non-VOA methods, they were not presented to the
agency.
---------------------------------------------------------------------------

    \152\ The ECE horizontal aim test procedure is in R112 Annex 9.
This procedure is not suitable for headlamps in the U.S. because it
relies on features in the beam pattern, such as the kink, that are
not required to be present in a lower beam pattern by FMVSS No. 108.
    \153\ See S<IP_ADDRESS>.
---------------------------------------------------------------------------

    NHTSA agrees, however, that several of the requirements for
horizontal VHADs (in S<IP_ADDRESS>.2.1-4) are not necessary for ADB
systems. S<IP_ADDRESS>.2.1 requires that each graduation must represent a
change in the horizontal position of the mechanical axis not greater
than 0.38[deg] (2 in at 25 ft) to provide for variations in aim at
least 0.76[deg] (4 in at 25 ft) to the left and right of the
longitudinal axis of the vehicle, and must have an accuracy relative to
the zero mark of less than 0.1[deg]. As the commenters alluded to, this
minimum accuracy of graduation is likely not adequate for aligning the
camera and headlamps. NHTSA expects that a more accurate method will be
utilized to align the lamps and the camera and does not expect this
alignment procedure to be manually conducted by non-expert vehicle
owners. Similarly, S<IP_ADDRESS>.2.2-3 pertain to the readability of those
graduations. S<IP_ADDRESS>.2.4 specifies minimum horizontal indicator and
aiming ranges. Those limits are not relevant to ADB aim because they
are intended to align the lamp with the vehicle, whereas ADB systems
require the alignment of the lamp with the camera. NHTSA expects that
this alignment range will be determined by each manufacturer
appropriate for their camera installation and body tolerances.
Consequently, the final rule exempts ADB systems from these
requirements.
    With respect to harmonization, the agency recognizes that VHADs add
some additional cost, but the option to use a horizontal VHAD was
actually intended to facilitate harmonization by giving manufacturers a
way to meet both the ECE requirements (which require both a horizontal
and vertical aim adjustment) and the U.S. requirements (which require
only vertical aimability). A VOA headlamp intended for sale in both the
European and U.S. markets would likely have a vertical aiming screw and
a horizontal VHAD, while one intended for use only in the U.S. market
need only provide for vertical adjustment.\154\ In practice,
manufacturers wishing to sell essentially the same headlamp design in
both markets, but not utilize a horizontal VHAD, would typically design
a lamp with both a vertical and horizontal aiming screw, and lock out
(or make inaccessible) the horizontal screw in the U.S.-market version.
---------------------------------------------------------------------------

    \154\ 66 FR 42985, 42986 (Aug. 16, 2001).
---------------------------------------------------------------------------

d. Road Surface
    The NPRM proposed several specifications related to the quality of
the test track surface, including that the tests would be conducted on
a dry, uniform, solid-paved surface; that the road surface have an
International Roughness Index (IRI) measurement of less than 1.5 m/km;
and that the test course surface be composed of concrete or asphalt.
The proposal also included an allowance for momentary glare exceedances
that might be related to, among other things, imperfections in the road
surface. SAE J3069 specifies an identical IRI value and that the test
course surface be uniform, straight, flat and represent a typical road
surface.
Comments
    Intertek commented that the IRI is not simple to measure
quantitatively and that requiring a road surface quality of 1.5 m/km
will impose unnecessary restrictions on the test track. The commenter
recommend instead using the SAE J3069 value of 3 m/km.\155\ Auto
Innovators commented that, for its testing, longitudinal lane IRI
measurements were within the NPRM specification, averaging near 0.475
m/km, but that atypical IRI measurements across transverse lanes (east/
west) are unknown and may impact testing on curves.
---------------------------------------------------------------------------

    \155\ SAE J3069 JUN2016 states, in section 7.1, that it is
recommended that the road have an IRI of less than 1.5 m/km, while
the text accompanying Figure 5 states that the IRI should be less
than 3. SAE J3069 MAR2021 corrects the text in Figure 5 to state
1.5.
---------------------------------------------------------------------------

    ALNA commented that test ground conditions and variations should be
reflected in the requirements and suggested applying tolerances in
order to reflect variations such as ground unevenness. Toyota commented
that the NPRM did not sufficiently define the test track conditions and
that failure to do so would affect compliance test results.
Agency Response
    The final rule deletes the IRI specification. The purpose of the
IRI specification was to limit angular changes between the vehicle and
the illuminance meters throughout the test run. This was anticipated to
provide a boundary limit for which a vehicle manufacturer could certify
performance of its vehicle. In other words, the ADB system was not
expected to perform to the limits specified in the NPRM on a bumpy or
wavy road. However, during NHTSA's most recent testing, it was found
that a more direct approach--pitch adjustment--could be used to limit
this orientation. IRI values are a general measurement of road
roughness, but, in the context of the track test in this rule, are
essentially a proxy for vehicle pitch: A test conducted on a test track
surface with a low IRI will generally have less pitch variation than a
test conducted on a surface with a high IRI. Directly measuring vehicle
pitch eliminates the need for the IRI parameter.
    NHTSA believes that directly accounting for vehicle pitch addresses
Auto Innovators' concern that the transverse IRI may influence test
results (by influencing vehicle pitch, which in turn influences test
results) on curve scenarios. The area of the test facility that NHTSA
used for its most recent

testing had an IRI of 1.46 m/km in the EW direction and an IRI of 1.61
m/km in the NS direction. In conducting its testing, however, NHTSA
nested the straight, right, and left curves of each radius on the TRC
VDA large-area test facility. As such, those IRI measurements are not
direct measurements of the longitudinal or transverse paths taken
during ADB testing. While the final rule limits the number of
scenarios, it retains 6 different curved-path scenarios, including
various radii for right and left curves. These paths may have slight,
but potentially meaningful, differences in longitudinal IRI. While this
longitudinal test surface roughness measurement is possible along each
path, requiring a new IRI measurement any time the path is altered
would be unnecessarily burdensome, considering it is possible to
instead directly measure vehicle pitch. Additionally, the IRI can
change over time, especially considering large temperature changes; it
is possible that a path that in one season is under 1.5 m/km will
exceed that value in a different season. Replacing the IRI parameter
with a procedure for directly measuring and limiting the pitch
variation of the test vehicle eliminates these concerns.
    With respect to the comments by ALNA and Toyota, the commenters did
not identify specific additional ways to specify the test conditions.
For the reasons given here and elsewhere in the preamble, NHTSA
believes the final rule sufficiently accounts for test surface
conditions to control for the major sources of testing variability--
including vehicle pitch--related to the test track.
e. Ambient and Reflected Light
    The NPRM proposed to control for ambient and reflected light, which
can interfere with test results, in a few ways.\156\ Ambient
illumination recorded by the photometers must be at or below 0.2 lux;
testing must be conducted on dry pavement, and with no precipitation;
the test road must be free of retroreflective material; and the
pavement must not be bright white (to avoid intense reflections).
Notwithstanding such controls, some degree of ambient light is
unavoidable. Accordingly, in testing for compliance the agency proposed
to zero-calibrate the photometers. SAE J3069 similarly specifies that
the test track does not contain retroreflective material and that
testing be conducted during clear weather on dry pavement.
---------------------------------------------------------------------------

    \156\ Ambient light refers to light emitted from a source other
than the ADB system. This may include moonlight, light pollution
from nearby buildings, or light coming from the test fixture itself.
Reflected light refers to light from the ADB vehicle's headlamps
reflected off the road or other surfaces (including rain or fog
droplets) onto the photometric receptors.
---------------------------------------------------------------------------

Comments
    Intertek tentatively agreed with NHTSA's assessment of the impact
of stray and ambient light on the test. Some commenters, however,
stated that the proposal did not sufficiently control for ambient
light. The Alliance and Volkswagen commented that ambient light can
change throughout the data collection (e.g., due to clouds, the moon)
during a test, which could introduce uncontrolled variability and
difficulty in repeatability and reproducibility of test results. ALNA
suggested applying tolerances for variations in test course surface
conditions including ground reflectivity.
    Volkswagen commented that the presence of reflectors in the
environment could cause test results to vary and that the NPRM did not
address environmental conditions such as fog, dust, or pollution which
exist in real-world testing and can introduce variability that will
present challenges for repeatability and reproducibility. Mobileye
commented that the track test requirements should specify that fog and
dust should not be present when performing testing. TSEI recommended
the agency clarify how ambient conditions should be treated.
Agency Response
    The final rule adopts the proposed test procedures, but modifies
the photometer zero-adjustment procedure to reflect the fact that the
test uses fixtures, not stimulus vehicles. The meters will continue to
be zero-calibrated for each scenario tested.
    With respect to the comment about ambient light changing throughout
the test, NHTSA found that the ambient light did not change
significantly during a test session. Further, NHTSA's testing method
accounted for ambient conditions by measuring ambient illuminance
either immediately before or after each test trial and subtracting that
value from the recorded test data. The repeatability analysis, which
included testing on different nights, showed that the night on which
testing occurred did not appear to be a significant source of
variation. The commenters did not recommend any alternative methods to
account for ambient or reflected light. SAE J3069 does not specify how
ambient conditions or reflected lighting are to be treated aside from
requiring that ``[n]o other vehicle lighting devices shall be activated
or any retro-reflective material present and care should be taken to
avoid other sources of light, reflected or otherwise.'' \157\ Although
the final rule does not specify a baffle, the regulatory text does not
prohibit it if it provides more accurate results for a particular
location. The agency did not study adding baffles in a systematic way
because testing did not show stray light to be a significant
contributor to variability.
---------------------------------------------------------------------------

    \157\ <IP_ADDRESS> and <IP_ADDRESS>.
---------------------------------------------------------------------------

    With respect to reflectivity, as noted above, the proposal (and
final rule) specifies that the test road be free of retroreflective
material and that the pavement may not be bright white. With respect to
tolerances, although the agency does not expect reflectivity to affect
the illuminance measurements, the allowance for momentary exceedances
would be applied to spikes in illuminance caused by any such factors.
NHTSA is not aware of any standardized way of accounting for dust or
fog, and the commenters did not identify any such method. In any case,
the same test conducted on different nights did not lead to much
variation in results. Certainly, if ambient environmental conditions
were such that there was an unusual concentration of particulates--or
any other unusual conditions that would be likely to affect test
results--NHTSA would not attempt to conduct compliance testing. In
addition, NHTSA's testing showed that the ambient light did not appear
to fluctuate dramatically in the relatively short times it took to
perform a test run. And, as noted above, the recorded test data was
adjusted by subtracting the ambient illuminance. The agency therefore
believes that test outcomes will generally not be affected by changes
in ambient light.
f. Superelevation
    Superelevation refers to the degree of banking of a road. The NPRM
specified that the test track have a superelevation of 0% to 2%. We
explained that it was desirable to minimize the degree of banking
because photometry design as well as the existing and derived glare
limits are based on flat surfaces.
Comments
    Auto Innovators commented that it found that modifications to the
specified superelevation were necessary to accommodate the track
lengths at its test facility.
Agency Response
    The VDA test pad, on which NHTSA's most recent testing was
conducted, has

a slope of 1% in the direction between the two loops. That means that
the largest superelevation that we tested was less than 1%. The
superelevation would be 1% had we tested across the width of the pad
and 0% had we tested along the length of the pad. All the recent NHTSA
tests were conducted somewhere between these two extremes. Accordingly,
every test scenario traversed had a superelevation of less than 1%
(based on the TRC site plan).\158\
---------------------------------------------------------------------------

    \158\ See TRC site plan at www.trcpg.com/wp-content/uploads/2016/10/Vehicle-Dynamics-Area.pdf last accessed on February 16,
2021.
---------------------------------------------------------------------------

    We recognize that superelevation could, conceivably, influence test
results.\159\ Depending on the details of the curve/fixture location, a
large superelevation can either increase or decrease the likelihood
that the measured illuminance will exceed the relevant glare limit.
Superelevation effectively rotates the beam pattern around the
centerline of the vehicle. If the rotation causes the pattern to rotate
down with respect to the sensor location, it is less likely that the
measured illuminance will exceed the glare limit; if, on the other
hand, the rotation causes the pattern to rotate up with respect to the
sensor location, the measured illuminance is more likely to exceed the
glare limit. More specifically, on a left curve a positive
superelevation will always make it less likely that the glare limit
will be exceeded because the fixture is always on the left side of the
beam pattern and the superelevation causes a rotation of the beam
pattern counterclockwise. For the portions of a right curve at which
the photometric receptors are to the left of the beam pattern, a
positive superelevation will increase the likelihood that the measured
illuminance will exceed the glare limit because the beam pattern is
rotated clockwise for a positive superelevation on a right curve.
Finally, for straight-path test scenarios, a large positive
superelevation will always be more stringent because the ``crown'' in
the road rotates the beam pattern clockwise and the fixture is always
to the left.
---------------------------------------------------------------------------

    \159\ In addition, the wider the specified range of
superelevation, the more stringent the test, because the vehicle
must perform over a larger range of superelevation angles.
---------------------------------------------------------------------------

    We do not expect superelevation to have a meaningful impact on the
test results, especially compared to the effect of vehicle pitch, which
can materially impact test results. For this reason, we concluded that
it was not necessary to include an adjustment for superelevation.
g. Lane Divisions
    The NPRM specified that the test track lanes may have a median of
up to 6.1 m (20 ft) wide and should not have any barrier taller than
0.3 m (12 in.) less than the mounting height of the stimulus vehicle's
headlamps. SAE J3069 does not specify any lane divisions or medians but
does specify that the test track area be free from obstructions and
retroreflective markings.
Comments
    Mobileye commented that roads with narrow curves do not typically
have such wide medians, and this will place the stimulus vehicle at a
very wide angle to the host vehicle. Intertek questioned the need to
consider medians or barriers and suggested that the median be limited
to a standard lane divider. SL Corporation commented that a traffic
barrier is not necessary and may make it difficult for ADB systems to
accurately detect oncoming traffic, recommending that final rule
provide a more detailed specification if retained. SAE questioned the
inclusion of a 20-ft median for a 320-ft curve because medians of that
size are typically found only on higher speed interstate roads which do
not contain curves of that sharpness.
Agency Response
    NHTSA agrees with commenters that a median or barrier is not useful
for testing. These features are not included in the final rule.
h. Hills
    The NPRM did not propose testing on sloped (dipped or hilly) roads,
explaining that even headlighting systems with compliant lower beam
photometry can glare oncoming or preceding vehicles on sloped roads
because the hill geometry may place that vehicle in the brighter
portion of the lower beam pattern. NHTSA's testing was consistent with
this, showing ADB headlighting systems and FMVSS-compliant lower beams
glared oncoming and preceding vehicles on roads with dips.\160\ NHTSA
tentatively concluded that to require this performance of ADB systems
would be neither practical nor consistent with the approach of this
rulemaking (extending the existing lower beam glare requirements to ADB
systems).
---------------------------------------------------------------------------

    \160\ 2015 ADB Test Report, pp. 102, 108, 114.
---------------------------------------------------------------------------

Comments
    AAA asserted that the track test should include scenarios with
undulating roadways and hills but seemed to suggest that this might be
limited to ADB systems with higher-intensity upper beams (i.e., at the
ECE maximum). AAA commented that ADB technology has the ability to
avoid glaring other drivers in these situations, and that including
this in the test will create pressure to more quickly and successfully
address this.
Agency Response
    The final rule does not include testing on dips or hills for
several reasons. First, this approach would be more stringent than
current requirements. Current lower beams create glare for other
drivers on hills. The general approach of this rulemaking was to extend
the current headlamp requirements to ADB systems, not to increase the
stringency of existing requirements for ADB systems. Second, NHTSA's
testing indicated that current ADB systems did not perform well on hill
scenarios. Although including such scenarios in the track test could
help speed the development of ADB systems with these advanced
capabilities, it would likely make the systems more costly and slow
deployment. Finally, NHTSA has not developed test procedures for such
scenarios. This would take additional time and resources and would
require developing a complex test track that would be specific to ADB
testing. However, while it is outside the scope of the current
rulemaking to test ADB systems to ensure that they produce less glare
than current headlamps, NHTSA intends to monitor this issue and will
consider future action if warranted.
10. Data Acquisition and Measurement
a. Photometers
    The proposed regulatory text specified that the photometer must be
capable of a minimum measurement unit of 0.01 lux.
Comments
    Intertek suggested specifying that the photometric receiver have a
cosine response and be spectrally matched to the photonic response of
the human eye. It also suggested an accuracy limit of +/- 5% nominal
over the full range of illuminance from 0.01 lux to the upper limit
(about 100 lux).
Agency Response
    NHTSA's testing utilized a Minolta T10A illuminance meter. The
manufacturer's specifications indicated that it has a spectral response
within 6% of the (CIE) human eye photopic vision [V([lgr])] and a
cosine correction characteristic within 3%. The photometers used in
agency research

were capable of measuring light within 3% of the ideal cosine response.
NHTSA agrees with Intertek's suggestion and has modified the regulatory
text to include photometer specifications drawn from S<IP_ADDRESS>.3 and to
specify a cosine response within 3%.
    The agency also notes that the IIHS headlamp testing procedures
\161\ used baffles on the photometry equipment at 25 degrees to ensure
that the light captured was more directly attributable to the test
vehicle light source, and not to stray lighting that may be captured by
the photometer. This 25-degree angle is roughly equivalent to the
angles of incidence of light received from the light source when the
test vehicle is approaching the stimulus through a curve on the roadway
surface and equates to the angles at which ADB systems are typically
scanning for targets to shade. NHTSA finds the IIHS test method
specifications closely match our intent and has adopted similar
language to include a 25-degree angle of incidence.
---------------------------------------------------------------------------

    \161\ See supra note 93.
---------------------------------------------------------------------------

b. Sampling Rate
    The NPRM proposed to sample illuminance at a rate of at least 200
Hz. SAE J3069 specifies a sampling rate of 10 Hz, and IIHS test methods
sample illuminance at 200 Hz.
Comments
    Volkswagen commented that sampling at 200 Hz would lead to a more
complex selection of measuring equipment and analysis for each
experiment and supported the SAE J3069 specification. Global requested
that NHTSA explain the appropriateness of this minimum sampling rate
and whether a maximum sampling rate should be specified.
    Intertek commented that 200 Hz is near or exceeding the capability
of most high-grade light meters and recommended reducing the sampling
rate to 100 Hz in order to resolve illuminance in the ranges necessary
for this test. Intertek also stated that reducing the sampling time to
100 Hz is supported by the allowance of momentary exceedances up to 0.1
seconds in duration (100 Hz would include 10 measurements within that
0.1 seconds) and suggested determining acceptance based on a time-
averaged sampling rate at 10 Hz to account for very fast variances in
the illuminance level as well as the human eye response.
Agency Response
    After considering the comments, the final rule adopts a sampling
rate of at least 100 Hz. NHTSA is balancing the need for precise data
collection with the cost and availability of equipment. NHTSA agrees
that 200 Hz is faster than the minimum needed to verify compliance,
particularly considering the 0.1 second allowance, but the SAE sampling
rate of 10 Hz simply provides too little data to ensure that ADB
performance is within the specified glare limits. While a 200 Hz
sampling rate matches that used by NHTSA in both its most recent
research and in the research reported in the 2015 ADB Test Report (as
well as that used by IIHS), and did not present any issues, NHTSA
agrees with Intertek that a sampling rate as low as 100 Hz would
provide adequate date collection to detect exceedances lasting near the
0.1 s allowance. As described by Intertek, a 100 Hz data collection
method collects 10 readings within 0.1 s. This is adequate to judge a
short exceedance, and an extra 10 readings provided by a 200 Hz rate
would not substantially change that ability. A sampling rate of 10 Hz
however would collect only a single reading over 0.1 s, making it
difficult to judge the actual time a short exceedance lasts. The agency
considered adding a maximum sampling rate but does not believe doing so
is necessary because the final rule specifies an allowance for
momentary glare exceedances (up to 0.1 s) as well as a low-pass filter
with a cutoff frequency of 35 Hz.
    NHTSA is not incorporating time-averaged sampling due to concerns
that the delay associated with time-averaging would make it difficult
to properly synchronize illuminance and distance. This is particularly
important at higher vehicle speeds. Time-averaging (depending on the
parameters) could also collect illuminance levels from one location
over time and report that data at a moment while the vehicle is closer
to the fixture. This would have the result of shifting illuminance
levels down because all tests are arranged such that the vehicle
approaches the fixture, and never moves away from it.
c. Noise and Filtering
    The NPRM did not specify any filters other than the 0.1 s or 1m
spike allowance, and the proposal did not explore this issue although
it sought comment on it. The IIHS test procedure does specify that
photometric sensor signals be filtered through a low-pass filter with a
cutoff frequency of 35 Hz. This allows for accurate measurement of all
existing types of headlamp light sources, including pulse width
modulated systems like LEDs. IIHS test methods sample illuminance at
200 Hz, and any ambient offset for the measurements is based on the
minimum ambient illumination from 1-5 seconds after the test vehicle
has passed the measurement location.
Comments
    Global requested that the agency clarify which standards OEMs will
be permitted to use when removing test data noise from measured data,
and suggested incorporating any such standards in the final rule or the
formal compliance test procedure (NHTSA understands this to refer to
the laboratory test procedure, which is not part of the regulatory text
but is published separately by the Office of Vehicle Safety
Compliance). Intertek suggested that to ensure that all the energy is
accounted for, the minimum data acquisition rate should be 100 Hz, and
the data should be subject to averaging or boxcar smoothing to reduce
the effective sampling rate to a frequency of 10 Hz. Intertek
alternatively suggested an integrating photometer with a period of 100
ms. The final product would then be the filtered illuminance (with PWM,
pitch, and other sources of noise averaged out) reported with a
frequency of 10 Hz (or another frequency such as 25 or 33 Hz based on
the human eye response), or if boxcar averaging, it could be reported
at 100 Hz (with the understanding that each measurement carries 10 Hz
of averaging).
Agency Response
    In response to Global's request, the final rule specifies that
NHTSA will use a low-pass filter with a 35 Hz cutoff frequency.\162\
---------------------------------------------------------------------------

    \162\ As NHTSA has pointed out in the past, the FMVSS specify
the procedures NHTSA will use in compliance testing. While
manufacturers must exercise reasonable care in certifying that their
products meet applicable standards, they are not required to follow
the compliance test procedures set forth in a standard.
---------------------------------------------------------------------------

    The low pass filter essentially reduces high-frequency noise by
adjusting each data point by comparing it to the average of the
neighboring data. Any individual points that are higher than the
immediately adjacent points are reduced, and any points lower than the
immediately adjacent points are increased. As long as the general data
trends in the underlying signal are true (low frequency--allowed to
pass), then the signal will not be distorted by smoothing. This filter
is suitable for the types of measurements collected as it

results in the most complete response to noise without detrimental
effects on the data. Because the noise effects are assumed to be evenly
distributed with a standard deviation (d), the noise remaining in the
measurements will be approximately d over the square root of the smooth
width (m) of 35 samples at the 100 Hz we are collecting data. At the
finalized low-pass filter rate, that reduces the noise to less than
0.03 of the standard deviation of the noise in the lux. Filtering will
not eliminate the measurement noise and will result in a slight
reduction of the peak lux values measured during the track test. The
agency does not expect this to affect test results, however, both
because the reduction in the peak value is limited by the higher
sampling rate (100 Hz versus 10 Hz for SAE) and because even at the
broad width of the smoothing filter, the filter only smooths values
over roughly a third of the ``sudden spike'' timing, allowing for
differentiation of a spike from a non-compliance.
    The box-car averaging has the advantage of filtering out both
signal and test condition noise. Such data treatment is useful for
smoothing rapidly changing signal data, such as that type of data that
may result from vibratory effects as the test vehicle moves across the
track test bed. It is essentially equivalent to using a low pass
filter, as specified in the IIHS test procedure. The final rule is
therefore consistent with Intertek's comments.
d. Allowance for Momentary Glare Exceedances
    The NPRM proposed an allowance for momentary glare exceedances (or
``spikes'') of not greater than 0.1 second in duration or spanning 1 m
of vehicle travel. This was intended to account for variations in
illumination due to uncontrolled testing variables, such as minor
imperfections in the road surface.\163\ Minor imperfections in the road
surface can cause glare exceedances by affecting vehicle pitch.
---------------------------------------------------------------------------

    \163\ This is different from an allowance for an adaptation time
(referred to as ``reaction time'' in SAE J3069) which we understand
as referring to another possible reason for a testing allowance: To
account for the operation of the ADB system itself, because, as the
discussion in SAE J3069 points out, ``ADB cannot react
instantaneously.'' This is discussed in Section VIII.C.5 above.
---------------------------------------------------------------------------

Comments
    Some commenters believed the proposed allowance was insufficient.
Toyota stated that the requirements to minimize glare go beyond the
levels currently specified in the standard and beyond what is needed to
meet a safety need and that, given the strict allowance for momentary
glare, additional test parameters would need to be defined; for
example, the vehicle pitch can vary (due to the condition of the road,
suspension, tires, and the vehicle's acceleration), potentially
affecting the compliance result. Similarly, SAE and Volkswagen
commented that a 0.1 second allowance is insufficient, would frequently
be exceeded even by compliant lower beams (for example, due to
momentary changes in vehicle pitch), and it would be unreasonable to
expect an ADB system to comply with the glare limits in the numerous
proposed test scenarios with only that allowance. Auto Innovators
proposed that NHTSA increase this allowance to 2.5 seconds, based on
the human response time to the sudden appearance of an opposing or
preceding vehicle. ALNA agreed that it is appropriate to apply
tolerances in order to cover on-road application and reflect variations
in test ground conditions.
    SAE, Global, Ford, and the Alliance stated that in order to account
for otherwise uncontrolled-for test variability, NHTSA should follow
SAE J3069 such that the glare limits may be exceeded if the ADB
illuminance does not exceed 125% of the lower beam illuminance from the
vehicle measured under the same conditions. SAE, Global and Ford
commented that this better represents real-world conditions and
compensates for environmental factors such as dips and bumps in the
road, reflectivity of lane markers, ambient light, and vehicle pitch.
    Global commented that the term ``spike'' is not defined and
recommended that it be defined relative to accommodating the natural
behavior of certain headlamp light sources to have a ``spike'' of light
intensity during the sequence of use.
    Global also pointed out that in the proposed regulatory text (``no
longer that 1 meter'') ``that'' should be replace with ``than.''
    Auto Innovators commented that the distance exceedance limit should
be eliminated because specifying both a time and distance specification
is duplicative, and timing is more relevant to real-world driving.
Agency Response
    The final rule retains the 0.1 second component of the momentary
glare exceedance allowance and adds (as discussed in the next section)
an allowance for vehicle pitch.
    The momentary glare exceedance allowance accounts for testing-
related variability caused by noise and uncontrolled test factors (such
as uncontrolled ambient illuminance).\164\ NHTSA believes that 2.5
seconds is an inordinately long time for a ``momentary'' exceedance,
for the reasons discussed earlier.\165\ The agency also declines to
follow SAE J3069 and allow ADB illuminance to exceed lower beam
illuminance by up to 25%. The reasons for this are discussed in Section
VIII.C.4, Maximum Illuminance Criteria (Glare Limits). NHTSA agrees
with Global that there was a typographic error in the proposed
S<IP_ADDRESS>.8.1 (now at S<IP_ADDRESS>.2), which has been corrected in the
final rule. The agency also agrees that even at the slowest test speed
of 25 mph the limiting factor is time, not distance, and has removed 1
m from the text as it serves no practical purpose.
---------------------------------------------------------------------------

    \164\ NHTSA, in its testing, did not observe any test-related
variable other than pitch that led to a glare exceedance. While some
limited glare exceedances lasting less than 0.1 seconds were not
caused by pitch, these appeared to result from marginal performance
from the ADB system. The 0.1 second allowance means that such
exceedances would not be considered a noncompliance.
    \165\ See Section VIII.C.5, ADB Adaptation Time.
---------------------------------------------------------------------------

    NHTSA is removing the term ``spike'' and replacing it with a
clearer description of the adjustment: The agency will not consider, in
determining compliance, ``single illuminance values or consecutive
illuminance values occurring over a span of no more than 0.1 seconds
that exceed the applicable maximum illuminance[.]'' The momentary glare
exceedance duration may end in at least two ways. First, the
illuminance value can drop below the applicable glare limit. Second,
the glare limit itself might change (i.e., increase). This could happen
if the exceedance is experienced just before the glare limit changes.
In either case, if the glare limit is not exceeded for more than 0.1 s,
the exceedance will not be considered a noncompliance.
e. Vehicle Pitch
    Pitch refers to rotation of a vehicle about its transverse axis
appearing as an opposing vertical motion of the front and rear ends of
a vehicle. When a vehicle's pitch increases, the vehicle's front end,
and therefore the angle of its headlamps, will raise in an upward
direction away from the road surface. Conversely, when pitch decreases,
the vehicle's front end will lower, and the headlamps light will be
cast downward towards the road surface.
    The amount of glare perceived by other roadway users may be more
pronounced when the headlamp is pitched upward. Common causes of
changes in vehicle pitch angle include vehicle loading condition or
weight

distribution, tire inflation that deviates from specifications,
irregularities or pitting in the road surface, vehicle suspension
characteristics, and vehicle acceleration. As mentioned above, the NPRM
did not propose any adjustments to correct directly for or take vehicle
pitch into account as part of the compliance track testing, although it
specifically sought comment on this.
    In the IIHS test method, pitch effects are corrected by measuring
road surface pitch changes through a self-leveling horizontal rotary
laser system every 5 m along the test track surface. The pitch angles
at each measured position are measured, and photometers placed at
different heights provide the illuminance data for each measurement
location. Once this illuminance data is collected, a pitch correction
factor is calculated that is used to offset any exceedance of glare
limits based on the roadway conditions.
Comments
    As noted in the section above on allowances for momentary glare
exceedances, several commenters noted the potential effect of vehicle
pitch on test results. For this reason, Ford recommended NHTSA adopt
the IIHS pitch correction protocol. Ford commented that pitch
correction is essential to produce results that are independent of
differences in vehicle suspensions and are repeatable at different test
tracks and different locations on the test tracks themselves. Ford
noted that dynamic testing makes illuminance more difficult to measure
because throughout the driving event, the vehicle pitch changes and
effects from instrumentation inaccuracies increase proportionately. On
the other hand, Intertek claimed that pitch correction would not be
necessary unless there is a sustained change in pitch longer than 0.1
seconds.
Agency Response
    After analyzing the comments and its own testing NHTSA has modified
the proposal by adding in an explicit allowance for pitch variation:
The agency will not consider any illuminance measurements recorded
while the vehicle pitch exceeds the average pitch recorded throughout
the entire measurement distance range specified for that scenario by
more than 0.3 degrees.
    Although the NPRM did not propose any adjustments to directly take
vehicle pitch into account, the NPRM requested comment on this issue.
Further, the proposed test procedures controlled for the following
factors that could affect pitch:
     Vehicle loading and suspension--the headlamps will be
aimed when the vehicle is loaded as it will be during testing, and the
gas tank (if the vehicle is equipped with one) is maintained at lease
three-quarters full. The tires will be within 1 psi of recommended cold
pressure.
     Road surface--the road surface must have an IRI
measurement of less than 1.5 m/km.
     Vehicle acceleration--the vehicle speed must be maintained
within 1 mph of the target test speed throughout the test run.
    In addition to these procedures, as explained above, the proposal
also contained an allowance for momentary glare exceedances that was
intended to account for variations in illumination due to uncontrolled
testing variables, including minor imperfections in the road surface
that can cause glare exceedances by affecting vehicle pitch.
    Despite these specifications, NHTSA's test data revealed two
situations in which vehicle pitch still impacted measured illuminance
and were not accounted for in the provisions listed above.
    First, NHTSA repeatedly observed small cyclical pitch changes
related to road surface undulations, which affected illuminance
measurements. For one example, see Figure 34.
[GRAPHIC] [TIFF OMITTED] TR22FE22.032

    Here, where the maximum pitch occurs (at about 85 m), there is a
peak in the illuminance reading. The highest illuminance value (at
about 31 m) also coincides with a positive spike in pitch. (In these
instances, the pitch did not exceed the average pitch by more than 0.3
degrees, so if this were a compliance test, these values would still be
considered when assessing compliance; in any case, in this instance,
all illuminance values are still within the glare limits).
    To better understand the sources of the pitch oscillations
identified in testing, NHTSA collected pitch information both when the
test vehicle was moving, and when it was stationary at the same (or as
close as possible) location on the test surface. See Table 7. The pitch
measurements were similar, indicating that dynamic contributors were
generally small. Accordingly, although the testing did not show any
instances where pavement-related vehicle pitching led to a glare
exceedance that would be excused through the final pitch variation
allowance, the agency recognizes the possibility for this to occur and
has thus accounted for pitch in the regulatory text.

           Table 7--Vehicle Pitch in Static and Dynamic States
------------------------------------------------------------------------
                                                                 Pitch
                           Distance                              (deg.)
------------------------------------------------------------------------
Speed: 41 mph:
    148.982..................................................        0.3
    119.254..................................................       0.46
    59.605...................................................       0.51
    29.926...................................................       0.64
    15.145...................................................       0.65
Speed: 0 mph (static):
    149.058..................................................       0.17
    119.274..................................................       0.51
    59.650...................................................       0.46
    29.939...................................................       0.63
    15.152...................................................       0.63
------------------------------------------------------------------------

    Second, NHTSA observed pitch changes related to acceleration. For
example, NHTSA tested the lower beams on the Fusion at 69 mph in a
straight-path scenario. See Figure 35. When the vehicle reached the
beginning of the illuminance measurement range (220 m) it had not yet
attained the target speed, so it was still accelerating and pitching
upward, resulting in an ``exceedance'' of the applicable glare limit.
The pitch of 1.1 degrees during the exceedance was greater than 0.3
degrees over the average pitch of 0.68 degrees. This shows that pitch
in excess of the proposed allowance could lead to an exceedance of the
glare limits.\166\
---------------------------------------------------------------------------

    \166\ Because the target speed had not yet been attained, had
this been a compliance test, the measured illuminance value would
not be having been considered in determining compliance. We also
note that this glare exceedance lasted for more than 0.1 second, so
it would not have been addressed with the momentary glare allowance.
[GRAPHIC] [TIFF OMITTED] TR22FE22.033

    Based on these instances of vehicle pitch fluctuations impacting
measured illuminance (due to either the road surface or acceleration),
the final rule includes an allowance for vehicle pitch variation.
NHTSA's testing demonstrated that it is generally possible to maintain
pitch within less than 0.3 degrees of the average pitch recorded
throughout the entire measurement distance. We believe that no
allowance for pitch, or a higher pitch variation allowance (e.g., ``by
no more than 0.4 degrees)--resulting in a more stringent test--could
lead manufacturers to design headlamps providing sub-optimal visibility
(because manufacturers might aim the headlamps down to minimize the
possible effects of pitch during a compliance test).
    We believe this adjustment methodology is preferable to the IIHS
pitch correction procedure for the purposes of this rule. The IIHS test
procedure relies on interpolation, which introduces inaccuracy (without
knowing the linearity of the beam pattern). The final rule methodology
does not interpolate but instead measures pitch directly. By
controlling pitch to 0.3 degrees or less and regulating performance
only within that range, we are directly measuring the aspect of
performance that matters to safety. The IIHS procedure also requires
that the vehicle path be mapped with respect to pitch prior to running
the test. The final rule procedure does not require this, which
simplifies the test procedure.
11. Repeatability
    The NPRM included an analysis of the repeatability of the test data
from the 2015 ADB Test report.\167\ That test data was based on the
proposed test procedures, which utilized dynamic stimulus vehicles.
---------------------------------------------------------------------------

    \167\ NPRM, pp. 51789-51798.
---------------------------------------------------------------------------

Comments
    NHTSA received a variety of comments on the repeatability of the
proposed test. One commenter, Intertek, agreed with NHTSA's
repeatability analysis. Other commenters expressed concerns that the
proposed test procedures were not repeatable based upon the complexity
of the proposed test procedures and a variety of test conditions that
might affect repeatability. Commenters identified several factors they
argued would adversely affect repeatability.\168\
---------------------------------------------------------------------------

    \168\ A number of comments about repeatability were related to
the proposal to use stimulus vehicles. Because the final rule does
not use stimulus vehicles, we need not address those comments as the
issue is moot.
---------------------------------------------------------------------------

    Auto Innovators, MEMA, the Alliance, TSEI, and Volkswagen commented
that the proposed track testing was overly complicated and expressed
concerns that it would not lead to repeatable results.
    SAE commented generally that test results (both for tests conducted
on the same track and for tests conducted on different tracks) would be
sensitive to the environment because lighting measurements are affected
by small changes in conditions. Other commenters echoed this and
identified unspecified test conditions that they argued could introduce
uncontrolled variability, causing acceptable levels of repeatability
and reproducibility of the test scenarios to be extremely challenging
to achieve, particularly given the stringency of the requirements. The
Alliance and Volkswagen commented that, although the NPRM requires the
photometers to be zero-calibrated to the ambient light, the ambient
light can change throughout the data collection, introducing
uncontrollable variability. Volkswagen

also stated that the presence of reflectors in the environment may also
cause variances by redirecting part of the test vehicle lights into the
photometers. Volkswagen also commented that the NPRM only specified
that there be no precipitation and a dry road surface, but other
environmental conditions such as fog, dust, or pollution could affect
results. TSEI identified variation in road materials and reflectivity,
weather conditions, and road surface as other factors. Toyota
identified the test vehicle's suspension, tires, and acceleration/
deceleration during the test as affecting repeatability; it stated that
it is unclear whether any test track meets the ideal conditions
specified in the proposal, and, if so, whether such a test track can be
reasonably accessible to conduct compliance testing.
    Auto Innovators commented that to evaluate testing variability, one
member company repeated a test series using a vehicle tested by FTTA
and cited in the NPRM. The full test series was repeated under the same
conditions using comparable measurement equipment. The commenter stated
that, despite careful attention to test setup and test conditions, the
results varied from those obtained by FTTA to the extent that the
variation altered the compliance status of the vehicle.
Agency Response
    The final rule substantially reduces the complexity of the test,
especially by using test fixtures instead of stimulus vehicles and
streamlining the test scenarios. Further, while it is true that
lighting measurements can be sensitive to small changes in conditions,
NHTSA's testing has shown that measurement of headlamp illuminance
using the whole vehicle, rather than a component-level test, can be
accomplished in a repeatable manner.\169\ NHTSA has identified, and the
test parameters and conditions specified in the final rule control for,
the major sources of test-related variability, including vehicle pitch.
This final rule also includes a data filter, which will smooth out the
measured illuminance data, in addition to the proposed allowance for
momentary glare exceedances, which should address any otherwise
uncontrolled ambient illumination, among other things.
---------------------------------------------------------------------------

    \169\ 2105 ADB Test Report, p. 172.
---------------------------------------------------------------------------

    NHTSA conducted a series of tests to determine the level of
variability in the track test finalized today, as well as the SAE J3069
test method.\170\ To do this, NHTSA analyzed data from testing using
the original-equipment lower beams on a FMVSS-certified 2016 Volvo
XC90. Multiple runs of each test scenario were conducted to permit
different types of repeatability analyses, including: Same night
(gauge); different night (test procedure); and different headlamp
aiming technician (reproducibility). Data from these test trials were
analyzed for each measurement distance sub-range (interval),
calculating the mean, standard deviation, 95% confidence interval, and
95% prediction interval.\171\ Sample results of Test Number 1
(straight--oncoming) for the sub-range of 120 m to 220 m are shown
below in Tables 8 through 10. (Throughout this section, ``Test Number''
refers to the scenario test numbers as reported in the repeatability
report. Please see Table 1 (NHTSA Test Matrix) in that report. The test
scenarios in the repeatability report are the same as the test
scenarios specified in Table XXII of this final rule, but the numbering
of the test scenarios differs.) Data similar to this (i.e., 10 test
repetitions, 10 separate test days, and 3 headlamp aiming technicians)
were collected for every final rule scenario. Testing with the lower
beam headlamps activated (the test vehicle was not ADB-equipped)
allowed the agency to isolate variability to factors related to the
test and to be certain that ADB performance itself did not contribute
to variability. Oncoming and same direction data were collected during
the same run, using receptor heads (i.e., light sensors) placed in the
appropriate positions.
---------------------------------------------------------------------------

    \170\ See Mazzae, E.N., Baldwin, G.H.S., Satterfield, K., &
Browning, D.A. 2021. Adaptive Driving Beam Headlamps Test
Repeatability Assessment. Washington, DC: National Highway Traffic
Safety Administration. The discussion here is a summary of that
report, which has been placed in the docket for this rulemaking.
    \171\ NHTSA has used similar analyses before to assess the
reliability and repeatability of test methods developed for FMVSS.
As an example, refer to the test report ``Repeatability,
Reproducibility, and Sameness of Quiet Vehicle Test Data''
supporting the development of FMVSS No. 141, Minimum sound level for
hybrid and electric vehicles. See Docket number NHTSA-2016-0125-0006
at www.regulations.gov.

                Table 8--NHTSA Test No. 1, 220 m-120 m, Gauge (Measurement System) Repeatability
----------------------------------------------------------------------------------------------------------------
                                                                                Difference
                                                                                between pitch
                                                                                maximum (sub-
                                 Repetition    Car  eye point    Cycle  eye      Truck  eye     range) and pitch
    Descriptive statistic        (all in one        (lux)       point  (lux)    point  (lux)    average (entire
                                   night)                                                         measurement
                                                                                distance)
                                                                                (degrees)
----------------------------------------------------------------------------------------------------------------
                                            1          0.0688          0.0751          0.0652             0.0900
                                            2          0.0666          0.0802          0.0602             0.1600
                                            3          0.0751          0.0724          0.0618             0.1400
                                            4          0.0665          0.0764          0.0560             0.1000
                                            5          0.0686          0.0675          0.0561             0.1100
                                            6          0.0711          0.0722          0.0599             0.1000
                                            7          0.0709          0.0730          0.0542             0.1100
                                            8          0.0830          0.0763          0.0590             0.1000
                                            9          0.0693          0.0822          0.0574             0.0900
                                           10          0.0736          0.0822          0.0625             0.1400
Mean.........................  ..............          0.0714          0.0758          0.0592  .................
StdDev (S)...................  ..............          0.0049          0.0048          0.0034  .................
Min..........................  ..............          0.0665          0.0675          0.0542  .................
Max..........................  ..............          0.0830          0.0822          0.0652  .................
95% C.I. Margin of Error (+/-  ..............          0.0035          0.0034          0.0024  .................
 )...........................
95% C.I. Upper Limit.........  ..............          0.0749          0.0791          0.0617  .................
95% C.I. Lower Limit.........  ..............          0.0678          0.0724          0.0568  .................
95% Prediction Interval        ..............          0.0117          0.0113          0.0080  .................
 Margin of Error (+/-).......

95% P.I. Upper Limit.........  ..............          0.0831          0.0870          0.0673  .................
95% P.I. Lower Limit.........  ..............          0.0596          0.0645          0.0512
----------------------------------------------------------------------------------------------------------------

                      Table 9--NHTSA Test No. 1, 220 m-120 m, Test Procedure Repeatability
----------------------------------------------------------------------------------------------------------------
                                                                                Difference
                                                                                between pitch
                                 Repetition                                                      maximum (sub-
    Descriptive statistic         (one per     Car  eye point    Cycle  eye      Truck  eye     range) and pitch
                                   night)           (lux)       point  (lux)    point  (lux)    average (entire
                                                                                test  number
                                                                                range)  (degrees)
----------------------------------------------------------------------------------------------------------------
                                            1          0.0839          0.0905          0.0774             0.1048
                                            2          0.0847          0.0805          0.0564             0.1072
                                            3          0.0796          0.0857          0.0662             0.1030
                                            4          0.0713          0.0772          0.0522             0.1313
                                            5          0.0745          0.0865          0.0634             0.1061
                                            6          0.0777          0.0865          0.0614             0.1260
                                            7          0.0717          0.0745          0.0554             0.1226
                                            8          0.0794          0.0718          0.0559             0.1271
                                            9          0.0817          0.0884          0.0679             0.1210
                                           10          0.0815          0.0686          0.0581             0.0990
Mean.........................  ..............          0.0786          0.0810          0.0614  .................
StdDev (S)...................  ..............          0.0048          0.0076          0.0076  .................
Min..........................  ..............          0.0713          0.0686          0.0522  .................
Max..........................  ..............          0.0847          0.0905          0.0774  .................
95% C.I. Margin of Error (+/-  ..............          0.0034          0.0055          0.0054  .................
 )...........................
95% C.I. Upper Limit.........  ..............          0.0820          0.0865          0.0668  .................
95% C.I. Lower Limit.........  ..............          0.0752          0.0755          0.0560  .................
95% Prediction Interval        ..............          0.0113          0.0181          0.0179  .................
 Margin of Error (+/-).......
95% P.I. Upper Limit.........  ..............          0.0899          0.0991          0.0794  .................
95% P.I. Lower Limit.........  ..............          0.0673          0.0629          0.0435
----------------------------------------------------------------------------------------------------------------

                                                Table 10--NHTSA Test No. 1, 220 m-120 m, Reproducibility
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Difference
                                                                                between pitch
                                                                                maximum (sub-
            Descriptive statistic                      Aimer             Repetition     Car eye point     Cycle eye       Truck eye     range) and pitch
                                                                                (lux)        point (lux)     point (lux)    average (entire
                                                                                test  number
                                                                                range)  (degrees)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                              A                                     1          0.0545          0.0599          0.0578             0.1323
                                              B                                     1          0.0673          0.0672          0.0581             0.1522
                                              B                                     2          0.0658          0.0662          0.0556             0.0977
                                              C                                     1          0.0632          0.0631          0.0545             0.0983
                                              C                                     2          0.0676          0.0663          0.0540             0.1549
Mean........................................  .......................  ..............          0.0637          0.0645          0.0560  .................
StdDev (S)..................................  .......................  ..............          0.0054          0.0030          0.0019  .................
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The standard deviation is a measurement of the variation within the
data set. The 95th percentile confidence interval is the estimate of
the upper and lower illuminance values in which there is a 95%
probability that the true mean falls within this interval. The
confidence interval is calculated using the equation
[GRAPHIC] [TIFF OMITTED] TR22FE22.034

    Where the margin of error is calculated using t as the upper
critical value for the t distribution with n-1 degrees of freedom, S as
the standard deviation, n as sample size. The confidence interval is
then calculated by summing the mean (x) and the margin of error. The
95th percentile prediction interval is the estimate of the interval of
which there is a 95% probability that future measurements will be
within. The prediction interval is calculated using the equation:
[GRAPHIC] [TIFF OMITTED] TR22FE22.035

    Where the margin of error is calculated using t as the upper
critical value for the t distribution with n-1 degrees of freedom, S as
the standard deviation, and n as the sample size. The prediction
interval is then calculated by summing the mean (x) and the margin of
error.
    Note that CI95 and PI95 are
dependent on the number of values collected (t0.975 is large
for small sample sizes and decreases as more data are collected). That
is to say, the more data collected for a distribution, the more
confident we can be of where the true mean is located and where future
measurement values will fall. While a standard deviation can be
calculated for a very small sample size, CI and PI will be large for
small samples, even if the population standard deviation is small.
Taken together, the standard deviation and the prediction interval can
be used to quantify the repeatability of the test procedure. The
smaller the standard deviations and the tighter the prediction
interval, the smaller the range of values we will expect future values
to be within, indicating a tighter precision of measurement system.
    The magnitude of the prediction intervals can be used to determine
how a vehicle with a similar headlighting system and beam pattern is
likely to perform with respect to the glare limits. The prediction
interval indicates the range within which a similar vehicle's measured
illuminance value is 95% likely to fall (5% chance of not falling
within the range). If the upper end value of the prediction interval is
less than the glare limit for a measurement distance sub-range, then a
similar vehicle's measured value is at least 95% likely to be less than
the glare limit when tested by NHTSA.\172\ Because the repeatability of
the measurement system and test procedure produced small standard
deviations, the variability of the illuminance values should not differ
substantially, even if the maximum illuminance value for other
headlighting systems is higher. This assumption holds true provided the
headlamp beam pattern under test demonstrates similar gradients in and
around the measurement locations.
---------------------------------------------------------------------------

    \172\ For example, if this analysis produces a 95% prediction
interval of 0.180 lux and the limit is 1.8, a system with a true
performance of 1.62 or less will have a 95% or greater probability
of receiving a passing score if the agency were to do a compliance
test, using a single run.
---------------------------------------------------------------------------

    Table 11 below pools the standard deviation for the oncoming
straight and left curve scenarios (Test Number 1,3,4,7--each of these
tests provide similar means), and the same direction straight and left
curve scenarios (Test Number 2,5), and lists the standard deviation
observed for the oncoming right medium curve (Test Number 6) and
oncoming-right large curve (Test Number 8) for each measurement
distance sub-range.

                              Table 11--Test Procedure: Standard Deviation Results
----------------------------------------------------------------------------------------------------------------
                                                           Same direction
                                        Oncoming NHTSA       NHTSA test       Oncoming right     Oncoming right
                NHTSA                  test numbers  1,     numbers 2, 5        NHTSA test         NHTSA test
                                        3, 4, 7  (lux)         (lux)         number 6  (lux)    number 8  (lux)
----------------------------------------------------------------------------------------------------------------
Measurement Distance Sub-Range:                        All standard deviations were at or below:
                                     ---------------------------------------------------------------------------
    220 m-120 m.....................             0.0076  .................  .................  .................
    150 m-120 m.....................             0.0068  .................  .................  .................
    119.9 m-60 m....................             0.0156  .................  .................  .................
    100 m-60 m......................  .................             0.0153  .................  .................
    70 m-60 m.......................  .................  .................  .................             0.5996
    59.9 m-30 m.....................             0.0599             0.0494  .................             0.5921
    50 m-30 m.......................  .................  .................             0.9648  .................
    29.9 m-15 m.....................             0.0713             0.1324             0.0651             0.0602
----------------------------------------------------------------------------------------------------------------

                                                           Table 12--Prediction Interval Margin of Error Values of the Test Procedure
                                                                                [NHTSA Test]
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                 Glare
Measurement distance sub-range   limit    Test number 1      Test number 2      Test number 3      Test number 4      Test number 5      Test number  6      Test number 7      Test number  8
                                 (lux)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                     95th Percentile Prediction Interval Car Eye Point/Passenger Side Mirror (Values in lux)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
220 m-120 m...................     0.3  0.0113 (3.8%)....  .................  .................  .................  .................  ..................  0.0128 (4.3%)....  ..................
150 m-120 m...................     0.3  .................  .................  .................  0.0145 (4.8%)....  .................  ..................  .................  ..................
119.9 m-60 m..................     0.6  0.0357 (6.0%)....  .................  .................  0.0238 (4.0%)....  .................  ..................  0.0171 (2.9%)....  ..................
70 m-60 m.....................     0.6  .................  .................  .................  .................  .................  ..................  .................  1.4225 (237%) *
50 m-30 m.....................     1.8  .................  .................  .................  .................  .................  2.2890 (127%) *...  .................  ..................
59.9 m -30 m..................     1.8  0.0741 (4.1%)....  .................  0.0690 (3.8%)....  0.0933 (5.2%)....  .................  ..................  0.0812 (4.5%)....  1.4047 (78%) *
29.9 m-15 m...................     3.1  0.1436 (4.6%)....  .................  0.1672 (5.4%)....  0.1693 (5.5%)....  .................  0.1534 (4.9%).....  0.1637 (5.3%)....  0.1427 (4.6%)
100 m-60 m....................     4.0  .................  0.0331 (0.8%)....  .................  .................  0.0189 (0.5%)....  ..................  .................  ..................

59.9 m-30 m...................    18.9  .................  0.0963 (0.5%)....  .................  .................  0.1121 (0.6%)....  ..................  .................  ..................
29.9 m-15 m...................    18.9  .................  0.2348 (1.2%)....  .................  .................  0.3141 (1.7%)....  ..................  .................  ..................
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

    The prediction intervals shown in Table 12 are small compared to
the limits that are finalized for each measurement distance sub-range.
For instance, we found that within the sub-range of 120 m to 220 m Test
Number 1 resulted in a prediction interval of 0.0113 lux as compared to
the limit of 0.3 lux. This interval represents 3.8% of the limit.
    Both measurement system (gauge) repeatability results and full test
repeatability results revealed NHTSA test scenarios involving right
curves (Test Numbers 6 and 8) to be less repeatable than the other test
scenarios (marked with * in the table). Unsurprisingly, these two
scenarios showed a pattern of higher standard deviations with respect
to the other NHTSA test scenarios. SAE Test Drive 3, in which the test
fixture was located to the right of the test vehicle also showed a
pattern of higher standard deviations as compared to the other
scenarios. As is the case with many U.S. vehicle lower beam headlamps,
the 2016 Volvo XC90 lamps produced beam patterns with a higher right-
side horizontal cutoff. The variability of measurements recorded on the
right side of the vehicle (right curve scenarios) is attributable to
the cutoff at the right portion of the headlamp pattern of this vehicle
projecting near the location of the lower-mounted light sensors. The
lower beam headlamps tested in this repeatability study exceeded the
glare limits for these two-measurement distance sub-ranges as well. An
ADB pattern designed to meet the requirements finalized today will need
to provide a greater angular distance between the cutoff and the light
sensors to meet the minimum glare requirements as described earlier in
the right curve discussion. With such a design, the agency anticipates
that similar repeatability will be obtained for right curves as was
demonstrated for the other scenarios.
    Breaking down the 8 NHTSA test scenarios by measurement distance
sub-range and measurement points (light sensor locations) gives a total
of 99 data points. The finalized test method found the same pass/fail
results for 97 of the 99 data points in every one of the 10 test
procedure repetitions. For the vehicle's lower beam headlamps under
test, 94 of those data points, without fail, were under the glare limit
criteria and 3 of the data points consistently exceeded the glare
limits. The vehicle consistently failed to meet the glare criteria for
Test Number 6 (medium right curve) at the car eye point for the sub-
range 50 m-30 m. It also consistently failed to meet the glare
criterion for Test Number 8 (Large Right Curve) at the Car Eye and
Cycle Eye point for the sub-range 70 m-60 m. The 2 data points with
inconsistent results (sometimes the test reported that the vehicle met
the criteria and other times it reported a failure) were also found on
these two right curve tests. Test Number 6 had mixed results at the
cycle eye point for the sub-range 50 m-30 m and Test Number 8 had mixed
results at the car eye point for the sub-range 59.9 m-30 m. As
discussed above, we do not expect any mixed results for an ADB beam
pattern designed to meet the track test finalized today.
    NHTSA also conducted testing to examine the possibility of
variability introduced by different technicians visually aiming the
headlamps. This reproducibility analysis examined the effects of three
different technicians performing headlamp aiming prior to running a
test set. This analysis found only small differences in illuminance
measurements between datasets associated with different headlamp aiming
operators. The pooled standard deviations for each orientation are
shown in Table 13 below.

          Table 13--Reproducibility: Standard Deviation Results
------------------------------------------------------------------------
                                      Oncoming NHTSA     Same direction
                                     test numbers 1,       NHTSA test
                                      3, 4, 6, 7, 8       numbers 2, 5
                                          (lux)              (lux)
------------------------------------------------------------------------
Measurement Distance Sub-Range:      All standard deviations were below:
                                   -------------------------------------
    220 m-120 m...................             0.0055  .................
    150 m-120 m...................             0.0069  .................
    119.9 m-60 m..................             0.0123  .................
    100 m-60 m....................                N/A             0.0153
    70 m-60 m.....................             0.0122  .................
    59.9 m-30 m...................             0.0366             0.0521
    50 m-30 m.....................             0.0355  .................
    29.9 m-15 m...................             0.0933             0.1264
------------------------------------------------------------------------

    NHTSA also assessed the repeatability of the SAE J3069 test (Table
14). We found that the SAE test resulted in similar variability of both
measured illuminance and test outcomes.

                              Table 14--Test Procedure: Standard Deviation Results
----------------------------------------------------------------------------------------------------------------
                                                           Same direction
                                        Oncoming NHTSA       NHTSA test       Oncoming right     Oncoming right
                NHTSA                  test numbers  1,     numbers 2, 5        NHTSA test         NHTSA test
                                        3, 4, 7  (lux)         (lux)         number 6  (lux)    number 8  (lux)
----------------------------------------------------------------------------------------------------------------
Measurement Distance Sub-Range:                        All standard deviations were at or below:
                                     ---------------------------------------------------------------------------
    220 m-120 m.....................             0.0076  .................  .................  .................
    150 m-120 m.....................             0.0068  .................  .................  .................
    119.9 m-60 m....................             0.0156  .................  .................  .................
    100 m-60 m......................  .................             0.0153  .................  .................
    70 m-60 m.......................  .................  .................  .................             0.5996
    59.9 m-30 m.....................             0.0599             0.0494  .................             0.5921
    50 m-30 m.......................  .................  .................             0.9648  .................
    29.9 m-15 m.....................             0.0713             0.1324             0.0651             0.0602
----------------------------------------------------------------------------------------------------------------

                                      Oncoming SAE test    Preceding SAE                         Preceding SAE
                 SAE                     drives 1, 2      test drives  10,  Oncoming SAE test    test drive 12
                                            (lux)          11, 12  (lux)      drive 3  (lux)         (lux)
----------------------------------------------------------------------------------------------------------------
Measurement Distance:                                  All standard deviations were at or below:
                                     ---------------------------------------------------------------------------
    155.............................             0.0141             0.0228             0.1234             0.1436
    120.............................             0.0132             0.0231             0.1489             0.1909
    60..............................             0.0219             0.0226             0.2464             0.3020
    30..............................             0.0380             0.0341             0.0413             0.3503
----------------------------------------------------------------------------------------------------------------

D. Laboratory (Component-Level) Testing

1. Need for Laboratory Testing
    The NPRM proposed that an ADB system would also be subject to the
existing component-level laboratory-based upper and lower beam
photometry requirements. With respect to the adaptive beam, the NPRM
proposed that an area of reduced intensity meet the applicable Table
XIX lower beam photometry requirements (maxima and minima), and that an
area of unreduced intensity meet the applicable Table XVIII upper beam
photometry requirements. The NPRM proposed that when the ADB system is
producing a lower beam, that beam be subject to all the Table XIX lower
beam requirements, and when producing an upper beam, the beam be
subject to all the Table XVIII upper beam photometric requirements. The
NPRM proposed to require that the system provide only a lower beam when
the vehicle is travelling less than 25 mph (unless overridden by the
driver).\173\
---------------------------------------------------------------------------

    \173\ For a general explanation of the laboratory photometry
requirements, see the NPRM at p. 51770.
---------------------------------------------------------------------------

    This differed from SAE J3069 in some respects. SAE J3069 only
specifies that the lower beam maxima are not exceeded within the area
of reduced intensity, and that the lower beam minima be met in the area
of unreduced intensity. (These provisions reference the relevant SAE
photometric standards; the proposal instead appropriately referenced
the upper and lower beam photometric requirements in Tables XVIII and
XIX of the standard.)
Comments
    Some commenters supported the inclusion of at least some laboratory
testing requirements. AAA and Intertek supported applying the existing
upper beam photometric requirements to the upper beam, Consumer Reports
supported requiring that the part of the adaptive beam that is cast
near other vehicles not exceed the current lower beam maxima, and the
part of the adaptive beam that is cast onto unoccupied roadway not
exceed the current upper beam maxima. Consumer Reports also supported
applying the lower beam minima to areas of reduced intensity and the
upper beam minima to areas of unreduced intensity. Zoox supported
applying the existing laboratory requirements to the upper and lower
beams.
    In contrast, both SAE and Global disagreed that photometric
component testing is necessary in addition to vehicle testing. SAE
explained that, when SAE J3069 was published, component level testing
was included as an additional metric to aid in lamp manufacturers'
process controls and also because it is a familiar compliance method.
The SAE J3069 rationale accordingly explained that, if vehicle-level
testing of ADB systems were to be included in FMVSS No. 108, ``any need
for laboratory photometric requirements may be reconsidered for
removal.'' SAE therefore requested that the final rule not include
component testing.
Agency Response
    The final rule retains the laboratory testing requirements because
the full-vehicle track test alone may not be sufficient to ensure that
an ADB system provides adequate visibility and does not glare other
vehicles, as discussed further below. Accordingly, the final rule
applies the existing laboratory testing requirements to any beam an ADB
system may provide (a lower beam, an upper beam, or an adaptive driving
beam). (The different types of beams classified in the final rule are
discussed in Section VIII.D.2.)
    The full vehicle track test and the laboratory-based component test
are complementary. The full vehicle dynamic track test only evaluates
glare; it does not evaluate visibility. The final requirements include
laboratory testing requirements that ensure that the ADB system always
provides the driver with a minimum level of visibility.
    The laboratory testing requirements generally assure adequate
visibility by specifying minimum levels of light at certain locations
(test points) that roughly correspond to different locations on the
road. As explained in Section VIII.D.2, we have modified the proposal
to give manufacturers greater flexibility in determining which areas of
the roadway receive an area of reduced intensity or an area of
unreduced intensity. For the former, the appropriate minimum visibility
is the applicable lower beam minima; for the

latter, the appropriate minimum visibility is the applicable upper beam
minima. Similarly, the lower beam minima indicate the appropriate
minimum visibility for the lower beam, and the upper beam minima for
the upper beam.
    Laboratory testing will complement the track test to minimize glare
to other vehicles. The laboratory testing requirements minimize glare
by specifying photometric maxima at certain test points. The track test
evaluates whether an ADB system glares a test fixture in specific
scenarios. While the final track test requirements encompass many
common scenarios (e.g., a single oncoming vehicle in the adjacent
lane), they do not test every conceivable scenario. Laboratory testing
will therefore help serve as a backstop to the track test. Moreover,
the track test evaluates glare out to 220 meters. Extremely bright
upper beams (for example, an ECE-approved upper beam that exceeds the
current FMVSS No. 108 75,000 cd upper beam maximum) could create glare
further than this distance. The laboratory testing requirements will
therefore also ensure that upper beams are not exceedingly bright.
(Indeed, if the current upper beam maxima did not apply to the upper
beam of an ADB system, upper beam maximum intensity would effectively
be unregulated). Accordingly, the final rule specifies that the lower
beam and an area of reduced intensity must not exceed any applicable
Table XIX (lower beam) maxima, and the upper beam and areas of
unreduced intensity must not exceed any applicable Table XVIII (upper
beam) maxima.
2. Definitions of Areas of Reduced and Unreduced Intensity
    The NPRM proposed (in S<IP_ADDRESS>.6-.7) that ``when the system is
producing a lower beam with an area of reduced light intensity designed
to be directed towards oncoming or preceding vehicles, and an area of
unreduced intensity in other directions,'' the system must meet the
Table XIX (lower beam) photometric requirements within the area of
reduced intensity and the Table XVIII (upper beam) photometric
requirements in the within the area of unreduced intensity. The
proposed rule did not otherwise define the areas of reduced and
unreduced intensity.
Comments
    Several commenters suggested clarifications to the definitions or
references to the areas of reduced and unreduced intensity. ALNA, Zoox,
and Valeo commented that the definitions of the area of reduced
intensity and/or area or unreduced intensity were unclear. Mercedes
suggested expanding the definition of the area of reduced intensity to
include portions of the roadway other than those occupied by other
vehicles because sophisticated ADB systems are capable of dimming areas
of the beam pattern directed towards retroreflective signs or wet road
surfaces in order to minimize glare to the driver. Stanley requested
confirmation that the area of reduced intensity corresponds to the
windshield area of an oncoming vehicle and the area of unreduced
intensity refers to the area outside of the area of reduced intensity.
Ford suggested edits to clarify the regulatory text setting out the
dimmed and undimmed area requirements. It suggested that instead of
referring to the lower beam, the regulatory text refer to the
``adaptive driving beam,'' and suggested rearranging the regulatory
text. Valeo similarly commented that classifying the adaptive beam as a
lower beam is misleading because it is actually a modified driving or
upper beam and suggested including a definition of ``adaptive driving
beam.'' Intertek suggested requiring that the system emit a base lower
beam, which is only augmented by adding light to the portions of the
beam in which a preceding or oncoming vehicle is not detected, to the
limit that when there are no preceding or coming vehicles detected the
emitted beam is a compliant upper beam. This would, it contended,
ensure that the augmented lower beam is always compliant to the
applicable lower beam photometry requirements. Zoox commented that the
NPRM appeared to assume that the adaptive beam is a defined, static
beam pattern that is generated based on camera recognition of oncoming
or preceding traffic. It stated that the laboratory test requirements
should be technology neutral with respect to the manner and method of
controlling and producing an adaptive beam.
    Some commenters requested that the agency establish more specific
laboratory test requirements. Zoox commented that the proposed
laboratory test requirements were not clear on how to determine which
portion of an adaptive beam is to be checked against the lower beam or
upper beam minima and maxima. For example, a system may progressively
dim an LED array across the headlamp width as vehicle distance closes
for oncoming traffic. The ADB pattern may also differ for oncoming
versus preceding traffic. Zoox requested clarification of which test