FCWs provided for lead vehicle AEB and PAEB imminent crash scenarios
should maximize the likelihood that drivers will associate the FCW with
a forward crash of any sort. As such, the agency is not proposing
different symbols for the visual FCW modality based on the type of
forward obstacle to which the AEB is responding.
    When evaluating existing PAEB systems through NHTSA's 2020 research
testing, the agency found that during certain test scenarios, FCW did
not occur prior to the onset of automatic braking.\165\ NHTSA
tentatively concludes that, due to the dynamics of some pedestrian
crashes that result in a quick succession of events, it is impractical
to require that the warning and automatic braking be sequential, as it
could potentially hinder the reaction time of AEB systems. The agency
anticipates that FCW may occur at any time during the automatic braking
event. When it occurs after onset of automatic braking, the FCW would
serve to inform the driver that automatic braking is ongoing, rather
than solicit a driver response.
---------------------------------------------------------------------------

    \165\ As an example, when testing the Obstructed Running Child,
Crossing Path from the Right Scenario (see following paragraphs for
scenario description) with a MY 2020 Subaru Outback traveling at 16
km/h the onset of the alert was 0.92s (FCW on time history plot) and
service brake application was at 0.91 s (PAEB on time history plot)
essentially at the same time. ``Final Report of Pedestrian Automatic
Emergency Braking System Research Testing of a 2020 Subaru Outback
Premium/LDD,'' https://www.regulations.gov/document/NHTSA-2021-0002-0002, See: Figure D66. Time History for PAEB Run 180, S1d, Daytime,
16 km/h.
---------------------------------------------------------------------------

F. PAEB--Performance Test Requirements

    NHTSA is proposing that AEB-equipped vehicles avoid a collision by
applying the brakes automatically and alerting the vehicle operator
when a collision with a pedestrian is imminent under specified test-
track scenarios. Similar to the lead vehicle AEB performance test
requirements, NHTSA has tentatively concluded that a no-contact
requirement is necessary for PAEB testing in order to maximize safety.
Even low-speed vehicle impacts with pedestrians can result in
fatalities and serious injuries. NHTSA has tentatively concluded that a
no-contact criterion for the performance test requirements is
practicable to achieve, consistent with the need for safety, and may be
necessary to ensure test repeatability.\166\
---------------------------------------------------------------------------

    \166\ Requiring vehicles to avoid contact during testing
addresses practical considerations as well. These practical
considerations are discussed in section VI.G of this NPRM, in which
NHTSA seeks comment on alternatives to the no-contact requirement.
---------------------------------------------------------------------------

    The test scenarios proposed for PAEB evaluation involve track tests
and are based on previous research completed by the agency to evaluate
existing PAEB systems and on knowledge and experience from developing
the related NCAP test procedures.\167\ The proposed speed ranges and
other key parameters detailed in the following sections are based on
the observed capabilities of PAEB systems, limitations of the
pedestrian test mannequins, and the safety problem.\168\
---------------------------------------------------------------------------

    \167\ See Research section of this notice, 87 FR 13452 (Mar. 9,
2022) at 13472 and 13473, and https://www.regulations.gov/document/NHTSA-2021-0002-0002.
    \168\ See Safety Problem section of this notice.
---------------------------------------------------------------------------

    Manual brake application by the driver is not a parameter of the
proposed test scenarios for PAEB. However, NHTSA anticipates that,
because AEB systems will be tested under the proposed requirements with
manual brake activation for lead vehicle, that functionality will exist
for

PAEB.\169\ The absence of manual brake application in NHTSA's proposed
test parameters should not be construed to mean that AEB systems should
not function when a manually applied brake input is present.
---------------------------------------------------------------------------

    \169\ Since supplementing brake application is a functionality
that must already exist for the lead vehicle AEB based on this NPRM,
NHTSA anticipates the same capability will be provided when the
subject vehicle encounters an emergency braking situation involving
a pedestrian and manual braking is applied.
---------------------------------------------------------------------------

    The proposed series of on-track tests fall into three groups of
scenarios based on the pedestrian test mannequin actions. The first
group of scenarios involves the test mannequin crossing the path of the
vehicle. In each of the first group of scenarios, the test mannequin
travels perpendicular to the vehicle's path. In the second group, the
test mannequin is stationary within the path of the vehicle. In the
third group, the test mannequin is moving along the travel path of the
vehicle. In all scenarios, the test is set up such that the subject
vehicle would collide with the test mannequin if it did not
automatically brake. The key test parameters for the PAEB test
scenarios include the type of test mannequin, the initial location of
the test mannequin, the direction of travel of the test mannequin, the
point on the subject vehicle that would impact the test mannequin (the
overlap), the vehicle speed, the speed of the test mannequin, the
ambient light condition, and the headlamp beam used during darkness
    These key test parameters and the combinations in which they will
be used are summarized in Table 23. The sections that follow provide
more detail about how and why these key test parameters where selected.

                                                 Table 23--PAEB Collision Avoidance Key Test Parameters
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Speed (km/h)
                                          Pedestrian surrogate reference       Overlap  -----------------------------------------   Lighting condition
                                                     location                    (%)           Subject vehicle        Pedestrian
--------------------------------------------------------------------------------------------------------------------------------------------------------
Crossing Path.......................  Right.................................         25  Any 10-60.................            5  Daylight.
                                      Right.................................         50  Any 10-60                                Daylight.
                                      Right.................................         50  Any 10-60 \1\                            Lower Beams.
                                      Right.................................         50  Any 10-60                                Upper Beams.
                                      Right \2\.............................         50  Any 10-50.................        \3\ 5  Daylight.
                                      Left..................................         50  Any 10-60.................        \4\ 8  Daylight.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Stationary Along Path...............  Right.................................         25  Any 10-55.................            0  Daylight.
                                                                                Any 10-55 \1\.............               Lower Beams.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Any 10-55                                Upper Beams.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Moving Along Path...................  Right.................................         25  Any 10-65.................            5  Daylight.
                                                                                Any 10-65 \1\.............               Lower Beams.
                                                                                Any 10-65 \1\                            Upper Beams.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Final speed range requirements after an additional one-year phase-in.
\2\ Obstructed, running child.
\3\ Running child.
\4\ Running adult.

    There are certain test conditions in Table 23 where the test speed
would be implemented one additional year after the initial proposed
phase-in. Based on the performance of existing PAEB systems during the
agency's dark lower-beam and dark upper-beam pedestrian tests, NHTSA
proposes a reduced speed range for the first three years after the
proposed requirements are to take effect. As discussed further in this
notice, NHTSA has tentatively concluded that this approach would afford
adequate lead time for vehicle manufacturers and suppliers to adjust
their PAEB system designs for higher speed ranges in these scenarios.
Table 24 summarizes the scenarios to which these changes apply. The
agency proposes that four years after the date of publication of the
final rule, the performance testing requirements follow all the key
parameters in Table 23. A more detailed discussion on the phase-in
appears further below in this section. Concurrent with the development
of this proposal, NHTSA conducted testing of model year 2021 and model
year 2022 vehicles using the proposed performance test requirements.
The details of these tests and results are docketed with this proposed
rule.

                                      Table 24--PAEB Collision Avoidance Key Test Parameters, Reduced Speed Ranges
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Speed (km/h)
                                          Pedestrian surrogate reference      Overlap  ----------------------------------------
                                                     location                   (%)                                    Test        Lighting condition
                                                                                Vehicle            mannequin
--------------------------------------------------------------------------------------------------------------------------------------------------------
Crossing Path.......................  Right................................         50  Any 10-40................            5  Lower Beams.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Stationary Along Path...............  Right................................         25  Any 10-50................            0  Lower Beams.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Moving Along Path...................  Right................................         25  Any 10-60................            5  Lower Beams.
                                                                                Any 10-60................               Upper Beams.
--------------------------------------------------------------------------------------------------------------------------------------------------------

In all PAEB collision avoidance scenarios (see Table 23 and Table 24)
the vehicle must avoid a collision with the pedestrian through use of
the vehicle's AEB system without manual brake input.
    NHTSA evaluated various scenarios when developing the draft NCAP
test procedures for PAEB.\170\ During this evaluation, four scenarios
were found to account for 98 percent of functional years lost (i.e.,
the years of life lost due to fatal injury and the years of functional
capacity lost due to nonfatal injury) and the direct economic cost of
all vehicle-pedestrian crashes, but they only accounted for 46 percent
of all national pedestrian cases from NHTSA's General Estimate Systems
database.\171\ These scenarios were subject vehicle traveling straight
ahead and pedestrian crossing the road, subject vehicle traveling
straight ahead and pedestrian walking along/against traffic, subject
vehicle turning right and pedestrian crossing the road, and subject
vehicle turning left and pedestrian crossing the road.
---------------------------------------------------------------------------

    \170\ Mikio Yanagisawa, Elizabeth Swanson, and Wassim G. Najm
(2014, April) Target Crashes and Safety Benefits Estimation
Methodology for Pedestrian Crash Avoidance/Mitigation Systems
(Report No. DOT HS 811 998) Washington, DC: National Highway Traffic
Safety Administration, p. xi.
    \171\ T. Miller, J. Viner, S. Rossman, N. Pindus, W. Gellert, J.
Douglass, A. Dillingham, and G. Blomquist, ``The Costs of Highway
Crashes''. FHWA-RD-91-055, October 1991.
---------------------------------------------------------------------------

    Further NHTSA research found that, on average, the subject vehicle
traveling straight ahead and pedestrian crossing the road and subject
vehicle traveling straight ahead and pedestrian walking along/against
traffic accounted for approximately 52 percent of vehicle-pedestrian
crashes and 90 percent of fatal vehicle-pedestrian crashes with a light
vehicle striking a pedestrian as the first event.\172\ Based on this
research, the following scenarios are proposed because they would have
the highest impact on the safety problem.
---------------------------------------------------------------------------

    \172\ Mikio Yanagisawa, Elizabeth D. Swanson, Philip Azeredo,
and Wassim Najm (2017, April) Estimation of potential safety
benefits for pedestrian crash avoidance/mitigation systems (Report
No. DOT HS 812 400) Washington, DC: National Highway Traffic Safety
Administration, p xiii.
---------------------------------------------------------------------------

1. PAEB Scenario Descriptions
Pedestrian Crossing Path From the Right
    The crossing path from the right scenarios consist of the subject
vehicle traveling straight ahead at a constant speed towards the adult
pedestrian test mannequin, which enters its travel path from the right
side of the vehicle.\173\ The subject vehicle must be able to avoid
contact with the pedestrian test mannequin crossing its path.
---------------------------------------------------------------------------

    \173\ Travel Path is the path projected onto the road surface by
a point located at the intersection of the subject vehicle's
frontmost vertical plane and longitudinal vertical center plane as
the subject vehicle travels.
---------------------------------------------------------------------------

    A basic setup for the pedestrian crossing the path of the vehicle
from the right scenarios with 25 percent and 50 percent overlap is
shown in Figure 7.
BILLING CODE 4910-59-P

[GRAPHIC] [TIFF OMITTED] TP13JN23.017

    In this scenario, an obstructed child pedestrian moves in the
vehicle's travel path. The child pedestrian is simulated by a child
pedestrian surrogate that appears from the right of the travel path.
The pedestrian surrogate crosses the subject vehicle's travel path from
in front of two stopped vehicle test devices. The VTDs are parked to
the right of the subject vehicle's travel path, in the adjacent lane,
at 1.0 m (3 ft) from the side of the subject vehicle. The VTDs are
parked one after the other and are facing in the same direction as the
subject vehicle.\174\ The basic setup for the obstructed running child
pedestrian scenario is shown in Figure 8. The subject vehicle must
avoid collision with the child pedestrian surrogate without manual
brake input.
---------------------------------------------------------------------------

    \174\ See the Proposed Test Procedure section of this NPRM for
further details.

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

[GRAPHIC] [TIFF OMITTED] TP13JN23.018

    In this scenario, a simulated running adult pedestrian (the
pedestrian surrogate) crosses into the path of the vehicle traveling
straight ahead at a constant speed. The pedestrian surrogate enters the
path from the left side of the vehicle. No contact between the subject
vehicle and pedestrian surrogate is allowed. For testing, the subject
vehicle travels at a constant speed when it encounters the pedestrian
surrogate crossing from the left side. Figure 9 shows the basic setup
for this scenario.

[GRAPHIC] [TIFF OMITTED] TP13JN23.019

    In this scenario the pedestrian surrogate, with its back to the
subject vehicle, is stationary in the travel path of the subject
vehicle at a 25 percent overlap. The subject vehicle travels at a
constant speed and encounters the stationary pedestrian surrogate
positioned in the subject vehicle's path. The subject vehicle must
completely avoid a collision with the pedestrian surrogate. Figure 10
shows the basic setup for the pedestrian stationary in the path of the
subject vehicle.

[GRAPHIC] [TIFF OMITTED] TP13JN23.020

    In this scenario, a moving pedestrian is traveling along the
vehicle's path. The vehicle must avoid collision with the pedestrian
surrogate. Figure 11 shows the basic setup for this scenario.

[GRAPHIC] [TIFF OMITTED] TP13JN23.021

2. Overlap
    The overlap is the location on the subject vehicle where the
vehicle would collide with the pedestrian surrogate. Overlap is defined
as the percent of the vehicle's width that the pedestrian would
traverse prior to impact if the vehicle's speed and pedestrian's speed
remain constant. Overlap is based on overall vehicle width, as shown in
Figure 12, and is the intended point of impact with the pedestrian
mannequin in the absence of vehicle braking. Two overlaps are proposed
for testing, a 25 percent overlap and a 50 percent overlap. The minimum
overlap is 25 percent to allow for the test mannequin to be fully in
the path of the vehicle. The overlap determines the available time for
the AEB system to detect and react when a collision with the test
mannequin is imminent--a 50 percent overlap allows for more time than a
25 percent overlap.\175\
---------------------------------------------------------------------------

    \175\ As an example, for the timing, for a road width of 3 m (10
ft), a subject vehicle width of 2 m (7 ft) and the constant
pedestrian speed of 5 km/h (3 mph), the time it takes the pedestrian
to travel from the edge of the road to the 25% overlap is 0.72 s and
the time it takes the pedestrian to travel to the 50% overlap is
1.08 s.

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

[GRAPHIC] [TIFF OMITTED] TP13JN23.022

BILLING CODE 4910-59-C
    For the scenarios involving a pedestrian crossing from the right,
two overlap conditions are proposed: A more challenging test condition
of 25 percent overlap and a 50 percent overlap to ensure system
robustness. The 25 percent overlap tests are performed only under
daylight conditions, while the 50 percent overlap tests are performed
in all lighting conditions. For the crossing path scenarios, as
described in the testing section of this notice, the pedestrian
surrogate continues to travel along its path either until collision
occurs or it clears the subject vehicle's path. NHTSA also considered a
75 percent overlap, and this condition was included in the testing
performed in 2020. As expected, due to the increase in time range
afforded by a larger overlap, the AEB performance observed when testing
at 75 percent overlap was substantially similar to the AEB performance
achieved when testing at 50 percent overlap.\176\ NHTSA believes that a
75 percent overlap need not be included in the proposed requirements
because the minimum performance is sufficiently addressed by testing at
the 25 percent and 50 percent overlap.
---------------------------------------------------------------------------

    \176\ For the 75% overlap condition the agency only performed
daylight testing. In general, when testing in the daylight
condition, AEB performance was similar, or better, when testing at
the 75% overlap versus testing at 50% and 25% overlaps.
---------------------------------------------------------------------------

    Based on the no contact criterion and braking performance observed
during its 2020 research testing of 11 vehicles, NHTSA is proposing to
test PAEB performance with the dark upper beam and dark lower beam
conditions at 50 percent overlap only. NHTSA has tentatively concluded
that, due to the reduced timing and AEB system reaction time observed
during the 25 percent overlap tests, testing at 25 percent overlap for
the dark upper beam and lower beam is not currently practicable. NHTSA
is also proposing to use only 50 percent overlap in the obstructed
child running from the right and the running adult from the left
scenarios due to the same reduced reaction time.
    NHTSA considered requiring testing at 25 percent overlap for all
crossing path scenarios. However, this would have required reducing the
subject vehicle speed to allow more reaction time for the AEB system to
avoid the pedestrian surrogate at the proposed speeds. NHTSA lacks
information as to practicable maximum test speed for this condition.
The proposal to test only at 50 percent overlap for certain scenarios
allows for testing at higher speeds, which is more representative of
the safety problem, while effectively encompassing tests at 25 percent
overlap and lower speeds.\177\ Further, if an AEB system is able to
avoid collision in daylight at 25 percent overlap, poor performance for
other crossing path scenarios would not be linked to the vehicle's
braking performance, but rather would likely be linked to the detection
and processing part of the AEB system.
---------------------------------------------------------------------------

    \177\ For the pedestrian test mannequin to reach the 50 percent
overlap, it must pass through the 25 percent overlap location. As an
example, for a road width of 3 m (10 ft), a vehicle width of 2 m (7
ft), a pedestrian speed of 5 km/h (3 mph), a 0.7 g average
deceleration and a AEB system which reacts when the pedestrian test
mannequin reaches the edge of the road, testing with the subject
vehicle speed of 27 km/h (17 mph) for the crossing path from the
right scenario at 50 percent overlap is equivalent to testing at 18
km/h (11 mph) at 25 percent overlap.
---------------------------------------------------------------------------

    The 25 percent overlap for the stationary and along path scenarios
emulate a pedestrian standing stationary or walking on the roadway in
the path of the subject vehicle. In along path scenarios in the real
world, the pedestrian is positioned towards the edge of the roadway in
the path of the subject vehicle. Positioning the pedestrian surrogate
at 25 percent overlap assures that the surrogate test target is fully
in the path of the vehicle. NHTSA has tentatively concluded that a 25
percent overlap for the along path scenarios also represents a more
stringent condition than 50 percent overlap for the AEB system, as it
ensures that the system has an adequate operational field of view and
is able to identify pedestrians that are not at the center of the
travel path.
3. Vehicle and Pedestrian Surrogate Travel Speeds
    The proposed subject vehicle and pedestrian surrogate travel speed
ranges for the PAEB test scenarios were informed by results from
NHTSA's 2020 research study and results from a NHTSA research program
examining four vehicles under dark lighting conditions for PAEB
performance.178 179

As in the case for lead vehicle AEB, the proposed speed ranges for PAEB
testing consider two primary factors--the ability of AEB systems to
consistently operate and avoid contact with the surrogate pedestrian
and the practical limits for testing safely.\180\
---------------------------------------------------------------------------

    \178\ 87 FR 13452 (Mar. 9, 2022).
    \179\ See 87 FR 13452 (Mar. 9, 2022) Tables 4, 5 and 6 for the
complete test matrix. The other 4 vehicles tested for PAEB
functionality under dark lighting conditions were only tested at 16
km/h and 40 km/h.
    \180\ Where possible and practicable, the proposed speed ranges
align with the latest NCAP proposed upgrade (87 FR 13452 (Mar. 9,
2022)). In instances where system performance for existing PAEB was
lower, or a safety need exists, the top speeds of the ranges were
adjusted accordingly.
---------------------------------------------------------------------------

    All proposed speed ranges for the PAEB tests have a lower bound of
10 km/h (6 mph). The upper bound is set at the highest speed NHTSA has
tentatively determined is practicable. The 10 km/h (6 mph) lower bound
for the speed range was based on the agency's tentative conclusion that
PAEB systems may not offer consistent performance at speeds below 16
km/h (10 mph) and corroborated by NHTSA's 2020 testing. The lower bound
of 10 km/h (6 mph) is 6 km/h (4 mph) less than that specified in the
2019 NHTSA draft PAEB research test procedure and is consistent with
the lower bound established for testing under Euro NCAP's rating
program and the lower bound proposed for NCAP testing.\181\ The agency
has tentatively concluded that testing at speeds below 10 km/h is not
practicable at this time and testing at speeds above 10 km/h
sufficiently addresses performance of AEB systems at low speeds.
Concurrent with the development of this proposed rule, NHTSA performed
PAEB testing on model year 2021 and 2022 vehicles using the proposed
performance requirements and test procedures. The results of that
testing provide additional support to the tentative conclusion that the
test conditions, parameters, and procedures are practical to conduct
and that the proposed requirements are practical for manufacturers to
achieve. The results of this testing are detailed in the PAEB report
docketed with the proposed rule.
---------------------------------------------------------------------------

    \181\ https://www.euroncap.com/en/for-engineers/protocols/vulnerable-road-user-vru-protection/, 87 FR 13452 (Mar. 9, 2022) and
https://www.regulations.gov/document/NHTSA-2019-0102-0005.

                       Table 25--User Manual PAEB Range of Functionality by Tested Vehicle
----------------------------------------------------------------------------------------------------------------
                                                                               Speed
                     Vehicle                     ---------------------------------------------------------------
                                                    Low (km/h)       Low (mph)      High (km/h)     High (mph)
----------------------------------------------------------------------------------------------------------------
V1..............................................             9.6               6            59.2              37
V2..............................................             4.8               3              80              50
V3..............................................             4.8               3            99.2              62
V4..............................................            11.2               7              80              50
V5..............................................             4.8               3             120              75
V6..............................................            11.2               7             160             100
V7..............................................             9.6               6              80              50
V8..............................................               8               5              72              45
V9..............................................             9.6               6              80              50
V10.............................................             4.8               3            59.2              37
V11.............................................             6.4               4            68.8              43
----------------------------------------------------------------------------------------------------------------

    About half of all pedestrian fatalities and injuries occur in areas
where the posted speed limit is 40 mph or lower.\182\ In order to
mitigate as much of the safety problem as possible, the agency is
proposing the highest practicable speeds for the upper bound of the
subject vehicle speed ranges. However, the testing speed may also be
limited by the ability to test safely and repeatably. The pedestrian
surrogates NHTSA plans to use for testing have a maximum impact speed
of 60 km/h (37.5 mph). Therefore, similar to the lead vehicle, the
highest subject vehicle test speed is determined by the speed
differential, which is equivalent to the maximum impact speed. The
maximum test speeds for crossing pedestrian and stationary adult
scenarios are 60 km/h (37.5 mph), and 65 km/h (40.4 mph) for the
pedestrian surrogate moving away from vehicle at 5 km/h (3.1 mph)
scenario, which corresponds to a 60 km/h (37.5 mph) speed
differential). The 65 km/h (37.5 mph) proposed subject vehicle speed is
consistent with NCAP's request for comments notice but is 5 km/h (3.1
mph) greater than the Euro NCAP test speed.\183\
---------------------------------------------------------------------------

    \182\ See Safety Problem section of this notice.
    \183\ Euro NCAP test speeds, https://www.euroncap.com/en/for-engineers/protocols/vulnerable-road-user-vru-protection/, 87 FR
13470 (Mar. 9, 2022).
---------------------------------------------------------------------------

    When testing at higher speeds and dark lower and dark upper beam
lighting conditions, PAEB performance was not consistent across the
tested fleet. The test results, however, showed that for the majority
of test conditions, at least one of the AEB systems for the MY 2019 and
2020 test vehicles could perform at the proposed speed ranges. NHTSA
believes that this aggregate performance of available production AEB
systems is not indicative of shortcomings in the overall capability of
AEB technology, but is due to differences in how manufacturers have
developed perception and decision-making algorithms for specific
scenarios absent an FMVSS. To afford time to manufacturers to adjust
the performance of their AEB systems to the proposed requirements, we
are proposing an extended phase-in period for some test conditions.
    NHTSA observed a similar trend with the deployment of AEB
technology approximately four years ago, when performance was
inconsistent in NHTSA's NCAP program for the lead vehicle AEB
scenarios. AEB systems failed to meet all of the NCAP performance
levels at that time, but AEB performance quickly improved as
manufacturers updated and improved software.
    The proposed walking and running speeds of the pedestrian
surrogates are based on the action of the pedestrian in the test
scenario. For walking adult scenarios and the running child scenario,
the pedestrian surrogate speed is 5 km/h (3 mph), and for the running
adult condition, the pedestrian surrogate speed is 8 km/h (5 mph).
Research performed by Directorate-General for Research and Innovation
and published in 2014 identified these speeds as most appropriate for
PAEB

testing.\184\ The proposed pedestrian surrogate speeds and the
stationary pedestrian surrogate condition are also consistent with
previous NHTSA research, 2019 draft NHTSA PAEB test procedures, and
Euro NCAP.\185\
---------------------------------------------------------------------------

    \184\ https://cordis.europa.eu/docs/results/285/285106/final1-aspecss-publishable-final-report-2014-10-14-final.pdf at pg. 19.
    \185\ 87 FR 13452 (Mar. 9, 2022), Euro NCAP test speeds, https://www.euroncap.com/en/for-engineers/protocols/vulnerable-road-user-vru-protection/.
---------------------------------------------------------------------------

4. Crossing Path Scenario Testing Speeds
    Two speed ranges are proposed for the crossing path test
conditions--a range of 10 km/h (6 mph) to 60 km/h (37 mph) for all
adult pedestrian scenarios in the walking and running conditions
(pedestrian surrogate moving at 5 km/h (3 mph) and 8 km/h (5 mph),
respectively), and a range of 10 km/h (6 mph) to 50 km/h (31 mph) for
the running child (pedestrian surrogate moving at 5 km/h (3 mph))
obstructed view scenario.
    The proposed speed ranges for PAEB are based on the results from
the 2020 NHTSA research. When discussing the research as it relates to
this notice, the tested vehicles were assigned an identifier as shown
in Table 22. From the vehicles tested, V3 did not have PAEB
capabilities in most tests and is not further discussed. Testing
performed for the 25 percent overlap daylight condition at 16 km/h (10
mph) and 40 km/h (25 mph) (pedestrian surrogate speed 5 km/h (3 mph))
showed that four of the tested vehicles avoided a collision with the
pedestrian surrogate in all tests conducted and six vehicles avoided
collision with the pedestrian surrogate in all tests when tested at 40
km/h (25 mph) (See Table 26).
[GRAPHIC] [TIFF OMITTED] TP13JN23.023

    Figure 13 shows the automatic speed reduction from the testing
performed at the 25 percent overlap. As an example, if the subject
vehicle traveling at 40 km/h (25 mph) would approach a stopped object,
it would need to reduce its speed by 40 km/h (25 mph) to avoid
collision with the object. However, since the pedestrian surrogate
continues its movement even after reaching the overlap, the subject
vehicle does not need to come to a stop to avoid contact with the
pedestrian surrogate (for an example, see V9 at 40 km/h (25 mph) in
Figure 13). Different marker shapes are used based on the tested speed
and shading of the markers to differentiate between the trials where
the subject vehicle collided with the pedestrian surrogate and the
successful trials with no contact. As shown in the figures, a
successful no contact trial is represented by a shaded (filled) shape,
while the trials with contact are shown as shapes with no shade (no
fill). The only exception are the trials at 16 km/h (10 mph), where the
``x'' represents the no contact trials and the ``-'' represents the
trials with contact.
---------------------------------------------------------------------------

    \186\ https://www.regulations.gov/document/NHTSA-2021-0002-0002.

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

[GRAPHIC] [TIFF OMITTED] TP13JN23.024

    Even though testing was not performed at 60 km/h (37 mph) for the
crossing path from the right and 25 percent overlap condition, based on
the safety need and the consistency of the results observed at 40 km/h
(25 mph) for the 25 percent overlap, NHTSA has tentatively concluded
that the proposed performance testing requirements are practicable. The
agency is currently performing testing at the proposed speed ranges,
including the 60 km/h (37 mph) speed, to corroborate this conclusion.
NHTSA is proposing a range for the tested speeds from a low 10 km/h (6
mph) starting point to ensure system performance at all speeds, as
opposed to only testing at the highest practicable speeds. As an
example, the owner's manual of V5 shows the PAEB system working from 5
km/h (3 mph) up to 120 km/h (75 mph), but when tested, V5 failed to
avoid collision on all trials at 16 km/h (10 mph). These proposed
subject vehicle speed ranges are also consistent with Euro NCAP vehicle
speed ranges and the pedestrian surrogate speeds are consistent with
both NCAP's latest request for comments notice and Euro NCAP pedestrian
testing speeds.\188\
---------------------------------------------------------------------------

    \187\ Id.
    \188\ EuroNCAP test speeds, https://www.euroncap.com/en/for-engineers/protocols/vulnerable-road-user-vru-protection/, 87 FR
13470 (Mar. 9, 2022).
---------------------------------------------------------------------------

    The crossing path from the right at 50 percent overlap test
scenarios with an adult pedestrian surrogate in the daylight condition
was performed at a range of speeds from 16 km/h (10 mph) up to 60 km/h
(37 mph) in NHTSA's 2020 research study. From the 10 relevant vehicles,
3 avoided collision in all tests up to 50 km/h (31 mph) and one avoided
collision in all but one test up to 60 km/h (37 mph) (See Table 27).

[GRAPHIC] [TIFF OMITTED] TP13JN23.025

    Figure 14 shows the speed reduction at various tested speeds. For
clarity, not all tested speeds are shown. The testing speeds shown
represent the current PAEB research test procedures test speeds (16 km/
h (10 mph) and 40 km/h (25 mph)) and three other speeds relevant to the
proposed testing requirements. The three vehicles that avoided impact
on all tests up to 50 km/h (31 mph) were also able to significantly
reduce their speeds when tested at 60 km/h (37 mph). This suggests that
a slight tuning of the AEB systems would allow those systems to avoid
collision at 60 km/h (37 mph).
[GRAPHIC] [TIFF OMITTED] TP13JN23.026

    In the agency's crossing path from the right with 50 percent
overlap during dark lighting condition using the vehicle's upper beam
headlamps, one vehicle avoided collision in all but one test when
tested at speeds up to 60 km/h (37 mph), and another vehicle avoided
collision on all tests at speeds above 20 km/h (12 mph) and on most
tests at 16 km/h (10 mph). A total of four vehicles avoided collision
either on all or some of the tests at 60 km/h (37 mph) and on

all tests at 50 km/h (31 mph). Table 28 shows a summary of the tests
with no contact versus the total number of tests conducted at each test
speed.
[GRAPHIC] [TIFF OMITTED] TP13JN23.027

    The four vehicles that avoided contact with the test mannequin on
all or some of the tests at 60 km/h (37 mph) also achieved a speed
reduction of 30 km/h (19 mph) or more before collision in the tests
where contact was observed (See Figure 15), which suggests that the
systems can be adjusted with minimal hardware to the achieve consistent
collision avoidance at 60 km/h (37 mph).

[GRAPHIC] [TIFF OMITTED] TP13JN23.028

    When testing the crossing path scenario from the right with 50
percent overlap at night using the lower beam headlamps, performance
was generally worse than when testing with the upper beam headlamps or
during the daylight condition. Only two vehicles were tested at 50 km/h
(31 mph), one of which avoided contact in two out of four tests and the
other made contact in every test.\189\ V4 had no contact in four out of
five tests at 40 km/h (25 mph) and V6 avoided collision in all tests at
the same speed. From the 10 vehicles tested, 5 had at least one test
that resulted in collision avoidance at 40 km/h (25 mph). A summary of
the no contact tests and the total number of tests per vehicle at each
speed is presented in Table 29.
---------------------------------------------------------------------------

    \189\ In general, based on the testing matrix a vehicle was
tested at a higher speed only after it had a majority of no contact
tests at the previous tested speed. Conversely, testing at a 5 km/h
lower speed was performed only if the vehicle had a least one no
contact test at the higher speed.
[GRAPHIC] [TIFF OMITTED] TP13JN23.029

    Of the two vehicles tested at 50 km/h (31 mph), V6 only had tests
that resulted in contact but was able to achieve a speed reduction of
33 km/h (21 mph) in two tests and 23 km/h (14 mph) in the other. While
V4 was able to avoid contact in two tests, it only showed a speed
reduction of 13 km/h (8 mph) in the tests with contact. The five
vehicles that had at least one no contact run at 40 km/h (25 mph) also
achieved a speed reduction of 25 km/h (16 mph) or more (except for one
test for V9) on the tests which resulted in contact with the test
mannequin. Speed reduction by vehicle and tested speed for this
scenario is presented in Figure 16. The observed performance of AEB
systems when tested under the dark lower beam condition led the agency
to tentatively conclude that requiring PAEB at speeds up to 60 km/h (37
mph) is not practicable at this time, but achievable with an adequate
phase-in. Therefore, for this scenario, as well as other dark testing
scenarios (see Table 25), in order to afford manufacturers sufficient
time to adjust the performance of the AEB systems to the proposed test
requirements, the higher testing speeds are proposed to be implemented
four years (instead of three years) after the date of publication of
the final rule. Based on the results of NHTSA's testing, a 10 to 40 km/
h (6 to 25 mph) range is currently practicable (See Figure 16). Tests
conducted on model year 2021 and 2022 vehicles (available in the docket
of this proposed rule) and based on current data from NHTSA's 2020
research testing, NHTSA expects improved performance across all speeds.
[GRAPHIC] [TIFF OMITTED] TP13JN23.030

    Testing for the obstructed running child (child pedestrian
surrogate travelling at a speed of 5 km/h (3 mph)) scenario with a 50
percent overlap for the daylight condition found one vehicle that
avoided collision in all tests up to 50 km/h (31 mph) and in four out
of five tests from 60 km/h (37 mph). Another vehicle avoided collision
in all but one test up to 40 km/h (25 mph) and had two tests without
contact at 50 km/h (31 mph). Table 30 shows the ratio of no contact
tests to total test by vehicle and tested speed.

[GRAPHIC] [TIFF OMITTED] TP13JN23.031

    Only V4 was tested at 60 km/h (37 mph), and V4 avoided contact with
the child mannequin in four out of five tests and achieved a speed
reduction of more than 50 km/h (31 mph) in the test with contact. Of
the two vehicles tested at 50 km/h (31 mph), V4 avoided collision in
all cases. V2 avoided collision in two tests and achieved more than a
25 km/h (15.5 mph) speed reduction in two tests and a 19 km/h (12 mph)
speed reduction in a third. Figure 17 shows the speed reduction at the
test speed for all vehicles tested. Based on the observed performance
during testing, the agency has tentatively concluded that requiring
performance at speeds up to 50 km/h (31 mph) is practicable in daylight
conditions with an adequate phase-in. Concurrent with the development
of this proposed rule, NHTSA performed PAEB testing on model year 2021
and 2022 vehicles using the proposed performance requirements and test
procedures. The results of that testing provide additional support to
the tentative conclusion that the test conditions, parameters, and
procedures are practical to conduct and that the proposed requirements
are practical for manufacturers to achieve. The results of this testing
are detailed in the PAEB report docketed with this proposed rule.

[GRAPHIC] [TIFF OMITTED] TP13JN23.032

    NHTSA's testing of the running adult pedestrian scenario
(pedestrian surrogate travelling at 8 km/h (5 mph)) from the left was
performed at speeds from 40 km/h (25 mph) to 60 km/h (37 mph) with a 50
percent overlap during daylight.\190\ The results showed that five
vehicles made no contact with the pedestrian surrogate in at least one
test conducted at 60 km/h (37 mph) and all had no contact tests at 50
km/h (31 mph). One of the five vehicles, V2, avoided contact with the
test mannequin in all tests at 60 km/h (37 mph). A summary of the tests
is shown in Table 31.
---------------------------------------------------------------------------

    \190\ Only V5 and V11 were tested at 35 km/h (22 mph) due to
poor performance at 40 km/h per the test matrix.
[GRAPHIC] [TIFF OMITTED] TP13JN23.033

    For the 60 km/h (37 mph) tests, the vehicles that did not avoid
contact still exhibited significant speed reduction. In the one
instance where V1 collided with the test mannequin, it still achieved a
speed reduction of 42 km/h (26 mph). V4, V6 and V7 all achieved a speed
reduction of more than 35 km/h (22 mph) in all instances with contact
when tested at 60 km/h (37.5 mph). In general, except for V5 and two
tests (V9 at 40 km/h (25 mph) and V7 at 55 km/h (34 mph)) all vehicles
achieved significant speed reduction over all tested speeds. Figure 18
shows the speed reduction at the test speed for all vehicles tested.
The observed performance of five vehicles avoiding contact with an
adult surrogate running from the left in tests conducted at 60 km/h (37
mph) leads the agency to tentatively conclude that requiring
performance at speeds up to 60 km/h (37 mph) is practicable in daylight
conditions three years after the publication of a final rule.
[GRAPHIC] [TIFF OMITTED] TP13JN23.034

5. Stationary Scenario Testing Speeds
    NHTSA is proposing a range of subject vehicle travel speeds from 10
km/h (6 mph) to 55 km/h (34 mph) for the stationary pedestrian along
path scenario.
    NHTSA's 2020 research testing of this scenario during daylight
conditions found one vehicle, V1, that avoided collision with the test
mannequin on all tests but one at 60 km/h (37.5 mph), and two other
vehicles, V4 and V6, that avoided collision with the test mannequin
when tested at speeds up to 55 km/h (34 mph). For all the tests up to
55 km/h (34 mph), V4 avoided collision in all tests and V6 had only one
collision at 55 km/h (34 mph). Four other vehicles had some no contact
runs at 40 km/h (25 mph) and 9 of the 10 vehicles had no contact on all
tests at 16 km/h (10 mph). Table 32 shows a brief overview of test
results.

[GRAPHIC] [TIFF OMITTED] TP13JN23.035

    The three vehicles tested at 60 km/h (37 mph), vehicles V1, V4, and
V6, had considerable speed reduction on the tests where they collided
with the test mannequin. Where V1 collided with the test mannequin, it
achieved a speed reduction of 37 km/h (23 mph). Where V6 collided with
the test mannequin, it showed very consistent results and had a speed
reduction between 52 km/h (32 mph) and 55 km/h (34 mph) on all three
tests at 60 km/h (37.5 mph). Similarly, V4 had a speed reduction when
tested at 60 km/h (37.5 mph) of between 40 km/h (25 mph) and 45 km/h
(28 mph). The consistent speed reduction results at 60 km/h (37.5 mph)
reinforce the agency's opinion that minimal tunning is required for
existing systems to perform at the proposed requirements. Figure 19
shows the speed reduction at the test speed for all vehicles tested.

[GRAPHIC] [TIFF OMITTED] TP13JN23.036

    NHTSA upper beam testing using the stationary pedestrian along path
scenario under dark lighting conditions resulted in one vehicle, V4,
being able to avoid collision in all tests at speeds up to and
including 55 km/h (34 mph). The vehicle achieved an average speed
reduction of 48 km/h (30 mph) in three other tests conducted at 60 km/h
(37 mph). Two other vehicles avoided collision in all tests at 40 km/h
(25 mph) (See Table 33).
[GRAPHIC] [TIFF OMITTED] TP13JN23.037

    When tested at 60 km/h, V4 and V11 collided with the test
mannequin, but were still able to achieve significant speed reduction.
V4 had very consistent speed reductions ranging from 46 km/h (28.6 mph)
to 52 km/h (32.3 mph), and V11 achieved a speed reduction of 29 km/h
(18 mph) and 32 km/h (19.9 mph). When tested at 55 km/h (34 mph), V11
achieved a speed reduction of 25 km/h (15.5 mph) or more in two tests
and did not have a large speed reduction on the other test. At 50 km/h
(31.1 mph), V11 achieved speed reductions of more than 30 km/h (18.6
mph) when it contacted

the test mannequin. The other vehicles, where they did not avoid
contact at 40 km/h (25 mph), had a significant number of tests without
large speed reductions when they contacted the test mannequin. However,
V9 at 40 km/h (25 mph) showed an average speed reduction of 23.5 km/h
(14.6 mph) in the tests where it contacted the test mannequin. Figure
20 shows the speed reduction at the test speed for all vehicles tested.
[GRAPHIC] [TIFF OMITTED] TP13JN23.038

    Based on the results of the testing, NHTSA has tentatively
concluded that requiring testing up to 55 km/h (34.2 mph) is feasible
give the three-year phase-in period after the publication of the final
rule. At the speeds where some of the tested vehicles made contact, V4,
with similar hardware, was able to avoid collision. The agency
anticipates that the other vehicles will be able to avoid contact at
the proposed testing speed ranges through tunning of their systems to
the requirements. Concurrent with the development of this proposed
rule, NHTSA performed PAEB testing on model year 2021 and 2022 vehicles
using the proposed performance requirements and test procedures. The
results of that testing provide additional support to the tentative
conclusion that the test conditions, parameters, and procedures are
practical to conduct and that the proposed requirements are practical
for manufacturers to achieve. The results of this testing are detailed
in the PAEB report docketed with this proposed rule.
    The same vehicle that avoided collision in all tests up to 55 km/h
(34 mph) under dark conditions with upper beams (V4) also avoided
collision during all lower beam testing under dark conditions in tests
up to and including those performed at 50 km/h (31 mph) and during four
out of five tests at 55 km/h (34 mph). The other tested vehicles
contacted the test mannequin at speeds on all or most tests when tested
at speeds above 16 km/h (10 mph). A brief overview of the results for
the dark lower beam testing for the stationary along path scenario is
presented in Figure 21 and Table 34.

[GRAPHIC] [TIFF OMITTED] TP13JN23.039

    V4 had significant and consistent speed reduction of between 45 km/
h (28 mph) and 52 km/h (32 mph) when tested at 60 km/h (37 mph). V4
also reduced its speed by more than 30 km/h (19 mph) in the one
instance it contacted the test mannequin when tested at 55 km/h (34
mph). All other vehicles showed poor results at speeds above 16 km/h
(10 mph). Three vehicles had no meaningful AEB activation on all tests,
including 16 km/h (10 mph). V9 was the only vehicle that was able to
avoid collision on two tests at 40 km/h (25 mph) and had significant
speed reduction on the other tests at this speed. Figure 21 shows the
speed reduction at the test speed for all vehicles tested.
[GRAPHIC] [TIFF OMITTED] TP13JN23.040

    Given that V4, using commonly found hardware in AEB systems, was
able to avoid contact on every test up to 50 km/h (31.1 mph), avoided
contact on most tests at 55 km/h (34 mph), and achieved significantly
reduced speed on all other

higher speed tests (including 65 km/h (60 mph)), the agency has
tentatively concluded that a no contact requirement for speed ranges up
to 55 km/h (34 mph) is feasible. The proposed 50 km/h (31 mph) upper
bound of the range 3 years after final rule publication and 55 km/h (34
mph) 4 years after publication of the final rule is necessary due to
pedestrian crashes and fatalities predominantly happening at night and
at higher speeds (see safety section and PRIA). Concurrent with the
development of this proposed rule, NHTSA performed PAEB testing on
model year 2021 and 2022 vehicles using the proposed performance
requirements and test procedures. The results of that testing provide
additional support to this tentative conclusion. The results of this
testing are detailed in the PAEB report docketed with this proposed
rule.
6. Along Path Scenario Testing Speeds
    The proposed travel speed range for the pedestrian test mannequin
moving (walking at 5 km/h (3 mph)) along the vehicle's path is from 10
km/h (6 mph) to 65 km/h (40 mph). NHTSA's 2020 PAEB research testing
identified three vehicles that avoided contact with the test mannequin
during all tests performed at 65 km/h (40 mph) (V1 was only tested once
at 65 km/h (40 mph) where it avoided collision with the test
mannequin). Of these three vehicles, V6 avoided collision on all tests
and tested speeds up to 65 km/h (40 mph), V1 avoided collision on all
but one test up to 65 km/h (40 mph), and V9 avoided collision on all or
most of the tests up to 65 km/h (40 mph) and avoided collision on 2 out
of 5 tests at 70 km/h (44 mph). Another vehicle that performed well,
V4, avoided collision on all tests up to 60 km/h (37.5 mph). Table 35
provides a breakdown of tests based on the collision avoidance outcome.
[GRAPHIC] [TIFF OMITTED] TP13JN23.041

    V4 had a significant speed reduction of more than 40 km/h on all
tests when tested at 65 km/h (40 mph). On the test at 50 km/h (31.1
mph), where V1 collided with the target, it still achieved a speed
reduction of more than 30 km/h (18.6 mph). Speed reduction for this
scenario by relevant tested speeds is shown in Figure 22. Based on the
results from the 2020 testing, NHTSA has tentatively concluded that an
upper speed bound of 65 km/h (40 mph) is practicable three years after
the publication of the final rule.

[GRAPHIC] [TIFF OMITTED] TP13JN23.042

    Testing for the dark upper beam along path pedestrian test
mannequin moving scenario produced better performance than when testing
for the dark upper beam stationary scenario. In the along path moving
scenario, the test mannequin moves away from the subject vehicle at a
constant speed and continues moving even as the subject vehicle
decelerates during the AEB event. This has the potential to allow for
more time and distance to avoid collision. In the agency's research
testing, one vehicle, V11, avoided collision on all tests at speeds up
to 50 km/h (31.1 mph), had four out of five test runs at 55 km/h (34
mph) with no contact, and avoided collision once at 60 km/h (37 mph).
V4 avoided collision on all tests up to 40 km/h (25 mph), collided once
out of five tests at 50 km/h (31.1 mph), once out of five tests at 60
km/h (37 mph), and had one out of four no collision tests at 65 km/h
(40 mph). Another vehicle, V9, avoided collision on all tests at 50 km/
h (31.1 mph) and avoided collision on a majority of tests at the other
tested speeds except at 65 km/h (40 mph). A total of five vehicles
avoided collision on at least some of the tests at speeds up to 50 km/h
(31.1 mph). Table 36 presents a summary of the test results.

[GRAPHIC] [TIFF OMITTED] TP13JN23.043

    Figure 23 shows the speed reduction achieved by each vehicle by
tested speed. For example, when V11 contacted the test mannequin, it
achieved significant speed reduction. Another vehicle achieving
significant speed reduction in the tests where it contacted the test
mannequin across all tested speeds was V4. This vehicle was the only
one to avoid collision at 65 km/h (40 mph), and even though it only
avoided collision in one test, it achieved a speed reduction of more
than 50 km/h (31.1 mph) in all others. The other vehicles did not
provide consistent results during testing, with a wide range of speed
reduction values. Because no vehicle was able to avoid collision on all
tests at the higher speeds, the agency is proposing that the upper
bound for the speed range for this scenario be 60 km/h (37 mph) three
years after publication of the final rule and 65 km/h (40 mph) four
years after publication of the final rule. Concurrent with the
development of this proposed rule, NHTSA performed PAEB testing on
model year 2021 and 2022 vehicles using the proposed performance
requirements and test procedures. The results of that testing provide
additional support to this tentative conclusion. The results of this
testing are detailed in the PAEB report docketed with this proposed
rule.

[GRAPHIC] [TIFF OMITTED] TP13JN23.044

    Similar to the stationary scenarios, the results from lower beam
testing in dark lighting conditions for the along path moving test
condition were less consistent than for the other lighting conditions.
The tested vehicles were able to avoid contact with the test mannequin
at higher speeds than in the stationary along path scenario. Two
vehicles were able to avoid contact with the test mannequin in at least
one test during tests performed at 60 km/h (37 mph). One vehicle, V4,
avoided contact with the test mannequin in all tests at 60 km/h (37
mph) and had two out of five no contact tests at 50 km/h (31.1 mph).
The other vehicle, V9, had one no contact test out of four at 60 km/h
(37.5 mph) and a majority of no contact tests at all lower tested
speeds. The results of the tests are presented in Table 37.
[GRAPHIC] [TIFF OMITTED] TP13JN23.045

    For the along path moving scenario dark lower beam testing, V4 had
significant speed reduction when tested at 65 km/h (40 mph) in two test
runs but failed to activate in a meaningful manner in one test. When
tested at 60 km/h (37 mph), V9 had two tests with a speed reduction of
at least 30 km/h (18.6 mph) and one test with no meaningful speed
reduction. The results from the other tested speeds for V4 and V9 show
that their AEB systems performed in a similar manner to their
performance for the upper speeds already discussed. In general, the
other tested vehicles performed poorly at all speeds except 16 km/h (10
mph) and did not show consistent speed reduction. Figure 24 shows the
speed reduction at the test speed for all vehicles tested.
[GRAPHIC] [TIFF OMITTED] TP13JN23.046

    Two vehicles avoided contacting the surrogate in at least one test
at 60 km/h (37 mph). NHTSA has tentatively concluded that this can be
achieved across the fleet three years after the publication of a final
rule. While no vehicle was able to avoid collision at a test speed of
65 km/h (40 mph), based on the fact that V4 and V9 (equipped with AEB
systems with hardware in common) were able to avoid collision in at
least one test at 60 km/h (37 mph), the agency tentatively concludes
that four years after the publication of the final rule, vehicles will
be able to achieve no contact at 65 km/h (40 mph). The need for testing
at higher speeds in dark lighting conditions is dictated by the safety
need, since as previously discussed, pedestrian fatalities
predominantly occur during dark conditions and at higher speeds.
Concurrent with the development of this proposed rule, NHTSA performed
PAEB testing on model year 2021 and 2022 vehicles using the proposed
performance requirements and test procedures. The results of that
testing provide additional support to this tentative conclusion. The
results of this testing are detailed in the PAEB report docketed with
this proposed rule.
7. PAEB Darkness Testing
    During agency testing, PAEB system performance was not consistent
for some of the proposed lighting conditions and speeds. However, the
agency has tentatively concluded that testing in dark lighting
conditions is necessary, and vehicles can be designed and produced to
avoid collisions in all dark lighting test conditions given an adequate
phase-in period. This is consistent with recent IIHS tests finding that
existing systems can perform in the dark-lighted conditions regardless
of their IIHS headlamp ratings.191 192 NHTSA tentatively
concludes that PAEB system performance is improving, and the latest
PAEB systems are already able to perform much better under the proposed
lighting conditions than previous iterations of the systems.\193\
Concurrent with the development of this proposed rule, NHTSA performed
PAEB testing on model year 2021 and 2022 vehicles using the proposed

performance requirements and test procedures. The results of that
testing provide additional support to the tentative conclusion that the
test conditions, parameters, and procedures are practical to conduct
and that the proposed requirements are practical for manufacturers to
achieve. The results of this testing are detailed in the PAEB report
docketed with this proposed rule.
---------------------------------------------------------------------------

    \191\ IIHS dark light press release: https://www.iihs.org/news/detail/pedestrian-crash-avoidance-systems-cut-crashes--but-not-in-the-dark.
    \192\ Id.
    \193\ ``The better-performing systems are too new to be included
in our study of real-world crashes . . . This may indicate that some
manufacturers are already improving the darkness performance of
their pedestrian AEB systems.'' Id.
---------------------------------------------------------------------------

    When tested, the observed crash avoidance performance of the tested
PAEB systems was best for the daylight and upper beam conditions. Table
38 shows the maximum speeds at which the test vehicles did not collide
with the test mannequin either on all trials or at least one trial.
Based on the previously detailed results of the 2020 testing, the
agency tentatively concludes that three years after final rule
publication, consistent performance is possible for the darkness
testing conditions through further tuning of existing AEB systems
without major hardware upgrades. The additional year of phase-in for
higher speed darkness performance requirements would allow time for
systems that currently do not perform consistently to be adjusted or
tuned to the proposed requirements. NHTSA has also concluded that the
crossing path running child from the right scenario and the running
adult from the left scenario with dark lower beam or upper beam are not
a practicable requirement at this time.

                                            Table 38--PAEB: Highest Speed at Which a Vehicle Avoided Contact on at Least One Trial Versus All Trials
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                         Crossing path--right,  50 percent overlap                            Stationary                                          Along-path
        Lighting condition        --------------------------------------------------------------------------------------------------------------------------------------------------------------
                                       At least one trial             All trials             At least one trial            All trials            At least one trial            All trials
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Daylight.........................  60 km/h..................  60 km/h..................  60 km/h..................  55 km/h.................  70 km/h.................  65 km/h.
Dark, Upper Beam.................  60 km/h..................  60 km/h..................  55 km/h..................  55 km/h.................  65 km/h.................  50 km/h.
Dark, Lower Beam.................  50 km/h..................  40 km/h..................  55 km/h..................  50 km/h.................  60 km/h.................  60 km/h.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

G. Alternatives to No-Contact Performance Test Requirement

    NHTSA is considering two alternatives to a no-contact requirement
for both the lead vehicle and pedestrian performance test requirements.
    The first alternative would be to permit low speed contact in
NHTSA's on-track testing. Under this alternative, the subject vehicle
would meet the requirements of the standard if it applied the brakes
automatically in a way that reduced the impact speed either by a
defined amount or to a maximum collision speed. The speed at which the
collision would be allowed to occur would be low enough that the crash
would be highly unlikely to be fatal or to result in serious injury.
    NHTSA seeks comment on the appropriateness of such a requirement,
any factors to consider surrounding such a performance level, and what
the appropriate reduction in speed or maximum impact speed should be.
NHTSA has considered this alternative separately for the lead vehicle
requirement and the pedestrian requirement and came to the same
tentative conclusion to propose a no contact performance requirement
for on-track testing in each case. However, NHTSA seeks comment on this
level of performance separately for the lead vehicle and pedestrian
requirements because the safety implications of low-speed impacts are
different for each of these two crash types.
    NHTSA also seeks comment on the potential consequences on testing
if vehicle contact were allowed. NHTSA has extensive experience with
performing AEB evaluations and has observed that it is possible for
even relatively low-speed collisions with the lead vehicle test device
or pedestrian test mannequin to potentially damage the subject vehicle.
For instance, if a test vehicle were to strike the lead vehicle test
device, even at a low speed, sensors on the vehicle could become
misaligned, and subsequent tests might not be representative of the
vehicle condition at time of first sale. For instance, cameras or radar
devices could become misaligned. Additionally, striking the vehicle
test device or pedestrian test mannequin might prematurely degrade the
appearance of the device and modify its specifications, including in
ways that are not immediately observable. For example, damage to the
test device might affect the radar cross section that requires a long
verification procedure to discover. NHTSA is concerned that any
performance test requirement that allows for vehicle contact could
result in expensive or time-consuming interruptions to repair the
subject vehicle or test device to ensure repeatable testing. NHTSA
seeks comment on this concern.
    The second alternative the agency is considering is a no contact
requirement that permits the vehicle to use multiple runs to achieve
the performance test requirements. For example, NHTSA's CIB and DBS
NCAP test performance criteria currently specify that the speed
reduction requirements for each test scenario must be met in at least 5
out of 7 tests runs. This approach would provide a vehicle more
opportunities to achieve the required performance and the agency more
statistical power in characterizing the performance of the vehicle. The
agency seeks comment on the number of repeated tests for a given test
condition and on potential procedures for repeated tests. The agency
also seeks comment on the merits of permitting a vehicle that fails to
activate its AEB system in a test to be permitted additional repeat
tests, including a repeat test process similar to that in the recent
revisions to UN ECE Regulation No. 151.\194\ Finally, the agency seeks
comment on whether there should be additional tests performed in the
event no failure occurs on an initial test for each series.
---------------------------------------------------------------------------

    \194\ Section 6.10.1 of UN ECE Regulation No. 151 provides
robustness criteria that specifies that each test condition is
performed two times. If vehicle does not meet the required
performance criteria in one of the two test runs, a third test may
be conducted. A test scenario is considered passed if the required
performance is met in two test runs. However, the total number of
failed test runs cannot exceed 10 percent for the lead vehicle and
pedestrian tests.
---------------------------------------------------------------------------

    In the request for comments on upgrades to NCAP, NHTSA sought
comment on an approach that permitted repeated trials for collision
avoidance requirements if an impact occurred with a minimum speed
reduction of at least 50 percent.\195\ This approach would not permit
repeated trials if an impact occurred above certain speeds during the
test series conducted for a given test scenario/condition. NHTSA seeks
comment on the implications if NHTSA were to require a partial speed
reduction, such as 50 percent, in

combination with an alternate approach for multiple trials. For
example, if a collision occurs and the relative impact speed is less
than 50 percent of the initial speed, the test is repeated. If a
collision occurs again, the subject vehicle would be noncompliant.
Alternatively, even if the subject vehicle avoids a collision, NHTSA
could test again. The number of repeated tests needed to meet the
performance test requirement would be established by NHTSA. If the
agency were to consider such an approach, what should be the required
speed reduction (e.g., 50 percent, 75 percent, etc.) and how many tests
must follow without a collision?
---------------------------------------------------------------------------

    \195\ 87 FR 13452 March 9, 2022.
---------------------------------------------------------------------------

H. False Activation Requirement

    NHTSA is also proposing to include two scenarios in which braking
is not warranted. These tests are sometimes referred to as ``false-
positive'' tests. AEB systems need to be able to differentiate between
a real threat and a non-threat to avoid false activations. NHTSA is
concerned that false activation events may introduce hard braking
situations when such actions are not warranted, potentially causing
rear-end crashes. The proposed false activation tests establish only a
baseline for system functionality. They are by no means comprehensive,
nor sufficient to eliminate susceptibility to false activations.
Rather, the proposed tests are a means to establish minimum
performance. NHTSA expects that vehicle manufacturers will design AEB
systems to thoroughly address the potential for false activations.\196\
Vehicles that have excessive false positive activations may pose an
unreasonable risk to safety and may be considered to have a safety-
related defect. Previous implementations of other technologies have
shown that manufacturers have a strong incentive to mitigate false
positives and are successful even in the absence of specific
requirements.
---------------------------------------------------------------------------

    \196\ From the NCAP request for comments notice ``Specifically,
the Alliance stated that vehicle manufacturers will optimize their
systems to minimize false positive activations for consumer
acceptance purposes, and thus such tests will not be necessary.
Similarly, Honda stated that vehicle manufacturers must already
account for false positives when considering marketability and
HMI.'' 87 FR 13452 (Mar. 9, 2022) at 13460.
---------------------------------------------------------------------------

    The two proposed false activation scenarios are the steel trench
plate and the vehicle pass-through test scenarios. Both of these tests
will include acceleration pedal release and testing both with and
without manual braking, similar to testing with a stopped lead vehicle.
NHTSA is proposing that, during each test trial, the subject vehicle
accelerator pedal will be released either when a forward collision
warning is given or at a headway that corresponds to a time-to-
collision of 2.1 seconds, whichever occurs earlier. For tests where
manual braking occurs, the brake is applied at a headway that
corresponds to a time-to-collision of 1.1 seconds.
1. Steel Trench Plate False Activation Scenario
    The steel trench plate test was introduced in the NHTSA NCAP test
procedures to assess whether a false positive condition could be
identified and consistently utilized.\197\ In the steel trench plate
test, a steel plate commonly used in road construction is placed on the
surface of a test track. The steel plate presents no imminent danger,
and the subject vehicle can safely travel over the plate without harm.
---------------------------------------------------------------------------

    \197\ CIB Non-Threatening Driving Scenarios (DOT HS 811 795);
NHTSA CIB--Crash Imminent Braking test procedure- https://www.regulations.gov/document/NHTSA-2015-0006-0025, https://www.regulations.gov/document/NHTSA-2015-0006-0176.
---------------------------------------------------------------------------

    In the steel trench plate false activation scenario, a subject
vehicle traveling at 80 km/h (50 mph) encounters a secured 2.4 m (7.9
ft) wide by 3.7 m (12.1 ft) long steel by 25 mm (1 in) thick ASTM A36
steel plate placed flat in the subject vehicle's lane of travel, and
centered in the travel path, with its short side toward the vehicle
(long side transverse to the path of the vehicle). The AEB system must
not engage the brakes to create a peak deceleration of more than 0.25g
additional deceleration than any manual brake application generates (if
used). The basic setup for the steel trench plate false positive test
is shown in Figure 25.
[GRAPHIC] [TIFF OMITTED] TP13JN23.048

2. Pass-Through False Activation Scenario
    The pass-through test, as the name suggests, simulates the subject
vehicle encountering two vehicles outside of the subject vehicle's path
that do not present a threat to the subject vehicle. The test is
similar to the UNECE R131 and UNECE R152 false reaction tests.\198\ In
the pass-through scenario, two VTDs are positioned in the adjacent
lanes to the left and right of the subject vehicle's travel path, while
the lane in which the subject vehicle is traveling is free of
obstacles.
---------------------------------------------------------------------------

    \198\ U.N. Regulation No. 131 (Feb. 27, 2020), available at
https://unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2015/R131r1e.pdf; U.N. Regulation No. 152, E/ECE/TRANS/505/Rev.3/Add.151/
Amend.1 (Nov. 4, 2020), available at https://unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2020/R152am1e.pdf.
---------------------------------------------------------------------------

    The two stopped VTDs are positioned parallel to each other and 4.5
m (14.8 ft) apart in the two adjacent lanes to that of the subject
vehicle (one to the left and one to the right with a 4.5 m (14.8 ft)
gap between them). The 4.5 m (14.8 ft) gap represents a typical travel
lane of about 3.6 m (11.8 ft) plus a reasonable distance at which a
vehicle would be stationary within the adjacent travel lanes.\199\
Similar to the steel trench plate false activation scenario, the AEB
must not engage the brakes to create a peak deceleration of more than
0.25g beyond any manual braking. In Figure 26, a basic setup for the
test is shown.
---------------------------------------------------------------------------

    \199\ Federal Highway Administration (Oct. 15, 2014), Range of
lane widths for travel lanes and ramps, https://safety.fhwa.dot.gov/geometric/pubs/mitigationstrategies/chapter3/3_lanewidth.cfm.

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

[GRAPHIC] [TIFF OMITTED] TP13JN23.049

3. Potential Alternatives to False Activation Requirements
    As alternatives to these two false activation tests, NHTSA is
considering removing the false activation tests completely, requiring a
robust documentation process or specifying a data storage requirement.
First, NHTSA seeks comment on the anticipated impacts on safety and the
certification burden if the agency were to finalize a rule that did not
contain one or both of the proposed false positive tests.
Alternatively, NHTSA is considering requiring that manufacturers
maintain documentation demonstrating that robust process standards are
followed specific to the consideration and suppression of false
application of AEB in the real world. Other industries where safety-
critical software-controlled equipment failures may be life-threatening
(e.g., aviation \200\ and medical devices) \201\ are regulated via
process controls ensuring that good software development engineering
practices are followed. This approach recognizes that system tests are
limited in their ability to evaluate complex and constantly changing
software-driven control systems. Software development lifecycle
practices that include risk management, configuration management, and
quality assurance processes are used in various safety-critical
industries. ISO 26262, ``Road vehicles--Functional safety,'' ISO 21448,
``Safety of the Intended Functionality (SOTIF),'' and related
standards, are examples of an approach for overseeing software
development practices. Process standards could be a robust approach to
the regulation of false positives because false activation of braking
is a complex engineering problem with multiple factors and conditions
that must be considered in the real world. The agency seeks public
comment on all aspects of requiring manufacturers to document that they
have followed process standards in the consideration of the real-world
false activation performance of the AEB system.
---------------------------------------------------------------------------

    \200\ 14 CFR 33.201 (a) The engine must be designed using a
design quality process acceptable to the FAA, that ensures the
design features of the engine minimize the occurrence of failures,
malfunctions, defects, and maintenance errors that could result in
an IFSD, loss of thrust control, or other power loss.
    \201\ 21 CFR 820.30(a)(1) Each manufacturer of any class III or
class II device, and the class I devices listed in paragraph (a)(2)
of this section, shall establish and maintain procedures to control
the design of the device in order to ensure that specified design
requirements are met.
---------------------------------------------------------------------------

    Finally, NHTSA is considering requiring targeted data recording and
storage of significant AEB activations. These data could then be used
by manufacturers to improve system performance, or by the agency to
review if a particular alleged false activation was part of a safety
defect investigation. NHTSA is considering a requirement that an AEB
event that results in a speed reduction of greater than 20 km/h (12
mph) activate the recording and storage of the following key
information: date, time, engine hours (i.e., the time as measured in
hours and minutes during which an engine is operated), AEB activation
speed, AEB exit speed (i.e., vehicle speed at which the AEB is
completely released), AEB exit reason (e.g., driver override with
throttle or brake, or system decision), location, and camera image
data. This information could be used by investigators to analyze the
source of the activation and determine if there was a false activation.
Such data would need to be accessible by the agency and potentially by
the vehicle operator for a full and transparent analysis. The agency
seeks comment on all aspects of this data collection approach as an
alternative to false activation testing, including whether this list of
potential elements is incomplete, overinclusive, or impractical.

I. Malfunction Detection Requirement

    NHTSA is proposing that AEB systems must continuously detect system
malfunctions. If an AEB system detects a malfunction that prevents it
from performing its required safety function, the vehicle would provide
the vehicle operator with a warning. The warning would be required to
remain active as long as the malfunction exists while the vehicle's
starting system is on. NHTSA would consider a malfunction to include
any condition in which the AEB system fails to meet the proposed
performance requirements. NHTSA is proposing that the driver must be
warned in all instances of component or system failures, sensor
obstructions, environmental limitations (like heavy precipitation), or
other situations that would prevent a vehicle from meeting the proposed
AEB performance requirements. While NHTSA is not proposing the
specifics of the telltale, NHTSA anticipates that the characteristics
of the alert will be documented in the vehicle owner's manual and
provide sufficient information to the vehicle operator to identify it
as an AEB malfunction.
    NHTSA is considering requirements pertaining to specific failures
and including an accompanying test procedure. For instance, NHTSA could
develop or use available tests that specify examples of how an AEB
system might be placed in a malfunctioning state, such as disconnecting
sensor wires, removing fuses, misaligning or covering sensors.
    NHTSA is considering minimum requirements for the malfunction
indication to standardize the means by which the malfunction is
communicated to the vehicle operator. Malfunctions of

an AEB system are somewhat different than other malfunctions NHTSA has
considered in the past. While some malfunctions may be similar to other
malfunctions NHTSA has considered in FMVSSs because they require repair
(loose wires, broken sensors, etc.), others are likely to resolve
without any intervention, such as low visibility due to environmental
conditions or blockages due to build-up of snow, ice, or loose debris.
    NHTSA is considering requiring that the malfunction indicator
convey the actions that a driver should take when an AEB malfunction is
detected. NHTSA seeks comment on the potential advantages of specifying
test procedures that would describe how the agency would test a
malfunction indicator and on the level of detail that this regulation
should require for a malfunction indicator. Additionally, NHTSA is
considering requiring more details for the indicator itself, such as a
standardized appearance (e.g., color, size, shape, illuminance). NHTSA
seeks comment on the need and potential safety benefits of requiring a
standardized appearance for the malfunction indicator and what
standardized characteristics would achieve the best safety outcomes.
NHTSA seeks comment on the use of an amber FCW warning indicator visual
icon as the malfunction indicator.
    NHTSA anticipates driving situations in which AEB activation may
not increase safety and in some rare cases may increase risk. For
instance, an AEB system in which sensors have been compromised because
of misalignment, frayed wiring, or other partial failure, could provide
the perception system with incomplete information that is then
misinterpreted and causes a dangerous vehicle maneuver to result. In
other instances, such as when a light vehicle is towing a trailer with
no independent brakes, or brakes that do not include stability control
functions, emergency braking may cause jack-knifing, or other dangerous
outcomes. NHTSA is considering restricting the automatic deactivation
of the AEB system generally and providing a list of situations in which
the vehicle is permitted to automatically deactivate the AEB or
otherwise restrict braking authority granted to the AEB system.
    In addition to these, NHTSA is considering allowing the AEB system
to be placed in a nonfunctioning mode whenever the vehicle is placed in
4-wheel drive low or when ESC is turned off, and whenever equipment
such as a snowplow is attached to the vehicle that might interfere with
the AEB system's sensors or perception system. The malfunction
indication requirements would apply in any such instance. NHTSA seeks
comment on the permissibility of automatic deactivation of the AEB
system and under which situations the regulation should explicitly
permit automatic deactivation of the AEB system.

J. AEB System Disablement

    This proposed rule would not permit manual AEB system disablement
at any speed above the proposed 10 km/h (6 mph) minimum speed threshold
above which the AEB system must operate. NHTSA seeks comment on whether
manual deactivation for an AEB system should be allowed at speeds above
10 km/h (6 mph), similar to what is allowed for ESC systems in FMVSS
No. 126.\202\ NHTSA seeks comment on the appropriate performance
requirements if the standard were to permit the installation of a
manually operated deactivation switch. Such requirements might include
limitations such that the default position of the switch be ``AEB ON''
with each cycle of the starting system, or the deactivation
functionality could be limited to specific speeds.
---------------------------------------------------------------------------

    \202\ 49 CFR 571.126 S5.4.
---------------------------------------------------------------------------

K. AEB System Performance Information

    This proposed rule has no requirements that the vehicle
manufacturer provide information to vehicle operators about how the AEB
system works. NHTSA is considering a requirement that manufacturers
provide information describing the conditions under which the AEB
system can avoid collisions, warning drivers that the AEB system is an
emergency system and not designed for typical braking situations, and
specifying the conditions under which the AEB system is not likely to
prevent a collision. NHTSA seeks comment on the potential safety
impacts of requiring such information be provided to vehicle operators
and any costs associated with such an information requirement.

VII. AEB Test Procedures

    To determine compliance with the proposed requirements, NHTSA
proposes to test AEB systems on a test track using specified procedures
and conditions. To establish the appropriate test procedures and
conditions, the agency considered several factors, including the
expected real-world conditions under which AEB systems need to operate
to effectively reduce crash risk, the procedures and conditions that
provide a high degree of test repeatability and reproducibility, the
procedures and conditions needed for safe testing, procedures and
conditions that are within the practical operating range of AEB
systems, the consistency between FMVSS and NCAP test procedures and
conditions, and harmonization with test procedures and conditions in
international AEB regulations and other test programs such as NCAP.
    NHTSA's 2014 draft CIB and DBS research test procedures are the
original basis for the proposed AEB-Lead Vehicle test procedures
included in this NPRM.203 204 Similarly, NHTSA's 2019 draft
research test procedure for PAEB systems is the original basis for the
PAEB test procedures in this NPRM.\205\ Those documents reflect the
agency's experience researching automatic braking systems at the NHTSA
Vehicle Research and Test Center. They also are the main source of
NHTSA's current NCAP test procedures for AEB-equipped vehicles.
---------------------------------------------------------------------------

    \203\ National Highway Traffic Safety Administration (2014,
August), Crash imminent brake system performance evaluation (working
draft). Available at: https://www.regulations.gov/document/NHTSA-2012-0057-0038.
    \204\ National Highway Traffic Safety Administration (2014,
August), Dynamic Brake Support Performance Evaluation (working
draft). Available at: https://www.regulations.gov/document/NHTSA-2012-0057-0038.
    \205\ National Highway Traffic Safety Administration (2019,
April), Pedestrian automatic emergency brake system confirmation
test (working draft). Available at: https://www.regulations.gov/document/NHTSA-2019-0102-0005.
---------------------------------------------------------------------------

    To the extent possible, the proposed test conditions (such as
environmental conditions, vehicle set-up, etc.) are the same in all
tests unless otherwise specified. This provides for simplified,
consistent test procedures and conditions.

A. AEB System Initialization

    NHTSA is proposing that AEB systems will be initialized before each
series of performance tests to ensure the AEB system is in a ready
state for each test trial. The electronic components of an AEB system,
including sensors and processing modules, may require a brief interval
following each starting system cycle to reset to their default
operating state. It also may be necessary for an AEB-equipped vehicle
to be driven at a minimum speed for a period of time prior to testing
so that the electronic systems can self-calibrate to a default or
baseline condition, and/or for the AEB system to become active. The
proposed initialization procedure specifies that, once the test vehicle
starting system is cycled on, it will remain on for at least one minute
and the vehicle is driven at a forward speed of at least 10 km/h (6
mph) before any performance trials

commence. This procedure also ensures that no additional driver actions
are needed for the AEB system to be in a fully active state.

B. Travel Path

    To maximize test repeatability, the travel path in each of the
proposed test scenarios is straight rather than curved. A straight path
simplifies vehicle motion and eliminates the more complex vehicle
control needed for curve-following and which is likely to be less
repeatable. NHTSA's draft research test procedures also specify
straight-line vehicle tests, and other AEB test programs including
NHTSA's NCAP employ a straight travel path.
    The intended travel path is the target path for a given test
scenario. For the proposed AEB tests as conducted by NHTSA for NCAP,
the travel path has been programmed into a robotic steering controller,
and a global positioning system (GPS) has been used to follow the
intended path. The proposed text does not limit the method for steering
the subject vehicle and as such any method including a human driver
could be used by the agency during compliance testing. Regardless of
the steering method, the positional tolerance would be maintained for a
valid test. The travel path is identified by the projection onto the
road surface of the frontmost point of the subject vehicle that is
located on its longitudinal, vertical center plane. The subject
vehicle's actual travel path is recorded and compared to the intended
path. For test repeatability, the subject vehicle's actual travel path
is measured during each test run and will not deviate more than a
specified distance from the intended path.
    NHTSA is proposing that the intended subject vehicle travel path be
coincident with the center of a test lane whenever there are two edge
lines marking a lane on the test track surface. If there is only one
lane line (either a single or double line) marked on the test track,
the vehicle path will be parallel to it and offset by 1.8 m (6 ft) to
one side (measured from the inside edge of the line). Modern vehicles
equipped with AEB often are equipped with other advanced driver
assistance systems, such as lane-centering technology, which detects
lane lines and which might be triggered if the travel path diverges
substantially from the center of a marked test lane, potentially
leading to unrepeatable results. These specifications reflect the
agency's NCAP tests for AEB.206 207
208
---------------------------------------------------------------------------

    \206\ National Highway Traffic Safety Administration (2014,
August), Crash imminent brake system performance evaluation (working
draft). Available at: https://www.regulations.gov/document/NHTSA-2012-0057-0038.
    \207\ National Highway Traffic Safety Administration (2014,
August), Dynamic Brake Support Performance Evaluation (working
draft). Available at: https://www.regulations.gov/document/NHTSA-2012-0057-0038.
    \208\ National Highway Traffic Safety Administration (2013,
February), Lane departure warning system confirmation test and lane
keeping support performance documentation. See https://www.regulations.gov, Docket No. NHTSA-2006-26555-0135.
---------------------------------------------------------------------------

C. Subject Vehicle Preparation

    NHTSA is proposing that there be no specific limitations on how a
subject vehicle may be driven prior to the start of a test trial. As
long as the specified initialization procedure is executed, a subject
vehicle may be driven under any conditions including any speed and
direction, and on any road surface, for any elapsed time prior to
reaching the point where a test trial begins. This is because the
manner in which a subject vehicle is operated prior to a crash imminent
situation should not compromise or otherwise affect the functionality
of the AEB system. Also, ancillary subject vehicle operation on and
around a test track will vary depending on exigencies of testing such
as test lane location. For example, a subject vehicle may need to be
driven across an unmarked section of pavement, be maneuvered using
unspecified steering, braking, and accelerator inputs, and/or be driven
in reverse in order to reach the start position for a test trial.

D. Subject Vehicle Tolerance Specifications

    NHTSA is proposing that the subject vehicle speed would be
maintained within a tolerance range of 1.6 km/h (1.0 mph) of the chosen test speed between the beginning of a test
and the onset of the forward collision warning. For test repeatability,
subject vehicle speed would be as consistent as possible from run to
run. Subject vehicle speed determines the time-to-collision, which is a
critical variable in AEB tests. In NHTSA's experience, subject vehicle
speed can be reliably controlled within the 1.6 km/h
(1.0 mph) tolerance range, and speed variation within that
range yields consistent test results. A smaller speed tolerance is
unnecessary for repeatability and burdensome as it may result in a
higher test rejection rate without any greater assurance of accuracy of
the AEB system's test track performance. This speed tolerance also is
the same as that specified in the agency's NCAP tests for AEB systems.
    NHTSA is proposing that, during each test trial, the subject
vehicle accelerator pedal will be released when a forward collision
warning is given or when the AEB system first engages, whichever is
sooner. Input to the accelerator pedal after AEB has engaged will
potentially interfere with the system and may override the automatic
braking. Therefore, it is necessary to fully release the subject
vehicle's accelerator pedal. The proposed procedure states that the
accelerator pedal is released at any rate and is fully released within
500 milliseconds. This ensures consistent release of the accelerator to
eliminate any interference with AEB engagement and improve test
repeatability. This procedure also better reflects real-world
conditions because a driver's first reaction to a forward collision
warning is likely to be accelerator release.\209\ This manner of
accelerator pedal control is the same as specified in the agency's NCAP
test procedures for AEB systems.
---------------------------------------------------------------------------

    \209\ Campbell, J.L., Brown. J.L., Graving, J.S., Richard, C.M.,
Lichty, M.G., Sanquist, T., . . . & Morgan, J.L. (2016, December).
Human factors design guidance for driver-vehicle interfaces (Report
No. DOT HS 812 360). Washington, DC: National Highway Traffic Safety
Administration.
---------------------------------------------------------------------------

    The accelerator pedal release can be omitted from tests of vehicles
with cruise control actively engaged because there is no driver input
to the accelerator pedal in that case. The AEB performance requirements
in this proposal are the same for vehicles with and without cruise
control engaged, and AEB systems must provide an equivalent level of
crash avoidance or mitigation whether or not cruise control is active.
    NHTSA is proposing that the subject vehicle yaw rate does not
exceed 1.0 deg/s prior to onset of when the subject vehicle
forward collision warning is given or the subject vehicle AEB system
first engages, whichever is sooner. The agency proposes to adopt this
tolerance for test repeatability. A 1.0 deg/s yaw rate
tolerance, which is the most stringent value among the yaw rate limits
specified in the agency's NCAP test procedures for AEB.
    NHTSA is proposing that the travel path of the subject vehicle does
not deviate more than 0.3 m (1.0 ft) laterally from the centerline of
the lead vehicle. For consistent test conduct, it is necessary to
maintain close alignment between the subject vehicle path and the lead
vehicle path. Significant misalignment of the travel paths may change
detection characteristics such as range and relative direction,
potentially resulting in test-to-test inconsistency. Therefore, the
agency proposes to use the tolerance requirement of 0.3 m (1.0 ft) for
the subject vehicle's lateral position, which is more stringent than

the lateral tolerance used in NHTSA's NCAP test procedures for AEB, but
less stringent than the lateral tolerance specified in NHTSA's NCAP
test procedures for PAEB. This tolerance is consistent with the SAE
International recommended practice for AEB. In this proposal, the same
lateral tolerance 0.3 m (1.0 ft) would be used for both lead vehicle
AEB and PAEB.

E. Lead Vehicle Test Set Up and Tolerance

    NHTSA is proposing that the speed of the lead vehicle would be
maintained within a tolerance of 1.6 km/h (1.0
mph) during slower-moving tests and during decelerating lead vehicle
tests until the lead vehicle initiates its deceleration. Like the
subject vehicle speed, the speed of the lead vehicle (i.e., the target
vehicle) is a key parameter that directly influences TTC and other test
outcomes. Results from a series of tests with run-to-run speed
variations outside this tolerance range may be inconsistent. Therefore,
for lead vehicle speed, the agency is proposing to use the same
tolerance of 1.6 km/h (1.0 mph) specified for
the subject vehicle speed, which also reflects the tolerance value used
for NHTSA's NCAP AEB tests.
    NHTSA is proposing that the lead vehicle would not diverge
laterally more than 0.3 m (1.0 ft) from the intended travel path. This
tolerance applies to both the slower-moving and decelerating lead
vehicle test scenarios (for the stopped lead vehicle scenario, the lead
vehicle is stationary and is centered on the projected subject vehicle
travel path). If the lead vehicle's lateral position deviates
significantly from the intended travel path, its alignment within the
field of view of the forward sensors of the subject vehicle will be
off-center, which can contribute to test series variability. The 0.3 m (1.0 ft.) tolerance for the lead vehicle's
lateral position is the same tolerance specified for the subject
vehicle's lateral position, which is consistent with the tolerance used
in the SAE recommended practice for AEB testing.\210\
---------------------------------------------------------------------------

    \210\ SAE International (2017), Automatic Emergency Braking
(AEB) System Performance Testing (SAE J3087).
---------------------------------------------------------------------------

    Controlled lead vehicle deceleration is essential for repeatable
decelerating lead vehicle AEB testing because the reaction of the
subject vehicle depends largely on the position and motion of the lead
vehicle. NHTSA is proposing that the lead vehicle will achieve the
specified deceleration within 1.5 seconds of the onset of lead vehicle
braking. Over this time period, the overall deceleration will be lower
than the target, but will rise over time, allowing for easier test
completion. This lead-in time also makes it easier for the test to be
performed while not making the test harder to pass. The lead vehicle
will maintain this deceleration until 250 milliseconds prior to the
vehicle coming to rest. Over these 250 milliseconds the vehicle
dynamics do not reflect the overall dynamics of the test, and any
acceleration data recorded is dismissed. This deceleration profile is
consistent with NHTSA's NCAP test procedures and SAE's industry
recommended practice for AEB systems.\211\
---------------------------------------------------------------------------

    \211\ SAE International (2017), Automatic Emergency Braking
(AEB) System Performance Testing (SAE J3087).
---------------------------------------------------------------------------

F. Test Completion Criteria for Lead Vehicle AEB Tests

    For lead vehicle tests, NHTSA is proposing test-completion criteria
to clearly establish the point at which a test trial has concluded. For
all lead vehicle scenarios, each test run is considered complete
immediately when the subject vehicle makes contact with the lead
vehicle. In the case of stopped or decelerating lead vehicle tests,
each test run also would be considered complete when the subject
vehicle comes to a complete stop without impact. For slower-moving lead
vehicle tests, the test is complete when the subject vehicle's speed is
less than the lead vehicle speed. These test completion criteria are
important in identifying a pass-fail outcome for AEB-equipped light
vehicles. These criteria also are needed to limit consideration of
vehicle motion or behavior after there is no longer a foreseeable
collision with the lead vehicle.

G. PAEB Test Procedures and Tolerance

    For PAEB testing, NHTSA proposes using the same general procedures
described above, as applicable, including procedures for subject
vehicle speed, yaw rate, travel path, lateral tolerance, subject
vehicle accelerator pedal release.
    Overlap refers to the test mannequin's potential impact point
measured horizontally across the front end of the subject vehicle. It
identifies the point on the subject vehicle that would contact a test
mannequin that is within the subject vehicle travel path if the subject
vehicle were to maintain its speed without braking. NHTSA proposes
using an overlap value of either 50 percent, the midpoint of the
subject vehicle's frontal surface, or 25 percent indicating the point
that is one-quarter of the subject vehicle width from the right side of
the subject vehicle. NHTSA is proposing a 0.15 m (0.5 ft) overlap
tolerance, which provides a high degree of test repeatability while
also allowing a spacing tolerance for the pedestrian test mannequin
position.
    NHTSA is proposing different test scenarios in which the pedestrian
test mannequin enters the path of the subject vehicle, including
entering from the right side and left side of the subject vehicle's
lane. For a pedestrian test mannequin initially positioned on the right
side, NHTSA proposes an origination point that is 4.0 0.1 m
(13.1 0.3 ft) from the subject vehicle's intended travel
path. For a pedestrian test mannequin initially positioned on the left
side, NHTSA proposes an origination point that is 6.0 0.1 m
(19.7 0.3 ft) from the intended travel path. These initial
pedestrian test mannequin positions are somewhat longer than those
specified in NHTSA's 2019 draft test procedures for PAEB, which specify
a right-side test mannequin offset of 3.5 m (11.5 ft) and left-side
test mannequin offset of 5.5 m (18.0 ft).\212\ NHTSA is proposing the
larger test mannequin offsets because the agency has found that the
test mannequin sways and oscillates in an inconsistent manner when it
is just starting to move, and the extra distance will provide time for
it to stabilize before entering the subject vehicle's travel path.
This, in turn, will enhance repeatability and accuracy of the test.
---------------------------------------------------------------------------

    \212\ National Highway Traffic Safety Administration (2019,
April), Pedestrian automatic emergency brake system confirmation
test (working draft). Available at: https://www.regulations.gov/document/NHTSA-2019-0102-0005.
---------------------------------------------------------------------------

    For test scenarios with a moving pedestrian test mannequin, NHTSA
proposes to specify the maximum distance for the pedestrian test
mannequin to reach its intended speed. NHTSA is proposing 1.5 m (4.9
ft) as the maximum distance which will be used for both crossing path
test scenarios and along path test scenarios. Although it is generally
desirable for the test mannequin to attain its final speed as quickly
as possible to efficiently execute tests, the agency has found that
acceleration that is too sudden often results in inconsistent, jerky
test mannequin motions that may compromise repeatability. NHTSA
therefore is proposing distances that are similar to the requirements
in NHTSA's 2019 draft research test procedures for a PAEB system.
    NHTSA is proposing that the simulated walking speed of the
pedestrian test mannequin be maintained within 0.4 km/h (0.2 mph)

during PAEB tests. In NHTSA's 2020 PAEB research experience in
conducting hundreds of tests, this amount of test mannequin speed
tolerance is consistently achievable and provides a high level of run-
to-run repeatability and consistent test results.
    NHTSA is proposing clear test completion criteria to establish a
point when a PAEB test may be considered fully concluded. In all PAEB
test scenarios, a test is immediately complete if the subject vehicle
makes contact with the pedestrian test mannequin. In test scenarios
with the pedestrian test mannequin either crossing or stationary within
the subject vehicle path, a test is complete when the subject vehicle
comes to a complete stop without contacting the pedestrian test
mannequin. In scenarios where the pedestrian mannequin moves along the
forward path of the subject vehicle, the test is complete when the
subject vehicle slows to below the pedestrian test mannequin speed.
These test completion criteria are important for identifying a pass-
fail outcome for PAEB-equipped light vehicles. These criteria also are
needed to limit consideration of vehicle motion or behavior after there
is no longer a risk of collision with a pedestrian test mannequin.
    NHTSA is proposing that, when conducting PAEB tests with two VTDs,
their left sides are aligned on the same plane, and they are positioned
1.0 0.1 m (3.3 0.3 ft) from the subject
vehicle's right side when coincident with the intended travel path. The
VTD positioning is consistent with NHTSA's 2019 draft research test
procedures for PAEB systems for the scenario where an obscured child
test mannequin runs into traffic from behind two parked vehicles. These
test specifications are repeatable and provide for consistent test
results.

H. False Positive AEB Test Procedures

    For the steel trench plate test, the starting point, L0,
is measured between the subject vehicle's front plane and the leading
edge (closest to the subject vehicle) of the steel trench plate. For
the pass-through scenario, the starting point is measured between the
front plane of the subject vehicle and the vertical plane that contains
the rearmost point of the vehicle test devices.
    NHTSA is proposing criteria to clearly establish when a false-
activation test trial may be considered fully concluded. For steel
trench plate tests, a test trial is complete when the subject vehicle
either comes to a stop or passes the leading edge of the steel trench
plate. For the pass-through test, a test trial is complete when the
subject vehicle either comes to a stop or passes between the vehicle
test devices. These criteria provide a definitive, observable pass-fail
basis for false-activation test outcomes in each of the two scenarios.

I. Environmental Test Conditions

    NHTSA proposes testing AEB systems in daylight and in darkness to
ensure performance in a wide range of ambient light conditions.
    For daylight testing, the proposed ambient illumination at the test
site is not less than 2,000 lux.\213\ This minimum level approximates a
typical roadway light level on an overcast day.\214\ The acceptable
range also includes any higher illumination level including levels
associated with bright sunlight on a clear day.
---------------------------------------------------------------------------

    \213\ This illumination threshold is the same as that adopted in
SAE J3087 ``Automatic Emergency Braking (AEB) System Performance
Testing.''
    \214\ During an overcast day (no sun), when the solar altitude
is around 6 degrees, the light intensity on a horizontal surface is
around 2,000 lux. Illuminating Engineering Society of North America.
1979. ``Recommended Practice of Daylighting.''
---------------------------------------------------------------------------

    To ensure test repeatability, the agency further proposes that
testing is not performed while the intended travel path is such that
the heading angle of the vehicle is less than 25 degrees with respect
to the sun \215\ and while the solar elevation angle is less than 15
degrees. The intensity of low-angle sunlight aligned directly into the
sensing element of a camera or other optical AEB sensor can saturate or
``wash out'' the sensor and lead to unrepeatable test results. Also,
low-angle sunlight may create long shadows around a test vehicle, which
could potentially compromise test repeatability.
---------------------------------------------------------------------------

    \215\ The horizontal angle between the sun and a vertical plane
containing the centerline of the subject vehicle would be not less
than 25 degrees for a valid test.
---------------------------------------------------------------------------

    For the proposed PAEB testing in darkness, the ambient illumination
at the test site must be no greater than 0.2 lux. This value
approximates roadway lighting in dark conditions without direct
overhead lighting with moonlight and low levels of indirect light from
other sources, such as reflected light from buildings and signage. An
illumination level of 0.2 lux also is the same level specified in the
test procedures for the recently issued final rule for adaptive driving
beams.\216\ This darkness level accounts for the effect ambient light
has on AEB performance, particularly for camera-based systems. This
ensures robust performance of all AEB systems, regardless of what types
of sensors they may use.
---------------------------------------------------------------------------

    \216\ 87 FR 9916.
---------------------------------------------------------------------------

    NHTSA proposes that the ambient temperature in the test area be
between 0 Celsius (32 [deg]F) and 40 Celsius (104 [deg]F) during AEB
testing. This ambient temperature range matches the range specified in
NHTSA's safety standard for brake system performance.\217\ These
temperatures represent a wide range of conditions that AEB-equipped
vehicles will encounter. While AEB controls and sensors can operate at
lower temperatures, the limiting factor in this case is the braking
performance. The reduced surface friction possible in below-freezing
temperatures may result in unrepeatable test conditions and may
adversely affect subject vehicle braking performance.
---------------------------------------------------------------------------

    \217\ FMVSS No. 135--Light vehicle brake systems.
---------------------------------------------------------------------------

    NHTSA is proposing that the maximum wind speed during AEB
compliance testing be no greater than 10 m/s (22 mph) for lead vehicle
avoidance tests and 6.7 m/s (15 mph) for pedestrian avoidance tests.
These are the same maximum wind speeds specified for AEB tests in the
agency's AEB NCAP procedures and PAEB draft research test
procedure.218 219 Excessive wind during testing could
disturb the test devices in various ways. For example, high wind speeds
could affect the ability of the VTD to maintain consistent speed and/or
lateral position. The pedestrian mannequin could bend or sway
unpredictably in excessively windy conditions. Test equipment that
needs to remain stable also could be affected by wind. To ensure test
repeatability, the agency has tentatively decided to adopt these wind
speed specifications to minimize wind effects during testing.
---------------------------------------------------------------------------

    \218\ National Highway Traffic Safety Administration (2014,
August), Crash imminent brake system performance evaluation (working
draft). Available at: https://www.regulations.gov/document/NHTSA-2012-0057-0038.
    \219\ National Highway Traffic Safety Administration (2019,
April), Pedestrian automatic emergency brake system confirmation
test (working draft). Available at: https://www.regulations.gov/document/NHTSA-2019-0102-0005.
---------------------------------------------------------------------------

    NHTSA is proposing that AEB compliance tests not be conducted
during periods of precipitation, including rain, snow, sleet, or hail.
The presence of precipitation could influence the outcome of the tests.
Wet, icy, or snow-covered pavement has lower friction, which may affect
the outcome of the test. More importantly, in those conditions compared
to dry conditions, it is more difficult to reproduce a friction level
with good precision. Therefore, the agency is proposing to adopt the
precipitation specification specified in the agency's NCAP test
procedures for AEB systems.
    NHTSA is proposing that AEB performance tests be conducted when
visibility at the test site is unaffected by

fog, smoke, ash, or airborne particulate matter. AEB systems may use
cameras to detect other vehicles and pedestrians. Reduced visibility
due to the presence of fog or other substances is difficult to
reproduce in a manner that produces repeatable test results. A current
industry standard specifies that the horizontal visibility at ground
level must be greater than 1 km (0.62 miles), and AEB test procedures
in the European NCAP use that requirement.220 221 NHTSA
believes a minimum visibility range is unnecessary to ensure test
repeatability. Therefore, the agency is proposing a limitation on the
presence of conditions that would obstruct visibility, including fog or
smoke during AEB testing, but is not proposing a minimum visibility
range. NHTSA seeks comment on whether to adopt a minimum level of
visibility.
---------------------------------------------------------------------------

    \220\ SAE International (2017), Automatic Emergency Braking
(AEB) System Performance Testing (SAE J3087).
    \221\ European New Car Assessment Program (Euro NCAP) (2019,
July), Test Protocol--AEB Car-to-Car systems, Version 3.0.2.
---------------------------------------------------------------------------

J. Test Track Conditions

    NHTSA is proposing that the test track surface have a peak friction
coefficient of 1.02 when measured using an ASTM F2493 standard
reference test tire, in accordance with ASTM E1337-19 at a speed of
64.4 km/h (40 mph), without water delivery.\222\ Surface friction is a
critical factor in brake system performance testing, including AEB. The
presence of moisture will significantly change the measured performance
of a braking system. A dry surface is more consistent and provides for
greater test repeatability. The proposed peak friction coefficient is
the same value that NHTSA selected for an update of a NHTSA FMVSS
related to surface friction for brake performance testing.\223\
---------------------------------------------------------------------------

    \222\ ASTM E1337-19, Standard Test Method for Determining
Longitudinal Peak Braking Coefficient (PBC) of Paved Surfaces Using
Standard Reference Test Tire.
    \223\ 87 FR 34800 (June 8, 2022), Final rule, Standard Reference
Test Tire.
---------------------------------------------------------------------------

    NHTSA is proposing that the test surface have a consistent slope
between 0 and 1 percent. The slope of a road surface can affect the
performance of an AEB-equipped vehicle.\224\ It also influences the
dynamics and layout involved in the proposed AEB test scenarios for
both lead vehicle AEB and PAEB. Therefore, NHTSA proposes to limit the
slope of the test surface by adopting the slope requirement specified
for AEB tests in the agency's lead vehicle AEB NCAP procedures and PAEB
draft research test procedure.225 226
---------------------------------------------------------------------------

    \224\ Kim, H. et al., Autonomous Emergency Braking Considering
Road Slope and Friction Coefficient, International Journal of
Automotive Technology, 19, 1013-1022 (2018).
    \225\ National Highway Traffic Safety Administration (2014,
August), Crash imminent brake system performance evaluation (working
draft). Available at: https://www.regulations.gov/document/NHTSA-2012-0057-0038.
    \226\ National Highway Traffic Safety Administration (2019,
April), Pedestrian automatic emergency brake system confirmation
test (working draft). Available at: https://www.regulations.gov/document/NHTSA-2019-0102-0005.
---------------------------------------------------------------------------

    NHTSA proposes that the lead vehicle and pedestrian test mannequin
be unobstructed from the subject vehicle's view during compliance tests
except where specified. Furthermore, each compliance test would be
conducted without any vehicles, obstructions, or stationary objects
within one lane width of either side of the subject vehicle's path
unless specified as part of the test procedure. This test condition is
the same as that specified in the agency's research test procedures for
AEB systems. The presence of unnecessary objects near the path of the
subject vehicle could interfere with detection of a lead vehicle or
test mannequin and have an unintentional effect on the field of view of
the AEB system, which may compromise test repeatability.

K. Subject Vehicle Conditions

    NHTSA is proposing that the subject vehicle be loaded with not more
than 277 kg (611 lb.), which includes the sum of any vehicle occupants
and any test equipment and instrumentation. The agency proposes this
lightly loaded vehicle specification because the primary goal of the
AEB testing is to measure the sensing and perception capability of a
vehicle, which is relatively insensitive to the level of the vehicle
load. In addition, braking tests with fully loaded vehicles are already
required and conducted under exiting FMVSS, such as FMVSS No. 135,
Light Vehicle Brake Systems, to measure the maximum brake capacity of a
vehicle.
    To maximize test repeatability, NHTSA is proposing that subject
vehicle brakes be burnished prior to AEB performance testing according
to the specifications of either S7.1 of FMVSS No. 135, which applies to
passenger vehicles with GVWR of 3,500 kilograms or less, or according
to the specifications of S7.4 of FMVSS No. 105, which applies to
passenger vehicles with GVWR greater than 3,500 kilograms. AEB
capability relies upon the function of the service brakes on a vehicle.
Thus, it is reasonable and logical that the same pre-test conditioning
procedures that apply to service brake performance evaluations should
also apply to AEB system performance evaluations.
    To maximize test repeatability, NHTSA is proposing that the subject
vehicle service brakes be maintained at an average temperature between
65 [deg]C (149 [deg]F) and 100 [deg]C (212 [deg]F). The brake
temperature is evaluated using either the front or rear brakes,
depending on which has a higher temperature. This temperature range is
the same as the range specified in NHTSA's safety standard for light
vehicle brake systems \227\ and is important for consistent brake
performance and test repeatability. Foundation brakes that are too cool
or too hot may perform with less consistency, such that stopping
distance may be unrepeatable. Hot or cold brakes also may fade or
experience stiction or other effects that exacerbate inconsistent brake
performance.
---------------------------------------------------------------------------

    \227\ FMVSS No. 135--Light vehicle brake systems.
---------------------------------------------------------------------------

    User adjustable settings, such as regenerative braking settings and
FCW settings, would be tested in any setting state. Furthermore,
adaptive and traditional cruise control may be used in any selectable
setting during testing. The agency would test vehicles with any cruise
control or adaptive cruise control setting to make sure that these
systems do not disrupt the ability for the AEB system to stop the
vehicle in crash imminent situations. However, for vehicles that have
an ESC off switch, NHTSA will keep ESC engaged for the duration of the
test.

VIII. Test Devices

A. Pedestrian Test Mannequins

    NHTSA is proposing specifications for two pedestrian test devices
to be used for compliance testing for the new PAEB requirements. These
specifications would be referenced within the PAEB test procedures and
NHTSA would use test devices meeting these specifications when it
performs compliance testing. The two pedestrian test devices would each
consist of a test mannequin and a motion apparatus (carrier system)
that positions the test mannequin during a test. NHTSA is proposing
specifications for a pedestrian test mannequin representing a 50th
percentile adult male and a pedestrian test mannequin representing a 6-
to 7-year-old child. NHTSA would use these pedestrian test mannequins
to ensure that light vehicles are equipped with PAEB systems that
detect pedestrians and automatically provide emergency braking to avoid
pedestrian test mannequin contact in the tests specified in this
proposal. NHTSA is proposing to

incorporate by reference specifications from three ISO standards.
1. Background
    Since the introduction of PAEB, vehicle manufacturers and other
entities have been engaged in testing and evaluating the technology.
Because testing cannot be performed with live pedestrians, test
mannequins have been developed to facilitate a safe and practical way
to perform these evaluations objectively. However, to ensure the PAEB
systems operate as intended, the test mannequins must be representative
of pedestrians from the perspective of the vehicle sensors. That is,
sensors used to detect the test mannequins must operate as if they were
detecting actual pedestrians in the real world, which in turn allows
the PAEB system to interpret and respond to the sensor data in a
realistic manner. This representativeness ensures that PAEB system test
results translate to real-world safety benefits.
    There have been several efforts by different organizations to
develop common specifications for PAEB testing, including an ISO
Standard, ISO 19206-2:2018, ``Road vehicles--Test devices for target
vehicles, vulnerable road users and other objects, for assessment of
active safety functions--Part 2: Requirements for pedestrian targets,''
and an SAE Recommended Practice, SAE International Standard J3116,
``Active Safety Pedestrian Test Mannequin Recommendation.'' ISO 19206-
4:2020, ``Road vehicles--test devices for target vehicles, vulnerable
road users and other objects, for assessment of active safety
functions--Part 4: Requirements for bicyclists targets,'' has color and
infrared reflectivity specifications. Additionally, Euro NCAP specifies
use of test mannequins that conform to the specifications in its
``Articulated Pedestrian Target Specification Document,'' \228\ which
sets specifications for size, color, motion patterns, and detectability
by vehicle sensors.
---------------------------------------------------------------------------

    \228\ European Automobile Manufacturers' Association (ACEA),
February 2016, ``Articulated Pedestrian Target Specification
Document,'' Version 1.0, available at https://www.acea.auto/publication/articulated-pedestrian-target-acea-specifications/.
---------------------------------------------------------------------------

    In November 2019, NHTSA published a Federal Register notice that
sought comment on NHTSA's draft research test procedure for PAEB
testing (84 FR 64405). The draft test procedures provided methods and
specifications for performing PAEB systems performance
evaluations.\229\ During the development of these test procedures,
NHTSA used the 4activePS pedestrian static mannequin that was developed
by 4Active Systems.\230\ The 4activePS pedestrian static mannequin was
developed specifically for testing PAEB systems and conforms to the
specifications in ISO 19206-2:2018. NHTSA continues to test with test
mannequins developed by 4Active Systems. However, NHTSA has
transitioned to performing tests using the 4activePA, which has
articulated legs.
---------------------------------------------------------------------------

    \229\ National Highway Traffic Safety Administration (2019,
April), Pedestrian automatic emergency brake system confirmation
test (working draft). Available at: https://www.regulations.gov/document/NHTSA-2019-0102-0005.
    \230\ Id. at 8, citing 4activeSystems GmbH. (n.a.). 4activePS
pedestrian static (web page). Traboch, Austria: Author. Available at
www.4activesystems.at/en/products/dummies/4activeps.html.
---------------------------------------------------------------------------

    The change from using static mannequins to mannequins equipped with
articulated, moving legs is in response to information that
demonstrates that articulated mannequins may be more representative of
actual pedestrians. In response to NHTSA's 2015 NCAP request for
comments notice, the agency received comments asking that NHTSA use
articulated mannequins to test PAEB systems. The commenters reasoned
that the articulated mannequins better represent actual pedestrians. In
response to these comments, NHTSA proposed, in its 2022 NCAP RFC, the
use of articulated mannequins.\231\ In adopting this approach, NHTSA
noted that using articulating mannequins would harmonize with other
major consumer information-focused entities that use articulating