[Federal Register Volume 78, Number 9 (Monday, January 14, 2013)]
[Proposed Rules]
[Pages 2797-2868]
[FR Doc No: 2013-00359]

Vol. 78

Monday,

No. 9

January 14, 2013

Part III

Department of Transportation

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

National Highway Traffic Safety Administration

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

49 CFR Parts 571 and 585

Federal Motor Vehicle Safety Standards; Minimum Sound Requirements for
Hybrid and Electric Vehicles; Draft Environmental Assessment for
Rulemaking To Establish Minimum Sound Requirements for Hybrid and
Electric Vehicles; Proposed Rules

Federal Register / Vol. 78 , No. 9 / Monday, January 14, 2013 /
Proposed Rules

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

DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Parts 571 and 585

[Docket No. NHTSA-2011-0148]
RIN 2127-AK93

Federal Motor Vehicle Safety Standards; Minimum Sound
Requirements for Hybrid and Electric Vehicles

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

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: As required by the Pedestrian Safety Enhancement Act (PSEA) of
2010 this rule proposes to establish a Federal motor vehicle safety
standard (FMVSS) setting minimum sound requirements for hybrid and
electric vehicles. This new standard would require hybrid and electric
passenger cars, light trucks and vans (LTVs), medium and heavy duty,
trucks, and buses, low speed vehicles (LSVs), and motorcycles to
produce sounds meeting the requirements of this standard. This proposed
standard applies to electric vehicles (EVs) and to those hybrid
vehicles (HVs) that are capable of propulsion in any forward or reverse
gear without the vehicle's internal combustion engine (ICE) operating.
This standard would ensure that blind, visually-impaired, and other
pedestrians are able to detect and recognize nearby hybrid and electric
vehicles, as required by the PSEA, by requiring that hybrid and
electric vehicles emit sound that pedestrians would be able to hear in
a range of ambient environments and contain acoustic signal content
that pedestrians will recognize as being emitted from a vehicle.
    The benefit of reducing the pedestrian injury rate per registered
vehicle of HVs to ICE vehicles when 4.1% of the fleet is HV and EV
would be 2790 fewer pedestrian and pedalcyclist injuries. We also
estimate that this proposal will result in 10 fewer pedestrian and
pedalcyclist injuries caused by LSVs. Thus, 2800 total injured
pedestrians are expected to be avoided due to this proposal
representing 35 equivalent lives saved. We do not estimate any
quantifiable benefits for EVs because it is our view that EV
manufacturers would have installed alert sounds in their cars without
passage of the PSEA and this proposed rule. Comparison of costs and
benefits expected due to this rule provides a cost of $0.83 to $0.99
million per equivalent life saved across the 3 and 7 percent discount
levels for the light EV and HV and LSV fleet. According to our present
model, a countermeasure that allows a vehicle to meet the proposed
minimum sound requirements would be cost effective compared to our
comprehensive cost estimate of the value of a statistical life of $6.3
million.

DATES: Comments must be received on or before March 15, 2013.

ADDRESSES: You may submit comments to the docket number identified in
the heading of this document by any of the following methods:
     Federal eRulemaking Portal: go to http://www.regulations.gov. Follow the online instructions for submitting
comments.
     Mail: Docket Management Facility, M-30, U.S. Department of
Transportation, West Building, Ground Floor, Rm. W12-140, 1200 New
Jersey Avenue SE., Washington, DC 20590.
     Hand Delivery or Courier: West Building Ground Floor, Room
W12-140, 1200 New Jersey Avenue SE., between 9 a.m. and 5 p.m. Eastern
Time, Monday through Friday, except Federal holidays.
     Fax:<PHONE_NUMBER>.
    Regardless of how you submit your comments, you should mention the
docket number of this document.
    You may call the Docket at<PHONE_NUMBER>.
    Instructions: For detailed instructions on submitting comments and
additional information on the rulemaking process, see the Public
Participation heading of the Supplementary Information section of this
document. Note that all comments received will be posted without change
to http://www.regulations.gov, including any personal information
provided.
    Privacy Act: Please see the Privacy Act heading under Rulemaking
Analyses and Notices.

FOR FURTHER INFORMATION CONTACT:
For non-legal issues, Ms. Gayle Dalrymple, Office of Crash Avoidance
Standards (telephone: 202-366- 5559) (fax:<PHONE_NUMBER>). Ms.
Dalrymple's mailing address is National Highway Traffic Safety
Administration, NVS-112, 1200 New Jersey Avenue SE., Washington, DC
20590.
For legal issues, Mr. Thomas Healy, Office of the Chief Counsel
(telephone:<PHONE_NUMBER>) (fax:<PHONE_NUMBER>). Mr. Healy's mailing
address is National Highway Traffic Safety Administration, NCC-112,
1200 New Jersey Avenue SE., Washington, DC 20590.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Executive Summary
II. Background
III. Pedestrian Safety Enhancement Act of 2010
IV. Consultation With External Organizations
V. Safety Problem
    A. Comparing the Vehicle to Pedestrian Crash Experience of
Internal Combustion Engine Vehicles to Hybrid and Electric Vehicles
    B. Need for Independent Mobility of People Who Are Visually
Impaired and Blind
VI. NHTSA Research and Industry Practices
    A. NHTSA Phase 1 Research
    B. NHTSA Phase 2 Research
    C. NHTSA Phase 3 Research
    D. International Approach to Pedestrian Alert Sounds
    E. SAE Sound Measurement Procedure
    F. Alert Sounds Currently Provided by Manufacturers
    G. The Notice of Intent To Prepare an Environmental Assessment
VII. NHTSA's Proposal
    A. Acoustic Specifications Developed To Enhance Detection and
Recognition
    B. Critical Operating Scenarios
    1. Stationary But Activated
    2. Reverse
    3. Acceleration and Deceleration
    4. Constant Speed
    C. Application
    1. The Definition of Hybrid Vehicle
    2. Vehicles With a GVWR Over 10,000 lbs
    3. Electric Motorcycles
    4. Low Speed Vehicles
    5. Quiet Internal Combustion Engine Vehicles
    D. Requirements
    1. Acoustic Parameters Designed According to a Detectability
Model
    2. Recognizability Requirements
    3. Prohibition Against Modifying a Vehicle Sound
    4. Phase-in Schedule
E. Compliance Test Procedure
    1. Test Condition
    2. Vehicle Condition
    3. Test Procedure
    a. Start-up
    b. Stationary But Activated and Directivity
    c. Reverse
    d. Constant Speed
    e. Pitch Shifting
    f. Recognizability
    g. Vehicles of the Same Make and Model Emitting the Same Sound
VIII. Alternatives Considered But Not Proposed
    A. Requiring Vehicle Sound To Be Playback of an Internal
Combustion Engine Recording
    B. Requiring That the Alert Sound Adapt to the Ambient
    C. Acoustic Profile Designed Around Sounds Produces by Internal
Combustion Engine Vehicles
    D. Acoustic Profiles Suggested by Manufacturers
    E. International Guidelines for Vehicle Alert Sounds
    F. Suggestions in Comments to the Notice of Intent That Did Not
Satisfy the

Statement of Purpose and Need for the Rulemaking
    G. Possible Jury Testing for Recognition of a Synthetic Sound
IX. NHTSA's Role in the Development of a Global Technical Regulation
X. Analysis of Costs, Benefits and Environmental Effects
    A. Benefits
    B. Costs
    C. Comparison of Costs and Benefit
    D. Environmental Effects
XI. Regulatory Notices and Analyses

I. Executive Summary

    As required by the PSEA,\1\ this rule proposes to establish FMVSS
No.141, Minimum Sound Requirements for Hybrid and Electric Vehicles,
which would require hybrid and electric passenger cars, LTVs, medium
and heavy duty trucks and buses, LSVs, and motorcycles to produce
sounds meeting the requirements of this standard. This proposed
standard applies to EVs and to those HVs that are capable of propulsion
in any forward or reverse gear without the vehicle's ICE operating. The
PSEA requires NHTSA to establish performance requirements for an alert
sound that is recognizable as motor vehicle in operation that allows
blind and other pedestrians to reasonably detect a nearby EV or HV
operating below the crossover speed. The crossover speed is the speed
at which tire noise, wind noise, and other factors eliminate the need
for a separate alert sound. The PSEA defines ``alert sound'' as ``a
vehicle-emitted sound to enable pedestrians to discern vehicle
presence, direction, location and operation.'' \2\ The legal authority
for this rulemaking comes from the PSEA and 49 U.S.C. 30111.
---------------------------------------------------------------------------

    \1\ Public Law 111-373, 124 Stat. 4086 (January 4, 2011).
    \2\ Id. at Section 2(2).
---------------------------------------------------------------------------

    This standard will ensure that blind, visually-impaired, and other
pedestrians are able to detect and recognize nearby hybrid and electric
vehicles by requiring that hybrid and electric vehicles emit sound that
pedestrians will be able to hear in a range of ambient environments and
contain acoustic signal content that pedestrians will recognize as
being emitted from a vehicle. The proposed standard establishes minimum
sound requirements for hybrid and electric vehicles when operating
under 30 kilometers per hour (km/h) (18 mph), when the vehicle's
starting system is activated but the vehicle is stationary, and when
the vehicle is operating in reverse.
    The requirements of this proposal apply only to those HVs that are
capable of propulsion in any forward or reverse gear without the
vehicle's ICE operating because these were the vehicles that the agency
believes fall under the definition of ``hybrid vehicle'' contained in
the PSEA. The agency chose a crossover speed of 30 km/h because this
was the speed at which the sound levels of the hybrid and electric
vehicles measured by the agency approximated the sound levels produced
by similar ICE vehicles. This proposal contains minimum sound
requirements for the activated but stationary operating condition
because the definition of alert sound in the PSEA, as explained in
Section III of this NPRM, requires the agency to issue minimum sound
requirements to allow pedestrians to detect hybrid and electric
vehicles. We have tentatively determined that this requirement can be
best met by requiring vehicles to emit sound in this operating
condition.
    At lower speeds, hybrid and electric vehicles produce less sound
than vehicles propelled by an ICE. At higher speeds, tire and wind
noise are the main contributors to vehicles noise output so at higher
speeds the sounds produced by hybrid and electric vehicles and ICE
vehicles are similar. Because hybrid and electric vehicles do not
produce as much sound as ICE vehicles when operating at lower speeds,
pedestrians and other road users may not be aware of the presence of a
nearby hybrid or electric vehicle. If a hybrid vehicle is involved in a
low speed maneuver (defined as making a turn, slowing or stopping,
backing up, entering or leaving a parking space, or starting in
traffic), it is 1.38 times more likely than an ICE vehicle to be
involved in a collision with a pedestrian and 1.33 times more likely to
be involved in a collision with a pedalcyclist. We believe that this
difference in accident rates is mostly attributable to the pedestrians'
inability to detect these vehicles by hearing them during these
maneuvers. We seek comment on this assumption.
    Statistics for pedestrian collision rates of hybrid and electric
vehicles with a GVWR over 4,536 kg (10,000 lb), and motorcycles were
not available because of the limited penetration of these vehicles into
the fleet. NHTSA expects that should the penetration of hybrid and
electric heavy vehicles, and motorcycles reach the current rate of
penetration of light hybrid and electric vehicles into the fleet, then
the difference in pedestrian collision rates between hybrid and
electric heavy vehicles, and motorcycles and their traditional ICE
counterparts will be similar to the difference in pedestrian collision
rates between light HVs and light ICE vehicles.
    In addition to analyzing crash data, the agency measured the sound
produced by HVs, EVs and ICE vehicles to determine the difference in
sound output between the propulsion types at different speeds and
conducted research to see if there was a difference in the ability of
pedestrians to detect approaching hybrid and electric vehicles versus
ICE vehicles. The agency also used acoustic models to determine the
frequency composition of sounds that would give pedestrians the best
chance to detect approaching hybrid and electric vehicles without
contributing undesirably to surrounding ambient noise levels.
    The proposed standard ensures that pedestrians will be able to
determine whether a hybrid or electric vehicle is accelerating or
decelerating by requiring the frequency content of the sound emitted by
the vehicle to increase in a manner that is similar to the sound
produced by ICE vehicles when accelerating and decelerating. The agency
developed the minimum sound specifications contained in this proposal
using a detection model that estimated the distance at which a
pedestrian would be able hear a given sound in the presence of a given
ambient sound profile. The standard also requires, as mandated by the
PSEA, that all vehicles of the same make, model and model year emit the
same sound.
    The PSEA requires that the final rule establishing this standard be
issued by January 4, 2014 and include a phase-in schedule that
concludes with ``full compliance with the required motor vehicle safety
standard for motor vehicles manufactured on or after September 1st of
the calendar year that begins 3 years after the date on which the final
rule is issued.'' For example the means that if the final rule is
issued January 4, 2014, compliance would commence on September 1, 2015,
which would mark the start of a three-year phase-in period. We
tentatively conclude that the following phase in schedule is reasonable
for manufacturers and allows the fastest implementation of the standard
for pedestrian safety:
    30 percent of the subject vehicles produced on or after September
1of the first year of the phase in;
    60 percent of the subject vehicles produced on or after September
1of the second year of the phase in;
    90 of the subject vehicles produced on or after September 1of the
third year of the phase in; and
    100 percent of all vehicles produced on or after, by September 1 of
the year that begins three years after the date that the final rule is
issued.

    As discussed in detail in Section X of this notice, the benefits of
this proposed rule, if made final, will accrue from injuries to
pedestrians that will be avoided, assuming that the rule will cause the
pedestrian injury rate for HVs and EVs to decrease to that of ICE
vehicles. As discussed in Section V, a traditional analysis of
pedestrian fatalities is not appropriate for this rulemaking. If HVs
and EVs continue to rise in popularity and increase their role in the
U.S. fleet to four percent of all vehicle registrations, unchanged by
rulemaking or industry action, a total of 2,790 injured pedestrians and
pedalcyclists would be expected over the life time of the 2016 model
year fleet due to the pedestrians' and pedalcyclists' inability to
detect these vehicles by hearing. We estimate that the benefit then of
reducing the pedestrian injury rate per registered vehicle of HVs to
ICE vehicles when four percent of the fleet is HV and EV would be 2,790
fewer injured pedestrians and pedalcyclists. We do not estimate any
quantifiable benefits in pedestrian or pedalcyclist injury reduction
for EVs because it is our view that EV manufacturers would have
installed alert sounds in their cars without passage of the PSEA and
this proposed rule. We also estimate that this proposal will result in
10 fewer injured pedestrians and pedalcyclists caused by LSVs.
---------------------------------------------------------------------------

    \3\ Scaled benefits and costs for low speed vehicles are
estimated directly proportional to light vehicles based on sales.
Scaled costs include both installation costs for the system and fuel
costs.

                                                              Discounted Benefits for Passenger Cars (PCs) and LTVs, MY2016, 2010$
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Pedestrians                             Pedalcyclists                                       Total PED + CYC
                                               -------------------------------------------------------------------------------------------------------------------------------------------------
                  3% discount                   3% discount  Total monetized             3% discount  Total monetized             3% discount  Total monetized
                                                   factor        benefits     Total ELS     factor        benefits     Total ELS     factor        benefits                 Total ELS
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
(PC)..........................................       0.8034      $58,640,938       9.27       0.8034      $64,106,653      10.14       0.8034     $122,747,591  19.41
(LTV).........................................       0.8022       26,945,946       4.26       0.8022       28,319,549       4.48       0.8022       55,265,495  8.74
                                               -------------------------------------------------------------------------------------------------------------------------------------------------
    Total.....................................  ...........       85,586,884      13.54  ...........       92,426,203      14.62  ...........      178,013,086  28.15
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Pedestrians                             Pedalcyclists                                       Total PED + CYC
                                               -------------------------------------------------------------------------------------------------------------------------------------------------
                  7% discount                   7% discount  Total monetized             7% discount  Total monetized             7% discount  Total monetized
                                                   factor        benefits     Total ELS     factor        benefits     Total ELS     factor        benefits                 Total ELS
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
(PC)..........................................       0.6700      $48,903,944       7.73       0.6700      $53,462,108       8.46       0.6700     $102,366,052  16.19
(LTV).........................................       0.6303       21,171,815       3.35       0.6303       22,251,074       3.52       0.6303      $43,422,889  6.87
                                               -------------------------------------------------------------------------------------------------------------------------------------------------
    Total.....................................  ...........       70,075,758      11.08  ...........       75,713,183      11.97  ...........      145,788,941  23.06
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

                                                       Total Costs for PCs and LTVs, MY2016, 2010$
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                      Sales      Fuel costs/    Fuel costs       Install     Install costs   Total cost/
           3% discount                 Sales        impacted         veh          (total)       costs/veh        total           veh        Total costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
(PC)............................       9,032,303       439,586         $4.73      $2,079,240        $30.00     $13,187,566        $34.73     $15,266,805
(LTV)...........................       7,164,729       231,685          5.33       1,234,880         30.00       6,950,542         35.33       8,185,421
                                 -----------------------------------------------------------------------------------------------------------------------
    Total.......................      16,197,032       671,270          4.94       3,314,119         30.00      20,138,107         34.94      23,452,226
--------------------------------------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                      Sales      Fuel costs/    Fuel costs       Install     Install costs   Total cost/
           7% discount                 Sales        impacted         veh          (total)       costs/veh        total           veh        Total costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
(PC)............................       9,032,303       439,586         $3.83      $1,683,613        $30.00     $13,187,566        $33.83     $14,871,178
(LTV)...........................       7,164,729       231,685          4.23         980,026         30.00       6,950,542         34.23       7,930,568
                                 -----------------------------------------------------------------------------------------------------------------------
    Total.......................      16,197,032       671,270          3.97       2,663,639         30.00      20,138,107         33.97      22,801,746
--------------------------------------------------------------------------------------------------------------------------------------------------------

                                                     Costs and Scaled Benefits for LSVs, MY2016 \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Sales ratio                                       Scaled                                          Scaled
              Discount rate                LSV to light        Sales       Scaled costs      injuries       Scaled ELS        Scaled      benefits minus
                                              vehicle                                        (undisc.)                       benefits      scaled costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
3%......................................           0.37%           2,500         $87,268           10.39          0.1049        $662,971        $575,703
7%......................................           0.37%           2,500          84,845           10.39          0.0859         542,959         458,114
--------------------------------------------------------------------------------------------------------------------------------------------------------

    NHTSA estimates the fuel and installation cost of adding a speaker
system in order to comply with the requirements of this proposal to be
around $35 per vehicle for light vehicles. We estimate the total fuel
and installation costs of this proposal to the light EV, HV and LSV
fleet to be $23.6M at the 3 percent discount rate and $22.9M at the 7
percent discount rate. The estimated total installation cost for hybrid
and electric heavy and medium duty trucks and buses and electric
motorcycles is $1.48M for MY 2016. We have only calculated the benefits
of this proposal for light EVs, HVs and LSVs because we do not have
crash rates for hybrid and electric heavy and medium duty trucks and
buses and electric motorcycles. To estimate the benefits of this
proposal we have converted injured pedestrians and pedalcyclists
avoided into equivalent lives saved. We estimate that the impact of
this proposal in pedestrian and pedalcyclist injury reduction in light
vehicles and LSVs will be 28.15 equivalent lives saved at the 3 percent
discount rate and 23.06 equivalent lives saved at the 7 percent
discount rate. The benefits of this proposal for the light EV and HV
and LSV fleet are $178.7M at the 3 percent discount rate and $146.3M at
the 7 percent discount rate. Comparison of costs and benefits expected
due to this proposal for the light EV, HV and LSV fleet provides a cost
of $0.83 to $0.99 million per equivalent life saved across the 3 and 7
percent discount levels. According to our present model, a
countermeasure that allows a vehicle to meet the proposed minimum sound
requirements would be cost effective compared to our comprehensive cost
estimate of the value of a statistical life of $6.3 million.

    Total Benefits and Costs Summary for Light Vehicles and Low Speed
                         Vehicles, MY2016, 2010$
------------------------------------------------------------------------
                                3% discount rate      7% discount rate
------------------------------------------------------------------------
Total Monetized Benefits....               $178.7M               $146.3M
Total Costs (Install+Fuel)..                 23.5M                 22.9M
Total Net Impact (Benefit--                 155.2M                123.4M
 Costs).....................
------------------------------------------------------------------------

II. Background

    Whether or not a vehicle can be easily detected by the sound it
makes is a product of vehicle type, vehicle speed, and ambient sound
level. Quieter vehicles, such as EVs and HVs, can reduce pedestrians'
ability to assess the state of nearby traffic and, as a result, can
have an impact on pedestrian safety. EVs and HVs may pose a safety
problem for pedestrians, in particular pedestrians who are blind or
visually impaired and who therefore rely on auditory cues from vehicles
to navigate. For these pedestrians, the primary safety issue arises
when an HV or EV operates quietly using its electric motor for
propulsion at low speeds. This is also the case when other auditory
cues, such as the noise from the vehicle's tires and wind resistance,
are less noticeable.
    Since August 2007, NHTSA has been monitoring the work of the
Society of Automotive Engineers' (SAE) Vehicle Sound for Pedestrians
(VSP) Committee. Participants in the VSP committee include vehicle
manufacturers, suppliers, consulting firms, government, and other
interested parties. The VSP committee's primary goal is to develop a
test procedure to measure the minimum sound output of a motor vehicle.
In September 2011, the SAE published the test procedure, Measurement of
Minimum Noise Emitted by Road Vehicles, (SAE-J2889-1).\4\ The purpose
of J2889-1 is to provide an objective, technology-neutral test to
measure the minimum sound emitted by a vehicle in a specified ambient
noise condition. This is a test procedure only and does not describe
the VSP committee's rationale, provide recommendations about how sounds
for HVs and EVs should be developed or produced, nor does it specify
the ambient condition at which a vehicle sound should be detectable for
the safety of pedestrians.
---------------------------------------------------------------------------

    \4\ Society of Automotive Engineers (2011) Measurement of
Minimum Noise Emitted by Road Vehicles, SAE-J2889-1. Warrendale, PA.
Available at http://standards.sae.org/wip/j2889/1/.
---------------------------------------------------------------------------

    On May 30, 2008, NHTSA published a notice \5\ in the Federal
Register announcing that the agency would hold a public meeting on June
23, 2008 for government policymakers, stakeholders from organizations
representing people who are blind or visually impaired, industry
representatives, and public interest groups to discuss the technical,
environmental and safety issues associated with EVs, HVs, and quiet ICE
vehicles, and the safety of pedestrians. The presentations submitted at
the public meeting and a transcript of the meeting can be found in
Docket No. NHTSA-2008-0108 on the Web site http://www.regulations.gov.\6\ Topics discussed at the meeting included a
statement of the problem, general pedestrian safety, sound measurement
and mobility, automotive industry perspective, SAE work and status,
potential solutions, and noise abatement. At the conclusion of the
public meeting, NHTSA indicated the agency's intention to put together
a research plan and encouraged participants to add comments and ideas
to the docket. NHTSA issued a research plan to investigate the topic of
quieter vehicles and the safety of pedestrians on May 6, 2009.\7\
---------------------------------------------------------------------------

    \5\ 73 FR 31187; May 30, 2008.
    \6\ The presentations are in document  0012 and the
transcript is in document  0023 (Docket No. NHTSA-2008-
0108-0012 and Docket No. NHTSA-2008-0108-0023, respectively).
    \7\ Quieter Cars and the Safety of Blind Pedestrians: The NHTSA
Research Plan, April 2009, available at http://www.regulations.gov/#!documentDetail;D=NHTSA-2008-0108-0025.
---------------------------------------------------------------------------

    In September 2009, NHTSA published a technical report documenting
the incidence of crashes involving hybrid-electric passenger vehicles
and pedestrians and pedalcyclists.\8\ The analysis included a sample of
8,387 hybrid and 559,703 ICE vehicles. The analysis used data from 12
states and a subset of model-year 2000 and later vehicles. The results
of the crash data analysis show that HVs are two times more likely than
ICE vehicles to be in a pedestrian crash where the vehicle is backing
out, slowing/stopping, starting in traffic, and entering or leaving a
parking space/driveway. The vehicles involved in such crashes are
likely to be moving at low speeds at which the difference between the
sounds emitted by ICE vehicles and HVs is substantial. The crash
incidence rate for the combined set of maneuvers is 0.6 percent and 1.2
percent for ICE vehicles and HVs respectively and the difference is
statistically significant. Some of the factors considered in this
analysis are: (1) vehicle maneuver prior to the crash; (2) speed limit
as a proxy for vehicle travel speed; and (3) weather and

lighting condition at the time of the crash.
---------------------------------------------------------------------------

    \8\ R. Hanna (2009) Incidence of Pedestrian and Bicyclists
Crashes by Hybrid Electric Passenger Vehicles, Report No. DOT HS 811
204. U.S. Dept. of Transportation, Washington, DC Available at
http://www-nrd.nhtsa.dot.gov/Pubs/811204.PDf.
---------------------------------------------------------------------------

    In October 2009, NHTSA issued a report entitled ``Research on
Quieter Cars and the Safety of Blind Pedestrians, A Report to
Congress.'' \9\ The report briefly discusses the quieter vehicle safety
issue, how NHTSA's research plan would address the issue, and the
status of the agency's research in implementing that plan.
---------------------------------------------------------------------------

    \9\ Research on Quieter Cars and the Safety of Blind
Pedestrians, A Report to Congress. U.S. Dept of Transportation,
Washington, DC, October 2009, available at http://www.nhtsa.gov/DOT/NHTSA/NVS/Crash%20Avoidance/Technical%20Publications/2010/RptToCongress091709.pdf.
---------------------------------------------------------------------------

    In April 2010, NHTSA issued a report presenting results of Phase 1
of the agency's research.\10\ This report documents the overall sound
levels and general spectral content for a selection of ICE vehicles and
HVs in different operating conditions, evaluates vehicle detectability
for two background noise levels, and considers countermeasure concepts
that are categorized as vehicle-based, infrastructure-based, and
systems requiring vehicle-pedestrian communications.
---------------------------------------------------------------------------

    \10\ Garay-Vega et al. (2010) Quieter Cars and the Safety of
Blind Pedestrians: Phase I, Report No. DOT HS 811 304, U.S. Dept. of
Transportation, Washington, DC. Available at http://www.nhtsa.gov/DOT/NHTSA/NVS/Crash%20Avoidance/Technical%20Publications/2010/811304rev.pdf.
---------------------------------------------------------------------------

    The results show that the overall sound levels for the HVs tested
are noticeably lower at low speeds than for the ICE vehicles tested.
Overall, study participants were able to detect any vehicle sooner in
the low ambient noise condition. ICE vehicles tested were detected
sooner than their HV twins except for the test scenario in which the
target vehicle was slowing down. In this scenario, HVs were detected
sooner because of the distinctive sound emitted by the regenerative
braking system on the HVs. Response time to detect a target vehicle
varies by vehicle operating condition, ambient sound level, and vehicle
type (i.e., ICE vehicle versus HV in EV mode).
    NHTSA initiated additional research (Phase 2) in March 2010 to
explore potential audible countermeasures to be used in vehicles while
operating in electric mode in specific low speed conditions.\11\ The
potential countermeasures explored included quantitative specifications
for sound levels and spectral profiles for detectability. The
feasibility of objectively specifying other aspects of sound quality
for the purpose of predicting recognizability was also explored.
---------------------------------------------------------------------------

    \11\ Garay-Vega et al. (2011) Quieter Cars and the Safety of
Blind Pedestrians, Phase 2: Development of Potential Specifications
for Vehicle Countermeasure Sounds, Report No. DOT HS 811 496. Dept.
of Transportation, Washington, DC. Available at http://www.nhtsa.gov/DOT/NHTSA/NVS/Crash%20Avoidance/Technical%20Publications/2011/811496.pdf.
---------------------------------------------------------------------------

    In our Phase 2 study, researchers assumed that acoustic
countermeasures should provide alerting information at least equivalent
to the cues provided by ICE vehicles. Groups representing people who
are blind or visually impaired have expressed a preference for sound(s)
that will be recognized as that of an approaching vehicle so that it
will be intuitive for all pedestrians.\12\ In the Phase 2 research,
acoustic data acquired from a sample of ICE vehicles was used to
determine the sound levels at which synthetic vehicle sounds, developed
as countermeasures, could be set. ICE equivalent sounds were specified
using overall A-weighted sound levels and, one-third octave band
spectral content. (See Appendix A, ``Glossary of Sound Engineering
Terms'' and Appendix B, ``Acoustic Primer'' for definitions and
explanations of all acoustic terms used in this notice.)
---------------------------------------------------------------------------

    \12\ Goodes et al. (2009) Investigation into the Detection of a
Quiet Vehicle by the Blind Community and the Application of an
External Noise Emitting System, SAE 2009-01-2189. Society of
Automotive Engineers, Warrendale, PA; Maurer (2008) The Danger Posed
by Silent Vehicles. National Federation of the Blind. Remarks made
for the United Nations Economic Commission for Europe, Working Party
on Noise. 47th GRB session February 19, 2008 Geneva. Informal
Document No. GRB-47-10. http://www.unece.org/trans/doc/2008/wp29grb/ECE-TRANS-WP29-GRB-47-inf10e.pdf.
---------------------------------------------------------------------------

    Psychoacoustic models and human subject testing were used to
explore issues of detectability, masking, and recognition of ICE-like
and alternative sound countermeasures. Psychoacoustic models showed
that frequency components between 1600 and 5000 Hz were more detectable
due to strong signal strength and relatively low ambient levels in this
range. Also, frequency components below 315 Hz were often masked by
urban ambient noise.\13\ Human subject studies were conducted to
evaluate countermeasure sounds in a controlled outdoor environment for
six miles per hour forward pass-by with the counter measure sound
output set at 59.5 A-weighted dB and then at 63.5 A-weighted dB
measured 2 meters from the vehicle centerline. The sounds included ICE-
like sounds, alternative (non-ICE-like) sounds designed according to
psychoacoustic principles to improve detectability, and sounds that
combine alternative sounds with some ICE-like components. In addition
to the countermeasure sounds, an ICE vehicle sound was included in the
study as a baseline for comparison purposes.
---------------------------------------------------------------------------

    \13\ The level and frequency of sounds masked by the ambient
will depend on the sound pressure level and shape of that ambient.
For a full description of the typical urban ambient used in this
study, see the full report cited in footnote 11.
---------------------------------------------------------------------------

    The results of this research show that synthetic sounds that
resemble those of an ICE produce detection distances similar to actual
ICE vehicles. Some of the synthetic sounds examined in the study that
were designed according to psychoacoustic principles produced detection
distances twice as long as those of ICE sounds. The study participants
had difficulty detecting synthetic sounds that contained only the
fundamental of the combustion noise of the engine (the lowest frequency
associated with the combustion).
    This research examined four potential ways in which countermeasure
sounds could be specified. The study examined countermeasure sounds
based on recordings of ICE vehicles, synthetically generated
countermeasure sounds that emulate the sounds of an ICE, non-ICE like
countermeasure sounds designed for maximum detectability at a given
sound-pressure level, and synthetically generated sounds that have
special characteristics to enhance detection and characteristics that
ensure that the sounds contain ICE-like components to enhance
recognizability. The report noted that an objective specification for
non-ICE-like sounds is more difficult to develop than one for synthetic
sound generators that emulate the sound of typical ICEs. The report
also noted that the former approach could result in a wider variety of
sounds, some of which might be not recognized as a vehicle or might be
perceived as annoying.
    In early 2011, NHTSA initiated additional research and data
collection activities to further support this rulemaking (Phase 3).
Acoustic measurements and analyses were completed to support the
development of specifications for alerting sounds and test procedures
for compliance with agency requirements. Acoustic data was gathered
from eight vehicles: four ICE vehicles and four EVs/HVs with alerting
sounds (one production and three prototype vehicles). The SAE J2889-1
test procedure was used to measure the sound levels for the stopped and
pass-by conditions. Acoustic measurements were completed on an ISO
10844:1994 noise pad. All HVs and EVs were measured in electric
propulsion mode.
    Variations on SAE J2889-1 were used to explore other aspects such
as directivity, sound level as a function of vehicle speed, and to
capture binaural recordings. Directivity refers to the relative
proportions of acoustical energy

that is emitted from a source, in this case a vehicle, as a function of
direction to the front, back, left, and right. Binaural recordings were
captured for potential use in future research activities. Acoustic
measurements, modeling, and sound simulation tools were used to
identify sound attributes that aid in detection of alert sounds and
recognition of these sounds as a motor vehicle.
    Two approaches were considered in the development of parameters for
alert sounds. In one approach, sound levels for the alert sound were
developed using loudness models and a calculation of safe detection
distances. In the other approach, sound levels for alert sounds were
based on the sound of current ICE vehicles. This research focused on
developing specifications that can be applied to all sounds and that
are objective and practical.
    All of the research activities summarized above are described in
more detail in Section VI. NHTSA Research and Industry Practices.

III. Pedestrian Safety Enhancement Act of 2010

    On January 4, 2011, the Pedestrian Safety Enhancement Act of 2010
(Public Law 111-373) was signed into law. The Pedestrian Safety
Enhancement Act (PSEA) requires NHTSA to conduct a rulemaking to
establish a Federal Motor Vehicle Safety Standard (FMVSS) \14\
requiring an ``alert sound'' \15\ for pedestrians to be emitted by all
types of motor vehicles \16\ that are electric vehicles \17\ (EVs) or
hybrid vehicles \18\ (HVs). The covered types of vehicles include light
vehicles (passenger cars, vans, sport utility vehicles and pickup
trucks), as well as LSVs, motorcycles, medium and heavy trucks and
buses. Trailers are specifically excluded from the requirements of the
PSEA. The PSEA requires NHTSA to establish performance requirements for
an alert sound that allows blind and other pedestrians to reasonably
detect a nearby EV or HV. The PSEA defines ``alert sound'' as a
vehicle-emitted sound that enables pedestrians to discern the presence,
direction,\19\ location, and operation of the vehicle.\20\ Thus, in
order for a vehicle to satisfy the requirement in the PSEA to provide
an ``alert sound,'' the sound emitted by the vehicle must satisfy that
definition. The alert sound must not require activation by the driver
or the pedestrian, and must allow pedestrians to reasonably detect an
EV or HV in critical operating scenarios such as constant speed,
accelerating, or decelerating. In addition to the operating scenarios
previously mentioned the definition of alert sound in the PSEA requires
the agency to establish requirements for a sound while the vehicle is
activated but stationary and when the vehicle is operating in reverse.
---------------------------------------------------------------------------

    \14\ NHTSA is delegated authority by the Secretary of
Transportation to carry out Chapter 301 of Title 49 of the United
States Code. See 49 CFR 501.2. This includes the authority to issue
Federal motor vehicle safety standards. 49 U.S.C. 30111.
    \15\ The definition of that term is discussed below.
    \16\ Section 2(4) defines the term ``motor vehicle'' as having
the meaning given such term in section 30102(a)(6) of title 49,
United States Code, except that such term shall not include a
trailer (as such term is defined in section 571.3 of title 49, Code
of Federal Regulations). Section 30102(a)(6) defines ``motor
vehicle'' as meaning a vehicle driven or drawn by mechanical power
and manufactured primarily for use on public streets, roads, and
highways, but does not include a vehicle operated only on a rail
line.
    \17\ Section2(10) of the PSEA defines ``electric vehicle'' as a
motor vehicle with an electric motor as its sole means of
propulsion.
    \18\ Section 2(9) of the PSEA defines ``hybrid vehicle'' as a
motor vehicle which has more than one means of propulsion. As a
practical matter, this term is currently essentially synonymous with
``hybrid electric vehicle.''
    \19\ The PSEA does not specify whether vehicle ``direction'' is
to be defined with reference to the vehicle itself (thus meaning
forward or backward) or the pedestrian.
    \20\ Section 2(2).
---------------------------------------------------------------------------

    The agency has concluded that the requirement in the PSEA that the
alert sound must allow pedestrians to ``discern vehicle presence,
direction, location, and operation,'' \21\ requires the agency to
establish minimum sound requirements for the stationary but activated
operating condition. The requirement that pedestrians be able to
discern vehicle presence must be read along with the requirements that
the sound allow pedestrians to discern direction, location, and
operation. The term ``presence'' means something that is in the
immediate vicinity. The term ``operation'' means a state of being
functional or operative. Read together the definition of alert sound
requires that pedestrians be able to detect vehicle presence when the
vehicle is in operation. A vehicle with an engaged ignition is in a
state of being functional even though it may not be moving. It is the
agency's position that the provision that pedestrians be able to detect
the presence of a vehicle that is turned on requires that the vehicle
emit a minimum sound level when the vehicle is stationary, but the
starting system is activated.
---------------------------------------------------------------------------

    \21\ Public Law 111-373, Sec.  2(2), 124 Stat. 4086 (2011).
---------------------------------------------------------------------------

    The agency believes that the PSEA requires the agency to establish
requirements for a sound while the vehicle is moving reverse for the
same reason that a sound while the vehicle is stationary is required.
The PSEA requires minimum sound level requirements promulgated by NHTSA
to allow pedestrians to discern vehicle presence and operation. A
vehicle moving in reverse is unquestionably operating, thus a minimum
sound level is required for this condition.
    The PSEA also requires that the minimum sound level requirements
promulgated by NHTSA allow pedestrians to discern the direction of the
vehicle. This language also indicates that the PSEA requires any
standard to establish minimum sound requirements for when the vehicle
is operating in reverse.
    Because the PSEA directs NHTSA to issue these requirements as a
FMVSS under the National Traffic and Motor Vehicle Safety Act (Vehicle
Safety Act),\22\ the requirements must comply with that Act as well as
the PSEA. The Vehicle Safety Act requires each safety standard to be
performance-oriented, practicable,\23\ and objective \24\ and meet the
need for safety. In addition, in developing and issuing a standard,
NHTSA must consider whether the standard is reasonable, practicable,
and appropriate for each type of motor vehicle covered by the standard.
---------------------------------------------------------------------------

    \22\ 49 U.S.C. Chapter 301.
    \23\ In a case involving passive occupant restraints, the U.S.
Circuit Court of Appeals for the District of Columbia said that the
agency must consider public reaction in assessing the practicability
of required safety equipment like an ignition interlock for seat
belts. Pacific Legal Foundation v. Department of Transportation, 593
F.2d 1338 (D.C. Cir. 1978). cert. denied, 444 U.S. 830 (1979).
    \24\ In a case involving passive occupant restraints, the U.S.
Circuit Court of Appeals for the 6th Circuit said, quoting the House
Report (H.R. 1776, 89th Cong. 2d Sess.1966, p. 16) for the original
Vehicle Safety Act, that ``objective criteria are absolutely
necessary so that `the question of whether there is compliance with
the standard can be answered by objective measurement and without
recourse to any subjective determination.' '' Chrysler v. Department
of Transportation, 472 F.2d 659 (6th Cir. 1972).
---------------------------------------------------------------------------

    As a FMVSS, the pedestrian alert sound system standard we are
proposing today would be enforced in the same fashion as other safety
standards issued under the Vehicle Safety Act. Thus, violators of the
standard would be subject to civil penalties.\25\ A vehicle
manufacturer would be required to conduct a recall and provide remedy
without charge if its vehicles were determined to fail to comply with
the standard or if the vehicle's alert sound were determined to contain
a safety related defect.\26\
---------------------------------------------------------------------------

    \25\ 49 U.S.C. 30112 and 30165.
    \26\ 49 U.S.C. 30118-30120.
---------------------------------------------------------------------------

    Under the PSEA, the standard must specify performance requirements
for an alert sound that enables blind and other pedestrians to
reasonably detect EVs

and HVs operating below their cross-over speed.\27\ The PSEA specifies
several requirements regarding the performance of the alert sound to
enable pedestrians to discern the operation of vehicles subject to the
Act. First, the alert sound must be sufficient to allow a pedestrian to
reasonably detect a nearby EV or HV operating at constant speed,
accelerating, decelerating and operating in any other scenarios that
the Secretary deems appropriate.\28\ Second, it must reflect the
agency's determination of the minimum sound level emitted by a motor
vehicle that is necessary to allow blind and other pedestrians to
reasonably detect a nearby EV or HV operating below the cross-over
speed.\29\ NHTSA plans to ensure that EVs and HVs are detectable to
pedestrians by specifying performance requirements for sound emitted by
these vehicles so that they will be audible to pedestrians in the
ambient noise environment typical of urban areas.
---------------------------------------------------------------------------

    \27\ Section 2(3) of the PSEA defines ``cross-over speed'' as
the speed at which tire noise, wind resistance, or other factors
make an EV or HV detectable by pedestrians without the aid of an
alert sound. The definition requires NHTSA to determine the speed at
which an alert sound is no longer necessary.
    \28\ Section 3(a). Under the PSEA, as with most legislation like
it, the Secretary of Transportation delegates responsibility for
achieving the legislation's objectives to the appropriate Department
of Transportation Administration, in this case NHTSA.
    \29\ Section 3(b).
---------------------------------------------------------------------------

    Nothing in the PSEA specifically requires the alert sound to be
electrically generated. Therefore, if manufacturers wish to meet the
minimum sound level requirements specified by the agency through the
use of sound generated by the vehicle's power train or any other
vehicle component, there is nothing in the PSEA to limit their
flexibility to do so.
    The alert sound must also reflect the agency's determination of the
performance requirements necessary to ensure that each vehicle's alert
sound is recognizable to pedestrians as that of a motor vehicle in
operation.\30\ We note that the requirement that the alert sound be
recognizable as a motor vehicle in operation does not mean that the
alert sound be recognizable as a vehicle with an internal combustion
engine (ICE). The PSEA defines ``conventional motor vehicle'' as ``a
motor vehicle powered by a gasoline, diesel, or alternative fueled
internal combustion engine as its sole means of propulsion.'' \31\ If
Congress had intended the alert sound required by the PSEA to be
recognizable as an ICE vehicle, Congress would have specified that the
sound must be recognizable as a ``conventional motor vehicle'' in
operation rather than a motor vehicle because Congress acts
purposefully in its choice of particular language in a statute.\32\
While the mandate that NHTSA develop performance requirements for an
alert sound that is recognizable as a motor vehicle does not mean that
the sound must be based solely on sounds produced by ICE vehicles, the
mandate does impose substantive requirements that the agency must
follow during the rulemaking. The Vehicle Safety Act defines a motor
vehicle as a ``vehicle driven or drawn by mechanical power and
manufactured primarily for use'' on public roads.\33\ The requirement
that the agency develop performance requirements for recognizability
means that the pedestrian alert sound required by this standard must
include acoustic characteristics common to all sounds produced by
vehicles driven by mechanical power that make those sounds recognizable
as a motor vehicle based on the public's experience and expectations of
those sounds. For example, pitch shifting and increases in sound
pressure level denote changes in speed and are common to all vehicles
driven by mechanical power. Further, sounds that the public currently
recognizes as generated by a vehicle driven by mechanical power have
tonal components.
---------------------------------------------------------------------------

    \30\ Section 3(b)(2).
    \31\ Section 2(5).
    \32\ Keene Corp. v. United States, 508 U.S. 200, 208 (1993).
    \33\ 49 U.S.C. Sec.  30102(a)(6).
---------------------------------------------------------------------------

    The PSEA mandates that the standard shall not require the alert
sound to be dependent on either driver or pedestrian activation. It
also requires that the safety standard allow manufacturers to provide
each vehicle with one or more alert sounds that comply, at the time of
manufacture, with the safety standard. Thus, a manufacturer may, if it
so chooses, equip a vehicle with different sounds to denote different
operating scenarios, such as reverse or start up. Each vehicle of the
same make and model must emit the same alert sound or set of sounds.
The standard is required to prohibit manufacturers from providing
anyone, other than the manufacturer or dealers, with a device designed
to disable, alter, replace or modify the alert sound or set of sounds
emitted from the vehicle. A manufacturer or a dealer, however, is
allowed to alter, replace, or modify the alert sound or set of sounds
in order to remedy a defect or non-compliance with the safety standard.
Additionally, vehicle manufacturers, distributors, dealers, and motor
vehicle repair businesses would be prohibited from rendering the sound
system inoperative under Section 30122 of the Vehicle Safety Act.
    It is the agency's intention that the requirements of this standard
be technology neutral. For this reason, we have chosen to establish
minimum sound requirements for a vehicle-level test. The agency
recognizes that, in the near term, most manufacturers would install
speaker systems that emit synthetically developed sounds in order to
meet the requirements of the proposed standard.
    The agency interprets the requirement in the PSEA that each vehicle
of the same make and model emit the same sound as applying only to
sound added to a vehicle for the purposes of complying with this
proposed standard. We also interpret the PSEA requirement that NHTSA
prohibit manufacturers from providing anyone with a means of modifying
or disabling the alert sound and the prohibition on making required
safety systems inoperative contained in Section 30122 of the Vehicle
Safety Act as applying only to sound added to a vehicle for the
purposes of complying with this proposed standard.
    Many changes to a vehicle could affect the sound produced by that
vehicle. In issuing this proposal the agency does not wish to prevent
manufacturers, dealers, and repair businesses from making modifications
to a vehicle such as adding a spoiler or changing the vehicle's tires
that may have the effect of changing the sound produced by the vehicle.
    The agency will test to ensure sounds produced by two vehicles of
the same model are the same (within 3 A-weighted dB) at the stationary
condition so that a determination of the sameness of the sounds is not
dependent on tire or wind noise or other factors that could influence a
vehicle's sound output. The agency will not consider any modifications
made to a vehicle that affect the mechanical, tire or wind noise
produced by that vehicle to make an alert sound added to the vehicle
inoperative.
    The PSEA requires NHTSA to consider the overall community noise
impact of any alert sound required by the new safety standard. In
addition, NHTSA will consider the environmental analysis required by
the National Environmental Policy Act (NEPA) when setting the standard.
    As part of the rulemaking process, NHTSA is required to consult
with various other organizations. This is further described in Section
IV below.

    In addition to requiring NHTSA to publish a final rule establishing
the standard requiring an alert sound for EVs and HVs by January 4,
2014, the PSEA requires that the agency provide a phase-in period, as
determined by NHTSA. However, full compliance with the standard must be
achieved for all vehicles manufactured on or after September 1st of the
calendar year beginning three years after the date of publication of
the final rule. Thus, if the final rule were promulgated sometime in
2014, the three-year period after the date of publication of the final
rule would end sometime in 2017. The first calendar year that would
begin after that date in 2017 would be calendar year 2018. Thus, under
that time scenario, full compliance would be required not later than
September 1, 2018.
    Finally, the PSEA requires NHTSA to conduct a study and report to
Congress whether the agency believes that there is a safety need to
require the alert sounds required by the FMVSS promulgated to meet the
mandate of the Act for some motor vehicles with internal combustion
engines. The report must be submitted to Congress by January 4, 2015.
If NHTSA determines that there is a safety need to require alert sounds
for those motor vehicles the agency must initiate a rulemaking to
require alert sounds for them.

IV. Consultation With External Organizations

    NHTSA is required by the PSEA to consult with the following
organizations as part of this rulemaking: The Environmental Protection
Agency (EPA) to assure that any alert sound required by the rulemaking
is consistent with noise regulations issued by that agency; consumer
groups representing visually-impaired individuals; automobile
manufacturers and trade associations representing them; technical
standardization organizations responsible for measurement methods such
as the Society of Automotive Engineers, the International Organization
for Standardization, and the United Nations Economic Commission for
Europe (UNECE), World Forum for Harmonization of Vehicle Regulations
(WP.29).
    The agency has established three dockets to enhance and facilitate
cooperation with outside entities including international
organizations. The first docket (No. NHTSA-2008-0108) \34\ was created
after the 2008 public meeting was held; it contains a copy of the
notice of public meeting in the Federal Register, a transcript of the
meeting, presentations prepared for the meeting and comment
submissions. It also includes NHTSA's research plan, our ``Notice of
Intent to Prepare an Environmental Assessment for the Pedestrian Safety
Enhancement Act of 2010'' published on July 12th 2011 in the Federal
Register, and the agency's Phase 1 and 2 research reports. (The Notice
of Intent [NOI] and the agency's research are discussed more fully
later in this document.) The second docket (No. NHTSA-2011-0100) \35\
was created to collect comments on the NOI; it also includes a copy of
that notice. The third docket (No. NHTSA-2011-0148) \36\ was created in
September 2011 to include materials related to the rulemaking process
(``The Pedestrian Safety Enhancement Act of 2010'', Phase 1 and 2
research reports, statistical reports, meeting presentations, etc.),
outside comments and items to be released in the future up to and
including this Notice of Proposed Rulemaking.
---------------------------------------------------------------------------

    \34\ http://www.regulations.gov/#!searchResults;rpp=10;po=0;s=NHTSA-2008-0108.
    \35\ http://www.regulations.gov/#!searchResults;rpp=10;po=0;s=%252BNHTSA-2011-0100.
    \36\ http://www.regulations.gov/#!searchResults;rpp=10;po=0;s=NHTSA-2011-0148.
---------------------------------------------------------------------------

    NHTSA has since 2009 also been hosting a series of roundtable
meetings with industry, technical organizations and groups representing
people who are visually-impaired. Below are the dates and topics of
discussion:
     April 14th, 2009: Status of Phase 1 research and industry
updates.
     August 4th, 2009: Phase 1 research plan.
     January 25th, 2010: Final results of Phase 1 research and
industry updates.
     June 24th, 2010: Phase 2 research plan and status of Phase
2 work.
     February 22nd, 2011: Final results of Phase 2 research.
Attendees were asked to submit comments.
    The following organizations have been participating in these
meetings: The Alliance of Automotive Manufacturers, the Global
Automakers (formerly Association of International Automobile
Manufacturers (AIAM)), American Council of the Blind, The American
Foundation of the Blind (AFB), the National Federation of the Blind
(NFB), The International Organization for Standardizations (ISO), The
Society of Automotive Engineers (SAE), the International Organization
of Motor Vehicles Manufacturers (OICA), The Environmental Protection
Agency (EPA) and Japan Automobile Manufacturers Association (JAMA).
    Representatives of the EPA have also been included in our
activities with outside organizations. They have been kept updated on
our research activities and have actively participated in our outreach
efforts. NHTSA has also kept up to date on EPA activities on the
international front through the activities of the UNECE Working Party
of Noise (GRB).
    The American Foundation of the Blind, the American Council of the
Blind and the National Federation of the Blind have provided NHTSA with
invaluable information about visually-impaired pedestrian safety needs
since the 2008 Public Meeting was held.
    The Alliance of Automotive Manufacturers and Global Automakers
(formerly the Association of International Automobile Manufacturers
(AIAM)) have met separately with the agency to discuss our research
findings and their ideas regarding this rulemaking. Members of both
organizations have also met separately with the agency to discuss their
own research findings and ideas for a potential regulatory approach to
address the safety issues of interest to the agency.
    Automotive manufacturers that produce EVs for the U.S. market have
developed various pedestrian alert sounds, recognizing that these
vehicles, when operating at low speeds, may pose an elevated safety
risk to pedestrians. They have made vehicles with sound alert systems
available for lease by NHTSA for research purposes. This information
has been helpful in the agency decision making process.
    The Society of Automotive Engineers (SAE) established the Vehicle
Sound for Pedestrians (VSP) subcommittee in November 2007 with the
purpose of developing a recommended practice to measure sounds emitted
by ICE vehicles and alert sounds for use on EVs and HVs. Their efforts
resulted in standard SAE J2889-1, Measurement of Minimum Noise Emitted
by Road Vehicles.\37\ The agency has been sending liaisons to the VSP
meetings since 2008. SAE is the U.S. technical advisory group to the
International Organization for Standardizations (ISO) and they both
have cooperated in the development of the standard. The ISO document
(ISO/NP 16254 Measurement of minimum noise emitted by road vehicles)
\38\ and SAE document are reported to be technically identical but this
has not been confirmed by NHTSA at this time. The agency is currently
using standard

SAE J2889-1 and ISO10844 \39\ as references in the test procedure
development.
---------------------------------------------------------------------------

    \37\ http://standards.sae.org/j2889/1_201109.
    \38\ http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=56019.
    \39\ http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=45358.
---------------------------------------------------------------------------

    The UNECE World Forum WP.29 determined that road transportation
vehicles propelled in whole or in part by electric means present a
danger to pedestrians and directed the Working Party on Noise (GRB) to
assess what necessary steps WP.29 should take to help mitigate the
problem. In response, GRB established an informal group on Quiet Road
Transport Vehicles (QRTV) \40\ to carry out the necessary activities to
address the quieter vehicles issue and the potential need for global
harmonization. NHTSA has been participating in the QRTV's meetings
since its foundation in 2010 and has kept the group informed about
ongoing agency research activities as well as the results from
completed research studies.
---------------------------------------------------------------------------

    \40\ Papers relating to the informal group periodic meetings may
be found at http://live.unece.org/trans/main/wp29/wp29wgs/wp29grb/qrtv_1.html, http://live.unece.org/trans/main/wp29/wp29wgs/wp29grb/qrtv_2.html, http://live.unece.org/trans/main/wp29/wp29wgs/wp29grb/qrtv_3.html, http://live.unece.org/trans/main/wp29/wp29wgs/wp29grb/qrtv_4.html, http://live.unece.org/trans/main/wp29/wp29wgs/wp29grb/qrtv_5.html, and http://live.unece.org/trans/main/wp29/wp29wgs/wp29grb/qrtv_6.html.
---------------------------------------------------------------------------

    At its March 2011 meeting, WP.29 adopted guidelines covering alert
sounds for electric and hybrid vehicles that are closely based on the
Japanese guidelines discussed more fully later in this document. The
guidelines were published as an annex to the UNECE Consolidated
Resolution on the Construction of Vehicles (R.E.3).
    Considering the international interest and work in this new area of
safety, the U.S. has proposed working on a new GTR, with Japan as co-
sponsor, to develop harmonized pedestrian alert sound requirements for
electric and hybrid-electric vehicles under the 1998 Global Agreement.
WP.29 is now working to develop a GTR that will consider international
safety concerns and leverage expertise and research from around the
world. Meetings of the working group are planned to take place
regularly with periodic reports to WP.29 until the expected
establishment date for the new GTR in November 2014. NHTSA is currently
leading the GTR development process.
    Other international organizations, such as the International
Organization of Motor Vehicles Manufacturers (OICA) and Japan
Automobile Manufacturers Association (JAMA) have been providing NHTSA
with their own research findings and have also been attending our quiet
vehicle meetings.

V. Safety Problem

A. Comparing the Vehicle to Pedestrian Crash Experience of ICE Vehicles
and HVs and EVs

Crash Risk
    Passenger hybrid electric vehicles first became available to
consumers in 2000, and their numbers as well as their proportion of the
passenger vehicle fleet have risen every year since their introduction.
According to the R.L. Polk and Company National Vehicle Population
Profile, there were 18,628 registered passenger HVs in 2001. By 2004,
there were 145,194 registered HVs comprising 0.1 percent of the
passenger vehicle fleet. By 2009, the number had grown to 1,382,605
registered HVs comprising 0.6 percent of the fleet.
    Advocacy groups have raised pedestrian safety concerns regarding
HVs because a vehicle using an electric motor may be quieter than an
ICE vehicle and may not emit the sounds that non-motorists rely on for
warning as vehicles approach them. In 2009, NHTSA released the report
``Incidence of Pedestrian and Bicyclist Crashes by Hybrid Electric
Passenger Vehicles'' which found that, when comparing similar vehicles,
77 out of 8,387 total HVs reported to be in any crash incident were
involved in pedestrian crashes, and 3,578 out of 559,703 total ICE
vehicles were involved in similar pedestrian crashes.\41\ The report
used data collected from 12 individual states. The years for which data
was available varied across different states. Generally, the data used
ranged from the years 2000 to 2006. HV crashes had an overall 40
percent higher chance to involve pedestrians. In situations involving
certain low-speed maneuvers, HVs were twice as likely to be involved in
a pedestrian crash as ICE vehicles in similar situations. The state
data set that NHTSA used to determine the pedestrian and pedalcyclist
crash rates for HVs did not include any information about the vision
status of the pedestrians involved in the crashes. Therefore, we were
unable to determine whether any of the pedestrians involved in these
crashes were blind or visually impaired.
---------------------------------------------------------------------------

    \41\ See footnote 6.
---------------------------------------------------------------------------

    A recent analysis updated and verified these previous findings \42\
by adding additional years of state crash files as well as by
increasing the number of states included in the analysis from 12 to 16,
with a total of 24,297 HVs (approximately three times the HVs of the
2009 study) and 1,001,000 ICE vehicles by Honda and Toyota, with five
different models, in 16 States during 2000-2008. This updated analysis
indicates that a total of 186 HVs and 5,699 ICE vehicles were involved
in pedestrian crashes. A total of 116 HVs and 3,052 ICE vehicles were
involved in crashes with bicycles. Overall, a statistical analysis
referred to as odds ratios indicates that the odds of an HV being in
either a pedestrian or bicycle crash is greater than the odds of an ICE
vehicle being in a similar crash, 19 percent higher for pedestrian
crash odds and 38 percent higher for bicycle crash odds.\43\ The crash
factors of speed limit, vehicle maneuver and location were examined to
determine the relative incidence rates of HVs versus ICE vehicles and
whether the odds ratio was different under different circumstances.
This finding also indicates that the largest differences between the
involvement of HVs and ICE vehicles in pedestrian crashes occur with
speed limits of 35 mph and lower and during certain, typically low-
speed, maneuvers such as making a turn, starting up, and pulling into
or backing out of a parking space. HVs were about 1.38 times more
likely to be involved in a pedestrian crash than a vehicle with an ICE
after completing a low speed maneuver. The results in this updated
analysis show trends similar to those first reported in our 2009
report. The sample sizes of pedestrian or bicycle crashes were verified
to validate the sufficient statistical powers in this updated analysis.
---------------------------------------------------------------------------

    \42\ Wu et al. (2011) Incidence Rates of Pedestrian And
Bicyclist Crashes by Hybrid Electric Passenger Vehicles: An Update,
Report No. DOT HS 811 526. Dept. of Transportation, Washington, DC.
Available at http://www-nrd.nhtsa.dot.gov/Pubs/811526.pdf.
    \43\ The incidence rates for pedestrian and pedalcyclist crashes
involving HVs and EVs were calculated from the State data by
comparing the pedestrian and pedalcyclist crash rates for all HVs
contained in the State data set with the crash rates for all ICE
vehicles from that data set. Because this proposal does not apply to
HVs that always have their ICE on while moving, the agency removed
the Honda Civic and the Honda Accord from the HV category and
included those vehicles in the calculations as ICE vehicles in
estimating the incidence rate used in the benefit calculations.
---------------------------------------------------------------------------

    The rate of crashes between HVs and pedalcyclists was different
than the rate of crashes between HVs and pedestrians. While a larger
percentage of pedalcyclist crashes for both HVs and ICE vehicles
occurred at posted speed limits of 35 mph and below, the difference in
rates of pedalcyclist crashes between HVs and ICE vehicles was higher
at speed limits above 35 mph that at speed limits of 35 mph and below.
For posted speed limits of 35 mph and below HVs showed an

increased rate of pedalcyclist crashes when compared to ICE vehicles,
however, the results were not statically significant. The difference in
pedealcyclist crash rates between HVs and ICE vehicles was also greater
when driving straight as compared to low-speed maneuvers.
    This updated analysis further included all vehicle models from all
manufacturers during the period covered by the study, beyond the five
models from Toyota and Honda, and a similar pedestrian crash trend was
also found from the expanded data. Comparisons restricted to HV and
similar ICE pairs (Prius and Corolla; Civic HV and ICE model) only were
also made. These comparisons also resulted in similar conclusions about
HV pedestrian crashes relative to ICE vehicle pedestrian crashes,
including that the odds of an HV being in a pedestrian crash is greater
than the odds of an ICE vehicle being in a similar crash.
    Despite the similarities in the overall sound level produced by the
two vehicles, the differential crash rate for the Civic HV and the ICE
version of the Civic was even larger than for other pairs of HVs and
ICEs. We note that the HV Civic is much different than the other hybrid
vehicles in the analysis because when the agency tested this vehicle,
we could not get the ICE engine to shutoff even at idle. Thus, unlike
the other HVs tested, the ICE was always on in this vehicle, but we
acknowledge that in the real-world, the ICE may shut-off at some point.
We do know that, although sound levels are similar, there are
differences between the frequency profile of the HV and ICE Civics, but
we do not know how pedestrians would perceive this difference either in
general or in the low-speed maneuvers used in our crash analysis. The
agency seeks comments on whether the differences in pedestrian crash
rates between HVs and ICEs are solely due to a pedestrians' inability
to detect the vehicle based on the vehicle's sound while operating
below the crossover speed or whether there may be other factors that we
have not identified that affect the difference in crash rates between
the two types of vehicles.
    While this updated analysis provides insightful comparisons of the
incidence rates of HVs versus ICE vehicles involved in pedestrian
crashes, there are some limitations to consider: the use of data from
16 states cannot be used to directly estimate the national problem
size; there is still not enough data to draw conclusions in all
scenarios of interest such as for individual low-speed maneuvers like
making a turn, starting up, or in parking lots.
Fatalities
    The Fatality Analysis Reporting System (FARS) contains a census of
all traffic fatalities. HVs and EVs that struck and killed a pedestrian
were identified using the Vehicle Identification Numbers (VINs)
contained in the 2001 through 2009 FARS files. During this period,
there were 53 pedestrian fatalities attributed to crashes involving 47
HVs and EVs. Almost all of these fatalities (47 of the 53) involved
vehicles that were identified as passenger vehicles. In 2008, there
were 10 HVs or EVs that struck and killed 10 pedestrians, and in 2009,
there were 11 HVs or EVs that struck and killed 11 pedestrians.
    However, these fatalities are not included in the target population
for analysis under this rulemaking for two reasons. The first is that
pedestrian fatalities are not as likely to occur at low speeds for
which the rate of HV pedestrian collisions is significantly higher than
collisions between ICE vehicles and pedestrians. This proposal would
establish minimum sound requirements for hybrid and electric vehicles
operating at speeds of 30 km/hr (18 miles per hour (mph)) and below. A
majority of pedestrian fatalities occur when the vehicle involved in
the collision is travelling at a speed greater than 18 mph. Overall, 67
percent of the pedestrian fatalities involving HVs or EVs and with
known speed limits occurred at a speed limit above 35 mph. For all
pedestrian fatalities with known speed limits, 62 percent occurred at a
speed limit above 35 mph and 61 percent of those involving passenger
vehicles occurred at a speed limit above 35 mph. The goal of this
proposal is to prevent injuries to pedestrians that result from
pedestrians being unable to hear nearby hybrid and electric vehicles.
At speeds of 35 mph and above, at which a majority fatal crashes
involving pedestrians occur, the sound levels produced by hybrid and
electric vehicles are the same as the sound levels produced by ICE
vehicles. Therefore, establishing minimum sound requirements for hybrid
and electric vehicles operating at low speeds is not expected to have
an impact on pedestrian fatalities.
    The second reason is that the rate of pedestrian fatalities per
registered vehicle for HVs and EVs is not larger (and is in fact lower)
than that for ICE vehicles. Using 2008 data, the fatality rate for
pedestrians in crashes with HVs and EVs is 0.85 fatalities per 100,000
registered vehicles, and the corresponding rate for ICE vehicles is
1.57 per 100,000 vehicles.
    There also could be fatalities involving HVs and EVs that occur in
non-traffic crashes in places such as driveways and parking lots.
However, a comprehensive search for HVs and EVs involved in pedestrian
fatalities could not be undertaken because NHTSA's Not in Traffic
Surveillance (NiTS) system does not provide VINs, and a search for
model names that indicate hybrid or electric vehicles did not identify
any crashes involving pedestrian fatalities.

B. Need for Independent Mobility of People Who Are Visually Impaired

    In addition to addressing the safety need in the traditional sense
of injuries avoided as a result of preventing vehicle-pedestrian
crashes, NHTSA believes it is important to note another dimension of
safety that should be taken into account with respect to pedestrians
who are blind or visually impaired. Pedestrians who are blind or
visually impaired need to be able to travel independently and safely
throughout their communities without fear of injury, both as a result
of collisions with motor vehicles and as a result of other adverse
events in the environments they must negotiate. To a far greater extent
than is the case for sighted people, vehicle sounds help to define a
blind or visually-impaired person's environment and contributes to that
person's ability to negotiate through his/her environment in a variety
of situations.\44\
---------------------------------------------------------------------------

    \44\ National Federation of the Blind (2011) How People Who are
Blind Use Sound for Independent Travel, memorandum to the docket
NHTSA-2011-0148, Washington, DC. This memorandum is the source for
this information.
---------------------------------------------------------------------------

    Two long-established navigation aids that visually-impaired people
use are the white cane and a guide dog. The modern white cane and the
techniques for its use help the user to navigate and allow sighted
people to recognize that a person is blind or visually impaired. Today,
the ``structured discovery'' method of teaching independent travel for
visually-impaired people emphasizes learning to use information
provided by the white cane, traffic sounds, and other cues in the
environment to travel anywhere safely and independently, whether the
individual has previously visited the place or not.
    Of the thirteen guide dog schools currently operating in the United
States, most require applicants for guide dogs to have at least some
skill in traveling with a long white cane, since the basic techniques
for using a white cane and a guide dog are similar in many

respects. A guide dog does not lead a person but simply guides him or
her around obstacles; the handler is still responsible for navigation.
    Whether a blind or visually-impaired person uses a white cane or
guide dog, the primary purpose of both travel tools is to help the
blind traveler identify and/or avoid obstacles in his or her path using
the sense of touch. The remaining information needed by a blind or
visually-impaired person to travel safely and independently is provided
primarily through the sense of hearing.
    When traveling with a white cane or guide dog, the primary sound
cue used by blind pedestrians is the sound of vehicle traffic, which
serves two purposes: navigation and collision avoidance. Navigation
involves not only ascertaining the proper time to enter a crosswalk and
maintain a straight course through an intersection while crossing, but
also the recognition of roadways and their traffic patterns and their
relationship to sidewalks and other travel ways a blind or visually-
impaired person might use.
    Sound emitted by individual vehicles, as opposed to the general
sound of moving traffic, is critical. The sound of individual vehicles
alerts blind travelers to the vehicle's location, speed, and direction
of travel. For example, a blind or visually-impaired person moving
through a parking lot can hear and avoid vehicles entering or exiting
the lot or looking for parking spaces; a blind person walking through a
neighborhood can hear when a neighbor is backing out of a driveway. The
vehicle sound also indicates to a blind or visually-impaired pedestrian
whether a vehicle is making a turn, and if so, in which direction. The
sound of individual vehicles also allows the blind traveler to detect
and react to unusual or unexpected vehicle movement.
    The sound of a vehicle that has an activated starting system but is
stationary (usually referred to as ``idling'' for vehicles with
internal combustion engines) alerts the blind or visually-impaired
traveler to the fact that the vehicle is not simply parked and that it
may move at any moment. The sound of a vehicle starting is important
for the same reason. If a blind person is approaching a driveway and
notes a vehicle that is stationary but running, or hears a vehicle
start, he or she will wait for the vehicle to pull out, or for an
indication that it will not, for example by noting that the vehicle
remains stationary for some time, indicating that the driver has no
immediate plans to move.
    Because traffic sound is a navigation aid for blind and visually-
impaired pedestrians, as well as an indispensable part of traveling
safely, blind people listen to the sound of traffic actively and
constantly when they are walking, even when they are not at an
intersection. The sound of traffic helps blind individuals follow the
roadway; this is critical, even when there is a sidewalk, to keep the
blind individual on course. Traffic sounds also allow the detection of
roadway changes like curves, forks, or merges. The sound of traffic is
particularly important in negotiating intersections. By listening to
the traffic, a blind or visually-impaired traveler can determine how
the intersection is controlled (traffic signal, stop sign, etc.); how
many lanes of traffic are involved; and any unusual characteristics of
the intersection (e.g., three-way intersections or roundabouts). These
determinations can be made by listening to the sounds of vehicle
engines--often through one or two entire signal cycles--to determine
driver behavior, which is usually a reliable indicator of the
characteristics of the intersection. This includes the sound of
stationary vehicles--particularly in multi-lane or oddly shaped
intersections--because it is important to identify which lanes of
traffic are active, when, and for how long; and to then follow the line
of traffic that most nearly parallels the direction in which the
traveler wishes to proceed. At the same time that the blind traveler is
listening to the overall traffic pattern, he or she also listens for
cues from individual vehicles, particularly when determining the
precise moment to enter the crosswalk. At signaled intersections, an
idling vehicle in the street parallel to the path of the traveler that
accelerates and moves through the intersection is an indication that a
traffic signal has just changed and that it is safe to proceed into the
cross street, with maximum time to complete the crossing. In general,
by crossing when the traffic flow is parallel to him or her, a blind
individual can safely cross most intersections without difficulty. The
individual will use the sound of the parallel traffic while crossing to
maintain a roughly straight line through the intersection. Figure 1
shows several examples of how a blind pedestrian would use the sound of
traffic to cross a complex intersection.

    Example 1:  A blind pedestrian standing at corner A (facing
corner B) ready to cross, will wait for the stationary vehicles
behind him/her to start moving as an indication that the traffic
light has changed. Then, the pedestrian will proceed to cross the
street and follow the parallel line of traffic on his left (from A
to B) confident there is enough time to safely cross the street.
    Example 2:  A blind pedestrian standing at corner A (facing
corner C) ready to cross, will use the sound of the stationary
vehicles on his/her left and the parallel traffic on his/her right
as guides to follow a straight path while crossing.
    Example 3:  A blind pedestrian at corner C (facing corner D)
ready to cross, will wait for the traffic from C to A to stop and
the parallel traffic across the intersection to start, to safely
walk from corner C to Corner D. The sounds from the stationary
vehicles on his/her left and the parallel traffic across the
intersection serve as guides to keep a straight path while crossing.

[GRAPHIC] [TIFF OMITTED] TP14JA13.029

    Using the white cane or guide dog and the sound of traffic, people
who are blind or visually-impaired have been able to navigate safely
and independently for decades. Blind and visually-impaired people
travel to school, the workplace, and throughout their communities to
conduct the daily functions of life primarily by walking and using
public transportation. Safe and independent pedestrian travel is
essential for blind or visually-impaired individuals to obtain and
maintain employment, acquire an education, and fully participate in
community life. Short of constantly traveling with a human companion, a
blind or visually-impaired pedestrian simply cannot ensure his or her
own safety or navigate effectively without traffic sound. To the extent
that there are more and more HVs and EVs on the road that are hard to
detect, people who are blind or visually impaired will lose a key
means--the sound of traffic--by which they determine when it is safe to
cross streets, but also by which they orient themselves and navigate
safely throughout their daily lives, avoiding dangers other than
automobiles.

VI. NHTSA Research and Industry Practices

    On May 6, 2009 NHTSA issued a research plan describing the research
relating to quieter vehicles it planned to conduct. This section
reports on the research completed to date.

A. NHTSA Phase 1 Research \45\
---------------------------------------------------------------------------

    \45\ see footnote 8.
---------------------------------------------------------------------------

    In April 2010 NHTSA released a report titled ``Quieter Cars and the
Safety of Blind Pedestrians: Phase 1'' referred to as Phase 1. This
report documented a study conducted by the John A. Volpe National
Transportation Systems Center (Volpe) under an interagency agreement.
This study documents the overall sound levels and general spectral
content for a selection of HVs and ICE vehicles in different operating
conditions, evaluates vehicle detectability for two ambient sound
levels, and considers countermeasure concepts. The study investigated
operating scenarios of concern for pedestrians who are blind or
visually impaired, documented acoustic measurements of hybrid, electric
and ICE vehicles and ambient environments in which blind or visually
impaired pedestrians might reasonably be expected to make travel
decisions based on sound alone, examined the auditory detectability of
vehicles in safety scenarios of concern to individuals who are blind or
visually impaired and examined potential countermeasures.
Safety Scenarios for Pedestrians Who Are Blind or Visually-Impaired
    As part of Phase 1 research NHTSA sought to identify operating
scenarios necessary for the safety of visually-impaired pedestrians.
The researchers identified these scenarios based on crash data,
literature reviews, and unstructured conversations with blind
pedestrians and orientation and mobility specialists. Scenarios were
defined by combining pedestrian vehicle environments, vehicle type,
vehicle maneuver/speed/operation, and considerations of ambient sound
level. The operating scenarios identified in Phase 1 are:
     Vehicle approaching at low speed: One of the strategies
used by pedestrians who are blind is to cross when the road is quiet.
This technique assumes that it is safe to proceed when a vehicle is
loud enough to be heard far enough away, there are no other masking
sounds present, and no other vehicles are detected.
     Vehicle backing out (as if coming out of a driveway):
There is a concern

quieter vehicles may not be detectable when backing out. This scenario
is complex for pedestrians since it is difficult to anticipate where
there may be a driveway and the driver's visibility may be limited. The
pedestrian may have limited time to react and respond to avoid a
conflict.
     Vehicle travelling in parallel and slowing: Pedestrians
who are blind often need to distinguish between a vehicle moving
through an intersection and a vehicle turning into their path. The
pedestrian needs to perceive this information when the vehicle is in
the parallel street, before it turns into his or her path. The sound of
slowing vehicles in the parallel street helps pedestrians identify
turning vehicles.
     Vehicle accelerating from stop: Pedestrians who are blind
use the sound of traffic in the parallel street to establish alignment
and to identify a time to cross. The sound of accelerating vehicles in
the parallel street indicates, for example, that the perpendicular
traffic does not have the right of way and thus a crossing opportunity
is available. Pedestrians may initiate their crossing as soon as they
detect the surge of parallel traffic or may delay the decision to make
sure traffic is moving straight through the intersection and not
turning into their path. A delay in detecting the surge of parallel
traffic may impact the opportunity to complete a crossing within the
designated walking interval.
     Vehicle stationary: The sound of vehicles idling provides
important cues. For example, the sound of a vehicle in the far lane
gives cues about the width of the road (number of lanes), and conveys
information about the distance to walk and the time needed to navigate
across the street. A quieter vehicle may not be detected when it is
stationary at intersections or parking lots and it may start moving
suddenly at the same time a pedestrian enters the conflicting path.
    NHTSA was able to gather crash data for collisions involving
pedestrians and HVs when the HV was operating in one of the scenario
described above (the crash report did not separately analyze vehicle
starting from a stop and the vehicle stationary conditions) immediately
prior to the crash in both the crash report released by NHTSA in
September of 2009 \46\ and the updated crash report released in October
2011.\47\ The 2011 report analyzed the crash rates for vehicles making
a turn, slowing/stopping, backing, entering and leaving a parking
space/driveway and starting in traffic separately and then analyzed all
those operating conditions together. Because of the sample size an
independent odds ratio was not available for any of the scenarios. When
taken together, however, these low speed operating conditions show a
statistically significant 1.38 odds ratio showing an increased risk of
pedestrian collisions.
---------------------------------------------------------------------------

    \46\ See footnote 7,
    \47\ See footnote 39.
---------------------------------------------------------------------------

    For this study, the sounds emitted by HVs and ICE vehicles were
measured and recorded under operating conditions representative of the
previously identified safety scenarios.\48\ The operating conditions
were as follows: (1) a vehicle backing up at 5 mph (mimicking a vehicle
backing out of a driveway); (2) a vehicle slowing from 20 to 10 mph
(mimicking a vehicle preparing to turn right from the parallel street);
(3) a vehicle approaching at a low constant speed (6 mph and 10 mph);
(4) a vehicle accelerating from a stop; and (5) a vehicle idling.
Average A-weighted sound levels for each of the six vehicles tested are
reported in Table 1.
---------------------------------------------------------------------------

    \48\ The SAE J2889-1 draft test method covers only two operating
conditions: stationary vehicle and 10 km/h (6 mph) constant speed
pass by. This study follows recommendations of the SAE draft method
with regard to instrument settings, calibration, meteorological
monitoring, etcetera; however, it deviates from the SAE method with
respect to operating condition, data measured, as well as height,
distance, and orientation of the microphones. For each measurement,
one-half second contiguous average SPLs were measured. The maximum
of these for each event were analyzed for the development of Table
1. These levels are representative of the sound level when the
vehicle is at or near the microphone line (line PP' in SAE J2889-1,
Figure 1).

                                       Table 1--Overall A-Weighted Sound Level at the Microphone Location (12 ft)
                                                        [Average A-weighted level, LAeq0.5s, dB]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                2009 Toyota
               Scenario/vehicle operation                   2010 Toyota     2009 Toyota     Honda Civic     Honda Civic      Highlande      2008 Toyota
                                                               Prius          Matrix          Hybrid            ICE           Hybrid        Highlander
--------------------------------------------------------------------------------------------------------------------------------------------------------
Approaching at 6 mph....................................            44.7            53.5            49.3            52.0            53.2            55.5
Backing out (5 mph).....................................            44.2            51.3            48.5            58.2            45.9            52.7
Slowing from 20 to 10 mph...............................            53.0            54.2            56.6            55.0            53.0            55.4
Acceleration............................................            62.9            63.1            65.4            63.5            64.8            64.9
Idling or Stationary but activated......................             \1\            47.8            44.8            46.0             \1\            48.1
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Background.

    Additionally, measurements were collected for vehicles approaching
at moderate constant speeds (20 mph, 30 mph, and 40 mph) in order to
document the convergence, if any, of HVs and ICE vehicles at higher
speeds. In general, HVs were quieter below approximately 20 mph, above
which either the vehicle's ICE engine turned on, tire and road noise
became dominant, or both. HVs also tended to have less high frequency
content than ICEs at low speeds. Further details and results from this
study can be found in NHTSA's final report DOT HS 811 304.\49\
---------------------------------------------------------------------------

    \49\ See Docket for this notice, Item  NHTSA-2011-0148-
0004.
---------------------------------------------------------------------------

Auditory Detectability of Vehicles in Critical Safety Scenarios \50\
---------------------------------------------------------------------------

    \50\ See footnote 8; Garay-Vega et al., Auditory Detectability
of Hybrid Electric Vehicles by Pedestrians Who Are Blind. 90th
Annual Meeting Transportation Research Board January 23-27, (2011),
Washington, DC Available at http://amonline.trb.org/12ktc8/1.
---------------------------------------------------------------------------

    In Phase 1, NHTSA compared the auditory detectability of HVs and
ICE vehicles by pedestrians who are legally blind. Forty-eight
independent travelers, with self-reported normal hearing, listened to
binaural \51\ audio recordings of two HVs and two ICE vehicles in three
operating conditions, and two different ambient sound levels. The
operating conditions included a vehicle: approaching at a constant
speed (6 mph); backing out at 5 mph; and slowing from 20 to 10 mph (as
if to turn right). The ambient sound levels were a quiet rural (31.2 dB
(A)) and a moderately noisy suburban ambient (49.8 dB (A)). Overall,
participants took longer to detect the two HVs tested

(operated in electric mode), except for the slowing maneuver. Vehicle
type, ambient level, and operating condition had a significant effect
on response time.
---------------------------------------------------------------------------

    \51\ Binaural recordings reproduce the acoustic characteristics
of the sound similar to how a human perceives it. Binaural
recordings reproduce a more realistic three dimensional sensation
than conventional stereo and are intended for playback through
headphones, rather than loudspeakers.
---------------------------------------------------------------------------

    Data collection included missed detection frequency and response
time (and corresponding time-to-vehicle arrival and detection
distance). Missed detection frequency is defined as instances when the
target vehicle is present and the participant fails to respond.
Response time is computed as the time from the start of a trial to the
instant the participant presses a space bar as an indication he/she
detects the target vehicle. Time-to-vehicle-arrival is the time from
first detection of a target vehicle to the instant the vehicle passes
the microphone line/pedestrian location. Detection distance is the
longitudinal space between the vehicle and the pedestrian (microphone)
location at the instant the participant indicated detection of a target
vehicle.
    A repeated measure of analysis of variance (ANOVA) was used to
analyze the main and interaction effects of the independent variables:
vehicle type, vehicle maneuver and ambient sound level. A separate
analysis was completed for each scenario, and a pair-wise t-test
compared each vehicle with the other (ICE vehicle and HV twins) for
each ambient sound level. The time-to-vehicle arrival for each vehicle-
ambient condition is shown in Table 2, Table 3 and Table 4 for each of
three scenarios.
    Vehicle Approaching at 6 mph (9.6 km/h) Pass by: The first
traveling situation examined was a pedestrian standing on the curb
waiting to cross a one-way street when there may be vehicles
approaching from the left. Some trials included a target vehicle and
some trials only included background noise. The target vehicle in this
scenario was traveling from the left at a constant speed of 6 mph.
There were vehicles in the background in all trials. The pedestrian had
to be able to detect a vehicle that would affect the decision about
when to start to cross the street. This scenario tested the distance
and time at which a pedestrian can detect a vehicle approaching at low
speed. On average, participants took 1.1 seconds longer to detect
vehicles in the high ambient sound condition than in the low ambient
sound condition. The main effect of ambient was statistically
significant. The mean time-to-vehicle-arrival was 5.5 and 4.3 seconds
for the low and high ambient condition respectively. Participants
detected both ICE vehicles sooner than the HV twins. The main effect of
vehicle type was statistically significant. The interaction effect of
vehicle type and ambient was also statistically significant, meaning
that the difference between when a passenger was able to detect an ICE
vehicle versus its HV twin was greater when ambient was high than when
it was low. Table 2 presents the individual differences between ICE
vehicles and their HV peers (i.e., Prius vs. Matrix and Highlander
hybrid vs. Highlander ICE); pair-wise comparisons are statistically
significant within a given ambient condition. Participants were more
likely to miss the Toyota HVs than the Toyota ICE vehicles approaching
at a constant low speed. The missed detection rates in the low ambient
condition were: 0.02 for the Prius; 0.01 for the Matrix; 0.03 for the
Highlander Hybrid; and 0.0 for the Highlander ICE vehicle. The
corresponding values in the high ambient condition were: 0.21 for the
Prius; 0.02 for the Matrix; 0.04 for the Highlander; and 0.01 for the
Highlander ICE vehicle.

  Table 2--Time-to-Vehicle Arrival and Detection Distance for 6 mph Vehicle Pass-by by Vehicle Type and Ambient
                                                    Condition
----------------------------------------------------------------------------------------------------------------
                                                                             Time-to-vehicle       Detection
                 Vehicle                         Ambient sound level           arrival (s)       distance (ft)
----------------------------------------------------------------------------------------------------------------
2010 Toyota Prius.......................  Low.............................                4.3               37.9
                                          High............................                2.4               20.9
2009 Toyota Matrix......................  Low.............................                5.5               48.4
                                          High............................                4.6               40.5
2009 Highlander Hybrid..................  Low.............................                5.3               46.6
                                          High............................                4.1               36.6
2008 Highlander ICE.....................  Low.............................                6.8               59.4
                                          High............................                6.3               55.1
----------------------------------------------------------------------------------------------------------------

    Vehicle Backing Out (5 mph (8 km/h) Reverse): The second traveling
situation was a pedestrian walking along a sidewalk with driveways on
the left side; the pedestrian heard distant vehicles in the background
in all trials. This is similar to walking in an area that is a few
blocks away from a main road. The target vehicle was a nearby vehicle
backing towards the pedestrian at a constant speed of 5 mph. This task
is complex for pedestrians since it is difficult to anticipate where
there may be a driveway and when a vehicle will move out of a driveway.
In addition, a driver's visibility may be limited and the pedestrian
may have very limited time to respond to avoid a conflict. The main
effect of ambient was statistically significant. The average time-to-
vehicle-arrival was 4.4 and 2.7 seconds for the low and high ambient
condition, respectively. Participants took longer to detect both HVs
than their ICE twins. The main effect of vehicle type was statistically
significant. Table 3 shows the individual differences between ICE
vehicles and their HV twins; pair-wise comparisons were statistically
significant within a given ambient condition. Participants were more
likely to miss the Toyota HVs than the Toyota ICE vehicles in the
backing out session. The missed detection rates in the low ambient
condition were: 0.05 for the Prius; 0.02 for the Matrix; 0.10 for the
Highlander Hybrid; and 0.02 for the Highlander ICE. The corresponding
values in the high ambient condition were: 0.11 for the Prius; 0.0 for
the Matrix; 0.26 for the Highlander; and 0.02 for the Highlander ICE.
On average, participants took longer to detect vehicles in the high
ambient sound condition than in the low ambient sound condition.

   Table 3--Time-to-Vehicle Arrival and Detection Distance for Vehicle
              Backing Out by Vehicle and Ambient Condition
------------------------------------------------------------------------
                                                        Time-to-vehicle
             Vehicle              Ambient sound level      arrival(s)
------------------------------------------------------------------------
2010 Toyota Prius...............  Low................                4.0
                                  High...............                2.5
2009 Toyota Matrix..............  Low................                5.2
                                  High...............                3.6
2009 Highlander Hybrid..........  Low................                3.3
                                  High...............                1.4
2008 Highlander ICE.............  Low................                5.2
                                  High...............                3.3
------------------------------------------------------------------------

    Vehicle Traveling in Parallel Lane and Slowing (Slowing from 20 to
10 mph (32 to 16 km/h): The third and last traveling situation examined
in the study was a pedestrian trying to decide when to start crossing a
street with the signal in his/her favor and a surge of parallel traffic
on the immediate left. The sound of slowing vehicles in the parallel
street helps blind pedestrians identify turning vehicles. In some
trials (no-signal condition), a vehicle continued straight through the
intersection at 20 mph, so pedestrians can cross whenever they choose.
However, in other trials there was a vehicle slowing from 20 mph to 10
mph as if to turn right into the pedestrian path (target vehicle). The
pedestrian had to be able to detect when the vehicle was slowing. This
scenario tests whether the pedestrian perceived this information when
the vehicle was in the parallel street. Participants were more likely
to miss the ICE vehicles approaching in the parallel lane and slowing
than the HVs in the same situation. Table 4 shows the time-to-vehicle
arrival and detection distance for the `vehicle slowing' scenario.
Pair-wise comparisons (HV vs. ICE twin) were statistically significant
within a given ambient condition. On average, participants detected HVs
sooner than their ICE vehicle twins. The main effect of vehicle type
was statistically significant. The trend observed in the vehicle-
slowing scenario (i.e., HVs are detected sooner than their ICE vehicle
twins) may be explained by a noticeable peak in the 5000 Hz one-third
octave band for the HVs tested during this operation. The tone emitted
was associated with the electronic components of the vehicles when
braking (e.g., regenerative braking). The missed detection rates in the
low ambient condition were: 0.05 for the Prius; 0.31 for the Matrix;
0.03 for the Highlander Hybrid; and 0.17 for the Highlander ICE
vehicle. The missed detection rates in the high ambient condition were:
0.05 for the Prius; 0.35 for the Matrix; 0.03 for the Highlander
Hybrid; and 0.17 for the Highlander ICE vehicle.

  Table 4--Time-to-Vehicle Arrival and Detection Distance for Vehicle Decelerating From 20 to 10 mph by Vehicle
                                           Type and Ambient Condition
----------------------------------------------------------------------------------------------------------------
                                                                             Time-to-vehicle       Detection
                 Vehicle                         Ambient sound level            arrival(s)       distance  (ft)
----------------------------------------------------------------------------------------------------------------
2010 Toyota Prius.......................  Low.............................                2.0               35.9
                                          High............................                1.9               33.8
2009 Toyota Matrix......................  Low.............................                1.1               18.0
                                          High............................                0.8               12.8
2009 Highlander Hybrid..................  Low.............................                3.0               58.8
                                          High............................                2.7               51.6
2008 Highlander ICE.....................  Low.............................                1.5               25.7
                                          High............................                1.3               21.8
----------------------------------------------------------------------------------------------------------------

    Table 5 shows the time-to-vehicle arrival by vehicle type, and
ambient condition. Considering all three independent variables, there
was a main effect of vehicle, vehicle maneuver, and ambient sound
level. Similarly, there were interaction effects between vehicle type
and ambient; vehicle type and maneuver, ambient and vehicle maneuver,
and a three way interaction between ambient, vehicle type and vehicle
maneuver.

              Table 5--Average Time-to-Vehicle Arrival by Scenario, Vehicle Type and Ambient Sound
----------------------------------------------------------------------------------------------------------------
                                                   Low ambient                          High ambient
              Scenario               ---------------------------------------------------------------------------
                                             HVs            ICE Vehicles           HVs            ICE Vehicles
----------------------------------------------------------------------------------------------------------------
Approaching at 6 mph................                4.8                6.2                3.3                5.5
Backing out (5 mph).................                3.7                5.2                2.0                3.5
Slowing from 20 to 10 mph...........                2.5                1.3                2.3                1.1
----------------------------------------------------------------------------------------------------------------

B. NHTSA Phase 2 Research

    In October 2011 NHTSA released a second report examining issues
involving hybrid and electric vehicles and blind pedestrian safety
titled ``Quieter Cars and the Safety of Blind Pedestrians, Phase 2:
Development of Potential Specifications for Vehicle Countermeasure
Sounds.'' The research conducted by Volpe first sought to define
acoustic specifications to be used as alert sounds for quiet vehicles
based on the sounds produced by ICE vehicles. Volpe then analyzed the
loudness of the ICE sounds in a suburban ambient using psychoacoustic
modeling. Volpe used human subject testing to evaluate the performance
of several different varieties of countermeasure sounds including ICE
sounds. Based on the results from the Phase I research, the
psychoacoustic modeling and the human subjects testing Volpe developed
potential specifications for vehicle countermeasure sounds.
    The Phase 2 research developed various options and approaches to
specify vehicle sounds that could be used to provide information at
least equivalent to the cues provided by ICE vehicles, including speed
change. In this research, acoustic data acquired from a sample of 10
ICE vehicles was used to determine the sound levels at which synthetic
vehicle sounds, developed as countermeasures, could be set. ICE-
equivalent sounds were specified as overall A-weighted sound levels and
spectral content at the one-third octave band level. Psychoacoustic
models and human-subject testing were used to explore issues of
detectability, masking, and recognition of ICE-like and alternative
sound countermeasures.
    The researchers determined that the elements of a specification for
vehicle sounds should consider sound output levels; pitch changes that
convey changes in vehicle speed; and acoustic qualities that determine
whether the sound is perceived as a vehicle. The options discussed in
the Phase 2 final report \52\ assume that the vehicle acoustic
countermeasure should:
---------------------------------------------------------------------------

    \52\ See footnote 11.
---------------------------------------------------------------------------

     Provide information at least equivalent to that provided
by ICE vehicles, including speed change; and
     Provide for detection of a vehicle in residential,
commercial and other suburban and urban environments. Note: Human-
subject tests for Phase 2 were conducted in an ambient level of
approximately 58-61 dB (A).
    Phase 2 work focused initially on the following two ideas: (1) the
lack of detectability of quieter vehicles can be remediated if they are
fitted with synthetic sound generators that emulate the sound of
typical ICEs; and (2) the specifications for the vehicle sounds can be
defined in terms of objective parameters--namely, overall sound output
as measured by the SAE J2889-1 procedure and spectral distribution
specifications for the minimum amount of sound level in one-third-
octave bands.
    Recognizability is more complex than detectability. Most sounds,
and sounds as complex as those emitted by an ICE, have numerous
properties in addition to loudness and spectral distribution that
affect human perception. Among these properties are rise time, decay
time, repetition rates, variations in pitch and loudness, and phase
relations among various components of the sound. These challenges can
be demonstrated, for example, by playing a recording of a sound
backwards, for example, that changes in these properties can render a
sound unrecognizable even though loudness and spectral distribution are
unchanged. There are no established quantitative metrics for many
qualities of a sound that a person might use for recognition.
    In the Phase 2 report Volpe first considered whether HVs and EVs
should be equipped with sounds that are based on the acoustic profile
of ICE vehicles. This concept is based on the assumption that the ICE
vehicles measured in this study are typical of the current fleet, emit
an acceptable amount of noise during low-speed operations, and that
some (e.g., ICE-like) countermeasure sounds can be based on the
statistical average of real-vehicle spectral characteristics.
Researchers developed the potential specifications for alert sounds
shown in Table 6 and Table 7 based on acoustic analysis of sounds
produced by ICE vehicles to demonstrate what acoustic specifications
for a vehicle alert sound might look like. The derivations of these
data are given in Section 5 of the Phase 2 final report.

  Table 6--Minimum Overall A-weighted Level (LAeq, 1/2; sec) by Vehicle
                                Operation
------------------------------------------------------------------------
                                                          LAeq, 1/2 sec,
                    Vehicle operation                          dB(A)
------------------------------------------------------------------------
6 mph...................................................            61.1
10 mph..................................................            63.6
15 mph..................................................            68.1
20 mph..................................................            70.2
Acceleration............................................            66.7
Start-up................................................            70.7
Stationary but activated................................            55.2
------------------------------------------------------------------------

    Table 7 shows the corresponding minimum A-weighted one-third-
octave-band spectra for each operating mode. ICE vehicles have energy
components in all frequencies (e.g., 100 to 20k Hz), however, the
psychoacoustic models implemented in this study show that energy
components in the one-third octave bands ranging from 1600 Hz to 5000
Hz contributed the most to detection, and those ranging from 315 Hz to
1600 Hz contributed additional detection and pitch information. These
spectral distribution limits are derived from the procedures described
in Section 6 of the Phase 2 final report.

                                   Table 7--A-weighted One-Third-Octave-Band Spectra at Microphone Line LAeq, 1/2 sec
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Stationary but
  1/3 Octave band center frequency, Hz         6 mph          10 mph          15 mph          20 mph       Acceleration       Startup        activated
--------------------------------------------------------------------------------------------------------------------------------------------------------
100 to 20000............................            61.1            63.6            68.1            70.2            66.7            70.7            55.2
315.....................................            43.9            46.9            50.2            52.5            49.8            44.2            37.3
400.....................................            46.5            48.7            53.0            54.1            51.4            46.6            39.0
500.....................................            47.9            51.2            55.6            57.1            53.4            51.8            42.1
630.....................................            49.0            52.5            56.9            59.1            54.6            52.4            42.3
800.....................................            51.1            54.6            59.5            62.3            55.1            55.2            43.2
1000....................................            51.4            55.2            60.2            63.2            55.6            57.8            44.9
1250....................................            52.2            54.6            59.6            62.2            57.2            60.5            46.3
1600....................................            52.0            54.3            58.8            61.3            57.0            61.1            45.4

2000....................................            50.3            52.0            56.1            57.9            55.7            60.5            44.6
2500....................................            49.1            50.3            53.9            54.9            55.1            61.1            43.8
3150....................................            48.6            49.2            52.4            52.1            54.9            61.6            44.1
4000....................................            46.9            47.5            50.5            49.5            53.2            60.9            42.4
5000....................................            44.1            45.0            47.8            46.4            50.8            59.2            40.3
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The Volpe Center examined two options \53\ under this first concept
(ICE-like sounds):
---------------------------------------------------------------------------

    \53\ In this section of the notice the word ``option'' refers to
countermeasure concepts developed in Phase 2 research and not
rulemaking options considered by the agency when developing this
proposal (see Sections VII and VIII for NHTSA's proposal and
alternatives considered, respectively).
---------------------------------------------------------------------------

Recordings of Actual ICE Sounds
    The first option under the ICE-like sound concept explored using
recordings of actual ICE vehicles as alert sounds. Recordings would be
made when the vehicle is operating at constant speeds, forward from 0
to 20 mph and in reverse at 6 mph. Other components of the vehicles
noise output (e.g., tire noise, aerodynamic noise, AC fan noise) would
be emitted regardless of whether an ICE is in use and would not be
included in these recordings. Sound generation systems with signal
processing capabilities would be used to continuously and monotonically
vary the sounds from one operating condition to the next according to
vehicle input (e.g. vehicle speed sensors, throttle sensors, etc.). In
this option, emitted sounds would be based on standardized recordings
with processing limited to pitch shifting in proportion to vehicle
speed and interpolation between sounds.
Synthesized ICE-Equivalent Sounds
    The second option under the ICE-like sound concept explored using
simulated ICE sounds directly synthesized by a digital-signal processor
(DSP) programmed to create ICE-like sounds (based on actual target
sounds) that would vary pitch and loudness depending on vehicle inputs.
This is in contrast to the first option, described above, in which the
sounds come directly from recordings of actual vehicles, and the
processor must store and interpolate among files representing every
mode of operation and for every speed within the 0 to 20-mph range.
Here, the resulting synthesized sounds would resemble those of the
first option, but have fewer spectral components. A synthesizer could
be simpler and cheaper than a sound generator based on real ICE sounds.
For this option, target sounds, recorded from actual vehicles for the
operations specified above would be used. The synthesized sounds would
then be developed to match the spectral shape of these target sounds.
(Note: by definition, power-spectra spectral lines have a resolution of
1 Hz).
    Sound generation systems with signal processing capabilities would
be used to continuously and monotonically vary the sounds from one
operating condition to the next according to vehicle input (e.g.
vehicle speed sensors, throttle sensors, etc.) and the synthesis
algorithms developed for their sounds. The two options listed above
assume that band-limited (315 Hz to 5000 Hz) ICE-like sounds will be
recognizable as motor vehicles.
Alternative, Non-ICE-Like Sounds Designed for Detectability
    The second concept, described in the Phase 2 final report, consists
of alternative countermeasure sounds with acoustic characteristics
different from ICE vehicles. Some of the countermeasures evaluated in
the human-subject studies have sound characteristics that could improve
detectability when compared to ICE-equivalent sounds. The following
sound characteristics can improve detectability of a sound source \54\:
---------------------------------------------------------------------------

    \54\ Stanton & Edworthy (Eds.) (1999) Human Factors in Auditory
Warnings
---------------------------------------------------------------------------

     Pulsating quality with pulse widths of 100 to 200 msec.
     Inter-pulse intervals of about 150 msec.
     Fundamental tonal component in 150 to 1000 Hz range.
     At least three prominent harmonics in the 1 to 4 kHz
range.
     Pitch shifting denoting vehicle speed change.
    The design of a non-ICE sound involves a complex tradeoff among
several factors including annoyance, cost, detectability, and overall
sound pressure level values. While the required sound pressure level
values for non-ICE-like sounds will generally be lower than for ICE-
like sounds for the same detection distance, there is no objective
basis upon which to calculate the difference in sound pressure level