[Federal Register Volume 77, Number 37 (Friday, February 24, 2012)]
[Notices]
[Pages 11200-11250]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-4017]
[[Page 11199]]
Vol. 77
Friday,
No. 37
February 24, 2012
Part II
Department of Transportation
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National Highway Traffic Safety Administration
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Visual-Manual NHTSA Driver Distraction Guidelines for In-Vehicle
Electronic Devices; Notice
Federal Register / Vol. 77 , No. 37 / Friday, February 24, 2012 /
Notices
[[Page 11200]]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
[Docket No. NHTSA-2010-0053]
Visual-Manual NHTSA Driver Distraction Guidelines for In-Vehicle
Electronic Devices
AGENCY: National Highway Traffic Safety Administration (NHTSA),
Department of Transportation (DOT).
ACTION: Notice of proposed Federal guidelines.
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SUMMARY: The National Highway Traffic Safety Administration (NHTSA) is
concerned about the effects of distraction due to drivers' use of
electronic devices on motor vehicle safety. Consequently, NHTSA is
issuing nonbinding, voluntary NHTSA Driver Distraction Guidelines
(NHTSA Guidelines) to promote safety by discouraging the introduction
of excessively distracting devices in vehicles.
This notice details the contents of the first phase of the NHTSA
Driver Distraction Guidelines. These NHTSA Guidelines cover original
equipment in-vehicle device secondary tasks (communications,
entertainment, information gathering, and navigation tasks not required
to drive are considered secondary tasks) performed by the driver
through visual-manual means (meaning the driver looking at a device,
manipulating a device-related control with the driver's hand, and
watching for visual feedback).
The proposed NHTSA Guidelines list certain secondary, non-driving
related tasks that, based on NHTSA's research, are believed by the
agency to interfere inherently with a driver's ability to safely
control the vehicle. The Guidelines recommend that those in-vehicle
devices be designed so that they cannot be used by the driver to
perform such tasks while the driver is driving. For all other
secondary, non-driving-related visual-manual tasks, the NHTSA
Guidelines specify a test method for measuring the impact of task
performance on driving safety while driving and time-based acceptance
criteria for assessing whether a task interferes too much with driver
attention to be suitable to perform while driving. If a task does not
meet the acceptance criteria, the NHTSA Guidelines recommend that in-
vehicle devices be designed so that the task cannot be performed by the
driver while driving. In addition to identifying inherently distracting
tasks and providing a means for measuring and evaluating the level of
distraction associated with other non-driving-related tasks, the NHTSA
Guidelines contain several design recommendations for in-vehicle
devices in order to minimize their potential for distraction.
NHTSA seeks comments on these NHTSA Guidelines and any suggestions
for how to improve them so as to better enhance motor vehicle safety.
DATES: Comments: You should submit your comments early enough to ensure
that the docket receives them not later than April 24, 2012.
Public Meetings: NHTSA will hold public meetings in March 2012 in
three locations: Washington, DC; Los Angeles, California; and Chicago,
Illinois. NHTSA will announce the exact dates and locations for each
meeting in a supplemental Federal Register Notice.
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: U.S. Department of
Transportation, 1200 New Jersey Avenue SE., West Building Ground Floor,
Room W12-140, Washington, DC 20590-0001
Hand Delivery or Courier: 1200 New Jersey Avenue SE., West
Building Ground Floor, Room W12-140, between 9 a.m. and 5 p.m. ET,
Monday through Friday, except Federal holidays.
Fax: 202-493-2251.
Instructions: For detailed instructions on submitting comments, 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. Please see the ``Privacy Act'' heading
below.
Privacy Act: Anyone is able to search the electronic form of all
comments received into any of our dockets by the name of the individual
submitting the comment (or signing the comment, if submitted on behalf
of an association, business, labor union, etc.). You may review DOT's
complete Privacy Act Statement in the Federal Register published on
April 11, 2000 (65 FR 19477-78) or you may visit http://DocketInfo.dot.gov.
Docket: For access to the docket to read background documents or
comments received, go to http://www.regulations.gov or the street
address listed above. Follow the online instructions for accessing the
dockets.
FOR FURTHER INFORMATION CONTACT: For technical issues, you may contact
Dr. W. Riley Garrott, Vehicle Research and Test Center, telephone:
(937) 666-3312, facsimile: (937) 666-3590. You may send mail to this
person at: The National Highway Traffic Safety Administration, Vehicle
Research and Test Center, P.O. Box B-37, East Liberty, OH 43319.
SUPPLEMENTARY INFORMATION: These proposed NHTSA Guidelines will lead to
issuance of final NHTSA Guidelines, which will not have the force and
effect of law and will not be regulations. Therefore, NHTSA is not
required to provide notice and an opportunity for comment. NHTSA is
doing so, however, to ensure that its final NHTSA Guidelines benefit
from the input of all knowledgeable and interested persons.
Table of Contents
I. Executive Summary
A. The Problem of Driver Distraction and Related Research
B. NHTSA Driver Distraction Program
C. Today's Proposal
II. Background
A. Acronyms Used in Document
B. The Driver Distraction Safety Problem
i. Estimation of Distraction Crash Risk Via Naturalistic Driving
Studies
ii. Summary of Naturalistic Driving Study Distraction Risk
Analyses
C. NHTSA's Driver Distraction Program
III. Why distraction guidelines?
IV. NHTSA Research To Develop Driver Distraction Metrics and
Measurement Methods
A. Timeline of NHTSA Driver Distraction Measurement Research
B. ``15-Second Rule'' Study
C. Collision Avoidance Metrics Partnership (CAMP) Driver
Workload Metrics Project
D. Measuring Distraction Potential of Operating In-Vehicle
Devices
E. Developing a Test To Measure Distraction Potential of In-
Vehicle Information System Tasks in Production Vehicles
F. Distraction Effects of Manual Number and Text Entry While
Driving
G. Principal Findings of NHTSA Driver Distraction Metric
Research
V. Driver Distraction Prevention and Reduction Guidelines
A. Currently Existing Driver Distraction Guidelines
B. Why NHTSA Is Issuing Its Own Guidelines for Limiting and
Reducing Driver Distraction
C. First Phase of NHTSA's Driver Distraction Guidelines Focuses
on Original Equipment Devices with Visual-Manual Driver Interfaces
D. Past NHTSA Actions on Driver Distraction
E. Challenges Relating to the Development of Interface
Guidelines to Minimize Driver Distraction
VI. Justification for Specific Portions of NHTSA Guidelines for
Reducing Driver
[[Page 11201]]
Distraction During Interactions With In-Vehicle Systems
A. Intended Vehicle Types
B. Existing Alliance Guidelines Provide a Starting Point
C. International Harmonization and Voluntary Consensus Standards
D. Statement of General Responsibilities
E. Scope--Devices for Which the NHTSA Guidelines Are Appropriate
F. Definition of a Task
G. Definition of Lock Out
H. Per Se Lock Outs
I. Steering Wheel-Mounted Control Restrictions
J. Maximum Downward Viewing Angle
K. Tests Considered To Determine What Tasks Should Be Accessible
While Driving
L. NHTSA's Preferred Tests for Determining What Tasks Should Be
Accessible While Driving
M. Eye Glance Acceptance Criteria
i. Selection of Manual Radio Tuning as the Reference Task
ii. The Alliance Guidelines Acceptance Criteria
iii. Recent NHTSA Research on Manual Radio Tuning
iv. Development of NHTSA's Eye Glance Acceptance Criteria
N. Human Subject Selection for Guideline Testing
O. Occlusion Test Protocol
P. Task Performance Errors During Testing
Q. Limited NHTSA Guidelines for Passenger Operated Equipment
VII. Implementation Considerations for the NHTSA Guidelines
A. Current Vehicles That Meet the NHTSA Guidelines
B. Expected Effects of the NHTSA Guidelines
C. NHTSA Monitoring to Determine Whether Vehicles Meet Guideline
Recommendations
VIII. Public Participation
IX. National Technology Transfer and Advancement Act
X. Guidelines for Reducing Visual-Manual Driver Distraction During
Interactions with In-Vehicle Devices
I. Executive Summary
A. The Problem of Driver Distraction and Related Research
The term ``distraction,'' as used in connection with these
guidelines, is a specific type of inattention that occurs when drivers
divert their attention away from the driving task to focus on another
activity. These distractions can be from electronic devices, such as
navigation systems and cell phones, or more conventional distractions
such as interacting with passengers and eating. These distracting tasks
can affect drivers in different ways, and can be categorized into the
following types:
Visual distraction: Tasks that require the driver to look
away from the roadway to visually obtain information;
Manual distraction: Tasks that require the driver to take
a hand off the steering wheel and manipulate a device;
Cognitive distraction: Tasks that require the driver to
avert their mental attention away from the driving task.
The impact of distraction on driving is determined not just by the
type of distraction, but also the frequency and duration of the task.
That is to say, even if a task is less distracting, a driver who
engages in it frequently or for long durations may increase the crash
risk to a level comparable to that of much more difficult task
performed less often.
NHTSA is concerned about the effects of driver distraction on motor
vehicle safety. Crash data show that 17 percent (an estimated 899,000)
of all police-reported crashes reportedly involved some type of driver
distraction in 2010. Of those 899,000 crashes, distraction by a device/
control integral to the vehicle was reported in 26,000 crashes (3% of
the distraction-related police-reported crashes).
For a number of years, NHTSA has been conducting research to better
understand how driver distraction impacts driving performance and
safety. The research has involved both integrated and portable devices,
various task types, and both visual-manual and auditory-vocal tasks
(i.e., tasks that use voice inputs and provide auditory feedback).
Additionally, both NHTSA and the Federal Motor Carrier Safety
Administration (FMCSA) have sponsored analyses focused on distracted
driving using data from naturalistic driving studies performed by the
Virginia Tech Transportation Institute (VTTI).
The automobile industry, Europe, and Japan have all conducted
valuable research that has increased the available knowledge regarding
driver distraction and its effects on safety. The results of this work
are summarized in various sets of guidelines that minimize the
potential for driver distraction during visual-manual interactions
while the vehicle is in motion. NHTSA has drawn heavily upon these
existing guidelines in the development of its Driver Distraction
Guidelines.
B. NHTSA Driver Distraction Program
In April 2010, NHTSA released an ``Overview of the National Highway
Traffic Safety Administration's Driver Distraction Program,'' \1\ which
summarized steps that NHTSA intends to take to reduce crashes
attributable to driver distraction. One part of this program is the
development of nonbinding, voluntary guidelines for minimizing the
distraction potential of in-vehicle and portable devices. The
guidelines will be developed in three phases. The first phase will
explore visual-manual interfaces of devices installed in vehicles. The
second phase will include portable and aftermarket devices. The third
phase will expand the guidelines to include auditory-vocal interfaces.
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\1\ ``Overview of the National Highway Traffic Safety
Administration's Driver Distraction Program,'' DOT-HS-811-299, April
2010. Available at http://www.nhtsa.gov/staticfiles/nti/distracted_driving/pdf/811299.pdf.
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C. Today's Proposal
This notice proposes the first phase of these NHTSA Driver
Distraction Guidelines, which cover certain devices installed in
vehicles as original equipment that are operated by the driver through
visual-manual means (meaning the driver looking at a device,
manipulating a device-related control with the driver's hand, and
watching for visual feedback from the device). The driver distraction
research discussed above shows that the types of tasks correlated with
the highest crash/near crash risk odds ratios tend to have primarily
visual-manual means of interaction, and, accordingly, this first phase
of guidelines focuses on visual-manual interfaces.
The purpose of the NHTSA Guidelines is to limit potential driver
distraction associated with secondary, non-driving-related, visual-
manual tasks (e.g., information, navigation, communications, and
entertainment) performed using integrated electronic devices. The NHTSA
Guidelines are not appropriate for conventional controls and displays
(e.g., heating-ventilation-air conditions controls, instrument gauges
or telltales) because operating these systems is part of the primary
driving task. Likewise, the NHTSA Guidelines are not appropriate for
collision warning or vehicle control systems, which are designed to aid
the driver in controlling the vehicle and avoid crashes. These systems
are meant to capture the driver's attention.
To facilitate the development of guidelines, NHTSA studied the
various existing guidelines relating to driver distraction prevention
and reduction and found the ``Statement of Principles, Criteria and
Verification Procedures on Driver-Interactions with Advanced In-Vehicle
Information and Communication Systems'' developed by the Alliance of
Automobile Manufacturers (Alliance Guidelines \2\) to
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be the most complete and up-to-date. The Alliance Guidelines provided
valuable input in current NHTSA efforts to address driver distraction
issues. While NHTSA drew heavily on that input in developing the NHTSA
Guidelines, it did incorporate a number of changes in an effort to
further enhance driving safety, enhance guideline usability, improve
implementation consistency, and incorporate the latest driver
distraction research findings.
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\2\ Driver Focus-Telematics Working Group, ``Statement of
Principles, Criteria and Verification Procedures on Driver-
Interactions with Advanced In-Vehicle Information and Communication
Systems,'' June 26, 2006 version, Alliance of Automobile
Manufacturers, Washington, DC.
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Since light vehicles comprise the vast majority of the vehicle
fleet, NHTSA focused its distraction research on this type of vehicle,
instead of heavy trucks, medium trucks, motorcoaches, or motorcycles.
Therefore, the NHTSA Guidelines contained in this notice cover light
vehicles, i.e., all passenger cars, multipurpose passenger vehicles,
and trucks and buses with a Gross Vehicle Weight Rating (GVWR) of not
more than 10,000 pounds. While much of what NHTSA has learned about
light vehicle driver distraction undoubtedly applies to other vehicle
types, additional research would be desirable to assess whether all
aspects of these NHTSA Guidelines are appropriate for those vehicle
types.
The NHTSA Guidelines limit potential driver distraction associated
with non-driving-related, visual-manual tasks through several
approaches:
1. The NHTSA Guidelines list certain secondary, non-driving-related
tasks that, based on NHTSA's research, are believed by the agency to
interfere inherently with a driver's ability to safely control the
vehicle. The Guidelines recommend that those in-vehicle devices be
designed so that they cannot be used by the driver to perform such
tasks while the driver is driving. The list of tasks considered to
inherently interfere with a driver's ability to safely operate the
vehicle include: displaying images or video not related to driving;
displaying automatically scrolling text; requiring manual text entry of
more than six button or key presses during a single task; or requiring
reading more than 30 characters of text (not counting punctuation
marks). The NHTSA Guidelines specify that this recommendation is
intended to prevent the driver from engaging in tasks such as watching
video footage, visual-manual text messaging, visual-manual internet
browsing, or visual-manual social media browsing while driving. The
recommendation is not intended to prevent the display of images related
to driving, such as images related to the status of vehicle occupants
or vehicle maneuvering or images depicting the rearview or blind zone
areas of a vehicle.
2. For all other secondary, non-driving-related visual-manual
tasks, the NHTSA Guidelines specify a test method for measuring the
impact of performing a task on driving safety and time-based acceptance
criteria for assessing whether a task interferes too much with driver
attention to be suitable to perform while driving. If a task does not
meet the acceptance criteria, the NHTSA Guidelines recommend that in-
vehicle devices be designed so that the task cannot be performed by the
driver while driving. More specifically, the NHTSA Guidelines include
two test methods for assessing whether a task interferes too much with
driver attention. One test method measures the amount of time that the
driver's eyes are drawn away from the roadway during the performance of
the task. The research mentioned above shows that long glances by the
driver away from the roadway are correlated with an increased risk of a
crash or near-crash. The NHTSA Guidelines recommend that devices be
designed so that tasks can be completed by the driver while driving
with glances away from the roadway of 2 seconds or less and a
cumulative time spent glancing away from the roadway of 12 seconds or
less. The second test method uses a visual occlusion technique to
ensure that a driver can complete a task in a series of 1.5 second
glances with a cumulative time spent glancing away from the roadway of
not more than 9 seconds.
3. In addition to identifying inherently distracting tasks and
providing a means for measuring and evaluating the level of distraction
associated with other non-driving-related tasks, the NHTSA Guidelines
contain several design recommendations for in-vehicle devices in order
to minimize their potential for distraction. The NHTSA Guidelines
recommend that all device functions designed to be performed by the
driver through visual-manual means should require no more than one of
the driver's hands to operate. The NHTSA Guidelines further recommend
that each device's active display should be located as close as
practicable to the driver's forward line of sight and include a
specific recommendation for the maximum downward viewing angle to the
geometric center of each display.
The agency believes that the NHTSA Guidelines are appropriate for
any device that the driver can easily see and/or reach (even if it is
intended for use solely by passengers), and, accordingly, any task that
is associated with an unacceptable level of distraction should be made
inaccessible to the driver while driving. However, the NHTSA Guidelines
are not appropriate for any device that is located fully behind the
front seat of the vehicle or for any front-seat device that cannot
reasonably be reached or seen by the driver.
NHTSA has opted to pursue nonbinding, voluntary guidelines rather
than a mandatory Federal Motor Vehicle Safety Standard (FMVSS) for
three principal reasons. First, this is an area in which learning
continues, and NHTSA believes that, at this time, continued research is
both necessary and important. Second, technology is changing rapidly,
and a static rule, put in place at this time, may face unforeseen
problems and issues as new technologies are developed and introduced.
Third, available data are not sufficient at this time to permit
accurate estimation of the benefits and costs of a mandatory rule in
this area. NHTSA's firm belief that there are safety benefits to be
gained by limiting and reducing driver distraction due to integrated
electronic devices is sufficient reason for issuing the NHTSA
Guidelines, but in order to issue a rule, we need a defensible estimate
of the magnitude of such benefits and the corresponding costs. (See
Executive Order 13563.)
Since these voluntary NHTSA Guidelines are not a FMVSS, NHTSA's
normal enforcement procedures are not applicable. As part of its
continuing research effort, NHTSA does intend to monitor manufacturers'
voluntary adoption of these NHTSA Guidelines to help determine their
effectiveness and sufficiency.
The main effect that NHTSA expects to achieve through its NHTSA
Guidelines is better-designed in-vehicle integrated electronic device
interfaces that do not exceed a reasonable level of complexity for
visual-manual secondary tasks. While voluntary and nonbinding, the
NHTSA Guidelines are meant to discourage the introduction of
egregiously distracting non-driving tasks performed using integrated
devices (i.e., those that the NHTSA Guidelines list as being inherently
distracting and those that do not meet the acceptance criteria when
tested under the test method contained in the Guidelines).
NHTSA seeks comments as to how to improve the NHTSA Guidelines so
as to improve motor vehicle safety. Because these Guidelines are
voluntary and nonbinding, they will not require action
[[Page 11203]]
of any kind, and for that reason they will not confer benefits or
impose costs. Nonetheless, and as part of its continuing research
efforts, NHTSA welcomes comments on the potential benefits and costs
that would result from voluntary compliance with the draft Guidelines.
NHTSA will review submitted comments and plans to issue a final
version of the visual-manual portion of its NHTSA Guidelines in the
form of a Federal Register notice during the first half of calendar
year 2012.
II. Background
A. Acronyms Used in Document
ADAM Advanced Driver Attention Metrics
AM Amplitude Modulation
ANPRM Advance Notice of Proposed Rulemaking
CAMP Collision Avoidance Metrics Partnership
CANbus Controller Area Network bus
CD Compact Disc
CDS Crashworthiness Data System (NASS-CDS)
DFD Dynamic Following and Detection
DOT Department of Transportation
EOT Enhanced Occlusion Technique
EORT Eyes-Off-Road Time
FARS Fatality Analysis Reporting System
FM Frequency Modulation
FMCSA Federal Motor Carrier Safety Administration
FMVSS Federal Motor Vehicle Safety Standard
FR Federal Register
GES General Estimates System (NASS-GES)
GVWR Gross Vehicle Weight Rating
HMI Human-Machine Interface
HVAC Heating, Ventilation, and Air Conditioning
ISO International Standards Organization
ISOES International Society for Occupational Ergonomics and Safety
IVIS In-Vehicle Information Systems
JAMA Japanese Automobile Manufacturers Association
LCT Lane Change Task
MGD Mean Glance Duration
MNTE Manual Number and Text Entry
NASS National Automotive Sampling System
NHTSA National Highway Traffic Safety Administration
NMVCCS National Motor Vehicle Crash Causation Survey
NPRM Notice of Proposed Rulemaking
NTTAA National Technology Transfer and Advancement Act
OE Original Equipment
OMB Office of Management and Budget
PAR Police Accident Report
PDT Peripheral Detection Task
R Task Resumability Ratio
SAE SAE International
SDLP Standard Deviation of Lane Position (lane position variability)
SHRP2 Strategic Highway Research Program 2
STI Systems Technology Incorporated
STISIM Systems Technology Incorporated Driving Simulator
TEORT Total Eyes-Off-Road Time
TGT Total Glance Time to Task
VTTI Virginia Tech Transportation Institute
B. The Driver Distraction Safety Problem
There has been a large amount of research performed on the topic of
driver distraction and its impact on safety. Research noted here will
provide a brief overview of the distraction safety problem. Many other
reports and papers have been published on various aspects of driver
distraction. Some of these additional reports and papers may be found
at www.distraction.gov.
NHTSA data on distracted driving-related crashes and the resulting
numbers of injured people and fatalities is derived from the Fatality
Analysis Reporting System (FARS) \3\ and the National Automotive
Sampling System (NASS) General Estimates System (GES).\4\
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\3\ FARS is a census of all fatal crashes that occur on the
roadways of the United States of America. It contains data on all
fatal crashes occurring in all 50 states as well as the District of
Columbia and Puerto Rico.
\4\ NASS GES contains data from a nationally-representative
sample of police-reported crashes. It contains data on police-
reported crashes of all levels of severity, including those that
result in fatalities, injuries, or only property damage. National
numbers of crashes calculated from NASS GES are estimates.
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The most recent data available, 2010 data, show that 17 percent of
all police-reported crashes (fatal, injury-only and property-damage-
only) involve reports of distracted driving. As can be seen in Table 1,
the percent of all police-reported crashes that involve distraction has
remained consistent over the past five years. These distraction-related
crashes lead to thousands of fatalities and over 400,000 injured people
each year, on average.
An estimated 899,000 of all police-reported crashes involved a
report of a distracted driver in 2010. Of those 899,000 crashes, 26,000
(3%) specifically stated that the driver was distracted when he was
adjusting or using an integrated device/control. From a different
viewpoint, of those 899,000 crashes, 47,000 (5%) specifically stated
that the driver was distracted by a cell phone (no differentiation
between portable and integrated). It should be noted that these two
classifications are not mutually exclusive, as a driver who was
distracted by the radio control may have also been on the phone at the
time of the crash and thus the crash may appear in both categories.
While all electronic devices are of interest, the current coding does
not separate other electronic devices other than cell phones.
Table 1--Police-Reported Crashes and Crashes Involving Distraction, 2006-2010 (GES)
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Distraction-
Police-reported related crashes Distraction-
Number of police- crashes involving involving an related crashes
Year reported crashes a distracted integrated involving an
driver control/device electronic device
\*\ \*\
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2006................................ 5,964,000 1,019,000 (17%) 18,000 (2%) 24,000 (2%)
2007................................ 6,016,000 1,001,000 (17%) 23,000 (2%) 48,000 (5%)
2008................................ 5,801,000 967,000 (17%) 21,000 (2%) 48,000 (5%)
2009................................ 5,498,000 957,000 (17%) 22,000 (2%) 46,000 (5%)
2010................................ 5,409,000 899,000 (17%) 26,000 (3%) 47,000 (5%)
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\*\ The categories for Integrated Control/Device and Electronic Device are not mutually exclusive. Therefore the
data cannot be added or combined in any manner.
Identification of specific driver-activities and driver-behavior
that serves as the distraction has presented challenges, both within
NHTSA's data collection and on police accident reports. Therefore, a
large portion of the crashes that are reported to involve distraction
do not have a specific behavior or activity listed; rather they specify
other distraction or distraction unknown. One could assume that some
portion of those crashes involve an electronic device, either portable
or integrated.
[[Page 11204]]
NHTSA is making substantial data collection revisions to FARS and
working on revisions to Model Minimum Uniform Crash Criteria (MMUCC) to
better capture and classify the crashes related to distraction.\5\ One
such improvement is the ability to separate the involvement of
integrated vehicle equipment as the distraction in fatal crashes in
FARS. With this improvement, NHTSA looks to track the involvement of
integrated devices over time in fatal crashes. As manufacturers are
increasingly developing communications systems that can integrate
portable devices into the vehicle or developing fully-integrated
systems in the vehicle, this tracking of data will be essential in
monitoring distraction involvement in fatal crashes.
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\5\ Since this is a re-coding of state records into a uniform
data set, and does not make contact with any specific subjects, no
OMB clearance is required for these revisions.
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i. Estimation of Distraction Crash Risk Via Naturalistic Driving
Studies
One approach to estimating the driving risks due to various types
of distraction is naturalistic driving studies. Naturalistic data
collection is an excellent method of determining distraction risks
because test participants (drivers) volunteer to drive an instrumented
vehicle in the same manner that they normally do for some period of
time. Unlike commanded task testing, in which an in-vehicle
experimenter instructs a test participant when to perform a task, in
naturalistic studies test participants perform tasks at will. The
unobtrusive data recording instrumentation installed in the vehicle
eliminates the distraction under-reporting problem seen in police
accident reports by recording data that describes what test
participants are doing at any time while driving.
For light vehicles, the NHTSA-sponsored 100-Car Naturalistic
Driving Study,6 7 8 9 10 performed by the Virginia Tech
Transportation Institute (VTTI), provides information about the effects
of performing various types of secondary tasks on crash/near crash
risks. Secondary tasks include communications, entertainment,
informational, interactions with passengers, navigation, and reaching
for objects tasks (along with many others) that are not required for
driving. For the 100-Car Study, VTTI collected naturalistic driving
data for 100 vehicles from January 2003 through July 2004. Each
participant's vehicle was unobtrusively fitted with five video cameras,
sensors that measured numerous vehicle state and kinematic variables at
each instant of time, and data acquisition. The vehicles were then
driven by their owners during their normal daily activities for 12 to
13 months while data were recorded. No special instructions were given
to drivers as to when or where to drive and no experimenter was present
in the vehicle during the driving. All of this resulted in a large data
set of naturalistic driving data that contains information on 241
drivers (100 primary drivers who performed most of the driving and 141
secondary drivers who drove the instrumented vehicles for shorter
periods of time) driving for almost 43,000 hours and traveling
approximately 2 million miles.
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\6\ Neale, V.L., Dingus, T.A., Klauer, S.G., Sudweeks, J., and
Goodman, M., ``An Overview of the 100-Car Naturalistic Study and
Findings,'' ESV Paper 05-0400, June 2005.
\7\ Dingus, T.A., Klauer, S.G., Neale, V.L., Petersen, A., Lee,
S.E., Sudweeks, J., Perez, M.A., Hankey, J., Ramsey, D., Gupta, S.,
Bucher, C., Doerzaph, Z.R., Jermeland, J., and Knipling, R.R., ``The
100-Car Naturalistic Driving Study, Phase II--Results of the 100-Car
Field Experiment,'' DOT HS 810 593, April 2006.
\8\ Klauer, S.G., Dingus, T.A., Neale, V.L., Sudweeks, J.D., and
Ramsey, D.J., ``The Impact of Driver Inattention on Near-Crash/Crash
Risk: An Analysis Using the 100-Car Naturalistic Driving Study
Data,'' DOT HS 810 594, April 2006.
\9\ Guo, F., Klauer, S.G., McGill, M.T., and Dingus, T.A.,
``Task 3--Evaluating the Relationship Between Near-Crashes and
Crashes: Can Near-Crashes Serve as a Surrogate Safety Metric for
Crashes?,'' DOT HS 811 382, September 2010.
\10\ Klauer, S.G., Guo, F., Sudweeks, J.D., and Dingus, T.A.,
``An Analysis of Driver Inattention Using a Case-Crossover Approach
On 100-Car Data: Final Report,'' DOT HS 811 334, May 2010.
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Data from the 100-Car Naturalistic Driving Study provides the best
information currently available about the risks associated with
performing a variety of secondary tasks while driving light vehicles
(vehicles under 10,000 pounds GVWR). However, even though this was a
large, difficult, and expensive study to perform, from an
epidemiological viewpoint, the study was small (100 primary drivers, 15
police-reported and 82 total crashes, including minor collisions).
Drivers from only one small portion of the country, the Northern
Virginia-Washington, DC, metro area, were represented.
The 100-Car Study was deliberately designed to maximize the number
of crash and near-crash events through the selection of subjects with
higher than average crash- or near-crash risk exposure.\11\ This was
accomplished through the selection of a larger sample of drivers below
the age of 25, and by the inclusion of a sample that drove more than
the average number of miles.
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\11\ Neale, V.L., Dingus, T.A., Klauer, S.G., Sudweeks, J., and
Goodman, M., ``An Overview of the 100-Car Naturalistic Study and
Findings,'' ESV Paper 05-0400, June 2005.
---------------------------------------------------------------------------
Due to the rapid pace of technological change, some devices (e.g.,
smart phones) and secondary tasks of great current interest (e.g., text
messaging) were not addressed by 100-Car Study data because they were
not widely in use at the time.
Subsequent to the 100-Car Naturalistic Driving Study, the Federal
Motor Carrier Safety Administration (FMCSA) sponsored an analysis of
naturalistic driving data \12\ to examine the effects of driver
distraction on safety for commercial motor vehicles (three or more axle
trucks, tractors-semitrailers (including tankers), transit buses, and
motor coaches). This analysis used data collected during two commercial
motor vehicle naturalistic driving studies. Since the data analyzed was
collected during two studies, this study will, hereinafter, be referred
to as the ``Two Study FMCSA Analyses.''
---------------------------------------------------------------------------
\12\ Olson, R.L., Hanowski, R.J., Hickman, J.S., and Bocanegra,
J., ``Driver Distraction in Commercial Vehicle Operations,'' FMCSA-
RRR-09-042, September 2009.
---------------------------------------------------------------------------
The Two Study FMCSA Analyses combined and analyzed data from two
large-scale commercial motor vehicle naturalistic driving studies: the
Drowsy Driver Warning System Field Operational Test \13\ and the
Naturalistic Truck Driving Study.\14\ The combined database contains
naturalistic driving data for 203 commercial motor vehicle drivers, 7
trucking fleets, 16 fleet locations, and approximately 3 million miles
of continuously-collected kinematic and video data. This data set was
filtered using kinematic data thresholds, along with video review and
validation, to find safety-critical events (defined in this report as
crashes, near-crashes, crash-relevant conflicts, and unintentional lane
deviations). There were a total of 4,452 safety-critical events in the
database: 21 crashes, 197 near-crashes, 3,019 crash-relevant conflicts,
and 1,215 unintentional lane deviations. In addition, 19,888 time
segments of baseline driving data were randomly selected for analysis.
---------------------------------------------------------------------------
\13\ Hanowski, R.J., Blanco, M., Nakata, A., Hickman, J.S.,
Schaudt, W.A., Fumero, M.C., Olson, R.L., Jermeland, J., Greening,
M., Holbrook, G.T., Knipling, R.R., and Madison, P., ``The Drowsy
Driver Warning System Field Operational Test, Data Collection
Methods,'' DOT HS 811 035, September 2008.
\14\ Blanco, M., Hickman, J.S., Olson, R.L., Bocanegra, J.L.,
Hanowski, R.J., Nakata, A., Greening, M., Madison, P., Holbrook,
G.T., and Bowman, D., ``Investigating Critical Incidents, Driver
Restart Period, Sleep Quantity, and Crash Countermeasures in
Commercial Vehicle Operations Using Naturalistic Data Collection,''
in press, 2008.
---------------------------------------------------------------------------
[[Page 11205]]
One major source of differences in the results obtained from
analyses of the 100-Car Study with those obtained from the Two Study
FMCSA Analyses is the different time frames in which their data
collections were performed. The 100-Car Naturalistic Driving Study data
collection was from January 2003 through July 2004. The Drowsy Driver
Warning System Field Operational Test collected data from May 2004
through September 2005 and the Naturalistic Truck Driving Study
collected data from November 2005 through May 2007. Due to the current
rapid changes occurring in portable and other consumer electronics, the
specific types of electronic device related distraction observed across
studies, while similar, were not identical. For example, while the Two
Study FMCSA Analyses found a high safety critical event risk due to
drivers engaging in text messaging, there was no text messaging
observed during the 100-Car Study. This is because the widespread
popularity of text messaging did not occur until after the 100-Car
Study data collection was completed.
ii. Summary of Naturalistic Driving Study Distraction Risk Analyses
Figure 1 gives a graphical representation of some of the secondary
task risk odds ratios determined by the 100-Car Naturalistic Driving
Study and the Two Study FMCSA Analyses. In this figure, a risk odds
ratio of 1.00 (shown as ``1'' in the figure) equates to the risks
associated with baseline driving. Risk odds ratios above 1.00 indicate
secondary tasks that increase driving risks while risk odds ratios
below 1.00 indicate protective effects (i.e., performing these
secondary tasks makes a crash or near-crash event less likely to occur
than driving and not performing any secondary task.) This figure
provides a quick, visual, summary of the risks associated with
performing a variety of secondary tasks while driving both light and
heavy vehicles.
[GRAPHIC] [TIFF OMITTED] TN24FE12.057
In summary, the various naturalistic data study analyses
established several important things about driver distraction which are
directly relevant to the NHTSA Guidelines for reducing driver
distraction due to device interface design:
Secondary task performance is very common while driving.
They were observed during the majority (54%) of the randomly selected
baseline time segments analyzed during the 100-Car Study analyses. Some
secondary task performance involves the use of electronic devices;
these secondary tasks are the primary focus of this document.
Secondary task performance while driving has a broad range
of risk odds ratios associated with different secondary tasks. The
observed risk odds ratios range from 23.2, indicating a very large
increase in crash/near-crash risk (a risk ratio of 1.0 means that a
secondary task has the same risk as average driving; a risk ratio of
23.2 means that risk associated with performance of this secondary task
is increased by 2,220 percent compared to average driving), to 0.4 (any
value less than 1.0 indicates a situation with less risk than average
driving indicating a protective effect; a risk ratio of 0.4 means that
risk associated with performance of this secondary task is reduced by
60 percent compared to average driving). This indicates that it may
well be possible to improve at least some of the secondary tasks with
high risk odds ratios (i.e., risky tasks) so as to make them
substantially safer to perform. The logical place to reduce crash/near-
crash
[[Page 11206]]
risk odds ratios for these secondary tasks is through improvements to
their driver interface.
It is clear from naturalistic driving research that the
secondary tasks with the highest risk odds ratios tend to have
primarily visual-manual interaction means with only a relatively small
cognitive component. Of course, every secondary task results in some
cognitive load; however, tasks that could be said to not require a lot
of thought, such as Reaching for a Moving Object, are towards the right
side of Figure 1. Only the secondary tasks, ``Interacting with
Passenger'' and ``Talking/Listening on Hands-Free Phone,'' are almost
exclusively cognitive in nature. Both of these secondary tasks have
risk odds ratios that are statistically significantly less than 1.00
(at the 95 percent confidence level). These two heavily cognitive
secondary tasks appear to have protective effects.
For this reason, and because it is far less clear how to measure
the level of cognitive distraction, the NHTSA Guidelines will initially
only apply to the visual-manual aspects of devices' driver interfaces.
Subsequent phases of development of these NHTSA Guidelines are planned
to extend them to cover the auditory-vocal portions of device
interfaces.
Long (greater than 2.0 seconds) glances by the driver away
from the forward road scene are correlated with increased crash/near-
crash risk. When drivers glance away from the forward roadway for
greater than 2.0 seconds out of a 6-second period, their risk of an
unsafe event substantially increases relative to the baseline.
C. NHTSA's Driver Distraction Program
NHTSA's safety mission is to ``save lives, prevent injuries, and
reduce economic costs due to road traffic crashes.'' One focus of this
mission is the prevention of road traffic crashes for which driver
distraction is a contributing factor.\15\
---------------------------------------------------------------------------
\15\ Information on NHTSA's efforts to address this problem can
be found at http://www.distraction.gov/.
---------------------------------------------------------------------------
In April 2010, NHTSA released an ``Overview of the National Highway
Traffic Safety Administration's Driver Distraction Program,'' \16\
which summarized steps that NHTSA intends to take to ``help in its
long-term goal of eliminating a specific category of crashes--those
attributable to driver distraction.'' NHTSA's Driver Distraction
Program consists of four initiatives:
---------------------------------------------------------------------------
\16\ ``Overview of the National Highway Traffic Safety
Administration's Driver Distraction Program,'' DOT-HS-811-299, April
2010. Available at http://www.nhtsa.gov/staticfiles/nti/distracted_driving/pdf/811299.pdf.
---------------------------------------------------------------------------
1. Improve the understanding of the extent and nature of the
distraction problem. This includes improving the quality of data NHTSA
collects about distraction-related crashes along with better analysis
techniques.
2. Reduce the driver workload associated with performing tasks
using both built-in and portable in-vehicle devices by working to limit
the visual and manual demand associated with secondary tasks performed
using in-vehicle devices. Better device interfaces will help to
minimize the amount of time and effort involved in a driver performing
a task using the device. Minimizing the workload associated with
performing non-driving, or ``secondary,'' tasks with a device will
permit drivers to maximize the attention they focus toward the primary
task of driving.
3. Keep drivers safe through the introduction of crash avoidance
technologies. These include the use of crash warning systems to re-
focus the attention of distracted drivers as well as vehicle-initiated
(i.e., automatic) braking and steering to prevent or mitigate
distracted driver crashes.
Although not the focus of this notice, NHTSA is, in parallel with
its NHTSA Guidelines development effort, performing a large amount of
research in support of the crash avoidance technologies initiative. For
example, NHTSA has completed, and reports should be published shortly,
research about how to best warn distracted drivers. We are also
performing a large amount of research on forward collision avoidance
and mitigation technologies such as Forward Collision Warning,
Collision Imminent Braking, and Dynamic Brake Assist.
4. Educate drivers about the risks and consequences of distracted
driving. This includes targeted media messages, drafting and publishing
sample text-messaging laws for consideration and possible use by the
states, and publishing guidance for a ban on text messaging by Federal
government employees while driving.
This notice is part of NHTSA's effort to address the second of
these initiatives, reducing driver workload by working to limit the
visual and manual demand associated with in-vehicle device interface
designs. As discussed in NHTSA's Driver Distraction Program, NHTSA's
intent is to ``develop voluntary guidelines for minimizing the
distraction potential of in-vehicle and portable devices''.\17\ The
current notice only contains voluntary NHTSA Guidelines for integrated
in-vehicle devices; portable devices will be addressed by Phase 2 of
the NHTSA Guidelines.
---------------------------------------------------------------------------
\17\ Ibid, P. 21.
---------------------------------------------------------------------------
Drivers perform secondary tasks (communications, entertainment,
informational, and navigation tasks not required to drive \18\) using
an in-vehicle electronic device by interacting with the device through
its driver interface. These interfaces can be designed to accommodate
interactions that are visual-manual (visual display and manual
controls), auditory-vocal, or a combination of the two. Some devices
may allow a driver to perform a task through either manual control
manipulation with visual feedback or through voice command with
auditory feedback to the driver.
---------------------------------------------------------------------------
\18\ Navigation tasks clearly have to be performed to drive.
However, such tasks as destination entry do not have to be performed
while driving but can instead be performed while the vehicle is
stationary.
---------------------------------------------------------------------------
For the purposes of this document, a driver's interactions with
device interfaces are described in terms of two functional categories
based upon the mode of interaction: visual-manual and auditory-vocal.
Visual-manual interactions involve the driver looking at a device,
making inputs to the device by hand (e.g., pressing a button, rotating
a knob), and visual feedback being provided to the driver. Auditory-
vocal interactions involve the driver controlling the device functions
through voice commands and receiving auditory feedback from the device.
Note that a single device's driver interface may accommodate both
visual-manual and auditory-vocal interactions.
These proposed voluntary NHTSA Guidelines are appropriate for in-
vehicle device tasks that are performed by the driver through visual-
manual means. The goal of the NHTSA Guidelines is to discourage the
implementation of tasks performed using in-vehicle electronic devices
unless the tasks and device driver interfaces are designed to minimize
driver workload experienced by a driver when performing the tasks while
driving. The NHTSA Guidelines specify criteria and a test method for
assessing whether a secondary task performed using an in-vehicle device
may be suitable for performance while driving, due to its minimal
impact on driving performance and, therefore, safety. The NHTSA
Guidelines also seek to identify secondary tasks that interfere with a
driver's ability to safely control the vehicle and to categorize those
tasks as being unsuitable for performance by the driver while driving.
[[Page 11207]]
III. Why distraction guidelines?
NHTSA is proposing voluntary NHTSA Guidelines to limit and/or
reduce visual-manual driver distraction due to integrated electronic
devices, instead of a mandatory Federal Motor Vehicle Safety Standard
(FMVSS), for several reasons. First, the rapid pace of technology
evolution cannot be fully addressed with a static rule put in place at
this time. Second, data is not sufficient at this time to permit
accurate estimation of the benefits of a possible distracted driving
rule, though NHTSA firmly believes that there are safety benefits to be
gained by limiting and reducing driver distraction due to integrated
electronic devices. Finally, NHTSA rules must have repeatable,
objective means for determining compliance and driver distraction
testing involves drivers with inherent individual differences that
present a unique challenge. Each of these reasons is discussed in
detail below.
In 2002, the Alliance of Automobile Manufacturers
developed a set of guidelines to address the agency's call that
manufacturers should develop a set of design principles to which future
products would be designed. The intent was to address the increasing
use of navigation units, infotainment, and complex controls appearing
in vehicles that, if used while driving, could present an additional
source of distraction for drivers leading to an increase in crashes.
Since that time, NHTSA has been monitoring and conducting driver
distraction research using a sample of the designs that have been
developed in accordance with the Alliance Guidelines. Our observations
are as follows: (1) Manufacturers have different interpretations of the
guidelines themselves, leading to different implementations, (2) newer
techniques exist to evaluate these interfaces than existed nearly a
decade ago, (3) the guidelines have not kept pace with technology, and
(4) more recent data compiled from naturalistic driving studies implies
that more stringent criteria are needed. Given these observations, we
believe it is appropriate to issue Federal guidelines to ensure that
current and future products continue to be designed in such a way as to
mitigate driver distraction as opposed to adding to it. In addition, we
believe Federal guidelines are appropriate because they can keep pace
with rapidly changing technology by providing a benchmark for designers
while allowing the agency and other researchers to continue their work
in this rapidly evolving area, including the assessment of test
procedures for regulatory purposes.
In-vehicle communications and electronics are currently
evolving at a pace that is not amenable to regulation. We believe that
establishing Federal guidelines at this time is appropriate for these
rapidly changing in-vehicle technologies, since it will provide a
comprehensive means to ensure the reasonableness of designs. As new
systems, features, functions, and types of control inputs are
developed, NHTSA should be able to develop voluntary NHTSA Guidelines
to address any potential safety issues as they arise. These NHTSA
Guidelines can be issued more quickly than regulations that go through
the rulemaking process.
Existing data provide a sufficient basis on which to
establish general NHTSA Guidelines that, if followed, will deter
manufacturers from introducing in-vehicle information and
communications systems that induce the kinds and duration of visual-
manual distraction that are demonstrably unsafe. In future years, data
from a major naturalistic research study that is currently being
conducted through the Strategic Highway Research Program 2 (SHRP2) \19\
should provide better information on the precise causation of
distraction related incidents.
---------------------------------------------------------------------------
\19\ Information about SHRP2 is at: http://trb.org/StrategicHighwayResearchProgram2SHRP2/Blank2.aspx.
---------------------------------------------------------------------------
Additionally, the test method developed by NHTSA in these
NHTSA Guidelines in its current form would not meet the statutory
requirements for establishing compliance with a FMVSS. Specifically,
NHTSA's authorizing legislation requires that FMVSS contain objective
and repeatable procedures, such as engineering measurement, for
determining compliance or non-compliance of a vehicle with the
standard. Driver distraction testing involves human drivers with
inherent individual differences that present a unique challenge. A
FMVSS with a compliance test procedure that entails driver involvement
would not meet those requirements due to the individual variability of
the drivers involved in the test.
Consider a brake compliance test; it tests the manufactured parts
that comprise the braking, wheel, and tire systems. NHTSA has gone to
considerable effort to tightly prescribe the actions of the
professional test driver so that they do not influence test results.
The main sources of test non-repeatability are the manufacturing
tolerances of the vehicle components and the variability in the road
surface. Again, NHTSA has tried to specify the road surface so as to
minimize test variability. Due to the tight specification of test
driver's actions and road surface, brake compliance testing is highly
repeatable.
In comparison, driver distraction tests involve average drivers as
a critical part of the test of the in-vehicle system. The driver's
actions cannot be tightly prescribed, as was done for brake testing.
Unfortunately, the level of driver distraction due to performing a task
using a device inherently depends upon the personal characteristics and
capabilities of the driver. The driver's manual dexterity, multi-
tasking ability, driving experience, state of health, age,
intelligence, and motivation (among other factors) may all influence
the level of distraction experienced while performing a task. In an
effort to ``average out'' individual differences, a group of 24 test
participants is used for the NHTSA Driver Distraction Guideline tests
described in this document. Furthermore, these NHTSA Guidelines contain
provisions designed to ensure that test participants are not biased
either for or against a task/device. However, there remains a chance
that one group of 24 test subjects will produce a test result that
finds a task or device suitable for performance while the vehicle is in
motion, while testing with another group of 24 subjects may find that
the task or device should be locked out. Therefore, the test would not
be repeatable and therefore is not appropriate for a FMVSS.\20\
---------------------------------------------------------------------------
\20\ One possible solution to the issue of non-repeatability due
to individual variability has been thought of by NHTSA. The idea is
to remove repeatability as an issue by only testing any given task
on a device one time. A company that wished to know whether a task
and/or device is acceptable for being performed while a vehicle is
not in ``Park'' would perform the NHTSA specified test using all of
the NHTSA specified test procedures for test participant selection,
test conduct, etc., and document the results. If NHTSA subsequently
was interested in monitoring whether that particular task and/or
device met the distraction test's acceptance criteria, NHTSA would
consider the company's documented record of the test as conclusive
proof of meeting the acceptance criteria of the test and not perform
the test itself. NHTSA would only perform testing if a company had
not performed the test. However, NHTSA has never tried such an
approach and does not wish to consider such a novel approach with a
complex topic such as driver distraction.
---------------------------------------------------------------------------
IV. NHTSA Research To Develop Driver Distraction Metrics and
Measurement Methods
A. Timeline of NHTSA Driver Distraction Measurement Research
NHTSA has been performing research addressing issues related to
driver distraction for nearly 20 years. Early research examined truck
driver
[[Page 11208]]
workload and the effects of using a route navigation system on driving
performance. In the last decade, research has been focused on assessing
the impact of cell phone use on driver performance and behavior. As the
availability of in-vehicle electronic devices has increased, NHTSA's
research focus has shifted to development of methods and metrics for
measuring distraction resulting from the use of any such device while
driving. Each research study has contributed to the development of a
broad set of metrics that characterize the impact of the performance of
distracting tasks on driving performance in a repeatable and objective
manner. The development of valid and sensitive measures of distraction
effects on driving performance is challenging because distraction
measurement inherently involves human test subjects. This section
summarizes several recent NHTSA studies that focused on developing a
valid, robust protocol for measuring driver distraction caused by the
use of in-vehicle electronic devices.
B. ``15-Second Rule'' Study
In the 1990s, SAE International worked to develop a recommended
practice for determining whether or not a particular navigation system
function should be accessible to the driver while driving. The draft
recommended practice (SAE J2364) 21 22 asserted that if an
in-vehicle task could be completed within 15 seconds by a sample of
drivers in a static (e.g., vehicle parked) setting, then the function
was suitable to perform while driving. NHTSA conducted a preliminary
assessment of the diagnostic properties of this proposed rule. Ten
subjects, aged 55 to 69 years, completed 15 tasks, including navigation
system destination entry, radio tuning, manual phone dialing, and
adjusting the Heating, Ventilation, and Air Conditioning (HVAC)
controls in a test vehicle. Correlations between static task
performance and dynamic task performance were relatively low. The
results were interpreted to suggest that static measurement of task
completion time could not reliably predict the acceptability of a
device. Based on these results, NHTSA looked to other metrics and
methods for use in assessing secondary task distraction in subsequent
research.
---------------------------------------------------------------------------
\21\ Green, P., ``Estimating Compliance with the 15-Second Rule
for Driver-interface Usability and Safety,'' Proceedings of the
Human Factors and Ergonomics Society 43rd Annual Meeting, 1999.
\22\ Green, P., ``The 15-second Rule for Driver Information
Systems,'' ITS America Ninth Annual Meeting Conference Proceedings,
Washington, DC, 1999.
---------------------------------------------------------------------------
C. Collision Avoidance Metrics Partnership (CAMP) Driver Workload
Metrics Project \23\
---------------------------------------------------------------------------
\23\ Angell, L., Auflick, J., Austria, P. A., Kochhar, D.,
Tijerina, L., Biever, W., Diptiman, T., Hogsett, J., and Kiger, S.,
``Driver Workload Metrics Task 2 Final Report,'' DOT HS 810 635,
November 2006.
---------------------------------------------------------------------------
The Driver Workload Metrics project conducted by the Collision
Avoidance Metrics Partnership (CAMP) consortium,\24\ in cooperation
with NHTSA, sought to develop performance metrics and test procedures
for assessing in-vehicle system secondary task distraction and its
impact on driving performance. The CAMP identified four categories of
driving performance metrics as having direct implications for safety:
driver eye glance patterns, lateral vehicle control, longitudinal
vehicle control, and object-and-event detection. A number of potential
surrogates thought to have predictive value with respect to the above-
mentioned performance measures were identified. CAMP's analyses sought
to determine which performance metrics discriminated between driving
with a secondary task and driving alone. The majority of metrics that
passed the evaluation criteria were related to eye-glance behavior.
Visual-manual tasks affected driving performance more than auditory-
vocal tasks. The project concluded that eye-glance data contain
important information for assessing the distraction effects of both
auditory-vocal and visual-manual tasks. One significant conclusion of
this work was that the interference to driving caused by in-vehicle
secondary tasks was multidimensional and no single metric could measure
all effects.
---------------------------------------------------------------------------
\24\ CAMP included researchers from Ford, GM, Nissan, and
Toyota.
---------------------------------------------------------------------------
D. Measuring Distraction Potential of Operating In-Vehicle Devices \25\
---------------------------------------------------------------------------
\25\ Ranney, T.A., Baldwin, G.H.S., Vasko, S.M., and Mazzae,
E.N., ``Measuring Distraction Potential of Operating In-Vehicle
Devices,'' DOT HS 811 231, December 2009.
---------------------------------------------------------------------------
Following the Driver Workload Metrics project, in 2006, NHTSA
explored the feasibility of adapting one or more existing driver
distraction measurement protocols for use with production vehicles
rather than pre-production prototypes. NHTSA wanted a well-documented,
simple, non-destructive test that would allow test vehicles to be
obtained by lease and therefore minimize research costs. Additional
protocol criteria included: (1) Ease of implementation, (2) the test
protocol's state-of-development, including extent of use and
documentation, (3) the level of training and staffing required, (4)
objective measures, and (5) the availability and interpretability of
data.
Test venues meeting these criteria included the personal computer-
based Advanced Driver Attention Metrics (ADAM) Lane Change Task (LCT)
\26\ and the Systems Technology Inc. (STI) low-cost, low-fidelity
driving simulator (STISIM-Drive). The LCT is a standalone driving
simulation that requires drivers to execute lane changes when prompted
by signs appearing in the scenario. The LCT combines vehicle control
performance, object detection, and response speed into a single summary
performance measure. Based on CAMP \27\ study recommendations, the
STISIM driving scenario used involved car following with occasional
oncoming traffic, in combination with the Peripheral Detection Task
(PDT) to provide a visual object-event detection component. A Seeing
Machines faceLab eye tracking system was used with both primary test
venues.
---------------------------------------------------------------------------
\26\ Mattes, S., ``The lane change task as a tool for driver
distraction evaluation,'' in GfA/17th Annual Conference of the
International-Society-for-Occupational-Ergonomics-and-Safety (ISOES)
Stuttgart, Germany: Ergonomia Verlag OHG, Bruno-Jacoby-Weg 11, D-
70597, 2003.
\27\ Angell, L., Auflick, J., Austria, P. A., Kochhar, D.,
Tijerina, L., Biever, W., Diptiman, T., Hogsett, J., and Kiger, S.,
``Driver Workload Metrics Task 2 Final Report,'' DOT HS 810 635,
November 2006.
---------------------------------------------------------------------------
Two initial experiments were conducted to evaluate the metrics
associated with the STISIM and LCT test venues and to assess the
metrics' sensitivity for detecting known and hypothesized differences
between different secondary tasks. Results showed that most metrics
were sensitive to changes in visual-manual load associated with visual
search tasks. STISIM driving performance and PDT metrics were the most
sensitive objective metrics and were generally more sensitive than LCT
metrics. A third experiment that compared the sensitivity of measures
obtained in the laboratory with that of an established test track
protocol showed similarity among patterns of workload ratings. However,
the laboratory simulator measures were more sensitive to secondary task
load differences than the corresponding test track measures.
Overall, the laboratory environment provided better control of test
conditions, particularly visibility, and less measurement error than
the test track. The limited fidelity of the simulator did not reduce
the sensitivity of the simulator-based metrics for detecting the
targeted differences between task conditions. The breadth of
[[Page 11209]]
STISIM/PDT measurement capabilities is also consistent with the general
consensus that multiple measures are necessary to fully characterize
distraction effects. Thus, the driving simulator protocol was retained
for further research.
E. Developing a Test To Measure Distraction Potential of In-Vehicle
Information System Tasks in Production Vehicles \28\
---------------------------------------------------------------------------
\28\ Ranney, T.A., Baldwin, G.H.S., Parmer, E., Domeyer, J.,
Martin, J., and Mazzae, E. N., ``Developing a Test To Measure
Distraction Potential of In-Vehicle Information System Tasks in
Production Vehicles,'' DOT HS 811 463, November 2011.
---------------------------------------------------------------------------
In 2009, NHTSA continued its efforts to develop a sensitive method
of driver distraction measurement using production vehicles. Research
was conducted using the visual occlusion technique, which involves
periodic interruption of vision (via electronically shuttered goggles
or some other apparatus) during the performance of a secondary task to
simulate the driver glancing at the roadway while driving. By summing
the duration of periods of unoccluded vision, the technique provides an
estimate of the time that the driver looks away from the roadway to
perform the secondary task. Because in the traditional occlusion
method, participants have no primary task load (to simulate the demands
of driving), the task completion time estimates do not include time
during which participants continue to work on the secondary task during
occluded intervals. To address this ``blind operation'' concern, an
Enhanced Occlusion Technique (EOT) was also examined. This technique
incorporated an auditory tracking task intended to simulate the demands
of driving without interfering with the visual demands of occlusion.
The study compared task completion times obtained with the
traditional occlusion protocol with those obtained using the EOT to
assess their relative abilities to assess the distraction effects of
secondary tasks. The experiment also sought to determine the extent to
which blind operation is eliminated by the EOT. Data from occlusion
trials were also used to compute indices of task resumability (R),
which indicate how amenable a task is to completion under conditions of
interruption, as in driving. Three navigation system tasks were used,
including destination entry by address, selecting a previous
destination, and searching a list of cities. Results showed that the
EOT eliminated some blind operation, but not all of it. Specifically,
with traditional occlusion, approximately 23 percent of the actions
required to perform the task was accomplished during occluded
intervals. With the EOT, the corresponding percentage was 11 percent.
The R metrics differed between the traditional occlusion and EOT
conditions, but neither R metric revealed differences between secondary
task conditions. This led to the conclusion that task resumability (R)
does not reflect the same performance degradation revealed by the
driving performance metrics. The destination entry by address task was
associated with a significantly higher level of (auditory) tracking
error than the previous destination task.
A complementary experiment was conducted as part of this project
using a multiple-target detection task to assess the distraction
potential of three navigation systems with comparable functionality.
Participants performed two navigation system tasks (destination entry
by address and previous destination) using one original equipment
system and two portable systems, each differing in their rated
usability. Metrics revealed strong and consistent differences between
baseline driving and driving with a secondary task. Three objective
metrics (car-following coherence, detection task mean response time and
the proportion of long glances) revealed differences between the
destination entry by address and previous destination tasks generally.
Based on the results of these experiments, it was concluded that it is
feasible to use a simulator-based test to assess the distraction
potential of secondary tasks performed with original equipment systems
integrated into production vehicles. Test results indicated that a
broad range of metrics, including measures of car-following, lateral
vehicle control, target detection, and visual performance, were
consistently and robustly sensitive to differences between categories
of secondary tasks and between baseline driving and driving while
performing secondary tasks. Fewer metrics were found to be sensitive to
differences between visual-manual task conditions: Lane-position
variability (SDLP), the time required for a following vehicle to react
to lead vehicle speed changes, and detection task response time.
While the EOT represented an improvement over the traditional
occlusion paradigm for providing information about the time required to
perform various secondary tasks, task duration estimates obtained with
either the traditional occlusion protocol or the EOT both differed from
comparable values obtained in a controlled driving situation. Due to
their increased sensitivity for detecting differences within task
conditions, the SDLP, the time required for a following vehicle to
react to lead vehicle speed changes, detection task response time and
proportion of correct responses are considered core metrics for
assessing distraction potential using driving simulation methods.
Measures based on eye position data, primarily the proportion of long
glances away from the forward roadway, also exhibited differences
between tasks.
F. Distraction Effects of Manual Number and Text Entry While Driving
\29\
---------------------------------------------------------------------------
\29\ Ranney, T.A., Baldwin, G.H.S., Parmer, E., Martin, J., and
Mazzae, E. N., ``Distraction Effects of Manual Number and Text Entry
While Driving,'' DOT HS 811 510, August 2011.
---------------------------------------------------------------------------
In 2010, NHTSA conducted research to further develop its driving
simulator method in order to assess the distraction potential of
secondary tasks performed using in-vehicle information systems in
production vehicles or portable electronic devices. The ``Dynamic
Following and Detection'' (DFD) method combines car following and
visual target detection, can be used with different vehicles, and
requires minimal set up effort. Performance degradation in measures of
lateral position, car following, and visual target detection, which are
recorded for trials with secondary tasks, is compared to baseline
driving performance and trials with a benchmark task (destination
entry). NHTSA conducted a study to assess the effects of performing
Manual Number and Text Entry (MNTE) tasks using integrated and portable
devices in a driving simulator scenario to compare the DFD metrics with
metrics specified in the Alliance of Automobile Manufacturers Driver-
Focus Telematics Guidelines (the Alliance Guidelines). This study was
also intended to evaluate different test participant selection criteria
and sample sizes.
Specifically, the study examined Alliance Guidelines' Principle
2.1, which states:
Systems with visual displays should be designed such that the
driver can complete the desired task with sequential glances that
are brief enough not to adversely affect driving.\30\
---------------------------------------------------------------------------
\30\ P. 38, Driver Focus-Telematics Working Group, ``Statement
of Principles, Criteria and Verification Procedures on Driver-
Interactions with Advanced In-Vehicle Information and Communication
Systems,'' June 26, 2006 version, Alliance of Automobile
Manufacturers, Washington, DC.
The Alliance proposed two alternatives for assessing compliance.
Alternative A includes two criteria that should be met: (1) durations
of single
[[Page 11210]]
glances to the task should generally not exceed 2 seconds; and (2)
total glance time to the task (TGT) should not exceed 20 seconds.
Alternative B identifies two driving performance measures (lane
exceedance frequency and car-following headway variability) and
outlines a generic test protocol in which task-related degradation is
related to degradation on a benchmark task (radio tuning).
For the MNTE study, an experiment was conducted in which 100
participants aged 25 to 64 years performed number and text entry tasks
during 3-minute drives using the STISIM driving simulator. Sensors
connected to the steering, brake, and throttle of a single stationary
2010 Toyota Prius (with engine off) provided control inputs to the
fixed-base driving simulator. The significant overlap in data
collection requirements between Alliance and DFD protocols allowed the
necessary data for a side-by-side comparison to be obtained from a
single experiment. The experiment had three independent variables: (1)
Portable device (hard button cell phone or touch-screen cell phone)
\31\; (2) benchmark (radio tuning or destination entry); and (3) driver
age. Secondary tasks performed included two methods of phone dialing
(10-digit dialing \32\ and contact selection), text messaging,
destination entry and radio tuning.
---------------------------------------------------------------------------
\31\ Test participants were unfamiliar with the device being
used as per the test procedure requirements.
\32\ Dialing using 10 digits was the only number of digits
examined in this study.
---------------------------------------------------------------------------
Study results showed that text messaging was associated with the
highest level of distraction potential. Ten-digit dialing was the
second most distracting task; radio tuning had the lowest level.
Although destination entry was no more demanding than radio tuning when
task duration effects were eliminated with DFD metrics, it exposes
drivers to more risk than radio tuning and phone tasks due to its
considerably longer duration. Modest differences between phones were
observed, including higher levels of driving performance degradation
associated with the touch screen relative to the hard button phone for
several measures. Additional analyses demonstrated that the way in
which task duration is considered in the definition of metrics
influenced the outcomes of statistical tests using the metrics. The
results are discussed in the context of the development of guidelines
for assessment of the distraction potential of tasks performed with in-
vehicle information systems and portable devices.
Additional analyses were conducted to compare the DFD and Alliance
Guidelines' decision criteria in a simulated compliance scenario. With
the large sample size (N = 100), both protocols supported the
conclusion that neither text messaging nor 10-digit dialing is suitable
for combining with driving; however, when a smaller (N = 40) sample was
used, the protocols led to different conclusions. Considering only the
vehicle performance metrics (not the eye glance metrics), samples of 20
participants did not provide sufficient statistical power to
differentiate among secondary tasks.
Driver age had significant effects on both primary and secondary
task performance; younger drivers completed more secondary task trials
on a given drive with relatively less primary task interference than
older drivers. Tests conducted using samples with wide age ranges (25-
64) required larger samples to compensate for reduced homogeneity
relative to samples with narrow age ranges.
Based on these results, two issues were identified as having
implications for developing guidelines to assess the distraction
potential of tasks performed with in-vehicle and portable systems. The
first issue pertains to the question of how to incorporate task
duration into the construction and interpretation of metrics. Secondary
tasks differ in duration and these differences influence the overall
exposure to risk. Metrics that summarize performance over varying
durations are influenced by differences in task duration. In contrast,
metrics that normalize for task duration summarize task performance
over equivalent time intervals and thus represent the expected
magnitude of performance degradation at any point in time during which
a task is performed. These approaches provide complementary
information, which could be used together to characterize the total
exposure to risk associated with different tasks. One approach toward
integration involves using duration-controlled metrics to estimate the
average level of performance degradation associated with a particular
secondary task and then multiplying this estimate by the average or
some specified percentile (e.g., 85th) task duration to estimate the
total exposure to risk associated with performing the task once.
The finding having the most prominent implications for developing
driver distraction guidelines for visual-manual interactions was that
the driving simulation method of measuring distraction potential is
most sensitive to differences in distraction levels of secondary tasks
when performed using more than 40 test participants of homogeneous age
range.
G. Principal Findings of NHTSA Driver Distraction Metric Research
Each of the research studies described above provided information
which laid the foundation for the NHTSA Guidelines. The principal
findings include the following:
Visual-manual secondary tasks affected driving performance
more than auditory-vocal tasks.\33\ This could change as auditory-vocal
interfaces become more prevalent and allow drivers to perform more
complex secondary tasks.
---------------------------------------------------------------------------
\33\ Angell, L., Auflick, J., Austria, P. A., Kochhar, D.,
Tijerina, L., Biever, W., Diptiman, T., Hogsett, J., and Kiger, S.,
``Driver Workload Metrics Task 2 Final Report,'' DOT HS 810 635,
November 2006.
---------------------------------------------------------------------------
Eye-glance data contained important information for
assessing the distraction effects of both auditory-vocal and visual-
manual tasks.\34\
---------------------------------------------------------------------------
\34\ Ibid.
---------------------------------------------------------------------------
The interference to driving caused by in-vehicle secondary
tasks was multidimensional and no single metric could measure all
effects.\35\
---------------------------------------------------------------------------
\35\ Ibid.
---------------------------------------------------------------------------
CAMP Driver Workload Metrics project concluded that
cognitive distraction played a much smaller role than visual
distraction.\36\ Again, this could change as auditory-vocal interfaces
become more prevalent and allow drivers to perform more complex
secondary tasks.
---------------------------------------------------------------------------
\36\ Ibid.
---------------------------------------------------------------------------
The research involved the development of sensitive test procedures
and metrics for measuring driver distraction. Some of the conclusions
drawn from the research which contributed to the basis of content in
the NHTSA Guidelines include:
Experimentation involving a fixed-based driving simulator
in a laboratory environment provided better control of test conditions,
particularly visibility, and less measurement error than did
experimentation utilizing a test track.\37\
---------------------------------------------------------------------------
\37\ Ranney, T.A., Baldwin, G.H.S., Vasko, S.M., and Mazzae,
E.N., ``Measuring Distraction Potential of Operating In-Vehicle
Devices,'' DOT HS 811 231, December 2009.
---------------------------------------------------------------------------
Limited fidelity of driving simulation did not reduce the
sensitivity of simulator-based metrics for detecting targeted
differences between task conditions.\38\
---------------------------------------------------------------------------
\38\ Ibid.
---------------------------------------------------------------------------
Metrics found to be sensitive to differences between
visual-manual task conditions include lane-position
[[Page 11211]]
variability (SDLP), the time required for a following vehicle to react
to lead vehicle speed changes, and detection task response time.\39\
---------------------------------------------------------------------------
\39\ Ranney, T.A., Baldwin, G.H.S., Parmer, E., Domeyer, J.,
Martin, J., and Mazzae, E.N., ``Developing a Test to Measure
Distraction Potential of In-Vehicle Information System Tasks in
Production Vehicles,'' DOT HS 811 463, November 2011.
---------------------------------------------------------------------------
Metrics found to be sensitive to differences between
auditory-vocal task conditions included the time required for a
following vehicle to react to lead vehicle speed changes, detection
task response time, and detection task proportion of correct
responses.\40\
---------------------------------------------------------------------------
\40\ Ibid.
---------------------------------------------------------------------------
Core metrics for assessing distraction potential using
driving simulator-based methods include lane-position variability, the
time required for a following vehicle to react to lead vehicle speed
changes, detection task response time, and the proportion of correct
responses due to their increased sensitivity for detecting differences
within task conditions.\41\
---------------------------------------------------------------------------
\41\ Ibid.
---------------------------------------------------------------------------
Differences in sample size and sample construction (test
participant age) have significant differences on test outcome. Sample
sizes larger than 40 participants are needed for the vehicle
performance metrics in order to provide adequate statistical power and
avoid effects of sample composition.\42\
---------------------------------------------------------------------------
\42\ Ibid.
---------------------------------------------------------------------------
A driving scenario involving a following task with
constant lead vehicle speed seems to provide a less realistic level of
driving task difficulty and may not sufficiently engage test
participants in the test protocol.\43\
---------------------------------------------------------------------------
\43\ Ibid.
---------------------------------------------------------------------------
With regard to specific tasks and their treatment in the NHTSA
Guidelines for visual-manual tasks, the following research findings
provided key input:
Text messaging was found to be more distracting than any
other secondary task considered in this study on a number of metrics.
The Alliance and DFD metrics and decision criteria both supported the
conclusion that text messaging is not suitable for performance while
driving.\44\
---------------------------------------------------------------------------
\44\ Ranney, T.A., Baldwin, G.H.S., Parmer, E., Martin, J., and
Mazzae, E.N., ``Distraction Effects of Manual Number and Text Entry
While Driving,'' DOT HS 811 510, August 2011.
---------------------------------------------------------------------------
Phone dialing using 10 digits was found to be only
slightly less distracting than text messaging. For larger sample sizes,
the Alliance and DFD metrics and decision criteria both suggested that
10-digit phone dialing is not suitable for performance while
driving.\45\ This study did not examine 7-digit phone dialing. However,
NHTSA is currently performing research to examine the suitability of 7-
digit phone dialing while driving.
---------------------------------------------------------------------------
\45\ Ibid.
---------------------------------------------------------------------------
V. Driver Distraction Prevention and Reduction Guidelines
A. Currently Existing Driver Distraction Guidelines
On July 18, 2000, NHTSA held a public meeting to address a growing
concern in the traffic safety community--driver distraction. This
meeting addressed the rapid emergence of informational and
entertainment devices, as well as cellular telephones. Consistent with
NHTSA's regulatory authority, the Agency issued a challenge to the
automotive industry--develop interface guidelines to reduce the
distraction potential of emerging technologies. The Alliance of
Automobile Manufacturers accepted the challenge by developing a set of
``best practices'' for ``telematic'' (communication, entertainment,
information, and navigation) devices. The first version of the
Alliance's Statement of Principles, Criteria and Verification
Procedures on Driver Interactions with Advanced In-Vehicle Information
and Communication Systems (referred to elsewhere in this document as
the Alliance Guidelines), were published in December 2000. Updates to
the Alliance Guidelines was published in April 22, 2002 (Version 2.0),
November 19, 2003 (Version 2.1), and, the most recent version (Version
3.0), on June 26, 2006.\46\
---------------------------------------------------------------------------
\46\ Driver Focus-Telematics Working Group, ``Statement of
Principles, Criteria and Verification Procedures on Driver-
Interactions With Advanced In-Vehicle Information and Communication
Systems,'' June 26, 2006 version, Alliance of Automobile
Manufacturers, Washington, DC.
---------------------------------------------------------------------------
The Alliance Guidelines consist of 24 principles (organized into
five groups: Installation Principles, Information Presentation
Principles, Principles on Interactions with Displays/Controls, System
Behavior Principles, and Principles on Information about the System)
that apply to each device's driver interface to ensure safe operation
while driving. Each principle includes, when appropriate for that
principle, a rationale, verification methods, acceptability criteria,
and examples. Quoting from the Alliance Guidelines,\47\ its principles
are as follows:
---------------------------------------------------------------------------
\47\ PP 1-5, Driver Focus-Telematics Working Group, ``Statement
of Principles, Criteria and Verification Procedures on Driver-
Interactions with Advanced In-Vehicle Information and Communication
Systems,'' June 26, 2006 version, Alliance of Automobile
Manufacturers, Washington, DC.
Section 1: Installation Principles
Principle 1.1: The system should be located and fitted in
accordance with relevant regulations, standards, and the vehicle and
component manufacturers' instructions for installing the systems in
vehicles.
Principle 1.2: No part of the system should obstruct the
driver's field of view as defined by applicable regulations.
Principle 1.3: No part of the physical system should obstruct
any vehicle controls or displays required for the driving task.
Principle 1.4: Visual displays that carry information relevant
to the driving task and visually-intensive information should be
positioned as close as practicable to the driver's forward line of
sight.
Principle 1.5: Visual displays should be designed and installed
to reduce or minimize glare and reflections.
Section 2: Information Presentation Principles
Principle 2.1: Systems with visual displays should be designed
such that the driver can complete the desired task with sequential
glances that are brief enough not to adversely affect driving.
Principle 2.2: Where appropriate, internationally agreed upon
standards or recognized industry practice relating to legibility,
icons, symbols, words, acronyms, or abbreviations should be used.
Where no standards exist, relevant design guidelines or empirical
data should be used.
Principle 2.3: Available information relevant to the driving
task should be timely and accurate under routine driving conditions
Principle 2.4: The system should not produce uncontrollable
sound levels liable to mask warnings from within the vehicle or
outside or to cause distraction or irritation.
Section 3: Principles on Interactions with Displays/Controls
Principle 3.1: The system should allow the driver to leave at
least one hand on the steering control.
Principle 3.2: Speech-based communication systems should include
provision for hands-free speaking and listening. Starting, ending,
or interrupting a dialog, however, may be done manually. A hands-
free provision should not require preparation by the driver that
violates any other principle while the vehicle is in motion.
Principle 3.3: The system should not require uninterruptible
sequences of manual/visual interactions. The driver should be able
to resume an operator-interrupted sequence of manual/visual
interactions with the system at the point of interruption or at
another logical point in the sequence.
Principle 3.4: In general (but with specific exceptions) the
driver should be able to control the pace of interaction with the
system. The system should not require the driver to make time-
critical responses when providing input to the system.
Principle 3.5: The system's response (e.g. feedback,
confirmation) following driver
[[Page 11212]]
input should be timely and clearly perceptible.
Principle 3.6: Systems providing non-safety-related dynamic
(i.e. moving spatially) visual information should be capable of a
means by which that information is not provided to the driver.
Section 4: System Behavior Principles
Principle 4.1: Visual information not related to driving that is
likely to distract the driver significantly (e.g., video and
continuously moving images and automatically scrolling text) should
be disabled while the vehicle is in motion or should be only
presented in such a way that the driver cannot see it while the
vehicle is in motion.
Principle 4.2(a): System functions not intended to be used by
the driver while driving should be made inaccessible for the purpose
of driver interaction while the vehicle is in motion.
Principle 4.2(b): The system should clearly distinguish between
those aspects of the system, which are intended for use by the
driver while driving, and those aspects (e.g. specific functions,
menus, etc) that are not intended to be used while driving.
Principle 4.3: Information about current status, and any
detected malfunction, within the system that is likely to have an
adverse impact on safety should be presented to the driver.
Section 5: Principles on Information about the System
Principle 5.1: The system should have adequate instructions for
the driver covering proper use and safety-relevant aspects of
installation and maintenance.
Principle 5.2: Safety instructions should be correct and simple.
Principle 5.3: System instructions should be in a language or
form designed to be understood by drivers in accordance with
mandated or accepted regional practice.
Principle 5.4: The instructions should distinguish clearly
between those aspects of the system that are intended for use by the
driver while driving, and those aspects (e.g. specific functions,
menus, etc.) that are not intended to be used while driving.
Principle 5.5: Product information should make it clear if
special skills are required to use the system or if the product is
unsuitable for particular users.
Principle 5.6: Representations of system use (e.g. descriptions,
photographs, and sketches) provided to the customer with the system
should neither create unrealistic expectations on the part of
potential users, nor encourage unsafe or illegal use.
The Alliance Guidelines provide a comprehensive set of
recommendations designed to limit visual-manual distraction while
driving. The document includes relevant definitions, human factors
principles for good device driver-interface design, methods for
verifying compliance with the principles, and a number of examples.
These Alliance Guidelines serves as an excellent foundation for the
development of the NHTSA Guidelines.
In addition to the Alliance Guidelines, numerous other standards
and guidelines documents have been developed. A summary of these is
contained in the SAE paper ``Driver Interface/HMI Standards to Minimize
Driver Distraction/Overload.''\48\ The two other sets of these
guidelines that most directly deal with driver distraction (in addition
to the Alliance Guidelines) were:
---------------------------------------------------------------------------
\48\ Green, P., ``Driver Interface/HMI Standards to Minimize
Driver Distraction/Overload,'' SAE Paper 2008-21-2002, 2008.
---------------------------------------------------------------------------
Commission Recommendation of 26 May 2008 on Safe and
Efficient In-Vehicle Information and Communication Systems; Update of
the European Statement of Principles on Human-Machine Interface
(referred to as the ``European Guidelines'').\49\
---------------------------------------------------------------------------
\49\ Commission of the European Communities, ``Commission
Recommendation of 26 May 2008 on Safe and Efficient In-Vehicle
Information and Communication Systems; Update of the European
Statement of Principles on Human-Machine Interface,'' 2008.
---------------------------------------------------------------------------
The Japan Automobile Manufacturers Association Guidelines
for In-vehicle Display Systems--Version 3.0 (referred to as the ``JAMA
Guidelines'').\50\
---------------------------------------------------------------------------
\50\ Japan Automobile Manufacturers Association, ``Guideline for
In-Vehicle Display Systems, Version 3.0,'' Japan Automobile
Manufacturers Association, Tokyo, Japan, August 2004.
---------------------------------------------------------------------------
The European Guidelines consist of 34 principles that each in-
vehicle device's driver interface should meet to ensure safe operation
while driving, as well as 16 safety recommendations for drivers,
employers, advertisers, and personnel working for vehicle-for-hire
operations. Driver interface principles are grouped into the following
areas: Overall Design Principles, Installation Principles, Information
Principles, Interactions with Controls and Displays Principles, System
Behavior Principles, and Information about the System Principles, most
of which are similar to the corresponding principles in the Alliance
Guidelines. The principles present in the European Guidelines that are
not present in the Alliance Guidelines are typically understood in the
latter and do not have verification methods given in the former. For
example, the first European Guidelines principle is:
The system supports the driver and does not give rise to
potentially hazardous behavior by the driver or other road
users.\51\
---------------------------------------------------------------------------
\51\ P. 7, Commission of the European Communities, ``Commission
Recommendation of 26 May 2008 on Safe and Efficient In-Vehicle
Information and Communication Systems; Update of the European
Statement of Principles on Human-Machine Interface,'' 2008.
While this principle is not explicitly written in the Alliance
Guidelines, reading them clearly shows that this principle is the
underlying one for all of the Alliance Guidelines.
Unlike the Alliance Guidelines, the European Guidelines do not
prescribe testing methods and acceptance criteria for determining
whether a task can safely be performed by the driver while a vehicle is
in motion. For example, one very important Alliance Guidelines
principle, Principle 2.1, is:
Systems with visual displays should be designed such that the
driver can complete the desired task with sequential glances that
are brief enough not to adversely affect driving.\52\
---------------------------------------------------------------------------
\52\ P. 38, Driver Focus-Telematics Working Group, ``Statement
of Principles, Criteria and Verification Procedures on Driver-
Interactions with Advanced In-Vehicle Information and Communication
Systems,'' June 26, 2006 version, Alliance of Automobile
Manufacturers, Washington, DC.
The Alliance Guidelines then follow this statement with many pages
describing how to verify that a device's interface meets this
principle. In contrast, the corresponding European Guidelines principle
---------------------------------------------------------------------------
reads:
Visually displayed information presented at any one time by the
system should be designed in such a way that the driver is able to
assimilate the relevant information with a few glances which are
brief enough not to adversely affect driving.\53\
---------------------------------------------------------------------------
\53\ P. 13, Commission of the European Communities, ``Commission
Recommendation of 26 May 2008 on Safe and Efficient In-Vehicle
Information and Communication Systems; Update of the European
Statement of Principles on Human-Machine Interface,'' 2008.
However, the European Guidelines limit statements about the
---------------------------------------------------------------------------
verification process to:
Compare design alternatives for the presentation of information:
the number and duration of glances needed to detect and acquire
relevant information presented at any one time should be
minimized.\54\
---------------------------------------------------------------------------
\54\ Ibid.
The JAMA Guidelines consist of four basic principles and 25
specific requirements that apply to each device's driver interface to
ensure safe operation while driving. Specific requirements are grouped
into the following areas: Installation of Display Systems, Functions of
Display Systems, Display System Operation While Vehicle in Motion, and
Presentation of Information to Users. Additionally, there are three
annexes: Display Monitor Location, Content and Display of Visual
Information While Vehicle in Motion, and Operation of Display Monitors
While Vehicle in Motion, as well as one appendix: Operation of Display
Monitors While Vehicle in Motion.
[[Page 11213]]
Approximately one-half of the specific requirements in the JAMA
Guidelines are essentially identical to the corresponding principles in
the Alliance and European Guidelines.
Like the Alliance Guidelines, the JAMA Guidelines prescribe
acceptance criteria for determining whether a task can safely be
performed by the driver while a vehicle is in motion. Based on the
specified acceptance criteria, the JAMA Guidelines imply the use of the
same testing methods (the JAMA Guidelines do not actually specify
testing methods) as are contained in the Alliance Guideline's
Alternative A verification options: Eye Tracker Measurement, Video
Recording of Test Participant's Eyes/Face, and Testing using Occlusion.
However, the JAMA acceptance criteria are more constraining than those
found in the Alliance Guidelines. The JAMA Guidelines limit the maximum
driver total glance time while performing a task (JAMA uses the same
definition for task as is used in the Alliance Guidelines) to 8.0
seconds or 7.5 seconds if occlusion is used (compare to the Alliance
Guidelines limits of 20.0 seconds for maximum driver total glance time
or 15.0 seconds for occlusion).
The JAMA Guidelines also contain a recommended limit on the amount
of dynamic test that can be displayed to the driver at one time. As the
JAMA Guidelines state:
The number of letters (e.g., characters, kana, alphabets)
displayed at a time shall not exceed 31,\55\ provided that a number
such as ``120'' or a unit such as km/h'' is deemed to be a single
letter irrespective of the number of digits. Punctuation marks are
not included in the count of letters.\56\
---------------------------------------------------------------------------
\55\ The JAMA Guidelines appear inconsistent as to the maximum
number of letters that they allow to be displayed at one time. The
above quote, which is taken from page 7 of the JAMA Guidelines
appears to set the maximum allow number of letters to 31. However,
the statement on page 13, ``display of 31 or more letters at a time
is prohibited,'' appears to contradict this 31 character maximum
value. NHTSA has selected the more conservative of these two values
for its proposal.
\56\ P. 7, Japan Automobile Manufacturers Association,
``Guideline for In-Vehicle Display Systems, Version 3.0,'' Japan
Automobile Manufacturers Association, Tokyo, Japan, August 2004.
The JAMA Guidelines are far shorter, and, as a result, far less
detailed than either the Alliance or European Guidelines.
Of the various driver distraction prevention and reduction
guidelines that were reviewed, NHTSA has decided that the current
version of the Alliance Guidelines serves as the best basis for the
development of the NHTSA Guidelines. They are the most complete of the
three guideline sets considered and contain far more information about
verification procedures than do the European or JAMA Guidelines. There
are only a few contradictions between the three sets of guidelines,
with the principal one being the JAMA Guidelines previously discussed
prohibition on performing non-driving related tasks while in motion.
The Alliance and European Guidelines are quite similar; a device
that meets one set of these guidelines will meet the other. The
Japanese Guidelines are more restrictive--they do not allow quite a
number of devices to function whenever the vehicle is in motion. As a
result, a vehicle that strictly follows the JAMA Guidelines should meet
all of the recommendations of both the Alliance and European Guidelines
but not necessarily vice-versa.
When there are items contained in either the European or JAMA
Guidelines that are not in the Alliance Guidelines, NHTSA has carefully
considered them and included them in the NHTSA Guidelines when we agree
with them (e.g., the 30 character limit in the NHTSA Guidelines on the
amount of text that may be read comes from the JAMA Guidelines).
As a convenience to readers, NHTSA has placed copies of the
Alliance, European, and JAMA Guidelines into the distraction
docket.\57\
---------------------------------------------------------------------------
\57\ Docket No. NHTSA-2010-0053.
---------------------------------------------------------------------------
B. Why NHTSA Is Issuing Its Own Guidelines for Limiting and Reducing
Driver Distraction
NHTSA has decided to issue its own guidelines for limiting and
reducing driver distraction associated with the use of in-vehicle
electronic devices while driving. Voluntary guidelines developed by
others in the past have been instrumental in the development of these
NHTSA Guidelines. The NHTSA Guidelines are being issued for the
following reasons:
So as to have guidelines available for all passenger cars,
multipurpose passenger vehicles, and trucks and buses with a Gross
Vehicle Weight Rating (GVWR) of not more than 10,000 pounds.
So as to have guidelines applicable to all communications,
entertainment, information, and navigation devices installed in
vehicles as original equipment.
So as to incorporate the latest driver distraction
research into the guidelines. There has been much research on driver
distraction in the five years since the Alliance Guidelines were last
updated; NHTSA believes that it is valuable to incorporate the results
of this recent research into guidelines that serve to reduce or prevent
driver distraction prevention.
Per the Highway Safety Act of 1970, NHTSA is responsible
for reducing deaths, injuries and economic losses resulting from motor
vehicle crashes; in short, NHTSA is responsible for vehicle safety.
While manufacturers also have a strong interest in safety, they are
also influenced by other factors, such as market forces. Therefore, the
NHTSA Guidelines will focus solely on safety and the safety impact of
final (i.e., consumer-ready) products. In contrast, other guidelines
focus more on the design process, which involves consideration of
factors in addition to safety, and include metrics that can be used on
prototype designs.
NHTSA has identified some aspects of the current Alliance
Guidelines that are loosely specified or provide multiple compliance
assessment options that may correspond to different levels of
associated safety. NHTSA would like to specify a test procedure that is
straight-forward, clearly defined, and well-substantiated in order to
aid the voluntary adoption of its NHTSA Guidelines. Minimizing the
opportunity for variability in carrying out the test procedure will
ensure that manufacturers would be able to easily and consistently
implement the NHTSA Guidelines across their light vehicle fleets.
Before undertaking this guideline effort, NHTSA met with several
manufacturers in 2010 to determine how they had implemented the
Alliance Guidelines. During these meetings, NHTSA learned that
implementation varies across, and sometimes within, manufacturers. This
information has been useful to NHTSA to attain a better understanding
of the practical considerations and constraints facing manufacturers
when developing vehicle technologies. This information has been taken
under consideration by NHTSA while drafting the new NHTSA Guidelines.
The NHTSA Guidelines, while adopting much of the content of the
Alliance Guidelines, incorporate a number of changes in an effort to
further enhance driving safety, to enhance guideline usability, to
improve implementation consistency, and to incorporate the latest
driver distraction research findings. The proposed NHTSA Guidelines and
their rationales, including the rationale for departures from the
Alliance Guidelines, are
[[Page 11214]]
discussed in detail in later portions of this notice.
C. First Phase of NHTSA's Driver Distraction Guidelines Focuses on
Original Equipment Devices With Visual-Manual Driver Interfaces
As discussed in NHTSA's Driver Distraction Program, NHTSA's intent
is to ``develop voluntary guidelines for minimizing the distraction
potential of in-vehicle and portable devices.'' Electronic devices in a
motor vehicle can divided into three broad classes, depending upon
their origin. These devices may have been built into a vehicle when it
is manufactured (i.e., original equipment devices), installed in a
vehicle after it has been built (i.e., aftermarket devices), or brought
into a vehicle (portable devices). The current notice only contains
voluntary NHTSA Guidelines for visual-manual interactions associated
with original equipment devices. Portable devices will be addressed by
Phase 2 of the NHTSA Guidelines. These and the remaining phases of the
NHTSA Guidelines are outlined in Table 2.
As noted earlier, drivers perform tasks using an in-vehicle
electronic device by interacting with the device through its driver
interface. The driver interfaces of these devices can be designed to
accommodate interactions that are visual-manual, auditory-vocal, or a
combination of the two.
The goal of the NHTSA Guidelines is to discourage the design of in-
vehicle device interfaces that do not minimize driver distraction
associated with secondary task performance. The NHTSA Guidelines
specify criteria and a test method for assessing whether a secondary
task performed using an in-vehicle device may be suitable for
performance while driving, due to its minimal impact on driving
performance and, therefore, safety. The NHTSA Guidelines also seek to
identify secondary tasks that interfere with a driver's ability to
safely control their vehicle and to categorize those tasks as ones that
are not suitable for performance by the driver while driving.
For each of the three possible origins of in-vehicle electronic
devices, both visual-manual and auditory-vocal interaction modes may be
possible. Table 2 indicates the order in which NHTSA plans to develop
its NHTSA Guidelines to address the different device origins and
interfaces.
Table 2--Matrix Showing NHTSA Driver Distraction Guideline Phases Based on Device Origins and Interaction Types
----------------------------------------------------------------------------------------------------------------
Origin of device
Type of interaction ------------------------------------------------------------------------------
Original equipment Aftermarket Portable
----------------------------------------------------------------------------------------------------------------
Visual-Manual.................... NHTSA Driver Distraction NHTSA Driver Distraction NHTSA Driver Distraction
Guidelines, Phase 1. Guidelines, Phase 2. Guidelines, Phase 2.
Auditory-Vocal................... NHTSA Driver Distraction NHTSA Driver Distraction NHTSA Driver Distraction
Guidelines, Phase 3. Guidelines, Phase 3. Guidelines, Phase 3.
----------------------------------------------------------------------------------------------------------------
This notice proposes Phase 1 of the NHTSA Driver Distraction
Guidelines. NHTSA plans to issue Phase 2 (aftermarket and portable
devices) of its NHTSA Guidelines in 2013 and Phase 3 (auditory-vocal
interfaces) in 2014. Our NHTSA Guidelines are being developed in these
phases because:
While some international and voluntary consensus standards
exist that relate to visual-manual interfaces for in-vehicle devices,
no similar standards for devices with auditory-vocal interfaces exist.
Auditory-vocal interfaces are newer than are visual-manual interfaces;
as a consequence less research has been performed on driver distraction
while using auditory-vocal interfaces. Research is needed on such
subjects as how to best measure the level of driver distraction induced
when auditory-vocal interfaces are used. Based on this shortage of
research, NHTSA intends to delay the extension of its NHTSA Guidelines
to cover auditory-vocal interfaces until Phase 3 of guideline
development.
From naturalistic driving research, the secondary tasks
with the highest risk odds ratios tend to be primarily visual-manual in
nature with only a relatively small cognitive component. Of course,
every secondary task results in some cognitive load; however, tasks
such as Reaching for a Moving Object or Eating require that the
driver's eyes and hands be used to perform non-driving tasks but do not
require a lot of thought. It is not until the ninth highest risk odds
ratio in Figure 1; Talking/Listening to a Hand-Held Device that a
secondary task appears that is heavily cognitive in nature.\58\
Furthermore, this secondary task's risk odds ratio is not statistically
significantly different from 1.00 at the 95 percent confidence level.
In fact, there are no secondary tasks in Figure 1 that have risk odds
ratios which are statistically significantly greater than 1.00 that are
primarily cognitive in nature.
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\58\ It could be argued that ``Reading'' generates high
cognitive distraction. Clearly ``Reading'' generates a high visual
load. Unfortunately, we do not, at this time, have the ability to
measure the cognitive load generated by ``Reading.'' However, it
seems reasonable that the cognitive distraction generated would vary
depending upon what is being read. NHTSA believes that what are most
commonly being read by drivers are signs or simple printed material
that are not expected to generate high cognitive distraction.
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There may be special challenges associated with guidelines
for both aftermarket and portable devices. Given that for some device
types the only substantial difference between an integrated and a
portable version of the device will be the device location (fixed or
variable), most of the NHTSA visual-manual Driver Distraction Guideline
criteria are expected to also be appropriate for aftermarket and
portable devices with visual-manual driver interfaces. However, NHTSA
thinks that additional research is necessary to determine if there are
other considerations for guidelines for aftermarket and portable
devices. Therefore, NHTSA intends to implement the extension of its
NHTSA Guidelines to cover aftermarket and portable devices in Phase 2
of guideline development.
D. Past NHTSA Actions on Driver Distraction
Before this notice, NHTSA had published one Federal Register notice
that was related to driver distraction. On June 3, 2008, NHTSA denied
\59\ a petition from the Center for Auto Safety requesting that NHTSA
do the following:
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\59\ Federal Register, Vol. 73, No. 107, pp. 31663-31665, June
3, 2008.
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1. Issue a Notice of Proposed Rulemaking (NPRM) to require that any
personal communication systems integrated into a vehicle, including
cellular phones and text messaging
[[Page 11215]]
systems, be inoperative when the transmission shift lever is in a
forward or reverse gear.
2. Issue an Advance Notice of Proposed Rulemaking (ANPRM) to
consider requiring that other integrated telematic systems in vehicles
that significantly increase crash rates be inoperative when the
transmission shift lever is in a forward or reverse gear.
3. Increase efforts to support state programs to limit cell phone
use by drivers in moving vehicles in the same manner that it supports
state programs against drunk driving.
Part of NHTSA's rationale for denying the Center for Auto Safety
petition was, as stated in the Federal Register notice, the concern
that:
If integrated cell phones and other telematic devices were
required to be inoperative, drivers could instead use portable
devices such as their regular cell phones.\60\
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\60\ Ibid, P. 31664.
NHTSA remains concerned about the possibility of drivers increasing
their use of portable devices due to restrictions being placed on
integrated devices. Based on this concern, NHTSA considers it essential
that guidelines for aftermarket and portable devices be developed as
rapidly as feasible following the development of NHTSA Guidelines for
original equipment devices. As shown in Table 2 and explained in the
discussion following this table, the development of NHTSA Guidelines
for aftermarket and portable visual-manual device interfaces (Phase 2)
is planned to begin immediately following the completion of the
original equipment visual-manual NHTSA Guidelines (Phase 1).
E. Challenges Relating to the Development of Interface Guidelines To
Minimize Driver Distraction
Developing guidelines for device driver interfaces that minimize
distraction and its impact on driving performance is complicated.
Research is ongoing to identify the best methods and metrics by which
to measure the effects of distraction on driving performance. Even
though research on this topic has not been completed, NHTSA thinks it
important to be proactive and provide guidance on how manufacturers may
limit the range and complexity of in-vehicle device tasks that may be
considered in the future so as to ensure the safety of drivers and
fellow road users. Therefore, NHTSA presents in this notice its current
``best'' proposal based on information currently available.
The challenges involved in developing driver distraction guidelines
and assessing whether covered devices meet associated criteria are many
and non-trivial. These challenges include:
1. Ensuring that criteria that device tasks should meet are
rigorously developed, validated, and substantiated by experimental
data.
2. Developing Guideline criteria that are generalized to all device
types covered by these NHTSA Guidelines, including a wide range of
existing devices and tasks as well as ones that may appear in future
vehicles but have not yet been conceived.
3. Identifying sensitive metrics for measuring distraction and the
most appropriate characteristics of the sample population used to
assess the metrics.
4. Developing a test scenario for use in assessing the degree to
which in-vehicle device tasks meet Guideline criteria that simulates
the demand of actual driving under suitable and ``representative''
conditions.
5. Developing a repeatable and well-defined test protocol for use
in assessing the degree to which in-vehicle device tasks meet Guideline
criteria that implement the chosen driving scenario.
6. Formulating a tightly specified task definition to ensure that
similar tasks are assessed for their ability to meet Guideline criteria
in a similar manner by all relevant manufacturers.
7. Establishing criteria for the sample of experimental subjects to
be tested using the test protocol (i.e., number of test participants;
test participant age ranges, experience, etc.).
8. Assessing whether minimizing total eyes-off-road time spent on a
given secondary task actually results in an overall reduction in the
total amount of eyes-off-road time spent on all secondary tasks,
especially as the number of secondary tasks multiply with the
introduction of more and more entertainment, communication and
information devices, and capabilities.
Each of these challenges is elaborated upon in the following
paragraphs.
1. The Guideline and task performance criteria that devices should
meet need to be rigorously developed, valid, and substantiated by
experimental data. While driver distraction is a topic for which most
of the general public has opinions, decisions relating to what tasks a
driver should be free to perform while driving should be made based on
objective data. Having a data-based means of substantiating distraction
guidelines provides a firm foundation to guarantee that measurable
safety improvements are actually achieved.
2. Developing appropriate Guideline criteria for the broad range of
current and future device task types and input methods is highly
challenging. To date, a variety of manual means through which drivers
can make control inputs to in-vehicle systems have been used. NHTSA
Guidelines for systems with visual-manual interaction means should
cover all types of traditional input controls, touch screens, and means
of providing feedback to the driver. Beyond control input method, the
types of tasks available vary and the extent of electronic device
related tasks that may become available in future vehicles cannot be
known at this time. For these reasons, establishing guidelines that
will remain relevant in the long-term is a challenging issue.
3. Various metrics for characterizing distraction's impact on
driving performance have been developed, but are still being debated
within the research community and industry. Metric sensitivity and the
relationship between the metrics and crash risk are topics of much
contention. Some metrics require testing large numbers of test
participants in order to achieve sufficient statistical power to allow
significant effects to be observed, if they exist. Acceptance criteria
need to be selected and justified based on safety data.
4. A test scenario that simulates the demands of actual driving
under suitable and ``representative'' conditions needs to be defined in
order to provide a baseline for use in measuring the impact of
distracted driving. It should be insensitive to the dynamics of the
vehicles being tested so as to minimize the need for complex and
expensive vehicle characterization testing.
The amount of interference created by secondary task performance
while driving is dependent on the complexity of the driving scenario in
which the secondary task is performed. Drivers will have more spare
attentional capacity that may be used to perform secondary tasks in
less complex traffic conditions than they would in more complex traffic
conditions. Therefore, secondary task performance would be expected to
impact driving performance less in a low complexity driving situation
than in a high complexity one. Choosing the most appropriate level of
driving scenario complexity for assessment of distraction effects is
difficult and important.
5. A test procedure must be developed to be able to assess
adherence to the driver distraction guidelines criteria. While typical
compliance testing measures the effects of a known magnitude and type
of stimulus on a
[[Page 11216]]
specific vehicle design's motion or structural integrity, a test of
driver distraction measures the effects of a stimulus, the magnitude of
which is difficult to quantify, on the ability of a non-standardized
and variable system (i.e., the driver) to control a vehicle safely.
Given that the population of drivers varies widely in a number of
aspects including driving skill, multi-tasking ability, attentional
focus capacity, and propensity to perform non-driving tasks while
driving, the sample of drivers needed for a test to determine adherence
to the NHTSA Guidelines would need to be much larger than the sample
size of one typically associated with a vehicle performance compliance
test. Appropriate data reduction methods and tools also must be
developed.
6. In order to have a standardized test for measuring the impact of
secondary task performance on driving performance and safety, the test
criteria must be well-specified. In particular, a clear definition of a
``task'' must be asserted to specify the series of driver actions
needed to perform a secondary task that should be assessed for
adherence to the NHTSA Guidelines' criteria. Unclear task
specifications can result in inconsistent guideline adherence test
performance throughout the industry. While the definition of task used
in the Alliance Guidelines is short and conceptually clear, it can be
difficult to determine for real devices whether something is one task
or several. This is particularly challenging to do for devices and
tasks that have not yet been developed.
7. Characteristics of the sample of test participants to be
subjected to the test protocol (number of test participants; test
participant criteria including age, experience, conflicts of interest,
etc.) need to be identified. NHTSA is particularly worried about prior
test participant experience with the devices that are being evaluated.
Devices are frequently far more difficult to use (and hence,
distracting) when drivers are not familiar with them. However, the vast
majority of device usage is by drivers who use a device daily and are
highly familiar with their operation.
8. It must be determined whether minimizing the total eyes-off-road
time spent on a given secondary task actually results in an overall
reduction in the total amount of eyes-off-road time spent on all
secondary tasks. This is particularly important as the number of non-
driving secondary tasks seemingly multiplies as more entertainment,
communication and information devices, and capabilities are introduced
into vehicles. (Are the number and variety of secondary tasks in fact
multiplying or does it just seem that way?) Many people have speculated
that making it safer for drivers to perform secondary tasks while
driving will encourage drivers to perform more secondary tasks while
driving. This is another application of risk homeostasis theory; people
have an acceptable level of risk that they are comfortable with and
they compensate for reductions in risk by taking on additional risks so
as to maintain a relatively constant level of risk.
There is undoubtedly a certain amount of truth to risk homeostasis
theory with regard to driving safety. For example, over the last 50
years, numerous safety improvements have been implemented in motor
vehicles. Risk homeostasis theory predicts that drivers would drive
more dangerously so as to maintain their overall acceptable level of
risk. One way to do this is by driving faster. There is some evidence
that this has happened. Speed limits have been increased. While drivers
used to speed when the national speed limit was 55 mph, they still
speed today when interstate highway speed limits have been increased to
65 to 75 mph. However, there is a clearly decreasing trend in the
number of motor vehicle fatalities, especially when they are normalized
by the number of vehicle miles traveled.
What seems to have happened in the past is that safety improvements
have been partially, but not totally, offset by riskier driving
behavior (frequently by increases in driving speed). However,
substantial improvement in safety has remained, even after the changes
in driver behavior. True risk homeostasis did not occur, but we did see
behavioral adaptation as drivers partially compensated for the decrease
in risk.
NHTSA anticipates that similar changes in driver behavior may be
seen due to these NHTSA Guidelines. Some portion of the otherwise
expected improvement in safety and reduction in driver workload
associated with task performance may be used by drivers to perform more
secondary tasks. However, there should also be an improvement in
overall driving safety.
While NHTSA's primary focus is driving safety, other things are
also important to drivers. Drivers, like any other category of people,
will seek to have their personal needs met. Drivers are not forced to
perform additional secondary tasks just because they have a vehicle
designed for safe in-vehicle secondary task performance. Drivers
perform these additional secondary tasks to meet their own needs. Even
though some portion of the expected improvement in safety may be
negated by the performance of more secondary tasks, the overall quality
of life will be improved for drivers and other road users.
VI. Justification for Specific Portions of NHTSA Guidelines for
Reducing Driver Distraction During Interactions With In-Vehicle Systems
A. Intended Vehicle Types
These proposed NHTSA Guidelines are appropriate for all passenger
cars, multipurpose passenger vehicles, and trucks and buses with a GVWR
of not more than 10,000 pounds. These are what NHTSA has traditionally
called ``light vehicles.'' This category of vehicles has been the
primary focus of NHTSA's past driver distraction research.
Additionally, light vehicles have been a major platform for the push to
incorporate built-in advanced technology, entertainment, and
communications functions into vehicles. Focusing on this vehicle
category serves as a step towards ensuring that the increasing features
being offered in all vehicles do not produce an overwhelmingly
distracting in-vehicle environment for the driver that can degrade
safety. For these reasons, NHTSA has focused its distraction research
on light vehicles. While much of what NHTSA has learned about light
vehicle driver distraction undoubtedly applies to other vehicle types,
additional research would be needed to assess whether all aspects of
these NHTSA Guidelines are appropriate for application to those vehicle
types.
B. Existing Alliance Guidelines Provide a Starting Point
The NHTSA Guidelines derive in part from the document ``Statement
of Principles, Criteria, and Verification Procedures on Driver
Interactions with Advanced In-Vehicle Information and Communication
Systems including 2006 Updated Sections'' that was developed by the
Alliance of Automobile Manufacturer's Driver-Focus Working Group
(frequently referred to as the Alliance Guidelines).\61\ Portions of
the Alliance Guidelines have been carried over to the NHTSA Guidelines
without changes. When the NHTSA Guidelines differ from the Alliance
Guidelines, it is either due to recent research that has been performed
since the development
[[Page 11217]]
of the Alliance Guidelines or because NHTSA believes that the changes
made will increase the safety of the motoring public.
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\61\ Driver Focus-Telematics Working Group, ``Statement of
Principles, Criteria and Verification Procedures on Driver-
Interactions with Advanced In-Vehicle Information and Communication
Systems,'' June 26, 2006 version, Alliance of Automobile
Manufacturers, Washington, DC.
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A number of the Alliance Guideline principles are not included in
the NHTSA Guidelines. While NHTSA generally agrees with the excluded
principles, NHTSA thinks that these principles are not appropriate to
include in these NHTSA Guidelines.
The excluded principles, and their reasons for exclusion, are as
follows:
Principle 1.1: The system should be located and fitted
in accordance with relevant regulations, standards, and the vehicle
and component manufacturers' instructions for installing the systems
in vehicles.\62\
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\62\ P. 13, Driver Focus-Telematics Working Group, ``Statement
of Principles, Criteria and Verification Procedures on Driver-
Interactions with Advanced In-Vehicle Information and Communication
Systems,'' June 26, 2006 version, Alliance of Automobile
Manufacturers, Washington, DC.
NHTSA assumes that vehicle manufacturers will follow this principle
when deciding where to locate devices within their vehicles. However,
verification by NHTSA that devices meet this principle is difficult.
The Alliance Guidelines verification section for this principle does
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not offer much guidance; it merely states:
Design to conform and validate by appropriate means as may be
specified by relevant standards or regulations or manufacturer-
specific instruction.\63\
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\63\ Ibid, P. 14.
As discussed above, NHTSA intends to monitor whether vehicles meet
these NHTSA Guidelines to help determine their effectiveness and
sufficiency. Accordingly, the NHTSA Guidelines do not include
principles for which there is no reasonable method for NHTSA to assess
Guideline adherence. It is hard for NHTSA to do this, at least for some
devices, without having access to information known to the manufacturer
but not necessarily to NHTSA. For these reasons, we do not believe it
is feasible for NHTSA to develop the methods needed to monitor
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adherence to this principle.
Principle 1.5: Visual displays should be designed and
installed to reduce or minimize glare and reflections.\64\
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\64\ Ibid, P. 37.
Vehicle manufacturers report that they follow this principle when
installing when deciding where to locate devices within their vehicles.
Additionally, verification by NHTSA that devices meet this principle is
difficult. The Alliance Guidelines verification section for this
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principle again does not offer much guidance; it merely states:
Verification should be done by appropriate means (e.g.,
analysis, inspection, demonstration, or test).\65\
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\65\ Ibid, P. 37.
Furthermore, glare and reflections on device interfaces only
indirectly contribute to driver distraction (and thereby affect
safety). Finally, glare and reflection reduction and minimization is a
complex problem that is best left to the vehicle designer. For all of
these reasons, it does not seem feasible for NHTSA at this time to
develop the complicated methods needed to monitor adherence to this
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principle.
Principle 5.1: The system should have adequate
instructions for the driver covering proper use and safety-relevant
aspects of installation and maintenance.\66\
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\66\ Ibid, P. 79.
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Principle 5.2: Safety instructions should be correct
and simple.\67\
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\67\ Ibid.
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Principle 5.3: System instructions should be in a
language or form designed to be understood by drivers in accordance
with mandated or accepted regional practice.\68\
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\68\ Ibid.
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Principle 5.4: The instructions should distinguish
clearly between those aspects of the system that are intended for
use by the driver while driving, and those aspects (e.g. specific
functions, menus, etc) that are not intended to be used while
driving.\69\
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\69\ Ibid.
All four of these principles relate to the adequacy of the
instructions that are provided to the driver. NHTSA does not have an
objective means to determine instruction adequacy for a potentially
broad range of device instructions. Therefore, we have excluded these
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four principles from the NHTSA Guidelines.
Principle 5.5: Product information should make it clear
if special skills are required to use the system or if the product
is unsuitable for particular users. \70\
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\70\ Ibid.
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Principle 5.6: Representations of system use (e.g.
descriptions, photographs, and sketches) provided to the customer
with the system should neither create unrealistic expectations on
the part of potential users, nor encourage unsafe or illegal
use.\71\
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\71\ Ibid.
Both of these principles relate to the appropriateness of content
in information about the device provided to the driver by the vehicle
manufacturer. NHTSA does not believe that it is appropriate for NHTSA
to determine the appropriateness of content in information provided to
the driver by the vehicle manufacturer. Therefore, we have excluded
both of these principles from the NHTSA Guidelines.
C. International Harmonization and Voluntary Consensus Standards
NHTSA is aware of the fact that since vehicles designed in many
countries are sold in the United States and that vehicles designed in
the United States are sold in many countries, motor vehicle
manufacturers' desire internationally harmonized regulations.
Unfortunately, comprehensive, internationally-harmonized, driver
distraction prevention and reduction guidelines do not yet exist.
(Although the high degree of similarity between the Alliance and
European Guidelines is a good start towards international
harmonization, NHTSA would like to see these guidelines made more
stringent so as to better protect the safety of the motoring public.)
Where international and voluntary consensus standards exist that are
useful for portions of the NHTSA Guidelines, they have been carefully
considered and utilized when appropriate. Specifically, for performing
occlusion testing, NHTSA has used International Standards Organization
(ISO) International Standard 16673:2007, ''Road Vehicles--Ergonomic
Aspects of Transport Information and Control Systems--Occlusion Method
to Assess Visual Demand due to the use of In-Vehicle Systems.''
Additionally, NHTSA has used SAE Surface Vehicle Recommended Practice
J941-2010, ``Motor Vehicle Drivers' Eye Locations,'' published March
16, 2010, to determine the driver's eye point when determining the
downward viewing angle to device displays.
NHTSA hopes that, in the future, it will be possible to develop the
NHTSA Guidelines into an internationally harmonized practice.
The remainder of this section consists of a detailed discussion and
justification of major items in the NHTSA Guidelines.
D. Statement of General Responsibilities
New in-vehicle technologies are being developed at an extremely
rapid pace. NHTSA does not have the resources to evaluate the safety
implications of every new device before it is introduced into vehicles.
Such a practice would dramatically slow the rate of introduction of new
technology into vehicles. Finally, and most importantly, adopting such
a practice is unnecessary in light of the National Traffic and Motor
Vehicle Safety Act of 1966's \72\ requirement that each manufacturer
bears primary responsibility for products that they produce that are in
[[Page 11218]]
motor vehicles. A manufacturer that produces a vehicle or item of motor
vehicle equipment that either does not comply with the FMVSSs or
contains a defect creating an unreasonable risk to safety must recall
the vehicle or equipment and provide the owner a remedy. 49 U.S.C.
30118-30120.
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\72\ 80th Congress, Statute 718.
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Accordingly, a section has been included in the NHTSA Guidelines
emphasizing that, to protect the general welfare of the people of the
United States; manufacturers are responsible for refraining from
introducing new in-vehicle devices that create unreasonable risks to
the safety of the driving public.
E. Scope--Devices for Which the NHTSA Guidelines Are Appropriate
The NHTSA Guidelines are appropriate for all information,
navigation, communications, and entertainment systems integrated into
the vehicle by the vehicle manufacturer. Note that, unlike the Alliance
Guidelines, these NHTSA Guidelines are considered to be appropriate for
both conventional and advanced varieties of information, navigation,
communications, and entertainment systems.
The NHTSA Guidelines are not appropriate for collision warning or
vehicle control systems. These systems are intended to aid the driver
in controlling the vehicle and avoiding crashes and, therefore, are
justified in capturing the driver's attention. The purpose of collision
warning systems, in particular, is to alert the driver quickly to an
unsafe condition and motivate the driver to make control inputs in an
effort to avoid a crash. The idea of minimizing distraction stemming
from this type of system is in conflict with their purpose--providing
safety warnings to inattentive drivers.
In addition, other conventional controls and displays such as
heating-ventilation-air conditioning (HVAC), instrument panel gauges
and telltales, etc., are also out-of-scope for the NHTSA Guidelines.
This is because operating vehicle control systems and looking at the
related displays are part of the primary driving task, and are
therefore not considered a distraction. Furthermore, attempting to
include these devices in the scope of these NHTSA Guidelines could
result in conflicts with either current or possible future Federal
Motor Vehicle Safety Standards.
F. Definition of a Task
NHTSA tasked the Virginia Tech Transportation Institute (VTTI) to
examine the Alliance Guideline's existing definition of a task to
assess whether improvements to the definition could be made. In
addition to reviewing the Alliance Guidelines, VTTI interviewed nine
outside experts from academia, government, and industry about their
use, and possible improvements to, the Alliance Guideline's definition.
VTTI's interviews found that experts were generally satisfied with
the Alliance Guideline's definition of a task but believed that it
could use some clarifications. Based on their self-reporting, the
experts were generally using the Alliance Guideline's definition of a
task consistently except for differences as to the precise start and
end points of a task. These differences could affect whether a task
meets the acceptance criteria for assessing whether a secondary task
performed using an in-vehicle device may be suitable for performance
while driving, due to its minimal impact on driving performance and,
therefore, safety.
Additional details regarding this VTTI expert panel effort will be
summarized in a NHTSA report to be released in 2012.
One VTTI recommendation that has been adopted in the NHTSA
Guidelines is to emphasize that only tasks that can be reasonably
subjected to a test should be subjected to a test, i.e., do not test a
task that is unbounded in duration and do not test a task that has no
measurable magnitude or dose. Therefore, VTTI recommended that NHTSA
refer to tasks in its NHTSA Guidelines as Testable Tasks. These
Testable Tasks have well defined points at which the Start of Data
Collection and End of Data Collection occur, which should resolve the
differences seen between various experts on this issue of task start
and end points.
Finally, VTTI recommended that NHTSA provide additional explanatory
information and examples about Testable Task definitions. This
information will be provided in a forthcoming NHTSA Technical Report.
G. Definition of Lock Out
To achieve the purpose of the NHTSA Guidelines, tasks that that do
not meet the guideline criteria (or devices that are inherently
distracting such as full-motion video displays) should be disabled so
that they will not be accessible (i.e., be ``locked out'') to the
driver while ``driving'' a motor vehicle.
On October 1, 2009, President Obama issued an Executive Order,
``Federal Leadership on Reducing Text Messaging While Driving,'' \73\
that instructed Federal employees and contractors not to perform text
messaging while driving a United States Government owned vehicle, while
driving their personal vehicle on official, United States Government,
business, or while driving and using a United States Government owned
electronic device. The Executive Order defines driving as follows:
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\73\ Executive Order, ``Federal Leadership on Reducing Text
Messaging While Driving,'' October 1, 2009, retrieved from http://www.whitehouse.gov/the_press_office/Executive-Order-Federal-Leadership-on-Reducing-Text-Messaging-while-Driving/ on March 22,
2011.
``Driving'' means operating a motor vehicle on an active roadway
with the motor running, including while temporarily stationary
because of traffic, a traffic light or stop sign, or otherwise. It
does not include operating a motor vehicle with or without the motor
running when one has pulled over to the side of, or off, an active
roadway and has halted in a location where one can safely remain
stationary.\74\
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\74\ The U.S. Department of Transportation's Federal Motor
Carrier Safety Administration (FMCSA) and Pipeline and Hazardous
Materials Safety Administration (PHMSA) use a slightly different
definition of driving. Their definition limits driving to operating
a commercial motor vehicle on a highway. NHTSA is basing its
definition of driving upon the one contained in the Executive Order
because NHTSA is concerned with all vehicles operating on any type
of roadway.
NHTSA is proposing to make its definition of ``driving'' in the
context of these NHTSA Guidelines consistent with the Executive Order's
definition of ``driving.'' However, because these NHTSA Guidelines are
meant for vehicle manufacturers designing in-vehicle integrated
electronic device interfaces, the agency is proposing a definition that
is framed in terms of the status of the vehicle rather than the conduct
of the driver. Specifically, the NHTSA Guidelines recommend disabling
unreasonably distracting tasks and/or devices while driving. For the
NHTSA Guidelines, ``while driving'' is defined as any time the
vehicle's engine is turned on and its transmission is not in ``Park''
(for automatic transmission vehicles; for manual transmission vehicles
this changes to when the transmission is not in ``Neutral'' or the
parking brake is ``Off'').\75\
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\75\ Without the addition of expensive equipment vehicle
manufacturers cannot know when the driver has pulled over to the
side of, or off of, an active roadway and has halted in a location
where the vehicle can safely remain stationary. For automatic
transmission-equipped vehicles, the vehicle manufacturer can
determine the position of the gear shift (this information is
available on the Controller Area Network Bus (CANbus) for all modern
vehicles). So operationally, NHTSA is equating placing the vehicle
in ``park'' with ``the vehicle has halted in a location where the
vehicle can safely remain stationary.'' For manual transmission
vehicles, placing the vehicle in ``park'' is replaced by placing the
vehicle in ``neutral'' with the parking brake on. Again, these are
things that the vehicle manufacturer easily determine (available
from the CANbus) and do not add extra cost.
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[[Page 11219]]
H. Per Se Lock Outs
The NHTSA Guidelines contain a recommended list of ``per se'' lock
outs for in-vehicle devices tasks that are considered unsafe for
performance by the driver while driving. Per se lock outs are ones
based on either public policy or law. They are meant for in-vehicle
device tasks that are either obviously inappropriate for performance by
a vehicle driver while driving or ones (such as photographic or
graphical moving or still images not related to driving) for which the
task-based test paradigm used to determine the acceptability of a task
for performance while driving will not work due to the task being
unbounded in some aspect.
After much consideration, NHTSA has decided to propose the
following list of tasks considered to be suitable for lock out on a per
se basis:
Displaying photographic or graphical moving visual images
not related to driving. This would include things such as video phone
calls and other forms of video communication, as well as pre-recorded
video footage, and television. Images considered to be related to
driving include information that is useful in monitoring vehicle
occupant status, maneuvering the vehicle, or assisting in route
planning. Short, scrolling lists under the control of the driver (e.g.,
navigation system destinations) should not be significantly distracting
provided the information is presented in accordance with these NHTSA
Guidelines. A visual image depicting blind zone areas around the
vehicle would be considered information related to the driving task.
Also, weather information that relates to the vicinity of the car,
intended route information (such as a closed exit), or emergency
information (such as the approach of an emergency response vehicle) are
all considered to be information related to driving.
Displaying photographic or graphical static visual images
not related to driving. This would include album art and personal
photos, among other things.
Automatically scrolling text.
Manual text entry (e.g., drafting text messages, keyboard-
based text entry). The driver should not input more than 6 button or
key presses during the performance of a task. This limit is based on an
assumed driver eyes-off-road time of 2.0 seconds per button or key
press and NHTSA's maximum permitted total eyes-off-road time for a task
of 12.0 seconds.
Reading more than 30 characters, not including punctuation
marks, of visually presented text (a number, no matter how many digits
it contains, and a units designation (e.g., mpg) each count as only one
character). This character limit is taken from the JAMA Guidelines and
is intended to prevent such tasks as reading text messages, reading
electronic books, and manual Internet browsing. As pointed out by
Transport Canada:
The JAMA Guidelines are currently the most demanding
recommendations set by the industry internationally.\76\
\76\ ``Strategies for Reducing Driver Distraction from In-
Vehicle Telematics Devices: A Discussion Document,'' prepared by the
Standards Research and Development Branch of the Road Safety and
Motor Vehicle Regulations Directorate of Transport Canada, TP 14133
E, April 2003.
NHTSA believes that all of these activities are either obviously
inappropriate for performance by a vehicle driver (e.g., manual text
entry while driving) or ones for which the task-based test paradigm
used to determine lock outs on a task-by-task basis will not work
(e.g., viewing video images not related to driving, viewing static
images not related to driving, and automatically scrolling text) or
both (e.g., reading more than 30 characters of visually presented
text).
Rearview images presented for the purpose of aiding a driver to
detect obstacles in the vehicle's path during a backing maneuver should
not be locked out when presented in accordance with the allowable
circumstances specified in FMVSS No. 111 since this information is
driving related and for the purposes of improving safety.
I. Steering Wheel-Mounted Control Restrictions
The NHTSA Guidelines recommend that all device functions accessed
via visual-manual interaction by the driver should be operable by
using, at most, one of the driver's hands in order to be considered
suitable for performance while driving.
For device controls located on the steering wheel, the Alliance
Guidelines state that no device tasks should require simultaneous
manual inputs from both hands, except in the following condition: one
of the two hands maintains only a single finger input (e.g., analogous
to pressing ``shift'' on a keyboard). After due consideration, NHTSA
has decided that it is not comfortable with this exception. NHTSA is
concerned that tasks that require the simultaneous use of both hands,
even one for which only a single finger input is required from one
hand, will result in an unsafe situation. Therefore, the NHTSA
Guidelines recommend against driver interfaces that utilize this
special case of two-handed control.
J. Maximum Downward Viewing Angle
The NHTSA Guidelines recommend that the each device's active
display area be located as close as practicable to the driver's forward
line of sight. They include a specific recommendation for the maximum
downward viewing angle to the geometric center of each display.
To determine a display's downward viewing angle, a nominal driver
eye point must be selected. The NHTSA Guidelines recommend that the
nominal driver eye point be that contained in the March 2010 revision
of SAE Surface Vehicle Recommended Practice J941 ``Motor Vehicle
Drivers' Eye Locations.''
Each device's display(s) should be mounted in a position where the
downward viewing angle, measured at the geometric center of each active
display area, is less than at least one of the following two angles:
The 2D Maximum Downward Angle, or
The 3D Maximum Downward Angle.
The 2D Maximum Downward Angle is equal to:
30.00 degrees for a vehicle with the height of the nominal
driver eye point less than or equal to 1700 millimeters above the
ground.
Given by the following equation for nominal driver eye
point heights greater than 1700 millimeters above the ground:
[[Page 11220]]
[GRAPHIC] [TIFF OMITTED] TN24FE12.058
These recommendations for the maximum display downward viewing
angle are the same as those contained in the Alliance Guidelines except
that the nominal driver eye point is slightly different. The Alliance
Guidelines set the nominal driver eye point at the point specified in
the June 1997 revision of SAE Surface Vehicle Recommended Practice J941
``Motor Vehicle Drivers' Eye Locations.'' The Alliance Guidelines then
add 8.4 mm to the height of the driver's nominal eye point. The
driver's eye point location used by the NHTSA Guidelines is close to
that used by the Alliance Guidelines for typical seat back angles.
Therefore, this change is not expected to have any effects on the
stringency of the NHTSA Guidelines compared to the Alliance Guidelines.
The only reason for making this change is to avoid using an older
version of an SAE standard when a newer version has already been
adopted.
K. Tests Considered To Determine What Tasks Should Be Accessible While
Driving
During development of the NHTSA Guidelines for visual-manual
interfaces, the Agency considered seven test protocols and sets of
acceptance criteria for determining whether performance of a task while
driving is unreasonably distracting and should be locked out. This
section will discuss the origins of these seven test protocols and sets
of acceptance criteria. The subsequent section will discuss which of
these test protocols and criteria NHTSA prefers for use in determining
whether a task is unreasonably distracting.
Several of the candidate test protocols and sets of acceptance
criteria were taken from the Alliance Guidelines. The Alliance
Guidelines contain two alternatives for determining whether a task is
unreasonably distracting for drivers while driving. These alternatives
are discussed under Principle 2.1 of the Alliance Guidelines:
Systems with visual displays should be designed such that the
driver can complete the desired task with sequential glances that
are brief enough not to adversely affect driving.\77\
---------------------------------------------------------------------------
\77\ Driver Focus-Telematics Working Group, ``Statement of
Principles, Criteria and Verification Procedures on Driver-
Interactions With Advanced In-Vehicle Information and Communication
Systems,'' June 26, 2006 version, Alliance of Automobile
Manufacturers, Washington, DC, P. 38.
---------------------------------------------------------------------------
The Alliance Guideline's Alternative A reads:
A visual or visual-manual task intended for use by a driver
while the vehicle is in motion should be designed to the following
criteria:
A1. Single glance durations generally should not exceed 2
seconds; and
A2. Task completion should require no more than 20 seconds of
total glance time to display(s) and controls.\78\
---------------------------------------------------------------------------
\78\ Ibid, P. 39.
The Alliance Guidelines include the following three verification
procedures for Alternative A:
1. Eye Tracker Measurement. An eye tracker is used to measure the
number and length of glances to the device while performing a task
while driving either in a driving simulator, on a test track, or on an
actual roadway using a standard driving scenario.
2. Video Recording of Test Participant's Eyes/Face. Post-testing,
video of the test participant's eyes and face is reviewed and the
number and length of glances to the device while performing a task
while driving either in a driving simulator, on a test track, or on an
actual roadway using a standard driving scenario is determined.
[[Page 11221]]
3. Occlusion Testing. Test participants perform the secondary task
(but not the driving task) while undergoing alternating periods of time
when they can and cannot see. The periods of time when they can and
cannot see are generated either by occlusion goggles or some other
means such as an opaque shutter that is placed and removed periodically
from in front of the test participants' eyes. When performing occlusion
testing, the Alliance Guidelines reduce the maximum permitted single
glance durations to 1.5 seconds (forced by the occlusion cycle time)
and the maximum permitted total glance time to 15 seconds. Note that
the Alliance Guidelines occlusion testing technique uses a different
occlusion cycle time (1.5 seconds open/1.0 second closed) than that
called for by ISO International Standard 16673:2007, ``Road Vehicles--
Ergonomic Aspects of Transport Information and Control Systems--
Occlusion Method To Assess Visual Demand due to the use of In-Vehicle
Systems'' (1.5 seconds open/1.5 seconds closed).
In developing these Guidelines, NHTSA considered the Alliance
Principle 2.1 Alternative A techniques for determining whether a task
is unreasonably distracting to be performed by drivers while driving.
For test participant and other road user safety reasons, NHTSA has
decided to recommend that NHTSA Guideline testing for the purposes of
determining whether a task is suitable for performance while driving
should not be performed on either test tracks or public roadways.
NHTSA's fear is that, if such testing were performed on either test
tracks or public roadways, it might be discovered that a task is
unreasonably distracting by having a crash occur. Therefore, the NHTSA
Guidelines suggest limiting testing to that performed in driving
simulators, vehicle mockups, or similar, non-dangerous, testing venues.
NHTSA considered three test protocols and sets of acceptance
criteria for determining whether a task is too distracting to be
performed by drivers while driving that were based on Alliance
Principle 2.1 Alternative A. For the purposes of this notice, Alliance
Alternative A Verification Option 1, Eye Tracker Measurement, and
Verification Option 2, Video Recording of Test Participant's Eyes/Face
were considered together by NHTSA as Option EGDS: Eye Glance Testing
Using a Driving Simulator. Alliance Alternative A Verification Option
3, Testing using Occlusion, was considered by NHTSA as Option OCC:
Occlusion Testing. Additionally, NHTSA considered a third verification
option that is a variant of the Alliance Alternative A techniques,
Option STEP: Step Counting.
The idea behind Option STEP: Step Counting is to first perform a
detailed task analysis of the task under consideration on the device
being studied. After the detailed task analysis has decomposed the task
into elemental components, a number of ``steps'' are assigned to each
elemental component. Tasks that require more than a set number of steps
are considered to be too distracting to be performed by drivers while
driving.
The Alliance Guideline's Alternative B reads:
Alternatively, the impact of a device-related visual or visual-
manual task on driving safety can be assessed directly by measuring
concurrent driving performance under dynamic conditions and relating
it to driving performance under specified reference conditions. The
influence of such a secondary task shall not be greater than that of
a scientifically-accepted reference task in terms of:
B1. Lateral position control: Number of lane exceedances
observed during secondary task execution should not be higher than
the number of lane exceedances observed while performing one or more
reference tasks (e.g., manual radio tuning) under standard test
conditions (e.g., same drivers, driving scenario) replicating
routine driving tasks; and
B2. Following headway: Car following headway variability
observed during secondary task execution should not be worse than
car following headway observed while performing one or more
reference tasks under standard test conditions (e.g., same drivers,
same driving scenario) replicating routine driving tasks. This
measure is influenced by speed changes of preceding traffic or lane
changes of other vehicles.\79\
---------------------------------------------------------------------------
\79\ Ibid, p. 39.
For Alliance Principle 2.1 Alternative B, the recommended Alliance
reference task is radio tuning. This task (which will be referred to as
manual radio tuning) does not use a preset button to switch to a
desired radio station. Manual radio tuning consists of first toggling
betweens bands (AM to FM or vice versa) and then using the tuning
controls to select a station at a specified frequency.
Alliance Principle 2.1 Alternative B consists of performing a task
while driving either in a driving simulator, on the test track, or on
an actual roadway using a standard driving scenario. However, for
previously discussed reasons of safety, the NHTSA Guidelines research
limit testing for this alternative to driving simulators.
NHTSA considered two test protocols and sets of acceptance criteria
for determining whether a task is too distracting to be performed by
drivers while driving that were based on Alliance Alternative B. These
were Option DS-BM: Driving Test Protocol with Benchmark and Option DS-
FC: Driving Test Protocol with Fixed Acceptance Criteria. Option DS-BM
is based on the test protocols used by Alliance member companies when
performing Alternative B testing and uses, as its name implies, radio
tuning as its reference task.
One concern with Alliance's implementation of the radio tuning
reference task is that it is insufficiently specific to prevent
designers from developing radios that are more difficult for drivers to
tune. While the Alliance has told NHTSA that they intended the
reference radio to be representative of a 1980's production radio, the
Guideline text lacks the detail needed to ensure a fixed-difficulty
reference task. As a result, some designers may interpret the Alliance
Guidelines to permit more complicated radios to be used, thereby
increasing the difficulty of the reference task and allowing more
complex secondary tasks to meet the benchmark acceptance criteria. To
better achieve the goal of a fixed-difficulty reference task, NHTSA
considered a similar option that instead uses fixed driving performance
values for lane exceedances and headway variability. This testing
option is called Option DS-FC: Driving Test Protocol with Fixed
Acceptance Criteria.
Over the past few years, NHTSA has worked independently on the
development of a test protocol and acceptance criteria for determining
whether a secondary task is too distracting for drivers to perform
while driving. This research is documented in a recently released NHTSA
technical report.\80\ The test protocol combines eye glance metrics
similar to those of Alliance Alternative A, driving performance
variability metrics similar to those of Alliance Alternative B, and
target detection metrics to attain a comprehensive protocol that NHTSA
believes is useable for both visual-manual and auditory-vocal driver
interfaces.
---------------------------------------------------------------------------
\80\ Ranney, T.A., Baldwin, G.H.S., Parmer, E., Domeyer, J.,
Martin, J., and Mazzae, E. N., ``Developing a Test to Measure
Distraction Potential of In-Vehicle Information System Tasks in
Production Vehicles,'' DOT HS 811 463, November 2011.
---------------------------------------------------------------------------
In developing this protocol, NHTSA considered two existing test
protocols and sets of acceptance criteria for determining whether a
task is too distracting to be performed by drivers while driving that
were based upon its
[[Page 11222]]
research. These were Option DFD-BM: Dynamic Following and Detection
Protocol with Benchmark and Option DFD-FC: Dynamic Following and
Detection Protocol with Fixed Acceptance Criteria. Option DFD-BM uses
route navigation system destination entry (entry of the full address
including house number, street name, and city name) as a reference
task. Unlike Option DS-BM, where the acceptance criteria are that the
appropriate metric values should not be worse than radio tuning, for
Option DFD-BM the acceptance criteria are that the appropriate metric
values should be better than those associated with the destination
entry reference task.
The use of a destination entry reference task gives NHTSA similar
concerns as were noted for the radio tuning reference task. If a very
detailed navigation system interface is not specified in the
guidelines, the opportunity may be left for designers to create route
navigation systems for which the destination entry task is more
difficult. The result would be a non-fixed reference task that could be
used to justify more complex secondary tasks as being suitable for
performance while driving. To alleviate this concern, NHTSA also
considered Option DFD-FC: Dynamic Following and Detection Protocol with
Fixed Acceptance Criteria. Option DFD-FC is very similar to Option DFD-
BM except that instead of using a reference task to determine
acceptance, under Option DFD-BM fixed values for the metrics would be
used.
Table 3 summarizes the seven test protocols and sets of acceptance
criteria for determining whether a task is unreasonably distracting and
should be locked out while driving.
Table 3--Summary of Distraction Test Protocols and Acceptance Criteria Considered by NHTSA
----------------------------------------------------------------------------------------------------------------
Option letter Test name Performance measures Acceptance criteria Testing venue
----------------------------------------------------------------------------------------------------------------
EGDS.................. Eye Glance Testing Duration of 85% of Driving Simulator.
Using a Driving individual eye individual glance
Simulator. glances away from durations less than
forward road view. 2.0 seconds.
Mean of
individual glance
durations less than
2.0 seconds.
Sum of
individual eye
glance durations
less than or equal
to 12.0.
Sum of
individual eye
glance durations
away from forward
road view.
OCC................... Occlusion Testing.... Sum of Sum of Occlusion.
shutter open times. shutter open times
less than 9.0
seconds.
STEP.................. Step Counting........ Number of Less than 6 Task Analysis.
steps required for steps required for
task. task.
DS-BM................. Driving Test Protocol Standard Performance Driving Simulator.
with Benchmark. deviation of headway. measures not
Lane greater than
exceedances. benchmark values.
DS-FC................. Driving Test Protocol Same as Performance Driving Simulator.
with Fixed Option DS-BM. measures not
Acceptance Criteria. greater than
specified values.
DFD-BM................ Dynamic Following and Duration of Option EGDS Driving Simulator.
Detection Protocol individual eye eye glance
with Benchmark. glances away from acceptance criteria
forward road view. plus.
Sum of Performance
individual eye measures less than
glance durations benchmark values..
away from forward
road view..
Standard
deviation of lane
position.
Car
following delay.
Percent of
visual targets
detected.
Visual
detection response
time.
DFD-FC................ Dynamic Following and Same as Option EGDS Driving Simulator.
Detection Protocol Option DFD-BM eye glance
with Fixed acceptance criteria
Acceptance Criteria. plus.
Performance
measures less than
specified values.
----------------------------------------------------------------------------------------------------------------
L. NHTSA's Preferred Tests for Determining What Tasks Should Be
Accessible While Driving
NHTSA has thoroughly evaluated all seven of the candidate test
protocols and acceptance criteria for determining what tasks should be
accessible while driving listed in Table 3. The evaluation criteria
used included:
Test protocol discriminatory capability,
Difficulty of performing test protocol, and
Repeatability of test protocol.
NHTSA is not, at this time, removing any of the test protocols and
acceptance criteria that are listed in Table 3 from consideration for
use as a task acceptability test protocol(s) in the NHTSA Guidelines.
However, the Agency is indicating that it prefers two of the Table 3
test protocols and that one, or both, of these test protocols are more
likely to be selected. Following due consideration of comments received
in response to this notice, NHTSA will select the test protocols and
acceptance criteria for determining what visual-manual tasks should be
accessible while driving.
NHTSA has decided that it prefers the following two test protocols
and their associated acceptance criteria:
Option EGDS: Eye Glance Testing Using a Driving Simulator,
and
Option OCC: Occlusion Testing.
The Agency's reasons for choosing these two options as its preferred
test protocols and acceptance criteria are
[[Page 11223]]
discussed in the remainder of this subsection.
Two of the test protocols and acceptance criteria that NHTSA
considered, Option DS-BM: Driving Test Protocol with Benchmark and
Option DFD-BM: Dynamic Following and Detection Protocol with Benchmark,
include benchmark tasks. For Option DS-BM, the benchmark task is manual
radio tuning while the benchmark task for Option DFD-BM is entering an
address into a route navigation system.
The goal of using a benchmark task is to increase the
discriminatory power of a test protocol by comparing the performance of
test participants performing a task using a device against that for the
benchmark task. Both theoretically, and in NHTSA's experimental
testing, the use of a benchmark task reduces the impact of individual
test participant differences on the outcome of testing.
However, NHTSA has decided that the drawbacks of using a benchmark
task outweigh the advantages. The main drawbacks regarding the use of a
benchmark task are:
The determination as to what tasks may be performed by the
driver while driving depends not just on the task and the device under
consideration but also on the design of the device with which the
reference task is performed. The level of detail of the benchmark task
specification will affect the repeatability of test results. For
example, if a reference task of manual radio tuning was specified with
minimal radio interface specifications, then performing a task with a
device might be deemed unsuitable for performance while driving in a
vehicle that had a very easy to tune radio but suitable for performance
while driving in a second vehicle that had a more difficult to tune
radio. Testing recently performed for NHTSA by VTTI has found large
vehicle-to-vehicle differences in driver performance during manual
radio tuning so NHTSA knows that this concern is real and not just
hypothetical.
Not all vehicles have a suitable device for performing the
benchmark task. While virtually all production vehicles have radios
suitable for performing the manual radio tuning task, the Alliance
Guidelines did consider it necessary to include specifications for
simulating a built-in radio to bound the difficulty of the benchmark
task. Many production vehicles do not have a built-in route navigation
system. Again, specifications could be developed for simulating a
built-in route navigation system. However, simulating the device used
for the reference task increases testing complexity and cost while
reducing the meaningfulness of a test.
Based upon its evaluation, NHTSA believes that two eye glance-
related test protocols and acceptance criteria, Option EGDS: Eye Glance
Testing Using a Driving Simulator, and Option OCC: Occlusion Testing,
are both acceptable methods for determining which tasks should have
lock outs during driving.
The eye glance-related test protocols have a number of advantages.
These include:
A clear relationship between eye glance-related metrics
and driving safety exists. A driver's vigilant monitoring of the road
and nearby vehicles is essential to safe driving.
A substantial research base exists that verifies the
correctness of the above statement and provides quantitative support
for it. Based on analyses of past naturalistic data, we know that
looking away from the forward roadway for up to 2.0 seconds has no
statistically significant effect on the risk of a crash or near-crash
event occurring. However, eyes-off-road times of greater than 2.0
seconds have been shown to increase risk at a statistically significant
level. The risk of a crash or near-crash event increases rapidly as
eyes-off-road time increases above 2.0 seconds.\81\
---------------------------------------------------------------------------
\81\ Klauer, S.G., Dingus, T.A., Neale, V.L., Sudweeks, J.D.,
and Ramsey, D.J., ``The Impact of Driver Inattention on Near-Crash/
Crash Risk: An Analysis Using the 100-Car Naturalistic Driving Study
Data,'' DOT HS 810 594, April 2006.
---------------------------------------------------------------------------
An obvious relationship between visual-manual distraction
and eye glance measures exists. Visual-manual distraction strongly
implies that the driver is looking away from the forward road scene.
Eyes-off-road time is measureable. While not easy to
measure, researchers have been working for more than 30 years to
develop better techniques for measuring driver eyes-off-road times. A
large amount of effort has focused on such topics as the best ways to
ensure coding reliability when reducing eye glance video and the
development of automated eye trackers.
Commercially available occlusion goggles allow occlusion
testing to be performed without having to develop new hardware.
ISO standards exist for both eye glance measurement (ISO
15007-1 and ISO 15007-2) and occlusion testing (ISO 16673). This allows
us to take advantage of years of test development effort by the
research community.
While both of these test protocols have some drawbacks, NHTSA
generally considers these issues to be relatively minor.
Option EGDS: Eye Glance Testing Using a Driving Simulator suffers
from two problems:
The need for a driving simulator in which to perform
testing. A driving simulator is an expensive piece of test equipment
that typically requires special, highly trained staff to operate
correctly. The driving simulator should be configured to model the
dynamics of the vehicle being tested. Option EGDS is not alone in
having this problem; Options DS-BM, DS-FC, DFD-BM, and DFD-FC also
require a driving simulator.
Difficulty in accurately measuring eye glance behavior
from data collected during testing. There are two main methods for
determining eye glance characteristics from test data: through the use
of an eye tracker and by manually extracting eye glance locations and
durations from video recorded data. There are substantial operational
problems associated with both of these methods. For example, using an
eye tracker requires extensive calibration for each test participant,
which substantially adds to the time and expense of testing. Manually
reducing video recorded data to obtain eye glance characteristics is
highly labor intensive, time consuming, and expensive. While both
methods can be used to determine the angle at which a participant's
head is aimed with respect to center, identifying the particular point
of gaze (i.e., where the eyes are pointed, or eye glance location) is
challenging. Both methods of measuring eye glance behavior are even
more difficult for test participants who wear eye glasses, such that
participants who require them to drive are at times avoided,
substantially reducing the test participant pool (in NHTSA's
experience, this is particularly a problem when trying to recruit older
test participants).
Option OCC: Occlusion Testing avoids both of the drawbacks that are
present for Option EGDS: Eye Glance Testing Using a Driving Simulator.
Testing does not have to be performed in a driving simulator so the
driving simulator related issues are avoided. The occlusion apparatus
constrains when driver eye glances to the task device occur, so the eye
glance analysis difficulties present for Option EGDS are not present
for Option OCC.
NHTSA's proposed occlusion testing uses a field factor of 75
percent to relate shutter open time during occlusion testing to eyes-
off-road time measured during driving simulator testing. The Alliance
Guidelines and ISO International Standard 16673:2007(E), ``Road
Vehicles--Ergonomic Aspects of Transport Information and Control
[[Page 11224]]
Systems--Occlusion Method to Assess Visual Demand due to the use of In-
Vehicle Systems'' also uses this 75 percent field factor. The JAMA
Guidelines, however, use a field factor of 93.75 percent.
The theoretical rationale of a field factor is that every time a
driver looks away from the forward roadway (for occlusion testing, each
such eye glance is assumed to be 2.0-seconds long), the first 0.50
seconds is spent transitioning the driver's eyes from the roadway to
the object being looked at (i.e., a saccade). As a result, only 1.5-
seconds of a 2.0-second eye glance are available for actually looking
at and manipulating the device interface. Therefore, occlusion testing
is performed in 1.5-second shutter open time periods each corresponding
to one 2.0-second eye glance focused away from the forward roadway.
NHTSA performed a small study to experimentally determine the most
appropriate field factor.\82\ NHTSA's testing produced a field factor
of 78 percent for occlusion testing that was quite close to the field
factor of 75 percent in the ISO Standard 16673. Since the NHTSA
Guidelines occlusion test procedure is based on the ISO Standard 16673,
the theoretical field factor of 75 percent is used instead of the
experimentally determined field factor of 78 percent throughout the
remainder of this document. Note that the use of the theoretical field
factor is slightly conservative in the sense that it results in shorter
viewing intervals; using the experimentally determined field factor
would increase the viewing intervals from 1.50 seconds to 1.56 seconds.
---------------------------------------------------------------------------
\82\ Ranney, T.A., Baldwin, G.H.S., Parmer, E., Domeyer, J.,
Martin, J., and Mazzae, E.N., ``Developing a Test to Measure
Distraction Potential of In-Vehicle Information System Tasks in
Production Vehicles,'' DOT HS 811 463, November 2011.
---------------------------------------------------------------------------
However, Option OCC has one major drawback of its own. Option OCC
does not really test for adherence to the criterion that single glance
durations generally should not exceed 2.0 seconds. The use of an
occlusion apparatus forcibly restricts single glance durations to be no
more than 1.5 seconds long (which, with the 75 percent field factor
being applied to occlusion testing, equates to a 2.0 second eye
glance). If a test participant can complete a task using the occlusion
protocol, it has been demonstrated that drivers can complete the task
with sub-2.0 second eye glance durations. However, just because drivers
can accomplish a task with sub-2.0 second eye glances does not mean
that they actually will limit themselves to sub-2.0 second eye glance
durations when not constrained by occlusion apparatus. Option OCC does
not include any mechanism for ensuring that, during actual driving,
drivers will limit themselves to sub-2.0 second eye glance durations
while performing a given task.
Option STEP: Step Counting has a major advantage over all of the
other test protocols and acceptance criteria considered by NHTSA in
that it does not require human testing to determine whether a task is
suitable for performing while driving. The task analysis that is
performed for this method should be quite objective since it is
generally quite clear how many button presses or other manual
operations have to be performed in order to perform a task. The
objectivity of Option STEP would be helpful if, at some future time,
NHTSA decided to convert its NHTSA Guidelines into a Federal Motor
Vehicle Safety Standard.
Since no human performance testing is actually performed, Option
STEP also avoids both of the drawbacks that are present for Option
EGDS: Eye Glance Testing Using a Driving Simulator.
While not having human performance testing gives Option STEP some
major advantages, it is also the source of this option's major
drawback. Option STEP is based on data using past and present vehicle
designs about the eyes-off-road time required for drivers to perform
common manual actions, such as button presses. However, there are no
guarantees that the eyes-off-road time required to perform these
actions will remain the same for future devices and in-vehicle tasks.
NHTSA does not want to determine that tasks performed on future devices
are safe to perform while driving without performing any human
performance testing.
Another issue with Option STEP is determining exactly what
constitutes a step in all situations. While it is fairly clear what a
step is for pressing buttons, it is not clear for driver operation of
such interface items as knobs or joysticks.
Based on recent NHTSA testing, the two test protocols and
acceptance criteria that NHTSA considered which were based on just
driving performance, Option DS-BM: Driving Test Protocol with Benchmark
and Option DS-FC: Driving Test Protocol with Fixed Acceptance Criteria,
both suffer from low statistical power when performed using an
economically reasonable number of test participants. When testing of a
task/device was performed using just 20 test participants, there were
almost no statistically significant differences in driver performance,
even between tasks that were found to be different by other testing
protocols. In order to obtain the power necessary to provide the
discriminatory capability needed to determine which tasks should
require lock outs during driving, many more (on the order of 100) test
participants would need to be tested. This would make this test
protocol impractically time consuming and expensive to perform for the
large number of tasks that will need to be screened.
One of the reasons for the low discriminatory capability of the
Options DS-BM and DS-FC test protocols and acceptance criteria was due
to their use of lane exceedances as a measure of test participant
performance. Lane exceedances have the advantage of being a measure of
driving performance that appears to generally relate directly to
safety.\83\ However, lane exceedances are low frequency events,
particularly during straight line driving. Secondary tasks can be
performed with no lane exceedances. The relative rarity of lane
exceedances means that a large amount of testing has to be performed to
obtain a statistically stable number of these events.
---------------------------------------------------------------------------
\83\ Research has indicated that one type of lane exceedance,
specifically those due to ``curve cutting,'' have no relationship to
safety.
---------------------------------------------------------------------------
One possible alternative to using lane exceedances as a measure of
test participant performance is to use the mean standard deviation of
lane position during task performance as a substitute measure of test
participant performance. This approach was used by the Dynamic
Following and Detection Test Protocol to increase the statistical power
of that test procedure.
The remaining two test protocols and acceptance criteria that NHTSA
considered, Option DFD-BM: Dynamic Following and Detection Protocol
with Benchmark and Option DFD-FC: Dynamic Following and Detection
Protocol with Fixed Acceptance Criteria, were both based on the Dynamic
Following and Detection (DFD) Test Protocol. This is a test protocol
that has been developed by NHTSA\84\ over the last few years in an
attempt to combine the Alliance Guidelines' test protocols and
acceptance criteria with the Peripheral Detection Task (PDT). This test
protocol is a driving simulator based test protocol. Unlike the other
test protocols evaluated, DFD results are based on a test participant
performing
[[Page 11225]]
the same task repeatedly for a 2.5-minute interval. The DFD also uses a
complex lead vehicle speed profile that the test participant is
supposed to follow as well as they can with a fixed headway. It has
acceptance criteria based upon eye glance characteristics, measures of
test participant driving performance, and test participant performance
in performing the PDT concurrently with other secondary tasks.
---------------------------------------------------------------------------
\84\ Ranney, T.A., Baldwin, G.H.S., Parmer, E., Domeyer, J.,
Martin, J., and Mazzae, E.N., ``Developing a Test to Measure
Distraction Potential of In-Vehicle Information System Tasks in
Production Vehicles,'' DOT HS 811 463, November 2011.
---------------------------------------------------------------------------
Testing performed by NHTSA\85\ has demonstrated that the DFD test
protocol generally works well for determining whether a task is overly
distracting and should be locked out while driving. Unfortunately,
adding additional measures of test participant performance and
additional acceptance criteria increase test procedure and data
analysis complexity. While this increased analysis complexity may well
be necessary when evaluating a device's auditory-vocal task
interactions, it appears to be unnecessary when evaluating visual-
manual device interfaces. A test protocol and acceptance criteria based
only on eye glance characteristics appears to be adequate for visual-
manual secondary tasks.
---------------------------------------------------------------------------
\85\ Ibid.
---------------------------------------------------------------------------
In summary, all of the candidate test protocols and acceptance
criteria that NHTSA evaluated have both advantages and drawbacks.
Therefore, NHTSA is not, at this time, removing any of the test
protocols and acceptance criteria from consideration for being the test
protocol(s) finally selected. However, NHTSA has concluded that the
following two test protocols and associated criteria might be best
suited for the visual-manual NHTSA Guidelines:
Option EGDS: Eye Glance Testing Using a Driving Simulator,
and
Option OCC: Occlusion Testing.
Therefore, a detailed discussion of the basis for the proposed
acceptance criteria will be given only for these two testing options.
M. Eye Glance Acceptance Criteria
The proposed acceptance criteria for Option EGDS: Eye Glance
Testing Using a Driving Simulator are:
For at least 21 of the 24 test participants, no more than
15 percent (rounded up) of the total number of eye glances away from
the forward road scene should have durations of greater than 2.0
seconds while performing the secondary task, and
For at least 21 of the 24 test participants, the mean
duration of all eye glances away from the forward road scene should be
less than 2.0 seconds while performing the secondary task, and
For at least 21 of the 24 test participants, the sum of
the durations of each individual participant's eye glances away from
the forward road scene should be less than, or equal to, 12.0 seconds
while performing the secondary task one time.
The rationale for the above acceptance criteria is discussed in the
remainder of this subsection. First, NHTSA's reasons for choosing
manual radio tuning as its reference task are explained. It is from the
manual radio tuning reference task that NHTSA's acceptance criteria
were developed. Next, this document will discuss the Alliance
Guidelines' task acceptance criteria. Then, recent NHTSA research on
driver distraction and performance during manual radio tuning is
presented. Finally, results from the recent NHTSA research on manual
radio tuning are used to develop acceptance criteria.
i. Selection of Manual Radio Tuning as the Reference Task
The above proposed acceptance criteria were developed based on the
idea of a ``reference'' task. A reference task strategy is used because
no general consensus exists as to the threshold at which an absolute
level of distraction due to a driver performing a task becomes
unacceptably high. However, methods for measuring distraction while
performing a secondary task have been developed. Since there is no
agreed upon absolute level at which distraction becomes unacceptably
high, a relative limit can be developed by comparing the distraction
level associated with a driver performing an ``acceptable'' reference
task with the distraction level associated with a driver performing new
tasks.
A reference task should be a commonly performed task that is
societally acceptable for drivers to perform while driving. The idea is
that any task that is more distracting than the selected reference task
should be locked out while driving. Tasks that create less distraction
than the selected reference task are suitable for the driver to perform
while the vehicle is in motion.
NHTSA has chosen traditional, manual radio tuning as its
recommended reference task. Manual radio tuning consists of first \86\
toggling betweens frequency bands (AM to FM or vice versa) and then
using the tuning controls (e.g., rotary knob or continuously-held push
button) to select a station at a specified frequency. The prescribed
manual radio tuning task does not use a preset button to tune to a
desired radio station, which would be considered ``automatic'' radio
tuning.
---------------------------------------------------------------------------
\86\ In some cases, the first step is to switch to the radio
function, or powering on the device.
---------------------------------------------------------------------------
The Alliance Guidelines also use manual radio tuning as their
reference task. The Alliance's rationale \87\ for radio tuning as the
reference task is that traditional, manual radio tuning:
---------------------------------------------------------------------------
\87\ P. 40, Driver Focus-Telematics Working Group, ``Statement
of Principles, Criteria and Verification Procedures on Driver-
Interactions with Advanced In-Vehicle Information and Communication
Systems,'' June 26, 2006 version, Alliance of Automobile
Manufacturers, Washington, DC.
---------------------------------------------------------------------------
Is a distraction source that exists in the crash record
88 89 and so has established safety-relevance;
---------------------------------------------------------------------------
\88\ Wang, J.S., Knipling, R.R., and Goodman, M.J., ``The Role
of Driver Inattention in Crashes: New Statistics from the 1995
Crashworthiness Data System,'' 40th Annual proceedings, Association
for the Advancement of Automotive Medicine, Vancouver, British
Columbia, Canada, October 1996.
\89\ Singh, S., ``Distracted Driving and Driver, Roadway, and
Environmental Factors,'' DOT HS 811 380, September 2010.
---------------------------------------------------------------------------
Is a typical in-vehicle task that average drivers perform;
Involves use of an in-vehicle device that has been present
in motor vehicles for more than 80 years;
Is an in-vehicle device task that is typical in terms of
technological complexity, as well as in terms of impacts on driver
performance; and
Represents a plausible benchmark for driver distraction
potential beyond which new devices, functions, and features should not
go.
Vehicle radios/stereos have long been the most common original
equipment system with functionality not directly related to driving.
Driving a car with the radio on is an extremely common and widely
accepted scenario for Americans. Given this fact, it seems reasonable
to allow other tasks to be performed that require a similar degree of
driver interaction and to discourage tasks that are more distracting
than that level.
The specific reference task of manual radio tuning as defined by
the Alliance involves a defined traditional radio design and two input
steps: a single button press followed by a longer knob turn or button
hold. Many of the most basic and common in-vehicle control inputs a
driver may make require only a single, short duration input (e.g., turn
on headlights, activate turn signal, adjust temperature). Considering
this, manual radio tuning could be considered a worst case traditional
task.
In recent years, multi-function in-vehicle information systems such
as BMW's iDrive, Ford's SYNC, and several others have come available.
[[Page 11226]]
These multi-function systems provide the driver with more than just
music and can involve more complex inputs and/or more steps for the
driver to accomplish tasks. Comparing newer, more complex tasks to the
historical standard of worst-case non-driving tasks allows a
perspective on relative safety to be ascertained.
Past research efforts have identified crashes that are believed to
be caused by driver distraction due to vehicle radio use. A 1996 study
by Wang, Knipling, and Goodman \90\ analyzed data collected during 1995
by NASS-CDS. This analysis found that distraction due to driver radio,
cassette player, or CD player usage was present in 2.1 percent of all
crashes. There were also 2.6 percent of crashes for which the source of
distraction was unknown. Distributing crashes with an unknown source of
distraction proportionately among the other identified sources of
distraction, the percentage of crashes with distraction due to driver
radio, cassette player, or CD player usage increases to 2.6 percent.
---------------------------------------------------------------------------
\90\ Wang, J.S., Knipling, R.R., and Goodman, M.J., ``The Role
of Driver Inattention in Crashes: New Statistics from the 1995
Crashworthiness Data System,'' 40th Annual proceedings, Association
for the Advancement of Automotive Medicine, Vancouver, British
Columbia, Canada, October 1996.
---------------------------------------------------------------------------
A more recent study by Singh \91\ analyzed data from NHTSA's
National Motor Vehicle Crash Causation Survey (NMVCCS) to estimate the
incidence of crashes due to radios and CD players (cassette players in
vehicles are a disappearing technology). This analysis found that
distraction due to driver radio or CD player usage was present in 1.2
percent of all crashes.
---------------------------------------------------------------------------
\91\ P. 5, Singh, S., ``Distracted Driving and Driver, Roadway,
and Environmental Factors,'' DOT HS 811 380, September 2010.
---------------------------------------------------------------------------
NMVCCS is NHTSA's most recent, nationally representative, detailed
survey of the causes of light motor vehicle crashes (essentially an
updated version of the Indiana Tri-Level Study of the Causes of Traffic
Accidents \92\ that was conducted in the 1970s). For NMVCCS driver
(including distraction- and inattention-related information), vehicle,
and environment data were collected during a three-year period (January
2005 to December 2007). A total of 6,949 crashes met the specified
criteria for inclusion in NMVCCS. Due to specific requirements that
must be met by crashes for inclusion in NMVCCS, the NMVCCS data differs
from other crash databases such as NASS-CDS or NASS-GES.
---------------------------------------------------------------------------
\92\ Treat, J.R., Tumbas, N.S., McDonald, S.T., Shinar, D.,
Hume, R.D., Mayer, R.E., Stansifer, T.L., and Castellan, N.J.,
``Tri-Level Study of the Causes of Traffic Accidents: Final Report.
Executive Summary,'' DOT HS 805 099, May 1979.
---------------------------------------------------------------------------
Unfortunately, there is no way to determine with the data currently
available to NHTSA (i.e., Singh, \93\ Wang, Knipling, and Goodman \94\)
the fraction of the observed crashes due solely to radio usage (or due
to radio tuning specifically).
---------------------------------------------------------------------------
\93\ Singh, S., ``Distracted Driving and Driver, Roadway, and
Environmental Factors,'' DOT HS 811 380, September 2010.
\94\ Wang, J.S., Knipling, R.R., and Goodman, M.J., ``The Role
of Driver Inattention in Crashes: New Statistics from the 1995
Crashworthiness Data System,'' 40th Annual proceedings, Association
for the Advancement of Automotive Medicine, Vancouver, British
Columbia, Canada, October 1996.
---------------------------------------------------------------------------
Making the further assumption that fatality, injury, and property
damage only crashes all have the same percentage of distraction due to
driver radio, cassette player, or CD player usage gives the estimates
shown in Table 4.
Table 4--Estimated Number of Fatalities, Injuries, and Property Damage
Only Crashes in 2009 Due to Radio, Cassette, or CD Player Use
------------------------------------------------------------------------
Wang,
Knipling,
Singh and
estimate Goodman
estimate
------------------------------------------------------------------------
Percentage...................................... 1.2% 2.6%
Fatalities...................................... 406 869
Injuries........................................ 27,000 57,000
Property Damage Only............................ 66,000 142,000
------------------------------------------------------------------------
As stated above, NHTSA accepts the use of manual radio tuning as a
reference task for indicating a driver distraction magnitude beyond
which new devices, functions, features, and tasks should not exceed.
NHTSA agrees with the Alliance rationale for using manual radio tuning
as the reference task and considers it suitable for use as a standard
to which new in-vehicle tasks may be compared.
ii. The Alliance Guidelines Acceptance Criteria
The Alliance Guidelines include three verification options for
their Alternative A: Eye Tracker Measurement, Video Recording of Test
Participant's Eyes/Face, and Testing using Occlusion. Two of these
verification options, Eye Tracker Measurement and Video Recording of
Test Participant's Eyes/Face, require the determination of test
participant eye glances. Both of these verification options are covered
by NHTSA Option EGDS: Eye Glance Testing Using a Driving Simulator. The
third Alliance Guidelines verification option, Testing using Occlusion,
is covered by NHTSA Option OCC: Occlusion Testing. The development of
acceptance criteria for Option OCC is discussed in a subsequent
subsection.
As discussed above, the Alliance Guidelines use manual radio tuning
as their reference task. The Alliance Guidelines acceptance criteria
were developed based on this reference task.
The Alliance Guidelines acceptance criteria were based upon the
85th percentile of driver eye glance performance during manual radio
tuning. As the Alliance points out, the 85th percentile response
characteristics or capability are a common design standard in traffic
engineering. For example, according to the Federal Highway
Administration, all states and most localities use the 85th percentile
speed of free flowing traffic as a basic factor in establishing speed
limits.\95\
---------------------------------------------------------------------------
\95\ Institute of Transportation Engineers, ``Speed Zoning
Information,'' March 2004, retrieved in August 2011.
---------------------------------------------------------------------------
The eye glance acceptance criteria times that are in the Alliance
Guidelines are based on a 1987 study by Dingus \96\ and a 1988 study by
Rockwell.\97\ However, neither of these studies actually measured the
total eyes-off-road time associated with manual radio tuning. The
Rockwell study determined that approximately 85 percent of driver eye
glances away from the forward road scene had durations of 1.90 seconds
or less. This value of 1.90 seconds was rounded up by the Alliance to
get their 2.0-second criterion. The Dingus study determined that the
85th percentile for the number of driver eye glances away from the
forward road scene was 9.4 glances. The 9.4 glances value was rounded
up by the Alliance to get 10 glances. The Alliance then multiplied the
10 glances by 2.0 seconds per glance to determine their acceptance
criteria of 20.0 seconds of total glance time.\98\
---------------------------------------------------------------------------
\96\ Dingus, T.A., Attentional Demand Evaluation for an
Automobile Moving-Map Navigation System, unpublished doctoral
dissertation, Virginia Polytechnic Institute and State University,
Blacksburg, VA, 1987.
\97\ Rockwell, T.H., ``Spare Visual Capacity in Driving
Revisited: New Empirical Results for an Old Idea,'' in A. G. Gale et
al (editors), Vision in Vehicles II (pp. 317-324, Amsterdam:
Elsevier, 1988.
\98\ When performing this determination, the Alliance is
treating total glance time to the task as being the same as total
eyes-off-road time.
---------------------------------------------------------------------------
Based on these studies, the Alliance Guideline's Alternative A have
two acceptance criteria:
A1. Single glance durations generally should not exceed 2
seconds; and
[[Page 11227]]
A2. Task completion should require no more than 20 seconds of
total glance time to display(s) and controls.\99\
---------------------------------------------------------------------------
\99\ P. 39, Driver Focus-Telematics Working Group, ``Statement
of Principles, Criteria and Verification Procedures on Driver-
Interactions with Advanced In-Vehicle Information and Communication
Systems,'' June 26, 2006 version, Alliance of Automobile
Manufacturers, Washington, DC.
For both of the eye glance verification options, the Alliance
---------------------------------------------------------------------------
Guidelines operationalize the A1 and A2 acceptance criteria as follows:
A task will be considered to meet criterion A1 if the mean of
the average glance durations to perform a task is <= 2.0 sec for 85%
of the test sample. A task will be considered to meet criterion A2
if the mean total glance time to perform a task is <= 20 sec for 85%
of the sample of test participants.\100\
---------------------------------------------------------------------------
\100\ Ibid, P. 53.
NHTSA has a concern with these Alliance-developed acceptance
criteria because neither of the studies used as a basis for the
criteria actually measured the total eyes-off-road time associated with
manual radio tuning. Rather, the Alliance estimated it from the data
available in the Dingus and Rockwell studies. NHTSA's concern is with
the way in which the estimate was developed. If 85 percent of driver
eye glances away from the road last for less than 2.0 seconds, the
probability of 10 glances away from the road each having an average
length of 2.0 seconds or greater is very small. As a result, due to
rounding up of both the guideline-recommended length of driver eye
glances and the number of driver eye glances during manual radio
tuning, the Alliance total glance time criterion of 20.0 seconds is not
the 85th percentile value that the Alliance advocates, but instead a
value that approximates the 100th percentile value for manual radio
tuning.
iii. Recent NHTSA Research on Manual Radio Tuning
To obtain data about driver performance during manual radio tuning,
NHTSA has recently sponsored two experimental studies, one with testing
performed by NHTSA \101\ and one with testing performed by VTTI.
---------------------------------------------------------------------------
\101\ This study had multiple objectives; a better understanding
of manual radio tuning was just one of the objectives.
---------------------------------------------------------------------------
The NHTSA study \102\ tested 90 test participants performing 541
instances of manual radio tuning in a 2010 Toyota Prius (trim level V)
connected to a personal computer-based driving simulator. Driving the
simulator required the test participant to follow a lead vehicle moving
at a varying rate of speed. Table 5 presents summary data from the
first (of, typically, 6) manual radio tuning trial for all 90 test
participants. The last two columns represent the respective percentile
values from distributions of each subject's proportion of glances
longer than 1.5 and 2.0 seconds, respectively. The glance data were
computed from eye tracker data. (Comparable data reduced manually from
video footage was also collected for these trials; this found similar
glance durations.)
---------------------------------------------------------------------------
\102\ Ranney, T. A., Baldwin, G. H. S., Parmer, E., Martin, J.,
and Mazzae, E. N., ``Distraction Effects of Number and Text Entry
Using the Alliance of Automotive Manufacturers' Principle 2.1B
Verification Procedure,'' NHTSA Technical Report number TBD,
November 2011.
Table 5--Summary of Eye Glance Measures During the First Manual Radio Tuning Performed by Test Participants in a
2010 Toyota Prius on the NHTSA Driving Simulator (N = 90)
----------------------------------------------------------------------------------------------------------------
Total eyes-off- Number of Mean glance Percent of Percent of
Measure or percentile road time glances from duration glances > 1.5 glances > 2.0
(seconds) road (seconds) seconds seconds
----------------------------------------------------------------------------------------------------------------
Mean............................ 7.11 8.04 0.89 20 3
Median.......................... 7.25 8 0.85 0 0
85th............................ 10.50 12 1.14 25 0
95th............................ 12.70 15 1.39 40 29
100th........................... 16.86 16 2.11 80 50
----------------------------------------------------------------------------------------------------------------
Items of relevance from Table 5 for NHTSA's determination of its
acceptance criteria include:
The 85th percentile total eyes-off-road time (TEORT) based
on the first radio tuning trial by each test participant was 10.50
seconds.
None of the first radio tuning trials by test participants
had a TEORT that exceeded 20.00 seconds. The longest initial radio
tuning trial took 16.86 seconds.
The 85th percentile mean glance duration (MGD) was 1.14
seconds. For only 1 out of 90 test participants was the mean glance
duration greater than 2.00 seconds during their first trial.
The 85th percentile proportion of glances longer than 2.00
seconds was zero percent. This means that 85 percent of test
participants performed their first radio tuning trial with no glances
away from the forward roadway of duration longer than 2.0 seconds.
The NHTSA data collection protocol had test participants perform
the manual radio tuning task multiple times. Table 6 presents the same
data as Table 5 except that Table 6 is based on data from all of each
test participants' radio tuning trials. The first trial data were
analyzed separately, as presented above, since repeatedly performing
the same task was expected to speed up test participant performance of
the task.
Table 6--Summary of Eye Glance Measures During all Manual Radio Tuning Performed by Test Participants in a 2010
Toyota Prius on the NHTSA Driving Simulator (N = 541)
----------------------------------------------------------------------------------------------------------------
Total eyes-off- Number of Mean glance Percent of Percent of
Measure or percentile road time glances from duration glances > 1.5 glances > 2.0
(seconds) road (seconds) seconds seconds
----------------------------------------------------------------------------------------------------------------
Mean............................ 6.49 7.54 0.87 10 3
Median.......................... 6.38 7 0.84 0 0
85th............................ 9.61 11 1.15 25 0
95th............................ 11.97 14 1.39 40 22
100th........................... 20.50 21 2.11 80 50
----------------------------------------------------------------------------------------------------------------
[[Page 11228]]
Differences between the first trial and all trial data are minor.
What differences do exist suggest that radio tuning performance
improves slightly with repeated performance. However, it is important
to note that, while the large number of trials included in Table 6
provides more precision in the estimation of the various metrics, the
construction of this distribution is not formally suitable for use with
inferential statistics, which require independence among all of the
individual data items. In this collection, the use of multiple data
points from each subject is not consistent with the independence
requirement. Items of relevance from Table 6 for NHTSA's determination
of its acceptance criteria include:
The 85th percentile TEORT value for repeatedly performing
radio tuning was 9.61 seconds. (Reduced from the 10.50 seconds found
for the first trial data.)
Only 1 out of 541 total radio tuning trials had a TEORT
value greater than 20.00 seconds. The second longest TEORT value was
17.28 seconds.
The 85th percentile mean glance duration was 1.15 seconds.
For only 1 out of 541 trials was the mean glance duration greater than
2.00 seconds. The second longest mean glance duration was 1.85 seconds.
The 85th percentile proportion of glances longer than 2.00
seconds was zero percent. Although not shown in Table 6, the 90th
percentile value for this metric was 14 percent. This means that 90
percent of 541 radio tuning trials were accomplished with no more than
14 percent of the glances away from the forward roadway being longer
than 2.00 seconds.
The VTTI radio tuning study had two testing phases. During Phase I,
test participants drove each of four vehicles on the VTTI Smart Road
while following a lead vehicle traveling at a constant speed of 45 mph.
One vehicle was tested using both of its two available methods for
tuning the radio, resulting in a total of five test conditions. The
five vehicles/configuration conditions tested were:
1. 2005 Mercedes R350
2. 2006 Cadillac STS
3. 2006 Infiniti M35
4. 2010 Chevrolet Impala with rotary knob tuning
5. 2010 Chevrolet Impala with push button tuning
During Phase II, test participants drove each of two vehicles on
the VTTI Smart Road while following a lead vehicle traveling during one
lap at a constant speed of 45 mph and during another lap at a variable
speed.\103\ One vehicle was again tested using both of its two
available methods for manually tuning the radio resulting in a total of
three test conditions. The three vehicles/configuration conditions
tested were:
---------------------------------------------------------------------------
\103\ The variable speed profile of the lead vehicle for this
second lap was similar to the one used by NHTSA during testing on
their driving simulator. There were two differences. First, slowing
down the lead vehicle on the NHTSA driving simulator was
accomplished by having the driver remove his/her foot from the
throttle pedal and allowing the vehicle to coast. However, due to
the vertical profile of the VTTI Smart Road, when going downhill,
the lead vehicle driver had to brake to produce the desired speed
variation. The resulting brake lights are likely to have impacted
the test participants' following behavior/performance. Second, the
speed reduction profile was more step-wise than the one used in the
simulator, since the lead vehicle speed was controlled by a trained
driver, not by automated means.
---------------------------------------------------------------------------
1. 2010 Chevrolet Impala with rotary knob tuning
2. 2010 Chevrolet Impala with knob/button tuning
3. 2010 Toyota Prius (exact same vehicle as tested by NHTSA)
A total of 43 participants between the ages of 45 and 65 took part
in this study. This participant sample was comprised of two separate
participant groups, as data collection occurred in phases listed above.
Invalid data points were removed, yielding at least 20 participants
with complete data for each phase as well as some participants with
missing data.
Data were analyzed for the longest duration manual radio tuning
trial for each test participant for each vehicle/configuration. Data
for a total of 228 manual radio tuning trials were obtained and
analyzed.
Table 7 summarizes the eye glance measures that were calculated by
VTTI for the manual radio tuning trial of longest duration performed by
each test participant in each of the vehicles/tuning methods/lead
vehicle speed profile conditions. The values shown for Total Glance
Time to Task, Total Eyes-Off-Road Time, and Average Duration of
Individual Glances to Device are all 85th percentile values. The
Duration of Longest Glance to Device values are the longest glances to
the device that were made for that vehicle/tuning method/lead vehicle
speed profile for any of the radio tuning trials that were analyzed.
Table 7--85th Percentiles of Eye Glance Measures During Manual Radio Tuning Trials Performed by in Various
Vehicles Test Participants on the VTTI Smart Road (N = 228)
[Duration of Longest Glance to Device and Total Number of Data Points are not 85th percentiles]
----------------------------------------------------------------------------------------------------------------
Duration of
Vehicle, tuning method, and lead Total glance Total eyes-off- Mean glance longest glance Total number
vehicle speed profile time to task road time duration to device of data points
(sec.) (sec.) (sec.) (sec.) (--)
----------------------------------------------------------------------------------------------------------------
Cadillac STS--Knob Tuning-- 15.9 16.3 1.7 2.9 21
Constant Speed.................
Chevrolet Impala--Button Tuning-- 13.2 13.9 1.3 2.4 41
Constant Speed.................
Chevrolet Impala--Knob Tuning-- 7.8 8.1 1.4 2.2 41
Constant Speed.................
Chevrolet Impala--Button Tuning-- 11.5 12.3 1.2 2.3 20
Varied Speed...................
Chevrolet Impala--Knob Tuning-- 8.4 8.5 1.4 2.4 20
Varied Speed...................
Infiniti M35--Button Tuning-- 17.6 17.6 1.7 4.5 21
Constant Speed.................
Mercedes R350--Button Tuning-- 15.4 16.6 1.4 2.6 22
Constant Speed.................
Toyota Prius--Knob Tuning-- 10.3 11.1 1.4 2.4 21
Constant Speed.................
Toyota Prius--Knob Tuning-- 11.3 11.3 1.6 2.7 21
Varied Speed...................
All VTTI Data................... 11.6 11.8 1.5 2.5 228
----------------------------------------------------------------------------------------------------------------
[[Page 11229]]
Items of relevance from Table 7 for NHTSA's determination of its
acceptance criteria include:
The 85th percentile Total Glance Time to Task (TGT) for
performing manual radio tuning varied from 7.8 to 17.6 seconds
depending upon the vehicle, tuning method, and lead vehicle speed
profile. The 85th percentile TGT for all of the VTTI radio tuning data
was 11.6 seconds.
The 85th percentile Total Eyes-Off-Road Time (TEORT) for
performing manual radio tuning varied from 8.1 to 17.6 seconds
depending upon the vehicle, tuning method, and lead vehicle speed
profile. The 85th percentile TEORT for all of the VTTI radio tuning
data was 11.8 seconds.
The 85th percentile TEORT exceeded the 85th percentile TGT
times by 0.0 to 1.2 seconds with an average increase of 0.2 seconds.
The 85th percentile mean glance durations ranged from 1.2
to 1.7 seconds depending upon the vehicle, tuning method, and lead
vehicle speed profile.
iv. Development of NHTSA's Eye Glance Acceptance Criteria
NHTSA proposes to base the acceptance criteria in these Guidelines
on test participants' Eyes-Off-Road Time (EORT) during task
performance. This differs from existing Alliance and JAMA Guidelines
which assess task-related eye glance behavior based upon just those eye
glances to the device upon which the task is being performed.\104\
---------------------------------------------------------------------------
\104\ However, the Alliance Guidelines do not consistently
distinguish between test participant glances to the device being
tested and test participant eye glances away from the forward
roadway and, in places, appear to treat the two as interchangeable.
For example, in the discussion on p. 42 of the Alliance Guidelines
on the basis for the Alliances A2 acceptance criterion of 20
seconds, the phrase ``mean number of glances away from the road
scene'' is used. However, this is equated to test participant
glances to the device being tested to develop the 20 seconds
acceptance criterion.
---------------------------------------------------------------------------
NHTSA proposes to use EORT because we would like to use eye tracker
data to determine whether a task meets the eye glance criteria.
However, based upon the experiences of NHTSA, eye tracker data do not
have quite enough accuracy to reliably characterize whether eye glances
are focused toward the device upon which the task is being performed or
toward some other in-vehicle location.\105\ Eye tracker data do have
sufficient accuracy to accurately characterize test participant eye
glances focused away from the forward roadway.
---------------------------------------------------------------------------
\105\ Ranney, T.A., Baldwin, G.H.S., Vasko, S.M., and Mazzae,
E.N., ``Measuring Distraction Potential of Operating In-Vehicle
Devices,'' DOT HS 811 231, December 2009. NHTSA's eye glance
measurement technology has been upgraded since this report was
written but the specific eye position limitation noted in that
report continues to be a problem. The report ``Developing a Test to
Measure Distraction Potential of In-Vehicle Information System Tasks
in Production Vehicles'' by Ranney, T.A., Baldwin, G.H.S., Parmer,
E., Domeyer, J., Martin, J., and Mazzae, E. N., DOT HS 811 463,
November 2011, discusses NHTSA's most recent work to upgrade its eye
glance measurement technology.
---------------------------------------------------------------------------
Total EORT, or the cumulative duration of eye glances away from the
roadway during task performance, will always equal or exceed the Total
Glance Time to Task (TGT). For the VTTI testing, the 85th percentile of
this difference ranged from 0.0 to 1.2 seconds with an average increase
of 0.2 seconds. Therefore, basing the test acceptance criteria on TEORT
instead of TGT gives a slight increase in test stringency. However,
this is partially compensated for by NHTSA's use of a reference task to
determine overall test stringency.
NHTSA finds reasonable the Alliance's technique of using the 85th
percentile of driver eye glance measures while performing manual radio
tuning as a way to set acceptance criteria for testing to determine if
a task is unreasonably distracting. As the Alliance points out, the
85th percentile response characteristics or capability are a common
design standard in traffic engineering. Other existing guidelines do
not appear to use this reference task technique for determining
acceptance criteria.
Occlusion testing (discussed in greater detail in a subsequent
subsection) involves unoccluded vision durations of 1.5 seconds. Using
the previously discussed 75 percent field factor for occlusion testing
versus driving simulator eyes-off-road time, each 1.5-second unoccluded
period corresponds to 2.0 seconds of driving simulator eyes-off-road
time. Therefore, specified acceptance criteria involving eyes-off-road
time should be a multiple of 2.0 seconds.
The NHTSA and VTTI manual radio tuning testing summarized in Tables
5 through 7 found 85th percentile Mean Glance Durations (MGD) that
ranged from 1.1 to 1.7 seconds depending upon the vehicle, tuning
method, test venue, and lead vehicle speed profile. All of these values
round to 2.0 seconds (equivalent to a shutter open time of 1.5 seconds
during occlusion testing). Therefore one proposed NHTSA acceptance
criterion is that, for 85 percent of test participants, the mean
duration of all individual eye glances away from the forward road scene
should be less than 2.0 seconds while performing the secondary task.
Since NHTSA is proposing to test a sample of 24 subjects, for at least
21 of the 24 test participants (85 percent rounded up to the next whole
number of test participants), the mean of all eye glances away from the
forward road scene should be less than 2.0 seconds while performing the
secondary task. The proposed NHTSA mean eye glance duration criterion
then is:
For at least 21 of the 24 test participants, the mean
duration of all individual eye glances away from the forward road scene
should be less than 2.0 seconds while performing the secondary task.
The above acceptance criterion only constrains the mean of the eye
glance distribution. This is necessary but, NHTSA believes, not
sufficient. As pointed out by Horrey and Wickens:
In general, the unsafe conditions that are likely to produce a
motor vehicle crash reside not at the mean of a given distribution
(in other words, under typical conditions), but rather in the tails
of the distribution.\106\
---------------------------------------------------------------------------
\106\ Horrey, W.J., and Wickens, C.D., ``In-Vehicle Glance
Duration: Distributions, Tails, and Model of Crash Risk,''
Transportation Research Record, Journal of the Transportation
Research Board, No. 2018, Transportation Research Board of the
National Academies, pp. 22-28, Washington, DC, 2007.
To ensure safety, it is also necessary to have another acceptance
criterion that minimizes the above 2.0-seconds tail of the eye glance
distribution.
The acceptance criterion that NHTSA is proposing is designed to
directly limit the tail of the eye glance distribution. The proposed
eye glance distribution tail-limiting criterion, for 85 percent of test
participants, limits the percentage of their long (more than 2.0
seconds) eye glances away from the forward road scene while performing
the secondary task to no more than 15 percent of their total number of
eye glances away from the road.
Typically, the number of eye glances away the forward road scene
will be fairly low for any task, function, or feature that passes all
of the eye glance criteria. For example, if the average eye glance
duration is 1.5 seconds, a task can have a maximum of eight eye glances
away the forward road scene and meet the TEORT acceptance criterion
(discussed below). Therefore, the method used for rounding when
calculating the 15 percent of eye glances value is important.
NHTSA has tentatively decided that, for any task that requires at
least two \107\
[[Page 11230]]
eye glances away from the forward road scene, it should be acceptable
for at least one of these eye glances to exceed 2.0 seconds in duration
(of course, the other two acceptance criteria would also have to be
met). This can be accomplished by always rounding up when calculating
the guideline-recommended number of eye glances exceeding 2.0 seconds
in duration. The proposed NHTSA eye glance distribution tail limiting
criterion then is:
---------------------------------------------------------------------------
\107\ For a task that only requires one glance away from the
forward roadway, the mean glance duration criterion cannot be met
unless that glance is less than 2.0 seconds long. Therefore, the
proposed NHTSA eye glance distribution tail limiting criterion does
not need to have a special case for one glance tasks.
---------------------------------------------------------------------------
For at least 21 of the 24 test participants, no more than
15 percent (rounded up) of the total number of eye glances away from
the forward road scene should have durations of greater than 2.0
seconds while performing the secondary task.
The NHTSA and VTTI manual radio tuning testing summarized in Tables
5 through 7 found 85th percentile Total Eyes-Off-Road Times (TEORT)
values that ranged from 8.1 to 17.6 seconds depending upon the vehicle,
tuning method, test venue, trial, and lead vehicle speed profile.
NHTSA is proposing to perform driver eye glance measurement in
conjunction with a driving simulator protocol. For test participants
driving a 2010 Toyota Prius, NHTSA measured a 85th percentile TEORT
value of 10.5 seconds for the first manual radio tuning trial performed
and 9.6 seconds using data from all trials. It is not clear which of
these values best typifies normal driving since drivers are generally
familiar with their own vehicle's radio, and have tuned it many times
but generally not consecutively.
The VTTI data collected under conditions that most closely match
the NHTSA experimental conditions for testing are those collected on
VTTI's Smart Road using a 2010 Toyota Prius (VTTI tested the exact same
vehicle) following a lead vehicle with varying speed. The VTTI measured
85th percentile TEORT for this condition is 11.3 seconds (versus
NHTSA's 10.5 seconds). From this data, it appears that driving
simulator measured TEORT values may be slightly shorter than ones
measured while driving on the Smart Road. However, the two studies'
results are similar enough (considering the variability present in
testing of this sort) that it is reasonable to analyze both sets of
results together and determine an overall TEORT.
The 85th percentile from the consolidated NHTSA and VTTI manual
radio tuning data is 11.3 seconds. For compatibility with occlusion
testing, the maximum TEORT needs to be a multiple of 2.0 seconds. The
nearest multiple of 2.0 seconds to 11.3 seconds is 12.0 seconds.
Therefore NHTSA is proposing that the acceptance limit for TEORT for
Option EGDS: Eye Glance Testing Using a Driving Simulator be 12.0
seconds. In other words, tasks with an 85th percentile TEORT greater
than 12.0 seconds should not be accessible by the driver while
driving.\108\
---------------------------------------------------------------------------
\108\ For the purposes of these NHTSA Guidelines, ``while
driving'' is defined as any time the vehicle's engine is turned on
and its transmission is not in ``Park'' (for automatic transmission
vehicles; for manual transmission vehicles change this to the
transmission is not in ``Neutral'' with the parking brake engaged).
---------------------------------------------------------------------------
As has been mentioned, the Alliance Guidelines include a TEORT
acceptance limit of 20.0 seconds for Principle 2.1, Alternative A. The
JAMA Guidelines include a TEORT acceptance limit of 8.0 seconds.
NHTSA's value of 12.0 seconds is between these two values. NHTSA
prefers the 12.0 second limit to either of the other two guidelines'
values because the NHTSA value is based on more recent, more thorough,
research.
Since NHTSA is proposing to test a sample of 24 test participants,
for at least 21 of the 24 test participants (85 percent rounded up to
the next whole number of test participants), the TEORT should be less
than 12.0 seconds while performing the secondary task. The proposed
NHTSA total eye glance duration criterion then is:
For at least 21 of the 24 test participants, the sum of
the durations of each individual participant's eye glances away from
the forward road scene should be less than, or equal to, 12.0 seconds
while performing the secondary task one time.
N. Human Subject Selection for Guideline Testing
The NHTSA Guidelines suggest that the following test participant
sample composition criteria be used for testing performed to determine
whether a device should be locked out under the NHTSA Guidelines:
1. To ensure that in-vehicle device secondary tasks can be
performed by virtually the entire range of drivers without being
unreasonably distracting, the recommended age range for test
participants is 18 years and older. NHTSA research has shown that
restricting test participant age range can improve test
repeatability.\109\ The lower limit, 18 years of age, is due to
concerns about testing with minors. There is no upper limit, however,
organizations may set an upper age limit (such as 65 years old) for
their testing if they can easily find the needed test participants and
they have health concerns about testing with elderly test participants.
---------------------------------------------------------------------------
\109\ Ranney, T. A., Baldwin, G. H. S., Parmer, E., Martin, J.,
and Mazzae, E. N., ``Distraction Effects of Number and Text Entry
Using the Alliance of Automotive Manufacturers' Principle 2.1B
Verification Procedure,'' NHTSA Technical Report number TBD,
November 2011.
---------------------------------------------------------------------------
2. Continuing with NHTSA's goal of ensuring that in-vehicle device
tasks can be performed by the entire age range of drivers without being
unreasonably distracting, the NHTSA Guidelines recommend that out of
each group of 24 test participants used for testing, there should be
Six test participants 18 through 24 years old, inclusive,
and
Six test participants 25 through 39 years old, inclusive,
and
Six test participants 40 through 54 years old, inclusive,
and
Six test participants 55 or more years old.
This should ensure adequate representation by a broad age range of
test participants in each sample of subjects.
The above age ranges are partially based on the age distribution of
drivers in the United States. NHTSA is focusing on the age distribution
of drivers rather than the age distribution of drivers involved in
fatal crashes because:
The age distribution of drivers involved in fatal crashes
due to electronic device distraction is not necessarily the same as the
age distribution of drivers involved in all fatal crashes. NHTSA
currently does not know the age distribution of drivers involved in
fatal crashes due to electronic device distraction.
The age distribution of drivers involved in fatal crashes
due to electronic device distraction may change in the future as new
electronic devices are introduced into service.
Table 8 shows the percentage of United States drivers 18 years of
age and older in each of the four test participant age ranges.
---------------------------------------------------------------------------
\110\ http://www.fhwa.dot.gov/policyinformation/statistics/2009/dl20.cfm.
Table 8--Percent of United States Drivers 18 Years of Age and Older in
Each Age Range \110\
------------------------------------------------------------------------
Percent of United States
Age range drivers in age range
------------------------------------------------------------------------
18-24.................................. 11.4%
25-39.................................. 26.8%
40-54.................................. 29.7%
55 and older........................... 32.1%
------------------------------------------------------------------------
The 18 through 24 years old, inclusive, age range is
overrepresented in test samples relative to their numbers in the
general driving population. There are two reasons for this. First,
drivers in
[[Page 11231]]
the 18 through 24 age range have a higher rate of fatalities (per
100,000 drivers in that age range \111\ or per 100 million vehicle
miles traveled \112\) than do drivers that are 25 years of age or
older. Second, at least anecdotally, younger drivers are more frequent
user of electronic technology than are older drivers. Therefore, NHTSA
believes that this age range should be overrepresented in each test
participant sample.
---------------------------------------------------------------------------
\111\ National Highway Traffic Safety Administration, ``Traffic
Safety Facts 2008,'' NHTSA Technical Report DOT HS 811 170, 2010.
\112\ United States Government Accountability Office, ``Older
Driver Safety, Knowledge Sharing Should Help States Prepare for
Increase in Older Driver Population,'' Report to the Special
Committee on Aging of the United States Senate, GAO-07-413, April
2007.
---------------------------------------------------------------------------
The 55 years and older age range is underrepresented in test
samples relative to their numbers in the general driving population.
While NHTSA considers it important that advanced electronic device
tasks be tested using drivers in this age range, as mentioned above,
older drivers are less frequent users of electronic technology than are
younger drivers. Therefore, NHTSA is proposing to underweight this age
range with six test participants rather than the eight called for by
their numbers in the general driving population.
NHTSA solicits comments on the age range and distribution of test
participants that are recommended to be in each test participant
sample. We could use the age distribution of drivers involved in fatal
crashes as the primary factor in determining the age range and
distribution of test participants. This would result in somewhat
different age ranges and distributions than are listed above. Would
this be better for ensuring safety while driving and using electronic
devices?
3. NHTSA also wishes to ensure that drivers of both genders be able
to safely utilize in-vehicle devices. The United States driver
population is 49.7 percent male and 50.3 percent female. For the
relatively small test participant samples used for distraction testing,
this implies that test participant samples should be evenly divided
between men and women (i.e., each sample of 24 test participants should
be balanced in gender overall and within each age range).
4. Another of NHTSA's concerns relates to ensuring that test
participants are impartial with regard to the testing. To ensure
fairness, test participants should not have any direct interest,
financial or otherwise, in whether or not any of the devices being
tested meets or does not meet the acceptance criteria. Therefore, NHTSA
has added test participant impartiality criteria to its NHTSA
Guidelines.
While auto manufacturers may have multiple categories of employees
that are not involved in vehicle systems or component development,
NHTSA believes that automaker employees will tend to be generally more
knowledgeable about vehicles and their current features than the
average member of the public. With this additional knowledge of
vehicles and their latest features, the employees may perform better in
testing due to this exposure to the automotive industry. Therefore we
feel that this impartiality criterion is essential to ensure that test
results represent the performance of average U.S. drivers. We welcome
comments on any available strategies that automakers may implement to
ensure impartial test participation by employees.
O. Occlusion Test Protocol
NHTSA is proposing that its Option OCC: Occlusion Testing test
protocol be the same as that specified in ISO 16673:2007.\113\ ISO
16673:2007 specifies a viewing interval (shutter open time) of 1.5
seconds followed by an occlusion interval (shutter closed time) of 1.5
seconds. NHTSA has selected the use of the ISO test protocol for its
occlusion test protocol in the interests of promoting international
regulatory harmonization.
---------------------------------------------------------------------------
\113\ International Standard 16673:2007, ``Road Vehicles--
Ergonomic Aspects of Transport Information and Control Systems--
Occlusion Method to Assess Visual Demand due to the use of In-
Vehicle Systems.''
---------------------------------------------------------------------------
NHTSA's past occlusion testing was performed with a viewing
interval (shutter open time) of 1.5 seconds followed by an occlusion
interval (shutter closed time) of 1.0 second. NHTSA is performing a
study during the summer of 2011 to examine what effects, if any, this
change to the length of the occlusion interval has on the results of
occlusion testing. This study will also ensure that there are no
unforeseen difficulties in performing occlusion testing using the ISO
16673:2007 test protocol.
ISO 16673:2007 states that occlusion testing results need to be
corrected for system response delays that are greater than 1.5
seconds.\114\ However, since the NHTSA Guidelines specify that the
maximum device response time for a device input should not exceed 0.25
second, no correction is needed for occlusion testing performed under
the NHTSA Guidelines.
---------------------------------------------------------------------------
\114\ Ibid, P. 13.
---------------------------------------------------------------------------
NHTSA is proposing to set the maximum recommended total viewing
interval (total shutter open time) for a task to be accessible to the
driver while driving at 9.0 seconds. As was previously discussed, NHTSA
is proposing to set the maximum recommended total glance time (time
during which the driver's eyes are looking at the device upon which the
task is being performed) for a task to be accessible to the driver
while driving for Option EGDS: Eye Glance Testing Using a Driving
Simulator at 12.0 seconds of total eyes-off-road time. The acceptance
criteria for Option OCC: Occlusion Testing should be consistent with
the Option EGDS acceptance criteria. Applying the earlier explained
field factor of 75 percent to the 12.0 seconds of total eyes-off-road
time criteria that NHTSA is proposing for Option EGDS: Eye Glance
Testing Using a Driving Simulator gives a maximum permitted total
shutter open time for the NHTSA Guidelines Option OCC: Occlusion
Testing of 9.0 seconds.
P. Task Performance Errors During Testing
Reaching the desired end state of a secondary task is generally
only possible if the driver follows the correct steps to complete the
task and makes no mistakes. If the driver presses the wrong button or
inputs an incorrect character, a correction typically must be made in
order to reach the desired end state. An interface associated with
frequent input errors by the driver could reasonably be considered a
greater source of distraction than one for which task performance is
performed without errors. Therefore, for the purposes of these NHTSA
Guidelines only data from ``error-free'' test trials performed by test
participants should be used for determining whether a task is suitable
for performance while driving. Using only data from error-free test
trials improves testing repeatability.
The precise definition of an error during device testing is
difficult to develop. NHTSA proposes that an error would be considered
to have occurred during a test trial if the test participant has to
backtrack or delete already entered inputs. If the device can
accommodate an incorrect entry without requiring backtracking and extra
inputs beyond those necessary to reach the desired end state of the
task, then no error would be deemed to have occurred. For example,
suppose that a task on a device could be accomplished either by
pressing Button ``A'' or by pressing first Button ``B'' and then Button
``C.'' If a test participant were asked to perform this task, either
[[Page 11232]]
pressing Button ``A'' or pressing first Button ``B'' and then Button
``C'' would result in a valid trial. If however, the test participant
first pressed Button ``B,'' then reset the device, and then pressed
Button ``A'' an error would have occurred.
A record should be kept during testing as to whether one or more
errors occurred during each test trial. If errors occur during more
than 50 percent of test trials while testing a sample of test
participants, then that task is deemed an ``unreasonably difficult
task.'' Unreasonably difficult tasks are not recommended for
performance while driving and should be locked out. (Note that in order
to check NHTSA's acceptance criteria; it is necessary for 24 test
participants to successfully complete each task. This may require
testing more than 24 subjects.)
Q. Limited NHTSA Guidelines for Passenger Operated Equipment
The NHTSA Guidelines are appropriate primarily for devices that are
intended to be operated by the vehicle driver. For the sake of clarity,
NHTSA believes it necessary to make a few general statements about
passenger operated equipment.
The NHTSA Guidelines should be appropriate for any devices that the
driver can easily see and/or reach. For any in-vehicle device that is
within sight and reach of the driver (even if it is intended for use
solely by passengers), any task that has associated with its
performance an unacceptable level of distraction should be locked out
whenever the vehicle's engine is on and its transmission is not in
``Park'' (the vehicle's transmission in ``Neutral'' and parking brake
engaged for manual transmission vehicles).
The NHTSA Guidelines are not appropriate for any device that is
located fully behind the front seat of the vehicle. Similarly, the
NHTSA Guidelines are not appropriate for any front-seat device that
cannot reasonably be reached or seen by the driver.
VII. Implementation Considerations for the NHTSA Guidelines
A. Current Vehicles That Meet the NHTSA Guidelines
All members of the Alliance of Automobile Manufacturers have
committed themselves to producing vehicles that meet the Alliance
Guidelines. Five years have passed since the current version of the
Alliance Guidelines was issued and NHTSA expects that most current
vehicle models produced by Alliance members meet the Alliance
Guidelines. However, this is an expectation based on statements by the
Alliance's members and is not based on any NHTSA testing of recently
designed vehicle models.
Some automobile manufacturers that are not members of the Alliance
(e.g., Honda) have also committed to producing vehicles that meet the
Alliance Guidelines. However, this commitment was made in 2010;
therefore, most of their vehicles may not yet meet the Alliance
Guidelines' recommendations.
Given the many common elements and details between the NHTSA
Guidelines and the Alliance Guidelines, NHTSA believes that many in-
vehicle device tasks will either meet the recommendations of these
proposed NHTSA Guidelines or be close to doing so. The changes to
existing devices and/or vehicles that already meet the Alliance
Guidelines so as to make them meet the NHTSA Guidelines are expected to
be minor.
There is no time frame in which vehicle manufacturers are expected
to produce vehicles that meet these guidelines; meeting them is
strictly voluntary. However, NHTSA believes that manufacturers will
take the initiative to implement these guidelines in an effort to
improve safety. Manufacturers choosing to implement these guidelines
for existing vehicle models would likely make any necessary changes to
meet the guidelines when a vehicle model undergoes a major revision.
Typically, major revisions occur on about a five-year cycle for
passenger cars and less frequently for light trucks. NHTSA believes
that it would be feasible for manufacturers to make the necessary
changes implementing these guidelines for existing vehicle models that
undergo major revisions two or more years after the final issuance of
these guidelines. Likewise, NHTSA believes it would be feasible for new
vehicle models that come onto the market two or more years after the
final issuance of these guidelines to meet them.
B. Expected Effects of the NHTSA Guidelines
The main effects that NHTSA hopes to achieve through its NHTSA
Guidelines are better designed vehicles and integrated electronic
device interfaces, neither of which exceeds a reasonable level of
complexity for visual-manual secondary tasks. This will be accomplished
through multiple recommendations that will discourage device interfaces
that lack evidence of sound human factors principles in their designs.
One important recommendation recommends a limit for allowable total
eyes-off-road time for any one task. The NHTSA Guidelines would
discourage the introduction of egregiously distracting integrated
devices and non-driving tasks.
The NHTSA Guidelines recommend against designing in-vehicle
electronic systems that allow drivers to perform the following
activities while the vehicle is ``moving'': \115\
---------------------------------------------------------------------------
\115\ More specifically, the NHTSA Driver Distraction Guidelines
recommend disabling unreasonably distracting tasks/device unless
either (1) the vehicle's engine is not running, or (2) the vehicle's
transmission is in ``Park'' (automatic transmission vehicles) or the
vehicle's transmission is in ``Neutral'' and the parking brake is on
(manual transmission vehicles).
---------------------------------------------------------------------------
Visual-manual text messaging,
Visual-manual internet browsing,
Visual-manual social media browsing,
Visual-manual navigation system destination entry by
address, and
Visual-manual 10-digit phone dialing.
The NHTSA Guidelines are expected to have little impact on current
vehicle designs. For many current vehicles, the only integrated
electronic device that is not required for driving is the stereo system
(radio and CD player). Based on the research that was performed in
support of the development these NHTSA Guidelines, integrated stereo
systems would either already meet, or be easily modifiable to meet,
these NHTSA Guidelines. For integrated electronic devices other than
the stereo system, if such devices are incorporated into vehicles built
by Alliance member companies (as well as some non-Alliance vehicle
manufacturers), then they are already covered by that organization's
guidelines. Since the NHTSA Guidelines share many common elements with
the Alliance Guidelines, NHTSA believes that many devices/vehicles
would either meet the recommendations of its NHTSA Guidelines or be
close to doing so.
The NHTSA Guidelines are expected to have a larger impact on future
devices that are integrated into vehicles. For future integrated
original equipment devices, these NHTSA Guidelines are expected to
encourage simple visual-manual driver interfaces. They should also help
encourage the introduction of visual-manual non-driving tasks into the
vehicle that are not unreasonably distracting. Research by Ford Motor
Company \116\ and VTTI \117\ has shown
[[Page 11233]]
reductions in Total Eyes-Off-Road Time through the use of an auditory-
vocal driver-vehicle interface. As a result, NHTSA anticipates that
manufacturers may consider relying more on auditory-vocal interactions
for task performance in future device designs.
---------------------------------------------------------------------------
\116\ Shutko, J., Mayer, K., Laansoo, E., and Tijerina, L.,
``Driver Workload Effects of Cell Phone, Music Player, and Text
Messaging Tasks with the Ford SYNC Voice Interface versus Handheld
Visual-Manual Interfaces,'' Ford Motor Company, SAE Paper 2009-01-
0786, 2009.
\117\ Owens, J. M., McLaughlin, S. B., and Sudweeks, J., ``On-
Road Comparison of Driving Performance Measures When Using Handheld
and Voice-Control Interfaces for Mobile Phones and Portable Music
Players,'' Virginia Tech Transportation Institute, SAE Paper 2010-
0101036, April 2010.
---------------------------------------------------------------------------
The goal of the NHTSA Guidelines is not to prevent drivers from
performing activities that they wish to perform while driving; instead,
the goal is to improve vehicle safety. These NHTSA Guidelines identify
only a few, clearly safety-detrimental tasks as ones that should not be
accessible to a driver while operating a vehicle. NHTSA believes that,
with thoughtful interface engineering and appropriate application of
well designed auditory-vocal interfaces, drivers can continue to
perform most of the activities that they wish to perform while driving
and also have improved vehicle safety.
As previously stated, for many current vehicles, the only
integrated electronic device that is not required for driving is the
stereo system (radio and CD player). Based on the research that was
performed in support of the development the NHTSA Guidelines, many
current integrated stereo systems already meet the recommendations of
the NHTSA Guidelines. Other stereos would need to be modified so as to
reduce their Total Eyes-Off-Road Time (TEORT) to perform a manual radio
tuning to meet these NHTSA Guidelines. NHTSA does not know what
percentage of existing integrated stereo systems would need to be
redesigned. Nor do we know by how much the recommended stereo system
modifications should improve safety. However, the recommended changes
to existing integrated electronic devices would be expected to have a
small but positive impact on vehicle safety.
For integrated electronic devices other than the stereo system
(when they exist), if such devices are installed into vehicles built by
Alliance member companies (as well as some non-Alliance vehicle
manufacturers), then they are already covered by that organization's
guidelines. Since the NHTSA Guidelines share many common elements with
the Alliance Guidelines, many existing in-vehicle devices already
either meet the recommendations of the NHTSA Guidelines or would be
close to doing so. As a result, the NHTSA Guidelines are expected to
encourage only minimal revisions to existing, integrated, original
equipment devices. Therefore, the NHTSA Guidelines are expected to have
only small benefits for many current, integrated, in-vehicle advanced
electronic devices.
The NHTSA Guidelines could have a larger impact on future devices
that are integrated into vehicles. For future integrated original
equipment devices, these NHTSA Guidelines encourage simpler visual-
manual driver interfaces and task performance. They should also help
encourage the introduction of visual-manual non-driving tasks into the
vehicle that are not unreasonably distracting. As a result, NHTSA
anticipates that future device designs may rely more on auditory-vocal
interactions for task performance.
NHTSA does not know the safety effects of the NHTSA Guidelines
expected impact on future devices that are integrated into vehicles.
The problem is one of trying to estimate the safety benefits of unknown
future systems that meet the NHTSA Guidelines versus unknown future
systems that do not meet the NHTSA Guidelines and which will, due to
the influence of the NHTSA Guidelines, never be developed. For these
future systems, we do not know what they will do, their market share,
how often drivers will want to use them, or how much of a reduction in
TEORT would result from the NHTSA Guidelines. The numerous unknown
factors make it impossible to calculate meaningful estimates of
benefits. However, the resulting impact is expected to have a positive
impact on vehicle safety.
There are certain non-driving tasks that are obviously
inappropriate to perform while driving, such as the driver watching
television. Many other in-vehicle device tasks are more reasonable to
perform while driving but, when equipped with a visual-manual driver-
vehicle interface, would be considered unreasonably distracting by the
NHTSA Guidelines (and, therefore, a manufacturer choosing to apply the
NHTSA Guidelines would lock out those tasks. However, research by Ford
Motor Company \118\ and VTTI \119\ has shown that through the use of an
auditory-vocal driver-vehicle interface reductions in Total Eyes-Off-
Road Time can be attained. As a result, NHTSA believes that many of
these in-vehicle device tasks may be suitable for performance by the
driver while driving if performed via an auditory-vocal interface.
---------------------------------------------------------------------------
\118\ Shutko, J., Mayer, K., Laansoo, E., and Tijerina, L.,
``Driver Workload Effects of Cell Phone, Music Player, and Text
Messaging Tasks with the Ford SYNC Voice Interface versus Handheld
Visual-Manual Interfaces,'' Ford Motor Company, SAE Paper 2009-01-
0786, 2009.
\119\ Owens, J. M., McLaughlin, S. B., and Sudweeks, J., ``On-
Road Comparison of Driving Performance Measures When Using Handheld
and Voice-Control Interfaces for Mobile Phones and Portable Music
Players,'' Virginia Tech Transportation Institute, SAE Paper 2010-
0101036, April 2010.
---------------------------------------------------------------------------
Since most in-vehicle device tasks that are reasonable to perform
while driving will still be performable while meeting the NHTSA
Guidelines, NHTSA does not expect to affect the overall size of the in-
vehicle device market with its NHTSA Guidelines. The goal of the NHTSA
Guidelines is not to prevent drivers from performing reasonable tasks
while driving but to enable them to perform such tasks in a minimally-
distracting and safe manner.
C. NHTSA Monitoring To Determine Whether Vehicles Meet Guideline
Recommendations
Since our voluntary NHTSA Guidelines are not a Federal Motor
Vehicle Safety Standard, the degree to which in-vehicle devices meet
the specified criteria would not be assessed in the context of a formal
compliance program. However, NHTSA does intend to monitor whether
vehicles meet these NHTSA Guidelines to help determine their
effectiveness and sufficiency. NHTSA has not determined the nature of
the monitoring it might adopt. At a minimum, some spot checking of
vehicles is likely.
NHTSA seeks comment as to how best to monitor manufacturers'
voluntary implementation of the recommendations contained in the NHTSA
Guidelines. In particular, NHTSA requests input from commenters in
response to the following questions:
Are these NHTSA Guidelines reasonable and applicable for
meeting their intended goals?
How likely are vehicle manufacturers to adopt these NHTSA
Guidelines?
How likely are equipment suppliers to adopt these NHTSA
Guidelines?
How should NHTSA monitor adoption of these NHTSA
Guidelines in order to evaluate their effectiveness? How should it make
public the results of that monitoring?
NHTSA will announce its plan for monitoring the adoption of these
guidelines as part of the final notice for Phase 1 of the NHTSA
Guidelines.
VIII. Public Participation
How do I prepare and submit comments?
Your comments must be written and in English. To ensure that your
[[Page 11234]]
comments are correctly filed in the Docket, please include the docket
number of this document in your comments.
Your comments must not be more than 15 pages long. (See 49 CFR
553.21.) We established this limit to encourage you to write your
primary comments in a concise fashion. However, you may attach
necessary additional documents to your comments. There is no limit on
the length of the attachments.
Comments may be submitted to the docket electronically by logging
onto the Docket Management System Web site at http://www.regulations.gov. Follow the online instructions for submitting
comments.
You may also submit two copies of your comments, including the
attachments, to Docket Management at the address given above under
ADDRESSES.
Please note that pursuant to the Data Quality Act, in order for
substantive data to be relied upon and used by the agency, it must meet
the information quality standards set forth in the Office of Management
and Budget (OMB) and DOT Data Quality Act guidelines. Accordingly, we
encourage you to consult the guidelines in preparing your comments.
OMB's guidelines may be accessed at http://www.whitehouse.gov/omb/fedreg/reproducible.html. DOT's guidelines may be accessed at http://dms.dot.gov.
How can I be sure that my comments were received?
If you wish Docket Management to notify you upon its receipt of
your comments, enclose a self-addressed, stamped postcard in the
envelope containing your comments. Upon receiving your comments, Docket
Management will return the postcard by mail.
How do I submit confidential business information?
If you wish to submit any information under a claim of
confidentiality, you should submit three copies of your complete
submission, including the information you claim to be confidential
business information, to the Chief Counsel, NHTSA, at the address given
above under FOR FURTHER INFORMATION CONTACT. In addition, you should
submit two copies, from which you have deleted the claimed confidential
business information, to Docket Management at the address given above
under ADDRESSES. When you send a comment containing information claimed
to be confidential business information, you should include a cover
letter setting forth the information specified in our confidential
business information regulation. (See 49 CFR part 512.)
Will the agency consider late comments?
We will consider all comments received before the close of business
on the comment closing date indicated above under DATES. To the extent
possible, we will also consider comments that are received after that
date. If a comment is received too late for us to consider in
developing any final guidelines, we will consider that comment as an
informal suggestion for future guidelines.
How can I read the comments submitted by other people?
You may read the comments received by Docket Management at the
address given above under ADDRESSES. The hours of the Docket are
indicated above in the same location. You may also see the comments on
the Internet. To read the comments on the Internet, go to http://www.regulations.gov. Follow the online instructions for accessing the
dockets.
Please note that even after the comment closing date, we will
continue to file relevant information in the Docket as it becomes
available. Further, some people may submit late comments. Accordingly,
we recommend that you periodically check the Docket for new material.
IX. National Technology Transfer and Advancement Act
Under the National Technology Transfer and Advancement Act of 1995
(NTTAA) (Pub. L. 104-113), ``all Federal agencies and departments shall
use technical standards that are developed or adopted by voluntary
consensus standards bodies, using such technical standards as a means
to carry out policy objectives or activities determined by the agencies
and departments.'' Voluntary consensus standards are technical
standards (e.g., materials specifications, test methods, sampling
procedures, and business practices) that are developed or adopted by
voluntary consensus standards bodies, such as SAE. The NTTAA directs us
to provide Congress, through OMB, explanations when we decide not to
use available and applicable voluntary consensus standards.
The agency is not aware of any applicable voluntary consensus
standards that are appropriate for driver distraction stemming from
driver interactions with in-vehicle electronic devices. However,
industry-developed standards do exist. These standards were reviewed
and formed the basis for the NHTSA Guidelines outlined herein.
In view of all of the research and analysis discussed above, NHTSA
proposes the following voluntary NHTSA Guidelines for in-vehicle
devices.
X. Guidelines for Reducing Visual-Manual Driver Distraction During
Interactions With In-Vehicle Devices
I. Purpose. The purpose of these guidelines is to reduce the number
of motor vehicle crashes and the resulting deaths and injuries that
occur due to a driver being distracted from the primary driving task
while performing non-driving activities with an integrated-into-the-
vehicle electronic device. The guidelines are presented as an aid to
manufacturers in designing in-vehicle devices so as to avoid unsafe
driver distraction resulting from use of the devices. Manufacturers
that choose to adhere to these guidelines do so voluntarily and
compliance with them is not required.
I.1 Protection Against Unreasonable Risks to Safety. Due to the
rapid rate of development of electronic in-vehicle devices, the
National Highway Traffic Safety Administration (NHTSA) cannot possibly
evaluate the safety implications of every new device before it is
introduced into vehicles. However, because they have obligations to
recall and remedy vehicles or motor vehicle equipment they manufacture
that present an unreasonable risk to safety (45 U.S.C. 30118-20),
manufacturers bear such obligations with regard to integrated-into-the-
vehicle electronic devices that create unreasonable risks to the
driving public.
I.2 Driver Responsibilities. Drivers are still responsible for the
safety of people and property while driving and interacting with
integrated-into-the-vehicle electronic devices. Drivers retain the
primary responsibility for ensuring the safe operation of the vehicle
under all operating conditions.
II. Scope. These guidelines are appropriate for driver interfaces
of original equipment electronic devices for performing non-driving
activities that are built into a vehicle when it is manufactured. They
are not appropriate for driving controls, driver safety warning
systems, any other electronic device that is necessary to drive a motor
vehicle, or any other electronic device that has a driver interface
that is specified by a Federal Motor Vehicle Safety Standard. Table 1
contains a non-exhaustive list of the types of devices for which these
guidelines are appropriate.
[[Page 11235]]
Table 9--Types of Devices and Tasks for Which These Guidelines Are
Appropriate
------------------------------------------------------------------------
------------------------------------------------------------------------
Vehicle Information....................... Vehicle Information Center.
Emissions Controls.
Fuel Economy Information.
Navigation................................ Destination Entry.
Route Following.
Real-Time Traffic Advisory.
Trip Computer Information.
Communications............................ Caller Identification.
Incoming Call Management.
Initiating and Terminating
Telephone Calls.
Conference Telephoning.
Walkie-Talkie-Like Services.
Paging.
E-mail.
Reminders.
Instant Messaging.
Text Messaging.
Entertainment............................. AM Radio.
FM Radio.
Satellite Radio.
Pre-recorded Music Players,
All Formats.
Television.
Video Displays.
Advertising.
Address Book.
Internet Searching.
Internet Content.
News.
Directory Services.
------------------------------------------------------------------------
II.1 Guidelines Intended for Driver Interfaces. These guidelines
are appropriate primarily for driver interfaces of devices. They are
appropriate to a limited extent (see Section VII) for devices intended
for use by front seat passengers. They are not appropriate for devices
that are located solely rearwards of the front seat of a vehicle.
II.2 Only Driver Interfaces Covered. These guidelines are not
appropriate for any aspect of covered devices other than their driver
interfaces. Specifically, they do not cover a device's electrical
characteristics, material properties, or performance.
II.3 Aftermarket and Portable Devices Not Covered. These guidelines
are only appropriate for devices that are installed in a vehicle by the
original manufacturer of the vehicle.
II.4 Auditory-Vocal Interfaces Not Covered. These guidelines are
not appropriate for devices having solely auditory-vocal interfaces or
to the auditory-vocal portions of device's interfaces that contain both
auditory-vocal and visual-manual elements.
II.5 Intended Vehicle Types. These guidelines are appropriate for
all passenger cars, multipurpose passenger vehicles, and trucks and
buses with a GVWR of not more than 10,000 pounds.
III. Standards Included by Reference.
III.1 International Standards Organization Standards.
III.1.a ISO International Standard 16673:2007(E), ``Road Vehicles--
Ergonomic Aspects of Transport Information and Control Systems--
Occlusion Method to Assess Visual Demand due to the use of In-Vehicle
Systems.''
III.2 SAE Standards.
III.2.a SAE Surface Vehicle Recommended Practice J941 MAR 2010,
``Motor Vehicle Drivers' Eye Locations.''
IV. Definitions.
IV.1 General Definitions.
IV.1.a Active Display Area means the portion of a display that is
being used. It excludes unused display surface and any area containing
physically manipulatable controls.
IV.1.b Device means all components that a driver uses to perform
secondary tasks (i.e., tasks other than their primary task of driving);
whether stand-alone or integrated into another device.
IV.1.c Distraction means the diversion of a driver's attention from
activities critical for safe driving to a competing activity. This
diversion of attention may be due to non-driving related tasks or to
driving related tasks involving information presented in an inefficient
manner or demanding unnecessarily complex inputs by a driver. Driver
distraction is accompanied by an approximately proportional decrease in
driving performance that can vary based on driver characteristics and
roadway environment.
IV.1.d Downward Viewing Angle means the angle by which a driver has
to look down from the horizontal to directly look at a device's visual
display. Both three-dimensional downward viewing angle and a two-
dimensional approximation are used in these guidelines.
IV.1.e Driver's Field of View means the forward view directly
through the windshield, rear and side views through the other vehicle
windows, as well as the indirect side and rear view provided by the
vehicle mirror system.
IV.1.f Driving means any condition in which the vehicle's engine is
running unless the vehicle's transmission is in ``Park'' (automatic
transmission vehicles) or the vehicle's transmission is in ``Neutral''
and the parking brake is on (manual transmission vehicles).
IV.1.g Driving-Related Task means an activity performed by a driver
that is essential to the operation and safe control of the vehicle.
IV.1.h Function means an individual action that a device can
perform. A device may have one or more functions.
IV.1.j Glance means a single ocular fixation by a driver. When
using eye tracker equipment that cannot distinguish different nearby
locations of individual fixations, glance may also be used to refer to
multiple fixations to a single area that the eye tracker treats as one
ocular fixation.
IV.1.k Glance Duration means the time from the moment at which the
direction of gaze moves towards a target to the moment it moves away
from that target. It should be noted that glance duration includes the
transition time to a target and the dwell time on the target.
IV.1.l Interaction means a transaction between a driver and a
device. Interactions include control inputs (defined later) and data
inputs (information that a driver sends or receives from the device
that is not intended to control the device). Depending on the type of
task and the goal, interactions may be elementary or more complex. For
the visual-manual interfaces covered by this version of the NHTSA
Driver Distraction Guidelines (NHTSA Guidelines), interactions are
restricted to physical (manual or visual) actions.
IV.1.m Lock Out means the disabling of one or more functions or
features of a device unless either (1) the vehicle's engine is not
running, or (2) the vehicle's transmission is in ``Park'' (automatic
transmission vehicles) or the vehicle's transmission is in ``Neutral''
and the parking brake is on (manual transmission vehicles).
IV.1.n Nominal Driver Eye Point means the XC and
ZC coordinates of the Cyclopean eye point as given by
Equations (2) and (5), respectively, of SAE Surface Vehicle Recommended
Practice J941 MAR 2010, Motor Vehicle Drivers' Eye Locations.
IV.1.o Subtend means, in a geometrical sense, to be opposite to and
delimit (an angle or side).
IV.2 Task-Related Definitions.
IV.2.a Control Input means a transaction between a driver and a
device that is intended to affect the state of a device. Control inputs
may be initiated either by a driver or as a response to displayed
information initiated by a device itself. For the visual-manual
interfaces covered by this version of the NHTSA Guidelines, control
inputs are restricted to manual control actions.
[[Page 11236]]
IV.2.b Dependent Task means a task that cannot be initiated until
another task (referred to as the antecedent task) is first completed.
Their start state is thus dependent upon the end state of another,
antecedent, task.
An antecedent task that is followed by a dependent task can be
distinguished from a task that contains two subtasks by examining the
end states of both the antecedent task and the dependent task. For the
antecedent task-dependent task case, both tasks will end with the
achievement of a driver goal (i.e., two driver goals will be achieved,
one for the antecedent task and one for the dependent task). In
contrast, for a task composed of two subtasks, only one driver goal
will be achieved.
For example, after choosing a restaurant from a navigation system's
point-of-interest list (antecedent task), a driver is offered an
Internet function option of making a reservation at the restaurant
(dependent task). The dependent task of making a reservation can only
be initiated following the task of selecting a restaurant from within
the navigation system.
IV.2.c End of Data Collection means the time at which a test
participant tells the experimenter ``done'' (or, by some means,
indicates non-verbally the same thing). Test participant eye glances
and vehicle driving performance are not examined after the end of data
collection. If a test participant eye glance was in progress at the end
of data collection, only the portion of it before the end of data
collection is used. If the end of data collection occurs when the
device is at the desired end state for a testable task, then a test
participant has successfully completed the testable task.
IV.2.d End State for a Testable Task means the pre-defined device
state sought by a test participant to achieve the goal of that testable
task.
IV.2.e Error means that a test participant has made an incorrect
input when performing a requested task during a test trial. An error
has occurred if the test participant has to backtrack during
performance of the task or delete already entered inputs. If the device
can accommodate an incorrect entry without requiring backtracking and
extra inputs beyond those necessary to reach the desired end state of
the task, then no error is deemed to have occurred.
IV.2.f Error-Free Trial means a test trial in which no errors are
made by the test participant while completing the task.
IV.2.g Goal means a device state sought by a driver. Goal
achievement is defined as achieving a device state that meets the
driver's intended state, independent of the particular device being
executed or method of execution.
IV.2.h Secondary Task means, in these guidelines, any interaction a
driver has with an in-vehicle device that is not directly related to
the primary task of driving. These tasks may relate to driver comfort,
convenience, communications, entertainment, information gain, or
navigation.
IV.2.i Start of Data Collection means the time at which the
experimenter tells a test participant ``begin'' (or, by some means,
issues a non-verbal command indicating the same thing). Test
participant eye glances and vehicle driving performance are examined
only after the start of data collection. If a test participant eye
glance was in progress at the start of data collection, only the
portion of it after the start of data collection is used. The start of
data collection should occur when the device is at the start state for
a testable task.
IV.2.j Start State for a Testable Task means the pre-defined device
state from which testing of a testable task always begins. This is
frequently the ``home'' screen, default visual display state, or other
default driver interface state from which a driver initiates
performance of the testable task. For dependent tasks, the start state
would be the end state of the previous testable task.
For a testable task for which there is only one point (e.g.,
screen, visual prompt, step) screen from which the task can be
initiated, that point would correspond to the start state. For a
testable task which can be initiated from more than one point, one of
these options is selected as the start state. (The desire here is to
reduce the amount of testing needed to ensure adherence with these
guidelines. It is generally not necessary to test all possible
transitions into a testable task.)
IV.2.k Sub-goal means an intermediate state on the path to the goal
toward which a driver is working. It is often distinguishable from a
goal in two ways: (1) It is usually not a state at which a driver would
be satisfied stopping; and (2) it may vary in its characteristics and/
or ordering with other sub-goals across hardware/interface functions,
and thus is system dependent.
IV.2.l Subtask means a sub-sequence of control operations that is
part of a larger testable task sequence--and which leads to a sub-goal
that represents an intermediate state in the path to the larger goal
toward which a driver is working.
Subtasks should not be treated as separate dependent tasks. For
example, entering the street name as part of navigation destination
entry is not a separate task from entering the street number; rather,
these are subtasks of the same task.
IV.2.m Successful Task Completion means that a test participant has
performed a testable task without substantial deviations from the
correct sequence(s) of control inputs and achieved the desired end
state for a testable task.
IV.2.n Testable Task means a sequence of control operations
performed using a specific method leading to a goal toward which a
driver will normally persist until the goal is reached. A testable task
begins with the device at a previously defined start state and
proceeds, if the testable task is successfully completed, until the
device attains a previously defined end state.
A testable task is a secondary task that is performed using an
electronic device with a specified sequence of control operations
leading to a goal and a defined start state and end state. It is called
a testable task because it is a secondary task that can be tested for
adherence with these guidelines. While performing a testable task
during testing to determine if a task causes an unacceptable level of
distraction, data collection begins at start of data collection and
continues until end of data collection.
IV.3 Task-Related Explanatory Material.
IV.3.a Testable tasks should be completely defined prior to any
testing to determine whether they are suitable to perform while driving
under these guidelines.
IV.3.b For testable tasks that have a variety of possible inputs of
different lengths (e.g., city names for navigation systems), a typical
or average length input should be used. Precise averages need not be
used and there may be some variation in length from input-to-input. For
example, for the input of city names into a navigation system, a length
restriction of 9 through 12 letters might be used.
V. Device Interface Recommendations. Each device's driver interface
should meet the recommendations specified in Section V under the test
procedures specified in Section VI of these guidelines.
V.1 No Obstruction of View.
V.1.a No part of the physical device should, when mounted in the
manner intended by the manufacturer, obstruct a driver's field of view.
V.1.b No part of the physical device should, when mounted in the
manner intended by the manufacturer, obstruct a driver's view of any
vehicle controls or displays required for the driving task.
[[Page 11237]]
V.2 Easy to See and Reach. The mounting location for a device
should not be in a location that is difficult to see and/or reach (as
appropriate) while driving.
V.3 Maximum Display Downward Angle. Each device's display(s) should
be mounted in a position where the downward viewing angle, measured at
the geometric center of each active display area and determined as
explained in Subsection VI.1, is less than at least one of the
following two angles:
The 2D Maximum Downward Angle, or
The 3D Maximum Downward Angle.
When the 2D Maximum Downward Angle is used, the downward viewing
angle is determined as explained in Subsection VI.1.a. When the 3D
Maximum Downward Angle is used, the downward viewing angle is
determined as discussed in Subsection VI.1.b.
V.3.a The 2D Maximum Downward Angle is equal to 30.00 degrees for a
vehicle with the height above the ground of the nominal driver eye
point less than or equal to 1700 millimeters above the ground.
[GRAPHIC] [TIFF OMITTED] TN24FE12.059
V.3.e Visual displays that present information highly relevant to
the driving task and/or visually-intensive information should have
downward viewing angles that are as close as practicable to a driver's
forward line of sight. Visual displays that present information less
relevant to the driving task should have lower priority, when it comes
to locating them to minimize their downward viewing angles, than
displays that present information highly relevant to the driving task.
V.4 Lateral Display Position. Visual displays that present
information relevant to the driving task and/or visually-intensive
information should be laterally positioned as close as practicable to a
driver's forward line of sight.
V.5 Per se Lock Outs. The following in-vehicle device tasks should
always be locked out unless either (1) the vehicle's engine is not
running, or (2) the vehicle's transmission is in ``Park'' (automatic
transmission vehicles) or the vehicle's transmission is in ``Neutral''
and the parking brake is on (manual transmission vehicles):
V.5.a Displaying dynamic or static visual photographic or graphical
images not related to driving including, but not limited to:
V.5.a.i Video-based entertainment in view of the driver; and
V.5.a.ii Video-based communications including video phone calls and
other forms of video communication.
V.5.b Dynamic map displays. The display of either static or quasi-
static
[[Page 11238]]
maps (quasi-static maps are static maps that are updated frequently,
perhaps as often as every few seconds, but are not continuously moving)
for the purpose of providing driving directions is acceptable. Dynamic,
continuously-moving maps are not recommended.
V.5.c The display of rearview images for the purposes of aiding a
driver in performing a backing maneuver should not be locked out when
presented in accordance with the allowable circumstances specified in
FMVSS No. 111.
V.5.d Displaying static photographic or graphical images not
related to driving. However, displaying driving-related images
including icons, line drawings, and either static or quasi-static maps
is acceptable.
V.5.e Automatically scrolling text. The display of continuously
moving text is not recommended. The visual presentation of limited
amounts of static or quasi-static text is acceptable
V.5.f Manual text entry. A driver should not enter more than six
button or key presses during a single task. This would include drafting
text messages and keyboard-based text entry.
V.5.g Reading more than 30 characters (not counting punctuation
marks, counting each number, no matter how many digits it contains, as
one character, and counting units such as mph as just one character) of
visually presented text.
V.5.h The per se lock outs listed above are intended to
specifically prohibit a driver from performing the following while
driving:
Watching video footage,
Visual-manual text messaging,
Visual-manual internet browsing, and
Visual-manual social media browsing.
V.6 Task Lock Outs. Any secondary task that draws a driver's
attention from the primary driving task to the point where safety is
reduced, as determined by the test procedure contained in Subsection
VI.2, should be locked out unless either (1) the vehicle's engine is
not running, or (2) the vehicle's transmission is in ``Park''
(automatic transmission vehicles) or the vehicle's transmission is in
``Neutral'' and the parking brake is on (manual transmission vehicles).
V.7 Sound Level. Devices should not produce uncontrollable sound
levels liable to mask warnings from within the vehicle or outside or to
cause distraction or irritation.
V.8 Single-Handed Operation. Devices should allow a driver to leave
at least one hand on the vehicle's steering control. All tasks that
require manual control inputs (and can be done with the device while
the vehicle is in motion) should be executable by a driver in a way
that meets all of the following criteria:
V.8.a When manual device controls are placed in locations other
than on the steering control, no more than one hand should be required
for manual input to the device at any given time during driving.
V.8.b When device controls are located on the steering wheel and
both hands are on the steering wheel, no device tasks should require
simultaneous manual inputs from both hands.
V.8.c A driver's reach to the device's controls should allow one
hand to remain on the steering control at all times.
V.8.d Reach of the whole hand through steering wheel openings
should not be required for operation of any device controls.
V.9 Interruptability. Devices should not require uninterruptible
sequences of visual-manual interactions by a driver. A driver should be
able to resume an operator-interrupted sequence of visual-manual
interactions with a device at the point of interruption or at another
logical point in the sequence. This subsection, including all of its
following sub-parts, is not appropriate for device output of
dynamically changing data.
V.9.a Except as stated in Subsection V.9.e, no device-initiated
loss of partial driver input (either data or command inputs) should
occur automatically.
V.9.b Drivers may initiate commands that erase driver inputs.
V.9.c A visual display of previously-entered data or current device
state should be provided to remind a driver of where the task was left
off.
V.9.d If feasible, necessary, and appropriate, the device should
offer to aid a driver in finding the point to resume the input sequence
or in determining the next action to be taken. Possible aids include,
but are not limited to:
A visually displayed indication of where a driver left
off,
A visually displayed indication of input required to
complete the task, or
An indication to aid a driver in finding where to resume
the task.
V.9.e Devices may revert automatically to a previous or default
state without the necessity of further driver input after a device
defined time-out period, provided:
It is a low priority device state (one that does not
affect safety-related functions or way finding), and
The state being left can be reached again with low driver
effort. In this context, low driver effort is defined as either a
single driver input or not more than four presses of one button.
V.10 Response Time. A device's response (e.g., feedback,
confirmation) following driver input should be timely and clearly
perceptible. The maximum device response time to a device input should
not exceed 0.25 second. If device response time exceeds 0.25 second, a
clearly perceptible indication should be given indicating that the
device is responding.
V.11 Disablement. Devices providing dynamic (i.e., moving) non-
safety-related visual information should provide a means by which that
information is not seen by a driver. A device visually presenting
dynamic non-safety-related information should make the information not
seen by a driver through at least one of the following mechanisms:
Dimming the displayed information,
Turning off or blanking the displayed information,
Changing the state of the display so that the dynamic,
non-safety-related information cannot be seen by a driver while
driving, or
Positioning or moving the display so that the dynamic,
non-safety-related information cannot be seen while driving.
V.12 Lock Out Functions not Intended for Driving Use. Device
functions not intended to be used by a driver while driving should be
locked out (i.e., made inoperable unless either (1) the vehicle's
engine is not running, or (2) the vehicle's transmission is in ``Park''
(automatic transmission vehicles) or the vehicle's transmission is in
``Neutral'' and the parking brake is on (manual transmission vehicles).
V.13 Distinguish Devices not Intended for Driving Use. Devices
should clearly distinguish between those aspects of a device which are
intended for use by a driver while driving, and those aspects (e.g.,
specific functions, menus, etc.) that are not intended to be used while
driving.
V.14 Device Status. Information about current status, and any
detected malfunction, within the device that is likely to have an
adverse impact on safety should be presented to the driver.
VI. Recommended Test Procedures.
VI.1 Determination of Downward Viewing Angle. The downward viewing
angle of each display is determined in two ways, two dimensionally (the
2D Downward Viewing Angle; Subsection VI.1.a explains how to calculate)
and three dimensionally (the 3D Downward Viewing Angle; Subsection
VI.1.b discusses how to calculate). As
[[Page 11239]]
discussed in Subsection V.3, the downward viewing angle of each display
should be less than at least one of the following two angles:
The 2D Maximum Downward Angle, or
The 3D Maximum Downward Angle.
VI.1.a Determination of 2D Downward Viewing Angle. Create a fore-
and-aft plane (Plane FA) through the nominal driver eye point as
determined using the March 2010 revision of SAE Surface Vehicle
Recommended Practice J941 ``Motor Vehicle Drivers' Eye Locations.''
Project the position of the geometric center of a display for which
this angle is being determined laterally (while maintaining the same
fore-and aft and vertical coordinates) onto Plane FA. Generate two
lines in Plane FA, Line 1 and Line 2. Line 1 is a horizontal line
(i.e., maintaining the same vertical coordinate) going through the
nominal driver eye point. Line 2 goes through the nominal driver eye
point and the projected onto Plane FA geometric center of the display.
The downward viewing angle is the angle from Line 1 to Line 2.
VI.1.b Determination of 3D Downward Viewing Angle. Generate two
lines, Line 3 and Line 4. Line 3 is a horizontal line (i.e.,
maintaining the same vertical coordinate) going through the nominal
driver eye point, as determined using the March 2010 revision of SAE
Surface Vehicle Recommended Practice J941 ``Motor Vehicle Drivers' Eye
Locations,'' and a point vertically above or at the geometric center of
the display for which the angle is being determined. Line 4 goes
through the nominal driver eye point and the geometric center of the
display. The downward viewing angle is the angle from Line 3 to Line 4.
VI.2 Driving Simulator Recommendations. A driving simulator is used
for most of the proposed test options (Options C, F, G, H, and J,
below) for determining whether driver operation of a device while
performing a secondary task produces an unacceptable level of
distraction. The driving simulator used for distraction testing should
conform to the recommendations in the following subsections.
VI.2.a The driving simulator should be capable of testing using a
substantial portion (the entire area that can be reached by a driver)
of a full-size production vehicle cab. To set up this portion of a
vehicle cab for testing, no modifications should be made to the
dashboard or driver interface other than the addition of sensors to
determine steering wheel angle, brake pedal position, and throttle
pedal position, driver gaze location, headway (distance from the
subject vehicle to a lead vehicle if one is present), lane position,
and other desired data. The portion of the actual production vehicle
cab being used for testing should be easily changeable.
VI.2.b The driving simulator should use information collected by
the steering wheel angle, brake pedal position, and throttle pedal
position sensors, along with an appropriate vehicle dynamics
simulation, to predict vehicle orientation and position, angular and
linear velocities, and angular and linear accelerations.
VI.2.c The driving simulator should record the following data
channels at a minimum of 30 times per second: Steering wheel angle,
brake pedal position, throttle pedal position, vehicle orientation and
position, lane position, headway, vehicle speed, and vehicle lateral
and longitudinal accelerations. Each of the above listed channels
should either be calculated or measured with a sensor having an
accuracy of 2 percent of full scale or better. The
simulator should also have a means of determining the exact time of the
start and end of each secondary task that is performed.
VI.2.d For test paradigms that require the determination of eye
glance location, the driving simulator should determine them in one of
two ways: (1) Through the use of an eye tracker or (2) by collecting
full motion video of each test participant's face and, subsequent to
testing, a human data reducer determines from this video the direction
of a test participant's gaze at each instant in time.
VI.2.e The driving simulator should generate and display color (16
bit minimum color depth), computer generated imagery of the forward
road scene. This imagery should be projected onto a large area screen
in front of the vehicle. The portion of the projection screen on which
computer generated imagery is displayed should have an area of at least
208325 mm wide by at least 137225 mm tall. The
projection screen should be placed 4700125 mm in front of
the nominal driver eye point. The computer generated image should
contain at least 880 by 500 pixels and should be updated at least 30
times per second. The time lag to calculate the computer generated
imagery should not be more than 0.10 second.
VI.2.f For test paradigms that require the performance of a visual
detection task, the driving simulator should be capable of displaying
the target to be detected.
VI.2.f.i The target to be detected consists of a filled-in, red
circle. The target should be sized such that it subtends a visual angle
of 1.00.2 degrees. It may be displayed in any one of six
positions. These positions are: vertically--all approximately at
horizon height, and horizontally, with respect to the driver's head
position--91, 55, and 11 to the
left of straight ahead, and 101, 145, and
171 degrees to the right of straight ahead.
VI.2.f.ii The target is displayed in one position at a time. The
target is displayed in a particular, randomly-selected (via a pick from
a uniform probability distribution) position for 1.5 seconds or until
the participant responds. The target disappears if a test participant
responds (via the micro-switch discussed in Subsection VI.2.g) while it
is displayed or within 0.5 seconds after the target disappears. After
the target disappears, it is not displayed for a period of time that
varies randomly (via a pick from a uniform probability distribution)
from 3.0 to 5.0 seconds.
VI.2.g For test paradigms that require the performance of a visual
detection task, the driving simulator should be capable of recording
both the time at which each target begins to be displayed and the time
when a test participant responds.
VI.2.g.i Test participant responses are recorded based on the
wirelessly-transmitted output of a finger-mounted button micro-switch.
The button micro-switch should be mounted, if feasible, on the index
finger of a test participant's left hand in such a way that a test
participant can easily momentarily depress the micro-switch button when
he or she sees a target displayed.
VI.2.g.ii If it is not feasible to mount the button micro-switch on
the index finger of a test participant's left hand, mount the button
micro-switch in a convenient location such that it can be easily
pressed while driving.
VI.2.g.iii If a test participant starts pressing the micro-switch
button either while the target is displayed or within 0.5 seconds of
the completion of a target display, it is counted as a correct
response.
VI.2.g.iv For correct responses only, the Visual Detection Task
Response Time is equal to the time from the beginning of the target
display to the start of the micro-switch button press. This measure
cannot be calculated for incorrect responses.
VI.2.h The driving simulator should display the vehicle's speed to
a driver.
VI.2.j The driving simulator should be capable of simulating the
driving
[[Page 11240]]
scenarios described elsewhere in this document.
VI.3 Recommended Driving Simulator Scenario.
VI.3.a The road being simulated should:
VI.3.a.i Be undivided and four lanes wide,
VI.3.a.ii Have a solid double yellow line down the center,
VI.3.a.iii Have solid white lines on the outside edges,
VI.3.a.iv Have dashed white lines separating the two lanes that go
in each direction,
VI.3.a.v Be flat (no grade or road crown), and
VI.3.a.vi Have a speed limit of 55 mph.
VI.3.a.vii All test data collection is performed on straight road
segments. However, the road being simulated may, if desired, contain
occasional curved segments not in the area used for data collection.
VI.3.b The driving scenario should proceed as follows:
VI.3.b.i The subject vehicle begins motionless in the right lane of
the road.
VI.3.b.ii Test participant accelerates vehicle up to approximately
the speed limit.
VI.3.b.iii After approximately 360 meters of travel, the lead
vehicle, which is initially traveling at the speed limit, appears in
the travel lane in front of the subject vehicle at the desired
following distance.
VI.3.b.iv The subject vehicle then follows the lead vehicle for the
remainder of the test. This is defined as the car following portion of
the test.
VI.3.c All testing is performed while driving in the right lane of
the simulated road.
VI.3.d A test participant should begin performing secondary tasks
as soon as feasible after the start of the car following portion of the
test.
VI.3.e The speed of the lead vehicle, as a function of time, will
be specified for each test. Each of the test options, below, that use a
driving simulator (Options EGDS, DS-BM, DS-FC, DFD-BM, and DFD-FC)
state the lead vehicle speed as a function of time.
VI.3.f Once the subject vehicle is following the lead vehicle,
oncoming or adjacent lane traffic may begin to appear. The oncoming or
adjacent lane traffic that is present is specified for each of the test
options, below, that use a driving simulator (Options EGDS, DS-BM, DS-
FC, DFD-BM, and DFD-FC).
VI.4 Test Participant Recommendations.
VI.4.a General Criteria. Each test participant should meet the
following general criteria:
VI.4.a.i Be in good general health,
VI.4.a.ii Be an active driver with a valid driver's license,
VI.4.a.iii Drive a minimum of 7,000 miles per year,
VI.4.a.iv Be in the age range of 18 through 75 years of age,
inclusive,
VI.4.a.v Have experience using a wireless phone while driving,
VI.4.a.vi Be comfortable communicating via text messages, and
VI.4.a.vii Be unfamiliar with the device(s) being tested.
VI.4.b Mix of Ages in Each Test Participant Sample. Out of each
group of twenty-four test participants used for testing a particular
in-vehicle device task, there should be:
VI.4.b.i Six test participants 18 through 24 years old, inclusive,
VI.4.b.ii Six test participants 25 through 39 years old, inclusive,
VI.4.b.iii Six test participants 40 through 54 years old,
inclusive, and
VI.4.b.iv Six test participants 55 years old or older.
VI.4.c Even Mix of Genders in Each Test Participant Sample. Each
sample of twenty-four test participants used for testing a particular
in-vehicle device task, should contain:
VI.4.c.i Twelve men and twelve women overall, and
VI.4.c.ii An equal balance of men and women in each of the age
ranges 18 through 24 years old, 25 through 39 years old, 40 through 54
years old, and 55 years old and older.
VI.4.d Test Participant Impartiality. Test participants should be
impartial with regard to the testing. To ensure fairness, test
participants should not have any direct interest, financial or
otherwise, in whether or not any of the devices being tested meets or
does not meet the acceptance criteria. (While auto manufacturers may
have multiple categories of employees that are not involved in vehicle
systems or component development, NHTSA believes that automaker
employees will tend to be generally more knowledgeable about vehicles
and their current features than the average member of the public. With
this additional knowledge of vehicles and their latest features, the
employees may perform better in testing due to this exposure to the
automotive industry. Therefore, their use as test participants is
discouraged.)
VI.5 Test Participant Device Training Recommendations. Each test
participant should be given training as to how to operate the driving
simulator (if one is being used) and how to perform each of the desired
secondary tasks using the devices being evaluated.
VI.5.a Test instruction should be standardized and be presented
either orally or in writing. The display and controls of the interface
should be visible during instruction. An instruction may be repeated at
the request of a test participant.
VI.5.b Each test participant should have the vehicle's controls and
displays explained to them, and shown how to adjust the seat. Since the
vehicle's mirrors are not used during this testing, there is no need to
explain to test participants how to adjust them.
VI.5.c Each test participant should be given instructions on the
driving scenario that they are to perform. These should include:
VI.5.c.i That he or she should drive in the right lane, and
VI.5.c.ii That, as a driver, their primary responsibility is to
drive safely at all times.
VI.5.d Test participants should be told the speed at which they are
to drive prior to the beginning of car following. Test participants
should be told that, once in car following mode, they should follow the
lead vehicle at as close to a constant following distance as they can
manage.
VI.5.e Test participants should be given specific detailed
instructions and practice as to how to perform each secondary task of
interest on each device being studied before that particular driving
trial.
VI.5.f Test participants should practice each secondary task of
interest on each device being studied with the driving simulator with
the vehicle parked. This practice may also be performed in a separate
parked vehicle. A test participant should practice a task as many times
as needed until they think that they have become comfortable in
performing the task.
VI.6 Eye Glance Measurement. While driving the simulator and
performing the secondary task, the length of each test participants eye
glances away from the forward roadway should be recorded and
determined.
VI.6.a Eye glance durations should be determined in one of two
ways: (1) through the use of an eye tracker or (2) by collecting full
motion video of each test participant's face and, subsequent to
testing, a data reducer determines from this video the direction of a
test participant's gaze at each instant in time.
VI.6.b The length of an individual glance is determined as the time
associated with any eye glances away from the forward roadway. Due to
the driving scenario, eye glances to the side of the roadway or to the
vehicle's mirrors are expected to be minimal.
VI.6.c Ensuring eye tracker accuracy and repeatability. If an eye
tracker is
[[Page 11241]]
used, the testing organization should have a procedure for ensuring the
accuracy and repeatability of eye glance locations. This will require
collecting full motion video of a small sample of test participant's
faces and having data reducer determine from this video the direction
of a test participant's gaze at each instant in time. The testing
organization should also have a written procedure for setting up and
calibrating the eye tracker.
VI.6.d Ensuring Full Motion Video Reduction Accuracy and
Repeatability. If full motion video is used, the testing organization
should have a procedure for ensuring the accuracy and repeatability of
eye glance locations. This will involve having multiple data reducers
analyze the same, relatively short segment(s) of full motion video and
checking that they obtained the same glance locations. The testing
organization should also have a written procedure for instructing and
training data reducers as to how to determine eye glance locations. To
the extent possible, data reducers should not have an interest as to
whether a secondary task/device being tested meets the acceptance
criteria. Data reducers should not be closely involved with the
development of a device.
VI.7 Task Performance Errors During Testing.
VI.7.a ``Error-Free'' Performance During Testing. During testing,
only data from ``error-free'' test trials performed by test
participants should be used for determining whether a task is suitable
for performance while driving.
VI.7.b Unreasonably Difficult Tasks. A record should be kept during
testing as to whether one or more errors occurred during each test
trial. If errors occur during more than 50 percent of test trials while
testing a sample of 24 test participants, then that task is deemed an
``unreasonably difficult task'' for performance by a driver while
driving. Unreasonably difficult tasks are not recommended for
performance while driving and should be locked out.
VI.8 Determination That a Task Should Be Locked Out. Any task that
draws a driver's attention from the primary driving task to the point
where it does not comply with the Subsection VI.8 test procedures,
should either be located and oriented so that it cannot be seen by a
driver unless either (1) the vehicle's engine is not running, or (2)
the vehicle's transmission is in ``Park'' (automatic transmission
vehicles) or the vehicle's transmission is in ``Neutral'' and the
parking brake is on (manual transmission vehicles). The following table
summarizes the test procedures that are currently being considered to
determine which tasks should be locked out.
Table 10--Summary of Distraction Test Protocols and Acceptance Criteria Considered by NHTSA
----------------------------------------------------------------------------------------------------------------
Option letter Test name Performance measures Acceptance criteria Testing venue
----------------------------------------------------------------------------------------------------------------
EGDS.................. Eye Glance Testing Duration of 85% of Driving Simulator.
Using a Driving individual eye individual glance
Simulator. glances away from durations less than
forward road view. 2.0 seconds.
Sum of Mean of
individual eye individual glance
glance durations durations less than
away from forward 2.0 seconds.
road view. Sum of
individual eye
glance durations
less than or equal
to 12.0 seconds.
OCC................... Occlusion Testing.... Sum of Sum of Occlusion.
shutter open times. shutter open times
less than 9.0
seconds.
STEP.................. Step Counting........ Number of Less than 6 Task Analysis.
steps required for steps required for
task. task.
DS-BM................. Driving Test Protocol Standard Performance Driving Simulator.
with Benchmark. deviation of headway. measures not
Lane greater than
exceedances.. benchmark values.
DS-FC................. Driving Test Protocol Same as Performance Driving Simulator.
with Fixed Option DS-BM. measures not
Acceptance Criteria. greater than
specified values.
DFD-BM................ Dynamic Following and Duration of Option EGDS Driving Simulator.
Detection Protocol individual eye eye glance
with Benchmark. glances away from acceptance criteria
forward road view. plus.
Sum of Performance
individual eye measures less than
glance durations benchmark values.
away from forward
road view.
Standard
deviation of lane
position.
Car
following delay..
Percent of
visual targets
detected.
Visual
detection response
time.
DFD-FC................ Dynamic Following and Same as Option EGDS Driving Simulator.
Detection Protocol Option DFD-FC. eye glance
with Fixed acceptance criteria
Acceptance Criteria. plus.
Performance
measures less than
specified values.
----------------------------------------------------------------------------------------------------------------
Note: Manufacturers are free to use any testing protocol that they desire to ensure that their products adhere
to the NHTSA Guidelines.
Option EGDS: Eye Glance Testing Using a Driving Simulator
EGDS.1 Test Apparatus. Testing should be performed using a driving
simulator that meets the recommendations contained in Subsection VI.2
using the driving scenario described in Subsection VI.3.
EGDS.2 Lead Vehicle Speed. For this testing, the lead vehicle
should travel at a constant speed of 50 mph.
[[Page 11242]]
EGDS.3 Test Device. The device under investigation should be
operational and fitted to a vehicle or simulator buck.
EGDS.4 Test Participants.
EGDS.4.a Twenty-four test participants should be enrolled using the
procedures described in Subsection VI.4.
EGDS.4.b Test participants initially should be unfamiliar with the
device being tested. As part of the test protocol, they should be
trained in the use of the device(s) that are being tested using the
procedures described in Subsection VI.5.
EGDS.5 Test Instructions. Test instruction should be standardized
and be presented either in oral or written format. The display and
controls of the interface should be visible during instruction. An
instruction may be repeated at the request of a test participant.
EGDS.6 Number of Trials. Each test participant should drive the
driving scenario two times, one time not performing any secondary task
(the Familiarization Trial), and a second time performing the secondary
task being studied (the Data Trial).
EGDS.7 Eye Glance Determination. Eye glances are determined for
each test participant while performing each secondary task using the
techniques described in Subsection VI.6.
EGDS.8 Acceptance Criteria. A task should not be allowed to be
performed by drivers unless either (1) The vehicle's engine is not
running, or (2) the vehicle's transmission is in ``Park'' (automatic
transmission vehicles) or the vehicle's transmission is in ``Neutral''
and the parking brake is on (manual transmission vehicles), or (3) the
following three criteria are all met:
EGDS.8.a For any of the test participants, no more than fifteen
percent (rounded up) of the total number of eye glances away from the
forward road scene should last for more than 2.0 seconds while
performing the secondary task one time.
EGDS.8.b For at least twenty-one of the twenty-four test
participants, the mean of all eye glances away from the forward road
scene should be less than 2.0 seconds while performing the secondary
task one time.
EGDS.8.c For at least twenty-one of the twenty-four test
participants, the sum of the durations of each individual participant's
eye glances away from the forward road scene should be less than, or
equal to, 12.0 seconds while performing the secondary task one time.
EGDS.9 Multiple Trials. To improve testing efficiency, multiple
Data Trials should be allowed to be made by the same subject. Only one
Familiarization Trial needs to be performed, prior to any desired
number of Data Trials. Also, multiple secondary tasks can be tested,
one after another, during the same Data Trial.
Option OCC: Occlusion Testing
OCC.1 Test Apparatus. Intermittent viewing of a device interface
can be provided by various means such as commercially-available
occlusion goggles, a shutter in front of the interface, or some other
means.
OCC.1.a Either the occlusion goggles, the shutter in front of the
interface, or other means used should be transparent during the viewing
interval and opaque during the occlusion interval.
OCC.1.b During the occlusion interval, neither the interface
displays nor controls should be visible to a test participant.
OCC.1.c During the occlusion interval, operation of the device
controls by a test participant should be permitted.
OCC.1.d The switching process between the viewing interval and the
occlusion interval should occur in less than twenty (20) milliseconds
and vice versa.
OCC.1.e Either the occlusion goggles, the shutter in front of the
interface, or the other means of allowing/blocking a test participant's
vision should be electronically controlled.
OCC.1.f The illumination levels during the viewing and occlusion
intervals should be comparable so that dark/light adaptation of test
participants' eyes is not necessary during the procedure.
OCC.2 Test Device. The device under investigation should be
operational and fitted to a vehicle, simulator buck, or vehicle mock-up
in a design which duplicates the intended location of the interface in
the vehicle (i.e., the viewing angle and control placement
relationships should be maintained).
OCC.3 Test Participants.
OCC.3.a Twenty-four test participants should be enrolled using the
procedures described in Subsection VI.4.
OCC.3.b Test participants initially should be unfamiliar with the
device being tested. As part of the test protocol, they should be
trained in the use of the device(s) that are being tested using the
procedures described in Subsection VI.5.
OCC.4 Test Instructions. Test instruction should be standardized
and be presented either in oral or written format. The display and
controls of the interface should be visible during instruction. An
instruction may be repeated at the request of a test participant.
OCC.5 Test Procedure. Testing is performed in accordance with ISO
International Standard 16673:2007, ``Road Vehicles--Ergonomic Aspects
of Transport Information and Control Systems--Occlusion Method to
Assess Visual Demand due to the use of In-Vehicle Systems'' with the
exception that where the ISO Standard states that at least ten
participants are to be tested, the current guidelines have fixed this
number at twenty-four participants to be tested.
OCC.5.a The viewing interval (shutter open time) should be 1.5
seconds. This should be followed by a 1.5-second occlusion interval
(shutter closed time). The sequence of viewing interval followed by
occlusion interval should occur automatically without interruption
until the task is completed or the trial is terminated.
OCC.5.b The initial condition for testing is occlusion in which a
test participant cannot see the device interface.
OCC.5.c Task stimuli (e.g., addresses, phone numbers, etc.) are
provided to a test participant prior to the start of testing. When the
task stimuli are given to a test participant, the device should be
occluded (i.e., a test participant cannot see the device interface) and
it should remain occluded until after testing has begun.
OCC.5.d Testing starts when a test participant tells the
experimenter that he or she is ready to begin. The experimenter then
triggers the alternating sequence of viewing intervals followed by
occlusion intervals. A test participant starts performing the task at
the beginning of the first viewing interval.
OCC.5.e When a test participant has completed the task, he or she
tells the experimenter that the task has been completed. The
experimenter stops the shutter operation.
OCC.5.f There should be an automatic means of recording the number
of shutter open intervals required to complete the task.
OCC.6 Acceptance Criterion. A task should not be allowed to be
performed by drivers unless either (1) The vehicle's engine is not
running, or (2) the vehicle's transmission is in ``Park'' (automatic
transmission vehicles) or the vehicle's transmission is in ``Neutral''
and the parking brake is on (manual transmission vehicles), or (3) the
following criterion is met:
[[Page 11243]]
OCC.6.a For at least twenty-one of the twenty-four test
participants, the task was successfully completed during six or fewer
viewing intervals (i.e., a maximum of 9.0 seconds of shutter open
time).
OCC.7 Multiple Trials. To improve testing efficiency, multiple Data
Trials should be allowed to be made by the same subject. Only one
Familiarization Trial needs to be performed, prior to any desired
number of Data Trials. Also, multiple secondary tasks can be tested,
one after another, during the same Data Trial.
Option STEP: Step Counting
STEP.1 Task analysis. A task analysis is performed to decompose the
secondary task being performed into an ordered sequence of its
elemental components that a driver would perform in order to
successfully complete a task. The elemental components of a task would
include such driver actions as:
Pressing a single button,
Glancing at a device display,
Choosing an entry from a list,
Picking up an object, or
Putting down an object.
STEP.2 Step Assignment. Each elemental component that constitutes a
secondary task is assigned a number of steps as follows:
STEP.2.a Each time that a driver presses a single button, one step
is assigned except that if a driver is pressing the same button
multiple times in rapid succession (e.g., pressing the ``3'' button on
a telephone three times to indicate an ``f''), all of the multiple
button presses are assigned one step.
STEP.2.b Each time that a driver looks at the device display, one
step is assigned.
STEP.2.c Each time that a driver chooses from an entry in a list, a
variable number of steps are assigned. The number of steps assigned
depends upon the length of the list as follows:
STEP.2.c.i If there are one through five entries in the list, then
five steps are assigned.
STEP.2.c.ii If there are six through nine entries in the list, then
seven steps are assigned.
STEP.2.c.iii If there are ten or more entries in the list, then
nine steps are assigned.
STEP.2.d Each time a driver picks up an object, three steps are
assigned.
STEP.2.e Each time a driver puts down an object, one step is
assigned.
STEP.3 Add Steps Together. All of the steps that have been assigned
from all of the elemental components that constitute a secondary task
are added together. The resulting number is the number of steps to
perform that secondary task.
STEP.4 Acceptance Criterion. A task should not be allowed to be
performed by drivers unless either (1) The vehicle's engine is not
running, or (2) the vehicle's transmission is in ``Park'' (automatic
transmission vehicles) or the vehicle's transmission is in ``Neutral''
and the parking brake is on (manual transmission vehicles), or (3) the
following criterion is met:
STEP.4.a The number of steps to successfully complete the task is
six or less.
Option DS-BM: Driving Test Protocol With Benchmark
DS-BM.1 Test Apparatus. Testing should be performed using a driving
simulator that meets the recommendations contained in Subsection VI.2
using the driving scenario described in Subsection VI.3.
DS-BM.2 Lead Vehicle Speed. For this testing, the lead vehicle
should travel at a constant speed of 50 mph.
DS-BM.3 Test Device. The device under investigation should be
operational and fitted to a vehicle or simulator buck.
DS-BM.4 Test Participants.
DS-BM.4.a Twenty-four test participants should be enrolled using
the procedures described in Subsection VI.4.
DS-BM.4.b Test participants initially should be unfamiliar with the
device being tested. As part of the test protocol, they should be
trained in the use of the device(s) that are being tested using the
procedures described in Subsection VI.5.
DS-BM.5 Test Instructions. Test instruction should be standardized
and be presented either in oral or written format. The display and
controls of the interface should be visible during instruction. An
instruction may be repeated at the request of a test participant.
DS-BM.6 Number of Trials. Each test participant should drive the
driving scenario six (6) times, one time not performing any secondary
task (the Familiarization Trial), and five more times performing the
secondary task being studied (the Data Trials).
DS-BM.7 Reference Task. During each Data Trial, in addition to the
secondary tasks that are being evaluated, a test participant should
perform one additional secondary task, Manual Radio Tuning. This Manual
Radio Tuning task serves as a reference task that is used to determine
whether the acceptance criteria listed in Subsection DS-BM.9, below,
are met.
DS-BM.7.a The Manual Radio Tuning task should be performed as
follows:
DS-BM.7.a.i Prior to the commencement of the Manual Radio Tuning
task, a test participant is told the frequency of the station to which
the radio is to be tuned.
DS-BM.7.a.ii Initially the radio is ``On.'' If the radio controls
are part of an integrated vehicle display, the integrated display
should be set so that the radio controls are not active.
DS-BM.7.a.iii If the radio controls are part of an integrated
vehicle display, a test participant performs the action(s) necessary to
make the radio controls active.
DS-BM.7.a.iv A test participant changes the radio band selection
from AM to FM (or vice versa). The station that the radio is tuned to
immediately after this band selection is made should be referred to as
the Initial Station.
DS-BM.7.a.v A test participant uses the radio tuning control to
tune the radio to the desired, new, station (referred to as the Final
Station) that is approximately one-third of the AM or FM (as
appropriate) band away from the Initial Station.
DS-BM.7.a.vi The Manual Radio Tuning has been completed when the
radio has been successfully tuned to the Final Station.
DS-BM.8 Metric Computation. Metric values should be determined
based on data recorded by the driving simulator from the start of a
secondary task to the end of a secondary task.
DS-BM.8.a Based on the recorded lane position data, determine how
many lane exceedances occurred during each secondary task. A lane
exceedance occurs whenever either:
DS-BM.8.a.i The right front or right rear tire of the vehicle is
totally to the right of the right lane edge line, or
DS-BM.8.a.ii The left front or left rear tire of the vehicle is
totally to the left of the left lane edge line.
DS-BM.8.a.iii No distinction is made between right and left side
lane exceedances. Similarly, no distinction is made as to whether only
the front tire, only the rear tire, or both tires have crossed the lane
edge line.
DS-BM.8.b Based on the recorded data for headway (distance from the
subject vehicle to a lead vehicle), the time headway (headway divided
by the nominal travel speed of 50 mph) is calculated as a function of
time. The standard deviation of time headway during the secondary task
is calculated.
DS-BM.9 Acceptance Criteria. A task should not be allowed to be
performed by drivers unless either (1) The vehicle's engine is not
running, or (2) the vehicle's transmission is in ``Park'' (automatic
transmission vehicles) or the vehicle's transmission is
[[Page 11244]]
in ``Neutral'' and the parking brake is on (manual transmission
vehicles), or (3) both of the following criteria are met:
DS-BM.9.a The number of lane exceedances occurring while the
secondary task is being performed is not statistically significantly
greater, at the 95 percent confidence level, than the number of lane
exceedances occurring while the manual radio tuning task is being
performed.
DS-BM.9.b The standard deviation of headway while the secondary
task is being performed is not statistically significantly greater, at
the 95 percent confidence level, than the standard deviation of headway
while the manual radio tuning is being performed.
DS-BM.9.c Data from all five Data Trials is used when making the
statistical significance calculations required by DS-BM.9.a and DS-
BM.9.b.
Option DS-FC: Driving Test Protocol With Fixed Acceptance Criteria
DS-FC.1 Test Apparatus. Testing should be performed using a driving
simulator that meets the recommendations contained in Subsection VI.2
using the driving scenario described in Subsection VI.3.
DS-FC.2 Lead Vehicle Speed. For this testing, the lead vehicle
should travel at a constant speed of 50 mph.
DS-FC.3 Test Device. The device under investigation should be
operational and fitted to a vehicle or simulator buck.
DS-FC.4 Test Participants.
DS-FC.4.a Twenty-four test participants should be enrolled using
the procedures described in Subsection VI.4.
DS-FC.4.b Test participants initially should be unfamiliar with the
device being tested. As part of the test protocol, they should be
trained in the use of the device(s) that are being tested using the
procedures described in Subsection VI.5.
DS-FC.5 Test Instructions. Test instruction should be standardized
and be presented either in oral or written format. The display and
controls of the interface should be visible during instruction. An
instruction may be repeated at the request of a test participant.
DS-FC.6 Number of Trials. Each test participant should drive the
driving scenario six (6) times, one time not performing any secondary
task (the Familiarization Trial), and five more times performing the
secondary task being studied (the Data Trials).
DS-FC.7 Metric Computation. Metric values should be determined
based on data recorded by the driving simulator from the start of a
secondary task to the end of a secondary task.
DS-FC.7.a Based on the recorded lane position data, determine how
many lane exceedances occurred during each secondary task. A lane
exceedance occurs whenever either:
DS-FC.7.a.i The right front or right rear tire of the vehicle is
totally to the right of the right lane edge line, or
DS-FC.7.a.ii The left front or left rear tire of the vehicle is
totally to the left of the left lane edge line.
DS-FC.7.a.iii No distinction is made between right and left side
lane exceedances. Similarly, no distinction is made as to whether only
the front tire, only the rear tire, or both tires have crossed the lane
edge line.
DS-FC.7.b Based on the recorded data for headway (distance from the
subject vehicle to a lead vehicle), the time headway (headway divided
by the nominal travel speed of 50 mph) is calculated as a function of
time. The standard deviation of time headway during the secondary task
is calculated.
DS-FC.8 Acceptance Criteria. A task should not be allowed to be
performed by drivers unless either (1) The vehicle's engine is not
running, or (2) the vehicle's transmission is in ``Park'' (automatic
transmission vehicles) or the vehicle's transmission is in ``Neutral''
and the parking brake is on (manual transmission vehicles), or (3) both
of the following criteria are met:
DS-FC.8.a The number of lane exceedances occurring while the
secondary task is being performed is not statistically significantly
greater, at the 95 percent confidence level, than 0.06 lane exceedances
per secondary task performed.
DS-FC.8.b The standard deviation of headway while the secondary
task is being performed is not statistically significantly greater, at
the 95 percent confidence level, than 0.35 seconds while a secondary
task is being performed.
DS-FC.8.c Data from all five Data Trials is used when making the
statistical significance calculations required by DS-FC.8.a and DS-
FC.8.b.
Option DFD-BM: Dynamic Following and Detection Protocol With Benchmark
DFD-BM.1 Test Apparatus. Testing should be performed using a
driving simulator that meets the recommendations contained in
Subsection VI.2 using the driving scenario described in Subsection
VI.3.
DFD-BM.1.a For this testing, the vehicle being tested should
contain a route navigation system. If the vehicle does not have an
integrated route navigation system, a portable one may be used.
DFD-BM.2 Lead Vehicle Speed. For this testing, the lead vehicle
should travel at a continually varying speed that is determined by
linear interpolation from a table of lead vehicle speed values versus
time. Multiple lead vehicle speed tables are used, with a different one
being used each time a test participant drives the simulator.
Electronic copies of these tables, in the form of Microsoft Excel
files, can be obtained from NHTSA.
DFD-BM.3 Test Device. The device under investigation should be
operational and fitted to a vehicle or simulator buck.
DFD-BM.4 Test Participants.
DFD-BM.4.a Twenty-four test participants should be enrolled using
the procedures described in Subsection VI.4.
DFD-BM.4.b Test participants initially should be unfamiliar with
the device being tested. As part of the test protocol, they should be
trained in the use of the device(s) that are being tested using the
procedures described in Subsection VI.5.
DFD-BM.5 Test Instructions. Test instruction should be standardized
and be presented either in oral or written format. The display and
controls of the interface should be visible during instruction. An
instruction may be repeated at the request of a test participant.
DFD-BM.6 Number of Trials. Each test participant should drive the
driving scenario two times, one time not performing any secondary task
(the Familiarization Trial), and a second time performing the secondary
task being studied (the Data Trial).
DFD-BM.7 Eye Glance Determination. Eye glances are determined for
each test participant while performing each secondary task using the
techniques described in Subsection VI.6.
DFD-BM.8 Reference Task. During each Data Trial, in addition to the
secondary tasks that are being evaluated, a test participant should
perform one additional secondary task, route navigation system
destination entry. This Destination Entry task serves as a reference
task that is used to determine whether the acceptance criteria listed
in Subsection DFD-BM.12, below, are met.
DFD-BM.8.a The Destination Entry task should be performed as
follows:
DFD-BM.8.a.i Initially the route navigation system is ``On.'' If
the route navigation system controls are part of an integrated vehicle
display, the integrated display should be set so that
[[Page 11245]]
the route navigation system controls are active.
DFD-BM.8.a.ii A test participant enters a complete address (house
number, street name, city name, and state abbreviation) into the route
navigation system. Choosing from an entry in a list of either
previously entered destinations or landmarks is not acceptable.
DFD-BM.8.a.iii The Destination Entry task has been completed when
the final button on the route navigation system is pressed to have the
system find the route to the address.
DFD-BM.8.b Addresses chosen for testing should have a three or four
digit house number, and a nine through twelve character street name
(see details in DFD-BM.8.c), have a seven through ten character city
name (see details in DFD-BM.8.d), and have a two character state
abbreviation.
DFD-BM.8.c The nine through twelve character street name should
always be two words with a space between them. The first word will be
the actual name, while the second word will be an abbreviation for the
type of street (Blvd, Ct, Rd, St, etc.). When determining the number of
characters in the street name, all characters of both the actual name
and the abbreviation as well as one character for the space in between
are counted.
DFD-BM.8.c.i The route navigation system may use an auto-complete
feature after a portion of the street name has been entered. Having a
test participant choose from a list generated by an auto-complete
feature is acceptable.
DFD-BM.8.d The seven through ten character city name should always
be one word.
DFD-BM.8.d.i The route navigation system may use an auto-complete
feature after a portion of the city name has been entered. Having a
test participant choose from a list generated by an auto-complete
feature is acceptable. The auto-complete feature may make it
unnecessary for a test participant to enter the two character state
abbreviation.
DFD-BM.8.e The route navigation system may have a test participant
enter a five-digit ZIP code instead of the city name and state
abbreviation.
DFD-BM.9 Continuous Task Performance. Each secondary task is
continuously performed for 3 minutes during the car following portion
of the test (see Subsection VI.3.b.iv).
DFD-BM.10 Visual Detection Task. During the car following portion
of the test, simultaneously with performing each secondary task, a test
participant also continuously performs the visual detection task that
is described below.
DFD-BM.10.a As explained in Subsections VI.2.f and VI.2.g, for the
visual detection task, the driving simulator should display a series of
targets to be detected. Each target consists of a filled-in, solid, red
circle that is displayed in any one of six positions. Target dimensions
and positions are described in VI.2.f. When a test participant sees a
target appear, he or she should respond as quickly as possible by
pressing the micro-switch typically attached to their left index
finger.
DFD-BM.10.b Outputs from the visual detection task consist of:
DFD-BM.10.b.i The number of visual targets displayed during the car
following portion of the test.
DFD-BM.10.b.ii The number of correctly identified visual targets
during the car following portion of the test (see Subsection VI.2.g.iii
for details on how to determine).
DFD-BM.10.b.iii The Visual Detection Task Response Time, defined as
the time when the test participant pressed the micro-switch minus the
time when each visual target begins to display on the projection
screen, is calculated for each time that a test participant's response
was correct (see Subsection VI.2.g.iv for details on how to determine).
DFD-BM.11 Metric Computation. Glance-by-glance Eyes-Off-Road Times,
Standard Deviation of Lane Position, Car Following Delay, Percent
Correctly Detected, and Visual Detection Task Response Time metrics
should be determined based on data recorded by the driving simulator
from the start of the 3 minutes of secondary task performance to the
end of the 3 minutes (the Data Interval). The following measures of
test participant performance are determined for each Data Interval:
DFD-BM.11.a Glance-by-glance Eyes-Off-Road Times. The lengths of
eye glances away from the forward road scene are determined for each
test participant for each Data Interval using the techniques described
in Subsection VI.6.
DFD-BM.11.b Standard Deviation of Lane Position. Based on the
recorded data for lane position, the Standard Deviation of Lane
Position during the Data Interval is determined.
DFD-BM.11.c Car Following Delay. The Car Following Delay for each
Data Interval is calculated as follows:
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DFD-BM.11.d Percent Correctly Detected. For each Data Interval, the
Percent Correctly Detected is equal to the percentage obtained by
dividing the number of a test participant's correct responses by the
total number of targets displayed during a trial.
DFD-BM.11.e Visual Detection Task Response Time. As explained in
Subsection VI.2.g.iii, the Visual Detection Task Response Time is
calculated for each target that is displayed during a Data Interval for
which a test participant gave a correct response.
[[Page 11247]]
DFD-BM.12 Acceptance Criteria. A task should not be allowed to be
performed by drivers unless either (1) The vehicle's engine is not
running, or (2) the vehicle's transmission is in ``Park'' (automatic
transmission vehicles) or the vehicle's transmission is in ``Neutral''
and the parking brake is on (manual transmission vehicles), or (3) both
of the recommendations DFD-BM.12.a and DFD-BM.12.b are met:
DFD-BM.12.a A secondary task meets the recommendations of DFD-
BM.12.a if it satisfies all three of the following criteria:
DFD-BM.12.a.i For at least 21 of the 24 test participants, no more
than 15 percent (rounded up) of the total number of eye glances away
from the forward road scene should have durations of greater than 2.0
seconds while performing the secondary task.
DFD-BM.12.a.ii For at least 21 of the 24 test participants, the
mean of all eye glances away from the forward road scene should be less
than 2.0 seconds while performing the secondary task.
DFD-BM.12.a.iii For at least 21 of the 24 test participants, the
sum of the durations of each individual participant's eye glances away
from the forward road scene should be less than, or equal to, 12.0
seconds while performing the secondary task one time.
DFD-BM.12.b A secondary task meets the recommendations of DFD-
BM.12.b if it satisfies at least three of the following four criteria:
DFD-BM.12.b.i The Standard Deviation of Lane Position during the
Data Intervals is statistically significantly less, at the 95 percent
confidence level, than the Standard Deviation of Lane Position during
the Data Intervals for the Destination Entry task.
DFD-BM.12.b.ii The Car Following Delay during the Data Intervals is
statistically significantly less, at the 95 percent confidence level,
than the Car Following Delay during the Data Intervals for the
Destination Entry task.
DFD-BM.12.b.iii The Percent Correctly Detected during the Data
Intervals is statistically significantly greater, at the 95 percent
confidence level, than the Percent Correctly Detected during the Data
Intervals for the Destination Entry task.
DFD-BM.12.b.iv The Visual Detection Task Response Time during the
Data Intervals is statistically significantly less, at the 95 percent
confidence level, than the Visual Detection Task Response Time during
the Data Intervals for the Destination Entry task.
DFD-BM.13 Testing Procedure Items.
DFD-BM.13.a To prevent familiarity with the lead vehicle's speed
profile from becoming an issue, a different speed profile should be
used for each test participant drive on the driving simulator.
DFD-BM.13.b It is acceptable for each test participant to perform
multiple secondary tasks in a single test participation session.
However, a test participant should not be tested performing more than
six secondary tasks in a single session.
DFD-BM.13.c Each test participant should only be tested for one 3-
minute interval while performing the same secondary task.
DFD-BM.14 Multiple Trials. To improve testing efficiency, multiple
Data Trials should be allowed to be made by the same subject. Only one
Familiarization Trial needs to be performed, prior to any desired
number of Data Trials. Also, multiple secondary tasks can be tested,
one after another, during the same Data Trial.
Option DFD-FC: Dynamic Following and Detection Protocol With Fixed
Acceptance Criteria
DFD-FC.1 Test Apparatus. Testing should be performed using a
driving simulator that meets the recommendations contained in
Subsection VI.2 using the driving scenario described in Subsection
VI.3.
DFD-FC.1.a For this testing, the vehicle being tested should
contain a route navigation system. If the vehicle does not have an
integrated route navigation system, a portable one may be used.
DFD-FC.2 Lead Vehicle Speed. For this testing, the lead vehicle
should travel at a continually varying speed that is determined by
linear interpolation from a table of lead vehicle speed values versus
time. Multiple lead vehicle speed tables are used, with a different one
being used each time a test participant drives the simulator.
Electronic copies of these tables, in the form of Microsoft Excel
files, can be obtained from NHTSA.
DFD-FC.3 Test Device. The device under investigation should be
operational and fitted to a vehicle or simulator buck.
DFD-FC.4 Test Participants.
DFD-FC.4.a Twenty-four test participants should be enrolled using
the procedures described in Subsection VI.4.
DFD-FC.4.b Test participants initially should be unfamiliar with
the device being tested. As part of the test protocol, they should be
trained in the use of the device(s) that are being tested using the
procedures described in Subsection VI.5.
DFD-FC.5 Test Instructions. Test instruction should be standardized
and be presented either in oral or written format. The display and
controls of the interface should be visible during instruction. An
instruction may be repeated at the request of a test participant.
DFD-FC.6 Number of Trials. Each test participant should drive the
driving scenario two times, one time not performing any secondary task
(the Familiarization Trial), and a second time performing the secondary
task being studied (the Data Trial).
DFD-FC.7 Eye Glance Determination. Eye glances are determined for
each test participant while performing each secondary task using the
techniques described in Subsection VI.6.
DFD-FC.8 Continuous Task Performance. Each secondary task is
continuously performed for 3 minutes during the car following portion
of the test (see Subsection VI.3.b.iv).
DFD-FC.9 Visual Detection Task. During the car following portion of
the test, simultaneously with performing each secondary task, a test
participant also continuously performs the visual detection task that
is described below.
DFD-FC.9.a As explained in Subsections VI.2.f and VI.2.g, for the
visual detection task, the driving simulator should display a series of
targets to be detected. Each target consists of a filled-in, solid, red
circle that is displayed in any one of six positions. Target dimensions
and positions are described in VI.2.f. When a test participant sees a
target appear, he or she should respond as quickly as possible by
pressing the micro-switch typically attached to their left index
finger.
DFD-FC.9.b Outputs from the visual detection task consist of:
DFD-FC.9.b.i The number of visual targets displayed during the car
following portion of the test.
DFD-FC.9.b.ii The number of correctly identified visual targets
during the car following portion of the test (see Subsection VI.2.g.iii
for details on how to determine).
DFD-FC.9.b.iii The Visual Detection Task Response Time, defined as
the time when the test participant pressed the micro-switch minus the
time when each target begins to display on the projection screen, is
calculated for each time that a test participant's response was correct
(see Subsection VI.2.g.iv for details on how to determine).
DFD-FC.10 Metric Computation. Glance-by-glance Eyes-Off-Road Times,
[[Page 11248]]
Standard Deviation of Lane Position, Car Following Delay, Percent
Correctly Detected, and Visual Detection Task Response Time metrics
should be determined based on data recorded by the driving simulator
from the start of the 3 minutes of secondary task performance to the
end of the 3 minutes (the Data Interval). The following measures of
test participant performance are determined for each Data Interval:
DFD-FC.10.a Glance-by-glance Eyes-Off-Road Times. The lengths of
eye glances away from the forward road scene are determined for each
test participant for each Data Interval using the techniques described
in Subsection VI.6.
DFD-FC.10.b Standard Deviation of Lane Position. Based on the
recorded data for lane position, the Standard Deviation of Lane
Position during the Data Interval is determined.
DFD-FC.10.c Car Following Delay. The Car Following Delay for each
Data Interval is calculated as follows:
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DFD-FC.10.d Percent Correctly Detected. For each Data Interval, the
Percent Correctly Detected is equal to the percentage obtained by
dividing the number of a test participant's correct responses by the
total number of targets displayed on the screen during the trial.
DFD-FC.10.e Visual Detection Task Response Time. As explained in
Subsection VI.2.g.iii, the Visual Detection Task Response Time is
calculated for each target that is displayed during a Data Interval for
[[Page 11250]]
which a test participant gave a correct response.
DFD-FC.11 Acceptance Criteria. A task should not be allowed to be
performed by drivers unless either (1) The vehicle's engine is not
running, or (2) the vehicle's transmission is in ``Park'' (automatic
transmission vehicles) or the vehicle's transmission is in ``Neutral''
and the parking brake is on (manual transmission vehicles), or (3) both
of the recommendations DFD-FC.11.a and DFD-FC.11.b are met:
DFD-FC.11.a A secondary task meets the recommendations of DFD-
FC.11.a if it satisfies all three of the following criteria:
DFD-FC.11.a.i For at least 21 of the 24 test participants, no more
than 15 percent (rounded up) of the total number of eye glances away
from the forward road scene should have durations of greater than 2.0
seconds while performing the secondary task.
DFD-FC.11.a.ii For at least 21 of the 24 test participants, the
mean of all eye glances away from the forward road scene should be less
than 2.0 seconds while performing the secondary task.
DFD-FC.11.a.iii For at least 21 of the 24 test participants, the
sum of the durations of each individual participant's eye glances away
from the forward road scene should be less than, or equal to, 12.0
seconds while performing the secondary task one time.
DFD-FC.11.b A secondary task meets the recommendations of DFD-
FC.11.b if it satisfies at least three of the following four criteria:
DFD-FC.11.b.i The Standard Deviation of Lane Position during the
Data Intervals is not statistically significantly greater, at the 95
percent confidence level, than 1.0 feet.
DFD-FC.11.b.ii The mean Car Following Delay during the Data
Intervals is not statistically significantly greater, at the 95 percent
confidence level, than 4.6 seconds.
DFD-FC.11.b.iii The mean Percent Detected during the Data Intervals
is statistically significantly greater, at the 95 percent confidence
level, than 80 percent.
J11.b.iv The mean Visual Detection Task Response Time during the
Data Intervals is not statistically significantly greater, at the 95
percent confidence level, than 1.0 second.
DFD-FC.12 Testing Procedure Items.
DFD-FC.12.a To prevent familiarity with the lead vehicle's speed
profile from becoming an issue, a different speed profile should be
used for each test participant drive on the driving simulator.
DFD-FC.12.b It is acceptable for each test participant to perform
multiple secondary tasks in a single test participation session.
However, a test participant should not be tested performing more than
six secondary tasks in a single session.
DFD-FC.12.c Each test participant should only be tested for one 3-
minute interval while performing the same secondary task.
DFD-FC.13 Multiple Trials. To improve testing efficiency, multiple
Data Trials should be allowed to be made by the same subject. Only one
Familiarization Trial needs to be performed, prior to any desired
number of Data Trials. Also, multiple secondary tasks can be tested,
one after another, during the same Data Trial.
VII. Recommendations for Passenger Operated Devices. These
guidelines primarily are appropriate for driver interfaces of devices
intended for use by a driver. They are appropriate to a limited extent
for devices intended for use by front seat passengers.
VII.1 Apply if Within Reach or View of Driver. These guidelines are
appropriate for devices that can reasonably be reached and seen by a
driver even if they are intended for use solely by front seat
passengers.
VII.2 Not for Rear Seat Devices. These guidelines are not
appropriate for devices that are located solely behind the front seat
of the vehicle.
VIII. Recommendations for Aftermarket and Portable Devices.
VIII.1 Aftermarket and Portable Device Guidelines in Future. NHTSA
intends, in the future, to extend its NHTSA Guidelines to cover
aftermarket and portable devices. At that time, NHTSA may revise the
metrics contained in the current guidelines or introduce new metrics.
VIII.2 Unreasonable Risks With Aftermarket and Portable Devices.
NHTSA reminds manufacturers that they are responsible for ensuring that
aftermarket and portable devices they produce which may reasonably be
expected to be used by vehicle drivers do not create unreasonable risks
to the driving public.
IX. Recommendations for Voice Interfaces.
IX.1 Auditory-Vocal Interface Guidelines (Future). NHTSA intends,
in the future, to extend its NHTSA Guidelines to cover the auditory-
vocal aspects of device interfaces. For now, only devices with tasks
performed through visual-manual interfaces and/or a combination of
visual-manual and auditory-vocal means are covered by the
recommendations that are contained in these guidelines.
IX.2 Unreasonable Risks with Auditory-Vocal Interfaces. NHTSA
reminds manufacturers that they are responsible for ensuring that
devices they produce which have auditory-vocal portions of their
interfaces do not create unreasonable risks to the driving public.
Issued on: February 15, 2012.
David L. Strickland,
Administrator.
[FR Doc. 2012-4017 Filed 2-16-12; 11:15 am]
BILLING CODE 4910-59-P