[Federal Register Volume 73, Number 42 (Monday, March 3, 2008)]
[Pages 11459-11462]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-4004]



National Highway Traffic Safety Administration

[NHTSA Docket No. NHTSA-2007-0038]

Notice and Request for Information and Comment on Development and 
Application of Crash Warning Interface Metrics

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

ACTION: Notice and request for information and comment on development 
and application of crash warning interface metrics.


SUMMARY: During the NHTSA-led Human Factors Forum on Advanced Vehicle 
Safety Technologies in early 2007, participants from the automobile 
industry, government, and academia gathered to discuss the research 
necessary to ensure that future design and operation of these 
technologies are developed with an understanding of the driver's 
ability to use them. Underlying this objective is a requirement to have 
techniques and metrics to quantify how well drivers can use and benefit 
from the technologies. Without common, reliable, and safety-related 
metrics, it is difficult to develop, evaluate, and compare different 
systems as well as to determine the impact of non-standardized warning 
    To address this issue, NHTSA is initiating a program to develop a 
set of standard metrics and test procedures to assess the Driver-
Vehicle Interface (DVI) of Advanced Crash Warning Systems (ACWS). ACWS 
are technologies to assist drivers who may be unaware of impending 
collisions by alerting them of potential threats. Examples include 
forward collision warnings, lane departure warnings, and road departure 
warnings. The DVI is the means by which ACWS communicate with drivers 
to help them avoid a threat. In order for ACWS to achieve their 
intended safety benefits, drivers need to be able to quickly understand 
the ACWS threat information and respond appropriately without 
confusion. The warning timing, reliability, warning modes, device 
controls, and displays are examples of the DVI characteristics that can 
affect the ability of drivers to achieve the intended safety benefits 
without possible adverse consequences. Crash Warning Interface Metrics 
(CWIM) are derived from tests of drivers' performance using ACWS, 
indicating the compatibility of the DVI with drivers' capabilities and 
    This notice invites comments, suggestions, and recommendations from 
all individuals and organizations that have an interest in the 
development and use of Crash Warning Interface Metrics. NHTSA requests 
comments to assist the agency in identifying, evaluating, and selecting 
CWIM and associated test methods for assessing the role of the DVI in 
influencing driver performance with ACWS.

DATES: You should submit your comments early enough to ensure that 
Docket Management receives them not later than April 17, 2008. Late 
comments may be considered.

ADDRESSES: You may submit comments identified by DOT Docket ID Number 
NHTSA-2007-0038 by any of the following methods:

[[Page 11460]]

     Federal eRulemaking Portal: Go to http://wwww.regulations.gov. Follow the online instructions for submitting 
     Fax: 202-493-2251.
     Mail: Docket Management Facility, M-30, U.S. Department of 
Transportation, West Building, Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery or Courier: West Building, Ground Floor, 
Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC, between 9 
a.m. and 5 p.m., Eastern Time, Monday through Friday, except Federal 
    Instructions: For detailed instructions on submitting comments and 
additional information on the rulemaking process, see the Public 
Participation heading in the SUPPLEMENTARY INFORMATION section of this 
    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).
    Docket: For access to the docket to read background documents or 
comments received, go to http://www.regulations.gov at any time or to 
West Building, Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., 
Washington, DC, between 9 a.m. and 5 p.m., Eastern Time, Monday through 
Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Eric Traube, Office of Human Vehicle 
Performance Research, National Highway Traffic Safety Administration, 
1200 New Jersey Avenue, SE., Washington, DC 20590. Telephone number: 
202-366-5673; E-mail [email protected].

SUPPLEMENTARY INFORMATION: One recent development in vehicle safety 
technology has been the introduction of Advanced Crash Warning Systems 
(ACWS). These systems alert drivers about emerging hazardous situations 
using auditory, visual, or haptic warnings. In some cases, limited 
vehicle control action, such as braking or steering, are initiated to 
alert drivers to respond. Systems that do not warn or provide some type 
of feedback to the driver would not be considered ACWS. Examples of 
ACWS include (but are not limited to) road departure warnings, lane 
change (blind spot) warnings, adaptive cruise control, curve speed 
warnings, and forward collision warnings.
    While the implementation of ACWS in production vehicles appears to 
be increasing, the question remains as to whether ACWS will produce 
significant safety improvements or will introduce unforeseen problems, 
particularly if drivers are unfamiliar with ACWS warnings. The NHTSA-
sponsored Human Factors Forum on Advanced Vehicle Safety Technologies 
was held in 2007 to begin to address this issue.
    A key to ACWS effectiveness is the quality of its interface, which 
can affect the driver's performance as well as acceptance of the 
technology. The interface of an ACWS consists of the controls that 
drivers use to adjust the system operation and any visual, auditory, or 
haptic warnings as well as operational cues that can influence driver 
actions. Whether drivers will be able to effectively utilize this 
feedback to avoid crashes may be determined through tests that measure 
various aspects of driver/vehicle response, such as brake reaction 
time, gas pedal release time, brake force, threat recognition, response 
appropriateness, eye glance behaviors, etc. Because different 
manufacturers employ different test protocols, measures, and criteria 
to determine the design of the Driver-Vehicle Interface (DVI), a 
variety of interfaces have been proposed and in some cases deployed in 
production vehicles.
    The Forum's focus on driver centered design highlighted the 
importance of these issues. Attendees stressed that future research 
should determine how to assess if drivers understand the system, if the 
system leads to appropriate driver reactions, and if drivers accept the 
new systems. Other discussion focused on the unintended consequences--
understanding how inadequate mental models may affect safety and how 
design can strengthen those models. In addition, discussion addressed 
research needs related to integration of interfaces when several 
warning systems are installed. Other topics included the question of 
designing interfaces compatible with the capabilities of the majority 
of the driving population and compatible with each other. The later is 
where the topic of interface standardization was addressed as an 
approach to minimize driver confusion.
    Without a meaningful basis for evaluating the driver/vehicle 
interface, the research topics suggested at the Forum would be 
difficult to resolve. In order to better evaluate and compare different 
ACWS interfaces, NHTSA has initiated a major research effort to develop 
human factors test protocols and related metrics of driver/system 
performance that will form the basis for a set of crash warning 
interface metrics (CWIM). The development of CWIM will benefit public 
safety by helping to identify effective ACWS. Secondly, CWIM will help 
to assess the whether lack of standardization of ACWS interface 
characteristics could confuse drivers and compromise system 
effectiveness. The issues of standardization and CWIM are interrelated 
because without metrics, the effects of non-standardized DVIs on driver 
performance cannot be objectively assessed. In addition, NHTSA may use 
results from the CWIM project to enhance test procedures developed 
under the Advanced Crash Avoidance Technology program and other ongoing 
    NHTSA requests comments to assist the agency in identifying, 
evaluating, and selecting CWIM and associated test methods for 
assessing the role of the DVI in influencing driver performance with 
ACWS. The agency is interested in comments related to both the 
scientific merit of different metrics as well as the practical or 
institutional considerations for end users of CWIM.
    While the research effort is making use of published research, 
guidelines, standards, and other materials, it will benefit greatly 
from the experience and opinion of various stakeholder groups, who face 
related issues. Therefore, we hope to receive comments that will 
reflect lessons learned, new ideas and approaches, criteria for optimal 
methods, practical concerns in application, and other information 
unlikely to be reflected in published literature. Responses to this 
notice may also help to provide greater consistency with current 
practice and assure maximum usefulness.
    The following are some of the key issues that the agency would like 
commenters to address. In addition to general comments, the agency 
requests submission of documents, studies, test protocols, or 
references relevant to the issues.

A. Potential Measures and Procedures

    (A1) What techniques, metrics, and criteria are now being used by 
vehicle manufacturers for developing and evaluating the human factor 
aspects of interface design and operation of ACWS at various stages of 
product development? What tools and environments (e.g. simulators, test

[[Page 11461]]

tracks, etc.) are used to evaluate DVIs? Are there ``lessons learned'' 
regarding their use, practicality, or acceptance? What measures and 
procedures are the most predictive of relevant safety parameters?
    (A2) To what extent are DVI assessment techniques shared industry-
wide and to what extent are these methods proprietary? What performance 
requirements, standards or guidance documents have been used by vehicle 
manufacturers and/or system suppliers to address the human factors 
aspects of the design and evaluation of CWIM for ACWS? Are they 
helpful? What are their limitations?
    (A3) If various functions (e.g., Adaptive Cruise Control (ACC), 
Frontal Crash Warning (FCW), Lane Departure Warning (LDW)) are packaged 
together as an integrated in-vehicle system, can CWIM be applied 
individually to each function or is there a need to treat each function 
in the context of the other functions present as well as other aspects 
of vehicle design? How can or should this be done? Are there common 
metrics and protocols that can be used to assess several ACWS?

B. Evaluation of CWIM

    (B1) What criteria should be used to determine the most sensitive, 
reliable, relevant, and useful metrics?
    (B2) If consumers are annoyed or otherwise dislike the system, they 
may turn it off or not purchase it. How should consumer acceptance or 
driver annoyance be evaluated with respect to their influence on system 
    (B3) Driver response to ACWS can vary from person to person. Even 
the same person can vary in performance depending on their state of 
mind, e.g., drowsy or distracted. What subsets of the population need 
to be included in developing criteria for CWIM? How should their needs 
and capabilities be integrated into the assessment?
    (B4) What type of evaluation of the DVI is being done or should be 
done to follow up on driver performance with production systems and its 
implication for the validity of CWIM?

C. Applying CWIM

    (C1) CWIM may be used by suppliers, vehicle manufacturers, and the 
Government to design, evaluate, and compare usability and potential 
safety implications of ACWS. However, protocols that are too 
complicated or costly may be difficult to implement. Protocols that are 
perceived as invalid or not sensitive to different characteristics of 
interface design may not be used. What are the practical considerations 
that need to be factored into the development of metrics and related 
test protocols to make them useful and also acceptable to those who 
must apply the methods? What factors should be considered in the choice 
of test equipment (e.g., simulators, test tracks, vehicle 
instrumentation) needed to collect driver data?
    (C2) As the number of ACWS increases in the vehicle fleet, the lack 
of standardization of the DVI among different vehicle makes and models 
may increase the likelihood of driver confusion in responding to the 
warning information intended to assist the driver. This lack of 
standardized design and operation of ACWS may reduce the safety 
benefits of these technologies. What mechanism (e.g., voluntary 
standards promulgated by SAE, ISO, or NHTSA or mandatory standards set 
forth in the FMVSS, etc.) should be used to standardize CWIM? How can 
standardization be balanced against restricting innovation? What test 
procedures and metrics can be applied to objectively evaluate the need 
for standardization? What criteria should be used to judge the need for 
    (C3) How should the criteria for acceptability be determined; that 
is, what determines if a DVI is ``good enough''? Also, how should the 
metrics be calibrated to determine if differences between measured 
values are of practical significance?

D. Research Needs

    (D1) What research or other steps are required to identify CWIM and 
establish their validity as a basis for assessment?
    (D2) What is the best way to encourage and coordinate international 
harmonized research on CWIM?

Public Participation

A. How do I prepare and submit comments?

    Your comments must be written and in English. To ensure that your 
comments are correctly filed in the Docket, please include the docket 
number of this document in your comments.
    Your primary comments must not be more than 15 pages long. (49 CFR 
553.21). However, you may attach additional documents to your primary 
comments. There is no limit on the length of the attachments.
    Please submit two copies of your comments, including the 
attachments, to Docket Management at the address given above under 
    Comments may also be submitted to the docket electronically on the 
Federal eRulemaking Portal at http://www.regulations.gov. Follow the 
online instructions for submitting comments.

B. How can I be sure 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.

C. How do I submit confidential business information?

    If you wish to submit any information under a claim of 
confidentiality, send three copies of your complete submission, 
including the information you claim to be confidential business 
information, to the Chief Counsel, National Highway Traffic Safety 
Administration, 1200 New Jersey Avenue, SE., Washington, DC 20590. 
Include a cover letter supplying the information specified in our 
confidential business information regulation (49 CFR part 512).
    In addition, send two copies from which you have deleted the 
claimed confidential business information to Docket Management at the 
address given above under ADDRESSES, or submit them electronically 
through the Federal eRulemaking Portal at http://www.regulations.gov. 

D. Will the agency consider late comments?

    We will consider all comments that Docket Management receives 
before the close of business on the comment closing date indicated 
above under DATES. To the extent possible, we will also consider 
comments that Docket Management receives after that date.

E. How can I read the comments submitted by other people?

    You may read the comments received by the Docket Management at the 
address given under ADDRESSES. The hours of the Docket are indicated 
above in the same location. To read the comments on the Internet, go to 
http://www.regulations.gov. Follow the online instructions for 
accessing the docket.
    Please note that even after the comment closing date, we will 
continue to file relevant information on 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.

[[Page 11462]]

    Issued on February 26, 2008.
Joseph N. Kanianthra,
Associate Administrator for Vehicle Safety Research.
 [FR Doc. E8-4004 Filed 2-29-08; 8:45 am]