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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations

This report is an archived publication and may contain dated technical, contact, and link information
Publication Number: FHWA-RD-00-022
Date: December 1999

Development of Countermeasures for Driver Maneuver Errors



This report was produced as part of a contract "Determine Causes of Driver Maneuver Errors," which called for a sequence of analytic and empirical research efforts in order to understand where and when drivers suffer misperceptions that lead to driving maneuver errors. In addition, the contract called for the development of highway safety countermeasures concepts to address those errors. This report presents a brief discussion of the purpose and scope of the project, describes the analytical and empirical activities, and presents the recommended countermeasures developed with the help of an expert panel. The recommended countermeasures merit further evaluation; in most cases, they are not recommended for immediate implementation.

Copies of this report can be obtained through the Research and Technology Report Center, 9701 Philadelphia Court, Unit Q, Lanham, Maryland 20706, telephone: (301) 577-0818, fax: (301) 577-1421, or the National Technical Information Service (NTIS), 5285 Port Royal Road, Springfield, Virginia 22161, telephone: (703) 605-6000, fax: (703) 605-6900.

Michael F. Trentacoste
Michael F. Trentacoste
Director, Office of Safety
Research and Development


Development of Countermeasures for Driver Maneuver Errors

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1. Report No.


2. Government Accession No. 3. Recipient's Catalog No.
4. Title and Subtitle

Development of Countermeasures for Driver Maneuver Errors

5. Report Date

December 1999

6. Performing Organization Code


7. Author(s)

Neil D. Lerner, Geoffrey V. Steinberg, and Fred R. Hanscom

8. Performing Organization Report No.
9. Performing Organization Name and Address

1650 Research Boulevard
Rockville, Maryland 20850

10. Work Unit No. (TRAIS)

NCP No. 3A6A-1162

11. Contract or Grant No.


12. Sponsoring Agency Name and Address

Office of Safety Research and Development
Federal Highway Administration
6300 Georgetown Pike
McLean, Virginia 22101-2296

13. Type of Report and Period Covered

Task D Report
3/97 - 1/99

14. Sponsoring Agency Code


15. Supplementary Notes

Contracting Officer's Technical Representative (COTR): Joseph Moyer, HSR-30; Kate Woerheide, SAIC. We acknowledge the helpful cooperation of Frank Barickman, VRTC, and the National Highway Traffic Safety Administration, for the use of and technical support with the DASCAR instrumented vehicle.

16. Abstract

Drivers may make errors that result in a collision with another vehicle, even when they are aware of the presence of the conflicting vehicle. This is because perceptual judgments about time, space, and speed, are imperfect, and can lead to misjudgments about the adequacy of a situation to allow some driving maneuver. Drivers may err in thinking there is more time available for the maneuver than is actually the case; or err in thinking the maneuver takes less time to execute than it actually does. Either misperception could lead to a decision to go ahead with a maneuver with less margin of safety than the driver assumes. Misperceptions of the time available of time required for various driving maneuvers under a range of conditions were studied in this project. In the laboratory experiment, research participants viewed video scenes, filmed from a driver's perspective, of a wide variety of situations. For each scene, the viewers made judgments about when some event would occur (e.g., approaching vehicle reaches them) or when some maneuver would be completed (e.g., own vehicle clears roadway when making a crossing maneuver). Participants' judgments were compared with actual values (for time available) or best estimates from engineering equations and empirical data (for time or distance required). A parallel on-the-road experiment, using similar procedures and a subset of the laboratory situations, was used to validate and benchmark the laboratory findings. The study found a general tendency for people to underestimate the time required to complete a maneuver. Across a range of maneuvers, about 60 percent of all time or distance required judgments were underestimated, relative to engineering and empirical estimates. This misjudgment is safety-critical, because driver perception that a maneuver will take less time than is actually the case may lead to decisions to accept maneuver opportunities that actually afford a smaller margin of error than the driver perceives. Such misestimates were particularly common for judgments of the time to achieve the prevailing traffic speed during turning of merging maneuvers, and for the time until one's vehicle reaches an intersection ahead. For judgments of the time available for a maneuver, the error was usually in a safety-conservative direction. That is, people felt they had less time than they actually did, so would be less likely to attempt a maneuver. However, even for time available judgments, there were meaningful numbers of safety-critical errors (overestimates of time available), especially for estimates of yellow signal phase time remaining and estimates related to a passing scenario. When the combined errors related to both maneuver requirements and availability were jointly considered, some situations emerged as particularly meriting consideration for safety countermeasures. These included: (1) approach to signalized intersections; (2) turns onto higher-speed roadways; (3) freeway merges; (4) passing; and (5) headway maintenance. Following the analysis of the experiment, efforts were undertaken, aided by an expert panel, to develop primarily infrastructure-based countermeasure concepts to address these problems. A number of promising ideas based around roadway design and operations were recommended for formal evaluation.

17. Key Words

Driver maneuver errors, safety, research program, human factors, older drivers.

18. Distribution Statement

No restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161.

19. Security Classif. (of this report)


20. Security Classif. (of this page)


21. No. of Pages


22. Price

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized



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