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Citation, Disclaimers, Suggestions

Report No. DOT HS 813 490

This edition of Countermeasures That Work was prepared by the University of North Carolina’s Highway Safety Research Center. In addition to the authors, the following researchers contributed to this edition: Christine Gomola, Michael Vann, Stephen Heiny, Wesley Kumfer, and Michael Clamann. While this is the 11th edition of Countermeasures That Work, a digital version is now available at where you can easily save and share information and countermeasures that you feel are most relevant. The first edition of Countermeasures That Work was prepared in 2005 by James H. Hedlund, Ph.D., of Highway Safety North, with the assistance of Barbara Harsha, executive director of the Governors Highway Safety Association. Additions and revisions have been made by James H. Hedlund of Highway Safety North and William A. Leaf of Preusser Research Group (2nd edition), UNC Highway Safety Research Center (3rd through 8th editions) and Battelle Memorial Institute (9th and 10th editions).

All sections have been revised and updated for this edition. Information and research studies through May 31, 2020, have been reviewed and included as appropriate. Additionally, some research published after May 31, 2020, was included but a comprehensive review of the literature published after June 2020 was not completed. Data has been updated to include information from the 2021 FARS (Fatality Analysis Reporting System) Annual Report File (ARF). Updates to the guide are based only on published research. Unpublished programs and efforts are not included in this edition. See also, What's New section


Suggested APA Format Citation:

Kirley, B. B., Robison, K. L., Goodwin, A. H., Harmon, K. J. O’Brien, N. P., West, A., Harrell, S. S., Thomas, L., & Brookshire, K. (2023, November). Countermeasures that work: A highway safety countermeasure guide for State Highway Safety Offices, 11th edition, 2023 (Report No. DOT HS 813 490). National Highway Traffic Safety Administration.


This publication is distributed by the U.S. Department of Transportation, National Highway Traffic Safety Administration, in the interest of information exchange. If trade or manufacturers’ names or products are mentioned, it is because they are considered essential to the object of the publication and should not be construed as an endorsement. The United States Government does not endorse products or manufacturers.

As with any attempt to summarize a large amount of sometimes-conflicting information, this guide is highly subjective. All statements, judgments, omissions, and errors are solely the responsibility of the authors and do not necessarily represent the views of NHTSA. Users who disagree with any statement or who wish to add information or key references are invited to send their comments and suggestions for future editions (see Preface for details). Although all web links in this guide are accurate at the time of publication, web links may change periodically. For broken links to NHTSA documents, search NHTSA’s behavioral safety research reports. For broken links to other reports or documents, refer to the website for the agency that produced the report.

New traffic safety programs are established, and research is conducted constantly. This report is not a comprehensive list of all research, current studies, or program information available on any countermeasure. Readers interested in any problem area or in specific countermeasures are urged to consult the references or contact NHTSA for up-to-date information.

User Suggestions and Future Editions

NHTSA will update this guide biennially and may expand it with additional topic areas and countermeasures as appropriate. Users are invited to provide their suggestions and recommendations for the guide.

  • How can it be improved, in form and content?
  • Specific comments on information in the guide.
  • Additional topic areas to include.
  • Additional countermeasures to include for the current topic areas.
  • Additional Key References to include.

Please send your suggestions and recommendations to:, or by mail to:

Countermeasures That Work
National Highway Traffic Safety Administration
Office of Behavioral Safety Research, NPD-300
1200 New Jersey Avenue SE
Washington, DC 20590