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Countermeasures That Work is a basic reference to assist State Highway Safety Offices in selecting effective, science-based traffic safety countermeasures for major highway safety problem areas. The guide:

  • describes major countermeasure strategies and specific countermeasures that are relevant to SHSOs;
  • summarizes their use, effectiveness, costs, and implementation time; and
  • provides references to the most important research summaries and individual studies.

Inclusion in this guide does not mean that all costs associated with that countermeasure are allowable costs with NHTSA grant funds. For a description of an optimal State countermeasure program, SHSOs should refer to the Uniform Guidelines for State Highway Safety Programs, which outline the principal components of each major program area (NHTSA, n.d., the main web page and portal). States should identify problem areas through systematic data collection and analysis and are encouraged to continue to apply innovation in developing appropriate countermeasures. The evaluations summarized in this guide allow SHSOs to benefit from the experience and knowledge gained by others and to select countermeasure strategies that have either been proven effective or have shown promise. States choosing to use innovative programs can contribute to the collective knowledge pool by carefully evaluating the effectiveness of their efforts and publishing the findings for the benefit of others.

What's Included

This guide contains 11 topic areas. Each topic begins with a brief overview of the topic, including emerging issues and some Key Resources. Next, a table lists the specific countermeasures included in the section and summarizes their effectiveness, costs, use, and implementation time. Effectiveness, cost, and time to implement can vary substantially from State to State and community to community. Costs for many countermeasures are difficult to measure, so the summary terms are approximate. Each topic area sub-section may contain a list of recommended “Key Resources.” Each topic area concludes with a list of references for that topic.

Countermeasure Effectiveness

The effectiveness of any countermeasure can vary immensely from State to State or community to community. What is done is often less important than how it is done. The best countermeasure may have little effect if it is not implemented vigorously, publicized extensively, and funded appropriately. The countermeasure effectiveness data presented in this guide probably shows the maximum effect that can be realized with high-quality implementation. Many countermeasures have not been evaluated well, or at all, as noted in the effectiveness data. Additionally, some countermeasures found to be effective many years ago may not be as effective today. Effectiveness ratings are based primarily on demonstrated reductions in crashes; however, changes in behavior and knowledge are factored into the ratings when crash information is not available.

Countermeasure effectiveness is shown using a five-star rating system:

5 Stars                Demonstrated to be effective by several high-quality evaluations with consistent results.

4 Stars               Demonstrated to be effective in certain situations.

3 Stars               Likely to be effective based on balance of evidence from high-quality evaluations.

2 Stars               Limited evaluation evidence, but adheres to principles of human behavior and may be effective if implemented well.

1 Star               No evaluation evidence, but adheres to principles of human behavior and may be effective if implemented well.

Additionally, some topic areas include countermeasures under the heading “Approaches That Are Unproven or Need Further Evaluation.” This section describes approaches that have been employed or recommended as countermeasures. However, when used alone, the existing evaluation evidence does not support their usefulness or there is no evaluation evidence available and further research is needed. Though these approaches may not be effective when used alone, they may be useful when incorporated into comprehensive, multifaceted programs. More detailed information can be found in previous editions of Countermeasures That Work. States, communities, and other organizations are encouraged to use 3-, 4-, or 5-star countermeasures. When implementing 1- and 2-star countermeasures or unrated approaches, they are encouraged to have the countermeasure evaluated in connection with its use.

What's Not Included

Since the guide is intended as a tool for SHSO use, it does not include countermeasures for which SHSOs have little or no authority or responsibility. For example, the guide does not include vehicle- or roadway-based solutions. Also, it does not include countermeasures that are nearly universal in every State, such as .08 grams per deciliter blood alcohol concentration laws. While the guide does not include substantive detail of specific post-crash care related countermeasures from EMS or 911 services; these services are supported by SHSOs, traffic safety partners, and State Offices of EMS and 911. Guidance on these countermeasures is available at and Finally, the guide does not include administrative or management topics such as traffic safety data systems and analyses, program planning and assessments, State and community task forces, or comprehensive community traffic safety programs.

What's New

Updated Star Ratings

To help SHSOs differentiate between countermeasures that are more and less likely to be effective, the star rating system previously used for the 1- and 2-star countermeasures has been updated for this edition to include principles of human behavior. The rating system for the 3-, 4-, or 5-star countermeasures did not change. 1- and 2-star countermeasures have the following updated definitions:

2 Stars   Limited evaluation evidence, but adheres to principles of human behavior and may be effective if implemented well.

1 Star   No evaluation evidence, but adheres to principles of human behavior and may be effective if implemented well.

Approaches That Are Unproven or Need Further Evaluation

Many topic areas now include a section called “Approaches That Are Unproven or Need Further Evaluation.” For more, see the What's Included section above.

Alcohol- and Drug-Impaired Driving

A significant change in the 11th edition is the separation of the Alcohol- and Drug-Impaired Driving topic area of the previous editions into two distinct topic areas: one focusing solely on alcohol-impaired driving and another on drug-impaired driving. As research into these topics has continued to evolve, it has become increasingly clear that, although intertwined, these two topic areas present unique challenges and varied countermeasures that warrant individual and nuanced discussion.