In transportation safety, the term "countermeasure" is generally used to describe a safety program or approach to address a specific type of crash. This term may be used interchangeably with "treatment" or "intervention." While some agencies focus on infrastructure countermeasures (e.g., traffic calming, bike lanes) or behavioral countermeasures (e.g., enforcement, safety campaigns), it is ideal for agencies to take a comprehensive approach of multiple countermeasures to address more complex problems.

Countermeasure effectiveness is usually evaluated by a change in the number of crashes. When crash data are not available, researchers and practitioners may consider changes in knowledge or road user behavior, such as speed or yielding rates, to determine countermeasure effectiveness, however, there is little research about how this type of evaluation correlates to safety. Before and after countermeasure studies to measure effectiveness are preferred since it can be challenging to infer safety results from cross-sectional studies. The effectiveness of any countermeasure can vary across geographies, as factors such as roadway design, public perception, law enforcement activities, lighting conditions, and more, are context specific. For a more advanced evaluation, with high quality data for multiple installations, researchers can calculate a Crash Modification Factor that estimates the safety effect.


Advancing Pedestrian and Bicyclist Safety: A Primer for Highway Safety summarizes promising engineering treatments and behavioral programs and includes a glossary and case studies.

PEDBIKESAFE describes the process for selecting and implementing countermeasures and each includes an interactive selection tool and case studies.

Countermeasures that Work provides guidance for selecting effective, evidence-based countermeasures for traffic safety problem areas including bicycle and pedestrian safety.

Systemic Pedestrian Safety Analysis and Risk Based Prioritization provides a method to identify sites for potential safety improvements based on specific risk factors for pedestrians.

Costs for Pedestrian and Bicyclist Infrastructure Improvements provides estimates of infrastructure costs for pedestrian and bicycle treatments.

Crash Modification Factor (CMF) Clearinghouse provides a searchable database of CMFs, which can be used to compute the expected number of crashes after implementing an infrastructure countermeasure.

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Road Diet Case Studies summarizes case studies from nine different agencies and features projects that use a variety of pedestrian and bicycle safety countermeasures.

Marketing Campaign and Pedestrian Hybrid Beacons (PHBs) Improve Safety for Pedestrians in Tampa, Florida features a multi-pronged safety project that has resulted in a crash reduction.

Publicly-Supported Road Diet Reduces Speeds in Alexandria, Virginia synthesizes a corridor project that improved safety for all road users, especially pedestrians.

City of Seattle Bicycle and Pedestrian Safety Analysis Project identifies locations to prioritize safety improvements with the goal of preventing future crashes.

Don't Cut Corners: Left Turn Pedestrian and Bicyclist Crash Study uses a data-driven approach to examine left turn pedestrian and bicyclist crashes in New York, New York.

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