USRAP Pilot Program Phase II

AAA Foundation for Traffic Safety · 2008 · AAA Foundation for Traffic Safety

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Summary

This report details the results of Phase II of the U.S. Road Assessment Program (usRAP) pilot program, conducted by the AAA Foundation for Traffic Safety in 2008. The research addresses the lack of a systematic road assessment program in North America to identify safety shortcomings and prioritize improvement investments. Motivated by the need to support federal mandates under SAFETEA-LU requiring states to identify the 5% of road locations with the most severe safety needs, the study aims to demonstrate the feasibility of using risk mapping to guide highway safety decisions. The primary objectives are to reduce deaths and serious injuries through systematic risk assessment and to ensure that risk data informs strategic route improvements. The methodology involved pilot studies in Florida and New Jersey, alongside further work in Iowa and Michigan from Phase I. The core protocol tested was "risk mapping," which uses historical crash data to classify road sections into five risk categories displayed on color-coded maps. Four primary map types were generated: Map 1 (crash density per mile), Map 2 (crash rate per 100 million vehicle-miles), Map 3 (ratio of crash rate to similar roads), and Map 4 (potential crash savings if rates were reduced to the average). In Florida, the study focused on rural state highways, analyzing five years of data (2001–2005) for fatal and serious injury crashes. Roads were segmented based on design type, traffic volume, and speed limits, with aggregation rules applied to ensure statistical reliability. Supplementary maps were also developed for specific crash types, including unbelted occupants, speed-related incidents, and alcohol-involved crashes. A minimum crash count threshold was applied to prevent short, low-volume segments from being falsely classified as high-risk. The findings demonstrate that risk mapping effectively identifies high-risk roadway sections. In Florida, the analysis covered 6,012 miles of rural state highways, identifying 12,002 fatal and serious injury crashes over the study period. The maps revealed that different metrics highlight different high-risk areas; for instance, Map 1 often flagged high-volume freeways due to absolute crash counts, while Map 2 adjusted for exposure, typically showing freeways as lower risk. The highest risk category (black) consistently represented 5% of the roadway length, aligning with federal reporting requirements. Supplementary maps successfully isolated specific safety issues, such as unbelted occupant crashes, allowing for targeted analysis. The study also confirmed that the protocols could be adapted to address state-specific concerns, such as commercial vehicle or older-driver crashes. The significance of this work lies in providing a practical tool for highway agencies to meet federal safety reporting mandates and prioritize limited improvement funds. The report concludes that usRAP risk maps offer a systematic approach to identifying safety needs, complementing existing engineering studies. It recommends further development of the "star rating" protocol, which assesses design features, and suggests that Phase III should focus on refining segmentation rules for low-crash-count areas and expanding the application of performance tracking to monitor safety changes over time. The study establishes that systematic risk assessment can drive public dialogue and support increased investment in highway safety.

Key finding

After Phase I and II pilot studies in four U.S. states, usRAP risk mapping with Maps 1–4 and five risk categories (including a highest-risk 5 percent band aligned with SAFETEA-LU) is a mature protocol for identifying priority road segments, but red or black segments must be interpreted carefully because high crash concentrations may reflect traffic exposure or driver populations rather than infrastructure deficiencies alone.

Methodology

modeling

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extract success cached 2 2026-06-10
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enrich skipped pubmed 5 2026-05-27
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tag success vector_similarity 18 2026-06-11
verify partial 2 2026-06-10

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