A Primer on Safety Performance Measures for the Transportation Planning Process

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Case Study: Identifying Regional Traffic Safety Needs

Local governments play a key role in identifying regional traffic safety needs. Goals, objectives, and performance measures developed though the regional transportation planning process should reflect statewide planning efforts and be incorporated into problem identification and project selection processes at the local level. The Southeast Michigan Council of Governments (SEMCOG) incorporates safety planning goals and performance measures into its regional transportation planning process by aligning its long-range transportation plan with the State's Strategic Highway Safety Plan (SHSP), providing data analysis support for project identification to local governments, and using safety performance measures to plan investments. The SEMCOG Traffic Safety Program provides data collection and technical analysis support to local governments by identifying high-crash locations and recommending potential solutions. The program ensures data collection, technical analysis and planning processes support SEMCOG's long-range planning goals and objectives.

The region's long-range transportation plan identifies five strategic goals, one of which is to promote a safe and secure transportation system. SEMCOG developed performance indicators for each goal and identified data analysis tools to track and analyze each measure. SEMCOG's long-range transportation plan is aligned with the SHSP fatality goal to set target performance measures for the region.

SEMCOG has developed quantitative tools for relating investment to performance for the transportation system. The MPO uses an asset management approach to develop a regional transportation investment plan based on the benefits meeting-specific performance targets. The approach estimates the budget needed to achieve specific performance targets, one of which is safety. The tools allow the region to estimate the benefits of various investment scenarios and compare to system performance at current investment levels. The MPO determines the percentage of regional investments needed to meet the performance measure goals and prioritizes safety mitigation strategies. SEMCOG conducts an analysis of various scenarios for allocating available safety funds. Based on that analysis, an investment approach for funding various safety mitigation strategies is recommended. Safety mitigation strategies include intersection signal improvements, intersection geometric improvements (i.e., turn lanes), and segment improvements (i.e., median barriers and center left-turn lanes).

To promote a comprehensive approach to traffic safety analysis, SEMCOG provides a central location for traffic crash data and a Traffic Safety Manual, which describes a comprehensive approach to traffic safety analysis. The innovative traffic records system uses Geographic Information Systems (GIS) to spatially analyze crash data obtained from the Michigan Department of State Police's Criminal Justice Information Center (CJIC). Traffic data reports on specific intersections and segments of roadway are available. The traffic data reports, high-crash location, transportation data map, and intersection and roadway segments databases allow users to identify issues related to SHSP emphasis areas or view community profiles.

The Traffic Safety Program develops maps and deficiency analyses for each goal and performance measure area. SEMCOG identifies road segments and intersections with safety deficiencies related to the SHSP emphasis areas and tags crashes in the regional crash database related to specific emphasis areas. The MPO provides lists of deficiencies to its local governments so they can identify projects for the State's annual call for safety projects and consider them in long-range planning.

The Traffic Safety Manual provides guidance for local transportation planning, ranging from collecting potentially useful information to ranking potential solutions. The guide describes what data to collect and how to analyze data to identify high-crash locations. The Traffic Safety Manual describes how to propose and prioritize appropriate mitigation strategies using the same benefit/cost analysis incorporated into Michigan's annual call for safety projects.

Results

SEMCOG sets investment levels based on safety performance measures that align with statewide goals. The agency uses a comprehensive regional approach to identify and prioritize projects. SEMCOG provides crash data to local agencies for high-risk location analysis and cost-benefit analysis. This approach ensures local safety analysis and project prioritization is aligned with the region's and State's long-range goals, objectives, and performance measures. The region has exceeded the statewide goal of reducing traffic crash fatalities to one per 100 million vehicle miles traveled.

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