Developing and Using State-Specific Safety Performance Functions (SPFS) in Virginia: Roadway Safety Data and Analysis

2015PDFTech ReportFHWA-SA-14-078Data analysisHighway safetyFreewaysMultilane highwaysTwo lane highwaysUnited StatesVirginiaUnited States. Federal Highway Administration. Office of SafetyUnited States. Federal Highway Administration. Office of SafetyFederal Highway AdministrationThe Virginia Department of Transportation (VDOT) emphasizes data-driven decision-making and desires to improve safety and safety data. From this desire, VDOT implemented a comprehensive set of State-specific Safety Performance Functions (SPFs) covering 98 percent of its State-maintained roadway locations. The impetus for VDOT developing their own SPFs and analytical tools arose from the decision that AASHTOWare Safety Analyst\u2122 did not meet their needs. VDOT developed State-specific SPFs using historical crash, traffic, and roadway inventory data. SPF developers worked closely with engineers throughout the development process to see whether each SPF was implementable for all types of improvements (spot, corridor, and systemic). To date, VDOT has developed 24 SPFs covering a majority of roadway facilities, including two-lane roads, intersections, and freeways/multi-lane highways. The purpose of this case study is to describe the successes and ongoing challenges related to developing and implementing a comprehensive set of State-specific SPFs in Virginia.84