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Virginia Develops and Uses State-Specific Performance Functions (SPFS)

Summary from: Roadway Safety Data Program | Developing and Using State-Specific Safety Performance Functions (SPFS) In Virginia | FHWA-SA-14-078

Publication Year: 2015


Background

The 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™ 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.

After performing network screening, the VDOT central office identifies the top 100 sections and top 100 miles of segments with the largest Potential for Safety Improvement (PSI). The list is then sent to the district engineers who determine which sites to prioritize based on practical experience and knowledge of their area. VDOT has noted several benefits of Virginia’s SPF implementation effort. For example, the advanced data-driven process leads to better use of funds, benefits for both systemic and spot improvements are quantifiable, VDOT can better manage public concerns, and VDOT can compare locations to prioritize projects. The SPF development team conducts training (including an annual “roadshow” to all nine districts) and hosts webinars to ensure district engineers understand the methodology and how to use the SPFs. VDOT has not mandated the use of SPFs and PSIs by the districts because the process of introducing a new methodology takes time, but the district engineers know it is the preferred method for network screening.

Read the Case Study Developing and Using State-Specific Safety Performance Functions (SPFS) In Virginia for more detailed information.

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Contacts

Stuart Thompson
FHWA Office of Safety
202-366-8090
Stuart.Thompson@dot.gov

Publication Year: 2015

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