Exploration of Work Zone Crash Causes and Implications for Safety Performance Measurement Programs

Police crash reports are a fundamental data source for state work zone safety performance measurement programs. Studies have often identified work zone crashes simply on the basis of their location and have not considered the causal role (if any) that the work zone played in the crash. This study reviewed two years of Virginia work zone crashes and identified crashes that had been directly influenced by a work zone (directly related crashes) from a data set of all crashes that had been reported as occurring in the vicinity of a work zone (coded crashes). This procedure was done to assess the degree to which work zone activities appeared to influence the likelihood or severity of crashes within the work zone. Work zone crash reports were examined individually, and crash trends and possible safety improvement measures were identified. The study found a disparity between coded crashes and directly related crashes. Only 23% of the coded crashes could be directly related to the work zone. Further, coded crashes tended to overrepresent the proportional increase in rear-end crashes and underrepresent the proportional increase in fixed object–off road crashes. Analysis also identified several potential avenues where work zone safety performance measures could be influenced by the Virginia Department of Transportation, including improved work zone traffic management planning, ingress and egress design, and traffic control placement. Improvements to work zone crash forms were also identified. Implications of the differences between coded and directly related crashes for work zone safety performance measures are also discussed.