Safety analysis of centerline rumble strips along rural two-lane undivided highways in Georgia
Pena, Marisha S.
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Vehicle crashes involving crossing over the roadway centerlines are among the most severe types of collisions nationwide. To address this issue, the Georgia Department of Transportation (GDOT) started implementing centerline rumble strips (CLRS) in rural locations across Georgia in 2005 and 2006. CLRS produce both an audible and tactile warning to alert drivers of impending lane departure into the lane of oncoming traffic. As of 2015, approximately 200 miles of CLRS have been installed by GDOT as a countermeasure for crossover crashes along rural two-lane undivided highways. This study evaluates the safety impacts of CLRS deployments in Georgia by analyzing two years of before and two years of after periods to evaluate the safety impacts associated with nine treatment sites and a control group of comparison sites with similar traffic and physical characteristics. The study dataset consisted of 154 target crashes along 126.46 miles of CLRS treatment sites and 1,391 crashes along control group sites. The empirical Bayes method was used to develop a crash modification factor for CLRS of 0.66, indicating a 34% reduction in crashes involving centerline crossings associated with the installation of centerline rumble strips. The sample size of fatal and injury crashes was too small to obtain separate crash modification factors for fatal crashes and injury crashes. The favorable crash modification factor (0.66) found in this study supports wider use of centerline rumble strips as a safety measure to address crashes involving vehicles that cross the centerline of the roadway. In addition to the safety analysis, this study also provided insights into the crash reporting process by conducting a comprehensive manual review of more than 17,000 crash reports. Approximately 6% of target crashes were found to be misclassified due to coding errors.