Abstract:
State Departments of Transportation (DOTs) across the nation fund selective enforcement campaigns to improve traffic safety. The Alabama Department of Transportation (ALDOT) deploys a mobile selective law enforcement campaign targeting the negative driver behaviors that contribute to the most severe crashes, including speeding, driving under the influence, and failing to wear a seatbelt. The focus of this research was to integrate officer patrol routes, citations issued, crashes, and selective enforcement periods into one spatial and temporal map to evaluate the effectiveness of selective enforcement in reducing crashes along state routes in Alabama from August 1, 2010 to July 31, 2011. Structured Query Language (SQL) and Geographic Information System (GIS) technology were used to organize selective enforcement data into a relational database, geolocate Electronic Citations (eCitations), verify and locate selective enforcement areas, incorporate Electronic Crash (eCrash) data, and evaluate the decreased and/or increases in crash frequencies and the number of citations issued before and during selective enforcement. The approach to locate and verify selective enforcement locations successfully identified 21 locations across the state of Alabama. Statistical analysis was performed using a Paired Difference t-test. When evaluating the locations both by area type of urban or rural and collectively, there were significant increases in the number of citations issued, with an average 254% increase. There were marked decreases in the number of crashes when crashes were separately analyzed by the location type. P-values of 0.148 and 0.122 for urban and rural locations, respectively, confirm the decrease in crash frequency with 85% confidence. There were minimal decreases in the number of crashes when evaluating the locations collectively; however, there was a slight decrease in crash severity, with an average 2.45% decrease. Therefore, selective law enforcement efforts and the increase of issued citations along state routes in Alabama have started to improve public safety and decrease the number of crashes at select areas. Future work will involve strengthening the crash decreases with a proposed selective enforcement campaign recommendation, developing crash modification factors, and calculating a return of investment.
