Effectiveness of Automated Speed Enforcement in Work Zones

Author/Presenter: Chitturi, Madhav; Benekohal, Rahim F.; Hajbabaie, Ali; Wang, Ming Heng; Medina, Juan C.
Abstract:

The performance of automated speed-radar photo enforcement (SPE) implemented in work zones in Illinois has been evaluated. The objective of SPE is to improve the speed limit compliance and improve safety in work zones. The down-the-road radar has been used to provide speed feedback to motorists and give them an opportunity to reduce their speeds. The across-the-road radar measures the speed of the vehicles when they are about 150 feet (ft.) upstream of the van, and if the measured speed exceeds a certain threshold, two photographs of the violating vehicle are taken. SPE reduces the average speeds of heavy vehicles significantly below the speed limit level (55 mph) on both lanes. The average speeds of free-flow heavy vehicles ranged from 44.8 mph to 52.2 mph, and the speed reductions ranged from 3.4 mph to 7 mph. The percentage reduction in speeding cars varies from 5 percent to 23 percent for free-flow cars, which is significantly smaller than the decreases at the treatment location.