Reduction of Speed in Work Zones Using ITS DMS Instant Feedback to Drivers: Vehicle Speed Versus Traffic Fine

Accidents in work zones produced 17 fatalities in Arizona and 840 fatalities and over 40,000 injuries nationally in 2009. Motorists nationwide can expect to drive through one active work zone for every 100 miles driven on the National Highway System, and the number of work zones should increase as roadways age. Research has shown that speeds exceeding those posted at work zones are the primary cause of workzone crashes and account for potentially up to 25 percent of the fatalities.

A literature review revealed five types of technology-driven, work-zone speed-control devices performed comparably to police presence and can supplement the Temporary Traffic Control Plans for work zones in the Manual of Uniform Traffic Control Devices (MUTCD) that the Arizona Department of Transportation (ADOT) uses along with its supplemental policies. Changeable message signs with radar (CMSR) affected speed reductions across various studies, including a South Carolina study in which a monetary fine message alternated with the speed message.

This study examined results of using a similar CMSR alternating a speed message with a monetary fine message on State Route 89 in Prescott, Arizona. This sign produced smaller mean speed reductions, but reduced by half the number of speeders driving 15 mph or more over the posted speed limit.

This research indicated that displaying a monetary fine message alternating with a vehicle speed message was effective in reducing higher speeds in the tested work zone. Based on these findings and the results of the South Carolina study, the researchers recommend that ADOT deploy mobile CMSR with alternating speed feedback and monetary fine messages in work zones wherever practicable.