Research Pays Off: Automated Speed Enforcement Slows Down Drivers in Work Zones

More than 7,000 crashes occur annually in highway work zones in Illinois, causing approximately 2,000 injuries. The number of work zone fatalities in the state reached a peak of 44, including 5 workers, in 2003. Speeding is one of the most important contributors, affecting the frequency and severity of work zone crashes. In 2004 the Illinois Department of Transportation deployed two self-contained vans to implement a legislatively mandated speed-radar photo enforcement (SPE) program in work zones on highways. The speeds of vehicles approaching the SPE vans are monitored with two radar systems: down-the-road radar and across the-road radar.

The speed obtained from the down-the-road radar is displayed on a light-emitting diode display on top of the SPE van. The display gives speeding drivers a final chance to reduce speed and comply with the work zone speed limit. If the speed of the vehicle, measured by across-the-road radar, is greater than a specified value, the two onboard cameras are activated to take pictures of the driver and the rear license plate of the vehicle. Trained Illinois State Police officers staff the SPE vans and regular speeding fines in work zones apply to violations.

Aggressive law enforcement, including the use of SPE vans, in conjunction with educational campaigns and improvements to work zone traffic control, have reduced work zone fatalities from a high of 44 in 2003 to 31 in 2009. Illinois DOT has expanded the SPE program to five SPE vans, one for each region in the state.

The success of SPE in Illinois led to similar initiatives in Maryland, Oregon, and Washington. The Research Advisory Committee of the American Association of State Highway and Transportation Officials recognized “Speed Photo Enforcement in Illinois Work Zones” as a high-value research project at the regional level.