Effect of Radar Drone Operation on Speeds at High Crash Risk Locations

At highway construction and maintenance work zones and other locations where roadway alignment, road surface, and traffic flow conditions have contributed to high crash rates, crash risk may be reduced by lower and more uniform speeds. The use of unattended (drone) radar has been found to reduce the mean speed of vehicles and the number traveling at very high speeds. Drivers using radar detectors to warn of police speed enforcement activities respond to the warning and slow down, as do drivers of nearby vehicles. Speeds were measured with and without radar drones in operation at 12 construction and maintenance work zones and high crash locations in Missouri. It was found that mean speeds were moderately lower when radar was operating, and this effect was slightly greater for tractor-trailers than for passenger vehicles, although not significantly so at most locations. However, moderate reductions in mean speed were associated with more meaningful reductions in the number of vehicles exceeding the speed limit by more than 10 mph (17 kph), especially among tractor-trailers.