Revisiting the Use of Drone Radar to Reduce Speed in Work Zones

Speeding through work zones is a major safety concern in South Carolina. Multiple traffic control devices aimed at reducing speeds in South Carolina work zones were evaluated. The majority of these speed control measures, with the exception of drone radar, were often found not to be practical for widespread, cost-effective implementation. The drone radar device has been tested for more than 20 years, though never before in South Carolina. The focus of this research was to determine the effect of drone radar as a speed reduction measure in work zones on Interstates and secondary highways during day and evening conditions, both for passenger cars and for tractor-trailers. One unique aspect of this study involves the use of a specialized detector to identify vehicles using radar detectors. Most documented research used visual inspection, which is not ideal for this determination, because many vehicles do not have their radar detectors in a visible location. The effectiveness of drone radar was evaluated on the basis of changes in mean speeds, 85th-percentile speeds, and percentage of vehicles exceeding the speed limit. Overall, drone radar caused mean speed reductions of 2 mph for the entire traffic stream. However, individual vehicles equipped with radar detectors reduced speeds ranging from 5 to 8 mph. Drone radar also caused 85th-percentile speeds to decrease between 1 and 5 mph, and a 20% speed reduction was shown in vehicles exceeding the speed limit.