Revisiting the Use of Drone Radar to Reduce Speed in Work Zones: South Carolina’s Experience

Speeding through work zones is a major safety concern in South Carolina. The authors evaluated multiple traffic control devices aimed at reducing speeds in South Carolina work zones and found that the majority of these speed control measures, with the exception of drone radar, are often not practical for wide spread, cost-effective implementation. The drone radar device has been tested for more than twenty years although never 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 for both passenger cars and tractor-trailers. One unique aspect of this study involves the use of a specialized radar 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 based on the following factors: changes in mean speeds, 85th percentile speeds, and percentage of vehicles exceeding the speed limit. Overall, the 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. The drone radar also caused 85th percentile speeds to decrease between 1 and 5 mph and a 20% speed reduction were shown in vehicles exceeding the speed limit.