Temporal Speed Reduction Effects of Drone Radar in Work Zones

Three experiments were conducted to evaluate the effectiveness of using drone (passive or unmanned) radar guns on vehicle speeds in work zones. Experiment 1 was an exploratory study to determine the immediate effects of using one drone radar gun on speed. Experiment 2 was conducted to evaluate the short-term effects of using one drone radar gun on speed. Experiment 3 measured the short-term effects of using two drone radar guns on speed. It was divided into three 1-hr time intervals to determine the lasting effects of using two radar guns on speed. The immediate effect of using one radar gun (Experiment 1) was a speed reduction of 13 to 16 km/hr (8 to 10 mph); however, such reduction should not be taken as a typical value. Experiment 2 showed that using one radar gun was not effective in reducing speed when drivers knew that it was drone radar. Experiment 3 indicated that the use of two radar guns increased the radar effectiveness, since drivers were not sure whether the signals would come from a police radar or drone radar. The effectiveness was consistent on trucks, but not on cars. The two-radar experiment reduced speeds of trucks by 5 to 10 km/ hr (3 to 6 mph) in most cases, but speeds of cars were reduced by 5 km/ hr (3 mph) only in two out of six cases. The speed reduction effects of the two-radar experiment on trucks were sustained over a time period of 3 hr.