The duration of speed reductions attributable to radar detectors

The duration of speed reductions attributable to radar detector use was observed. When the entire traffic stream was exposed to police radar, the proportion of vehicles traveling more than 10 mph over the speed limit dropped initially from 42% to 28%, but by one mile after exposure, this percentage had already increased to 38%. When speeding vehicles with radar detectors (about 45% of all speeding vehicles) were exposed to police radar, speeds dropped by approximately 15%, but by one mile after exposure, nearly half of the reduction was recovered. These findings indicate that radar detector users slow only briefly when alerted to police radar and that radar detectors are use primarily to avoid speed limit enforcement.