The effect of laser speed-measuring devices on speed limit law enforcement in Charleston, South Carolina

Abstract

Drivers exceeding the speed limit by more than 10 mph were identified and ticketed by the Charleston County, South Carolina police using two types of speed measuring devices: conventional police radar and a new laser device. The two types of enforcement were used alternately on the same roads at similar times. Under the laser enforcement condition, the police issued 534 tickets (54%) compared with 457 (46%) under radar enforcement. The increase in tickets issued under laser enforcement was observed at three of the four study sites, and the number of tickets per traffic volume increased at two of the three sites for which traffic volumes were available. Speeders ticketed under the laser enforcement condition were four times as likely to have radar detectors as those ticketed under the radar enforcement condition. Most of the additional speeders caught by the laser were using radar detectors. These data indicate that some speeders with radar detectors are avoiding detection when the police enforce the limit with radar.