Comparison of Automated Speed Enforcement and Police Presence on Speeding in Work Zones

This paper compares the effects of four speed management techniques on speed and speeding on interstate highway work zones. The techniques are speed feedback trailer, police car, the speed feedback trailer plus police car, and automated speed photo-radar enforcement (SPE). The effects on mean speed and degree of speeding were studied. The results showed that in both moderately and extensively speeding sites all law enforcement treatments (including variations of police presence and SPE) significantly reduced the mean speeds and degree of speeding. In the moderately speeding site, the Trailer+Police treatment reduced the mean speeds more than the other treatments. It reduced the mean speed of free flowing cars in the median lane by 8.4 down to 48.6 mph, while the other law enforcement treatments reduced it by 6.1 — 6.4 mph. In the extensively speeding work zone, the Trailer+Police and the SPE treatments reduced the mean
speeds similarly and more than the Police car alone. They reduced the mean speeds in the median lane by 7.8 mph down to 55.9 mph. In the moderately speeding site, Trailer + Police was more effective than the other treatments in reducing speeding. However, in the extensively – speeding site, all the law enforcement methods were similarly effective in reducing the speeding; yet 11% to 16% free flowing cars were speeding in median lane by more than 5 mph.