Effectiveness of speed trailers on low-speed urban roadways

Abstract

Efforts are being made to use speed management methods to match operating speeds to posted speeds and to reduce the variability in vehicle speeds. The effectiveness of many different methods of speed management has not been documented. This thesis documents the effectiveness of speed trailers for reducing speeds on low-speed urban roadways. At each test site, vehicle speeds were collected at upstream, trailer, and downstream locations using piezoelectric sensors. Vehicles were "tracked" along the roadway to observe speed changes. Speed data were collected before, during, and after the speed trailer was used. The results indicated that speed trailers are effective in reducing vehicle speeds and the proportion of speeders. Each study site had significant speed reductions at the trailer location when the trailer was present. It was concluded that the trailer was effective in reducing vehicle speeds and the proportion of speeders downstream when the trailer was present. Additionally, speed trailers are not effective in reducing speeds or the proportion of speeders after the trailer was removed. At all of the sites, vehicle speeds significantly increased close to the "before" values after the trailer was removed. The effects of the trailer on the variability in vehicle speeds were also studied. The variability followed the same trends as the vehicle speeds; it decreased when the trailer was present, and the effects were seen at the trailer and downstream locations. The results of this research indicate that speed trailers are effective in reducing speeds while they are present on the roadway and also downstream of the trailer. There were no indications of lasting effects in a temporal setting. The speed trailer is also effective in reducing the proportion of suggestions for future research. Recommendations include studying the effects of the placement of a speed trailer at one location for a longer period of time (a week), and the effects of speed trailers on high-speed roadways.