Speed Impacts of Temporary Speed Humps in Small Iowa Cities

Abstract. Many jurisdictions are faced with increased traffic speeds and volumes on residential streets. In an attempt to mitigate these unwanted traffic characteristics many jurisdictions have implemented traffic calming programs. The most commonly used traffic calming devices to reduce vehicle speeds are speed humps and speed tables. These devices have been shown to be effective in large urbanized areas but little information is available on their impact in smaller rural cities. This study examined the impact of speed humps and speed tables on vehicle speed profiles, mean vehicle speed, 85th percentile vehicle speed, and the frequency of speeders in the City of Atlantic (population of approximately 7,400). Temporary speed humps and speed tables were installed on two residential streets, Roosevelt Drive and Redwood Drive, in Atlantic. Speed data was collected during four periods: “before”, while the speed hump was in place, while the speed table was in place, and “after”. Speed data were collected and evaluated upstream of the devices, at the devices, and downstream of the devices. It was concluded that the speed humps and speed tables effectively reduced mean vehicle speed and 85th percentile vehicle speed at the location of the devices and downstream of the devices but not upstream of the devices. An evaluation of 85th percentile speed indicated that these devices are as effective in small rural cities as they are in more urbanized areas