Shauna Hallmarkshallmar@iastate.edu email >
Keith Knappkknapp@iastate.edu email >
Director, Iowa LTAP
About the research
The main objective of this research was to evaluate the impact of temporary speed humps and speed tables on vehicle speeds, vehicle speed profiles, and traffic volumes along local and/or collector streets in several rural Iowa cities. A 25 mile per hour (mph) temporary speed hump and a 30 mph temporary speed table, both made of recycled rubber, were purchased to test the impact of temporary devices. Two cities volunteered, and the speed hump/table was installed on two test streets in the city of Atlantic (Roosevelt Drive and Redwood Drive) and one test street in the city of Le Claire (Canal Shore Drive). The speed hump was installed first and then converted to a speed table. Each device was installed for a period of at least two weeks at the same location. Speed, volume, and resident opinion data were then collected and evaluated.
In general, the devices were shown to be effective with the temporary speed table performing as well or better than the speed hump. Both the speed hump and the speed table were effective in reducing mean speeds at the device and immediately downstream, while speeds immediately upstream and farther downstream were less likely to be affected. The speed hump and speed table also reduced the number of vehicles exceeding the speed limit in the immediate vicinity of the devices. However, an analysis of the volume data collected did not indicate any reductions in traffic volumes along Roosevelt Drive, Redwood Drive, or Canal Shore Drive that would suggest traffic diversion occurred.
The results of the resident survey in this study were consistent with those reported in other jurisdictions. Overall more respondents were supportive of the use of the temporary speed hump/table than opposed. In addition to perceived reduction of speed, a number of positive comments were received about increased safety levels, greater attention from drivers, and the less severe profile of the speed hump/table when compared to the more familiar speed bump. However, the responses from the resident survey related to the preference of temporary device were not conclusive.
The temporary speed hump and temporary speed table used in this study were easily installed and removed with little damage to the existing pavement. These temporary devices provide jurisdictions with the opportunity to test the use of speed humps or tables on residential streets and to evaluate the public?s opinion of the devices. These temporary devices may also be ideal for jurisdictions that have concerns of snow removal or those that experience unwanted traffic characteristics during certain times of a year only (e.g., recreational areas).