Use of Physical Devices for Traffic Calming Along Major Roads Through Small Rural Communities in Iowa.

Many rural communities have developed around highways or major county roads and as a result, the main street through small rural communities is often part of a high speed rural highway. Highways and county roads are characterized by high speeds outside the city limits and then transition into a reduced speed section through the rural community. Consequently, drivers passing through the community often enter at high speeds and then maintain those speeds throughout. Traffic calming in small rural communities along major roadways is common in Europe but the US does not have experience with applying traffic calming outside of major urban areas. Seven different low cost traffic treatments were implemented and evaluated in five rural Iowa communities. Two of the treatments physically affected the roadway cross-section and are presented in this paper. A speed table was placed along the major road (E 23) in Gilbert, Iowa and longitudinal channelizers were used to create a center island narrowing along R 38 in Slater, Iowa. Before and after speed studies were conducted. After speed studies were conducted at 1, 3, and 9 months after installation of the treatments to evaluate their effectiveness over time. Both treatments successfully reduced mean speed, 85th percentile speed, and fraction of vehicle traveling 5, 10, 15, and 20 mph over the posted speed limit and reductions were sustained over time.