Use of DSFS as a Speed Transition Zone Countermeasure in Small, Rural Communities

Small rural communities in the United States are often located along major state or county roadways and as a result, most of the traffic along their main thoroughfare is pass-through rather than local traffic. Unfortunately, drivers passing through these communities often enter at high rates of speeds which are sometimes significantly higher than the posted speed of the local segment. High speeds create a safety issue for rural communities. They also discourage pedestrian activities, such as walking and bicycling, and discourage community interaction and vitality. Rural communities often lack engineering staff and resources to address speed management. As a result, rural communities find it difficult to address speeds and in many cases, utilize stop signs and lower speed limits to address the problem which may lead to disregard for traffic control. Traffic calming in rural areas requires different considerations than urban areas and within the US, rural traffic calming is in its infancy with little experience or guidance for agencies to draw on. This paper summarizes the results of a study which evaluated several different types of dynamic speed feedback signs which were deployed within the speed transition zone for small rural communities in Iowa (USA). DSFS have been used in a number of applications in the US, such as within school zones and work zones. Their effectiveness was less known in rural community applications. Three different types of DSFS were deployed (simple speed feedback sign, alphanumeric sign, and speed limit sign with LED array). All signs were programmed to activate only for drivers traveling at some threshold over the posted speed limit at the community entrance. Overall, the dynamic speed feedback signs were shown to be very effective in reducing vehicle speeds at community entrance. In particular, large reductions were noted in most cases in the fraction of vehicles that were traveling significantly over the posted speed limit at the community entrance.