Evaluation of the effectiveness of vertical devices as a speed transition zone countermeasures in small, rural communities

Speeding is a major contributing factor in around 30 percent of fatal crashes nationally in the United States. Speeding in rural communities located along major highways is especially problematic given that drivers must transition from a major high-speed, rural roadway to a low-speed community setting. The rural roadway provides high-speed mobility outside the community, yet the same road within town provides local access and accommodates pedestrians as well as on-street parking, bicycles, and other features unique to the character of a small rural community. Since many rural communities are small, no clear delineation between rural homes and an actual township may be evident. As a result, drivers who have been traveling for some distance on a high-speed road outside the community may not receive the appropriate clues that the character of the roadway is changing and may not adjust their speed appropriately. Consequently, drivers often enter at high speeds and maintain those speeds as they travel through the community. Addressing speeding issues in rural communities is particularly challenging given that small rural communities often lack the engineering expertise and resources necessary to effectively address the persistent challenge of slowing high-speed through traffic. While traffic calming has been evaluated and used extensively on lower-speed urban roadways in the US, little information is available regarding the types of traffic-calming techniques that are appropriate and effective along major highways transitioning within rural communities. Typical traffic-calming techniques used on lower-speed roadways cannot be assumed to be portable to higher-speed roadways. To address the challenges of speed management along major highways through rural communities, the research team conducted a study to assess the effectiveness of different traffic calming countermeasures which were appropriate to the rural setting. Eleven different countermeasures were selected and evaluated in ten different small rural Iowa communities (USA) (typically < 5,000 population) (2; 3). This paper summarizes results for two of those countermeasures which utilized traffic control devices to narrow lanes and create vertical deflection. The objective of the countermeasure was to reinforce the changing nature of the roadway as drivers entered the community and to provide a sense of vertical friction.