Qiao, Y., Shellhamer, N., Labi, S., Fricker, J. D., & Sinha, K. C. (2019). Cost-effectiveness of converting signalized arterials to free-flow facilities (Joint Transportation Research Program Publication No. FHWA/IN/JTRP-2019/18). West Lafayette, IN: Purdue University. https://doi.org/10.5703/1288284317079
Traffic signals on four-lane divided signalized arterials impair mobility and exacerbate traffic congestion, driver frustration, crash risk, and overall user and community costs. This study examined the economic feasibility of converting this roadway type to freeflow corridors. A free-flowing facility does not refer to a freeway, but rather, a facility that is free of traffic control devices (such as traffic signals and stop signs) on the mainline. At the intersection level, four intersection alternatives were considered: signalized intersection (do nothing), two-way stop-controlled (TWSC) intersection, J-turn and interchange. The study developed a decision framework that evaluates the overall performance of upgrade alternatives at the intersection and corridor levels in terms of the total life-cycle agency and user cost associated with mobility and safety. It was found that when traffic volumes are low, the TWSC intersection has superior mobility performance over J-turn and signalized intersection. Interchange and J-turn exhibited superior safety performance compared to TWSC and signalized intersections. Interchange always has the highest mobility performance particularly where the major and minor road traffic volumes are high. The study also developed nomographs to present rankings of the alternatives and established decision boundaries based on major and minor road traffic volumes. The nomographs can help INDOT identify the appropriate intersection type based mainly on the major and minor road traffic volumes. At the corridor level, the two conversion alternatives are free-flow corridor (with a mix of TWSC, J-turn and interchanges) and freeway corridor (interchanges only). Overall, the evaluation results were found to be sensitive to traffic volumes and weight ratio of the agency cost to user cost dollar. The study also developed a spreadsheet program to facilitate implementation of the decision support framework.
arterials, two-way stop control, J-turn, free-flow corridor, intersection, interchange
Joint Transportation Research Program
Indiana Department of Transportation
West Lafayette, IN
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