Use of Directional Median Openings on Urban Roadways

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Use of Directional Median Openings on Urban Roadways

Y. Qi / X. Chen / Y. Wang / G. Liu / Y. Lu

Over the past decades, many states and local transportation agencies have installed directional median openings on divided roadways to improve arterial safety and operational performance. A directional opening is normally used to restrict crossing and left-turn movements from minor streets to help avoid potential conflicts. A series of potential benefits may be achieved by installing directional-median openings, including reduced crash rates, increased traffic capacity, and better operational performance. However, the benefits of directional median openings depend largely on proper implementation and on various factors, including geometric, traffic control, environmental conditions, and the type and placement of the downstream U-turn provisions. The goal of this research is to investigate the safety impacts of installing directional openings on median-divided urban roadways. To achieve this goal, the research : 1) synthesized existing related research; 2) compared the safety performance of directional median openings and full median openings, at subject opening locations and downstream U-turn locations; and 3) analyzed the contributing factors to the crashes occurred at the downstream U-turn locations of a directional median opening.