1372654 - Roundabout Influence Areas Along Rural and Suburban Corridors

Understanding the influence of roundabouts on traffic operations along connecting roadway segments is important for developing facility-level operational analyses along highway corridors. This study aims at assessing the spatial extent of the operational impacts of roundabouts along rural and suburban corridors. The study used vehicle trajectory data collected using a large number of test car runs along three roundabout corridors: two in the state of Washington and one in Colorado. The test cars were equipped with GPS data loggers which provided location coordinates along with other information every second during the experiments. Drivers’ speed profiles while driving through the roundabout corridors were established and analyzed. Study results provided important insights about the spatial extent of the operational effect of roundabouts on connecting approaches. Statistical analyses were conducted to estimate the upstream and downstream influence area at the three study sites and in testing the effect of traffic volume and posted speed limit on the influence area. Study results suggest that the downstream influence area is longer than the upstream influence area. Traffic flow level was found to have no significant effect on the roundabout influence area, however, posted speed limit was found to significantly affect the upstream and downstream roundabout influence areas.