Exploring operational characteristics of stop-controlled T-intersections on rural two-lane highways with passing lanes

Abstract

Left turn traffic at unsignalized T-intersection on undivided rural two-lane high-speed highways poses both operational and safety challenges. More complexities are faced by through drivers in the same direction as the stopped or slowed down left-turn vehicle must choose to either slow down and wait or bypass the left-turn vehicle. Therefore, this study intends to explore the operational characteristics of these facilities. The focus is on the reaction of the drivers behind the left-turn vehicle in terms of the types of maneuvers taken to avoid collision and the distance upstream for the evasive maneuvers using field observations. Further, the impact of the drivers’ reaction on the intersection delay is assessed using a simulation analysis of 17 generic 10.5-mile two-lane corridors with varying configurations of passing lanes at or near the intersection with and without a left-turn lane. The field observation findings from five sites reveal that drivers will move to the shoulder to avoid slowing and stopping or colliding with the left-turn vehicle. The distance at which drivers move to the shoulder differs for the sites studied. The simulation results show that a relatively similar magnitude of reduction in intersection delay could be achieved by addition of either passing lane or left-turn lane, such addition is beneficial for at least 17 000 vpd intersection volume where the passing lane does not end within 1 500 ft is downstream of the intersection. The findings are expected to improve traffic operations at T-intersections on rural two-lane highways.