An integrated approach for optimizing left-turn forbiddance decisions at multiple intersections

Left-turn forbiddance (with right-hand traffic) is a common operation strategy at intersections to improve efficiency. However, existing studies on left-turn forbiddance are often based on local conditions at a single intersection. This study is a first attempt to examine the optimal locations of left-turn forbiddance for multiple intersections along urban arterial roads, and to incorporate traffic redistribution along the arterial road due to left-turn forbiddance. We optimize the selection of locations to prohibit left-turn along arterial roads, the cycle length, and the green ratio to improve the effective capacity of the arterial road while the detour distance due to left-turn traffic redistribution is incorporated. We propose two mixed integer nonlinear programing models with different approaches to determine the green ratio. These are then tested with Weier Road in Jinan, China. We also compare system performances under the proposed models, current signal settings in place, and the Synchro-based model.