Estimating Permitted Left-Turn Capacities with Nonstrict Priority Crossing Maneuvers

Based on the fact that there are nonstrict priority left-turning maneuvers at signalized intersections with a permitted phase in some countries, this study proposes a left-turn unit-based approach to estimating permitted left-turn capacity with an exclusive lane. First, a field study is conducted to look at the capacity limitations and crossing decisions in a left-turn unit using regression analysis and classification tree techniques. With the core idea that left-turn units cross the intersection during the duration of the initial green time, or use gaps provided by opposing right-turning vehicles, the permitted left-turn capacity model is developed using the probability theory. It involves nine factors related to the phasing schedule, the intersection geometry, driving maneuvers, and the proportion of traffic streams making different movements. Finally, validation and discussion of the method compared with previous methods show the proposed model better reflects the operational traffic performance of an intersection with a permitted phase.