Arrival-based uniform delay model for exclusive protected-permitted left-turn lane at signalized intersections

Protected-permitted left-turn (PPLT) control strategies at signalized intersections are used to improve operational efficiency; however, only limited research has been done in modeling the delay for such phasing. The development and validation of uniform delay models for exclusive left-turn lanes with PPLT phases are presented. The proposed models are based on the arrival-based delay method, which directly considers the effects of platoon arrival rate and platoon duration in model development. Two arrival flow rates (one for platoon and one for nonplatoon) and two saturation flow rates (one for protected phase and one for permitted interval) were used to develop the delay models for PPLT. Results of a comparison of the control delays from the proposed models and the Highway Capacity Manual models with simulation results from CorSim indicated that the proposed models estimate the control delay more accurately.