A Study on Threshold of Exclusive Pedestrian Phase for Typical Signalized Intersections

Pedestrian-vehicle mixed in urban intersections is common and has negative effects on efficiency and safety of intersections.A cost model of intersection operations with or without exclusive phase signal for pedestrians is developed using delay cost and conflict cost as evaluation indices.Signal delay, conflict delay, and detour delay are all considered to calculate delay cost of pedestrians and non-motor vehicles.As for the conflict cost, based on traffic conflict theory, time headway is used to judge whether motor vehicles have conflicts with pedestrians or non-motor vehicles.Conflict possibility can be determined by arrival distribution of vehicles and pedestrians.The Sidaokou intersection in Beijing is chosen as a case study.Based on the collected data and genetic algorithm, the threshold of pedestrian flow is 750-900 ped/h for setting exclusive phase for pedestrians.With the increase of traffic flow, the requirement of pedestrian flow is descending at first, and then ascending at last.This study can provide a theoretical support for signal setting of urban intersections, and improve safety and convenience for pedestrians and non-motor vehicles.