Development of Signal Control Strategy for Oversaturated Intersections Using Wayside

Abstract The conventional real-time signal control strategy for oversaturated situation generally requires a number of detectors at the intersection in order to identify the queue length at each approach. Also, existing strategy for the spillback has limited effect due to the temporal spillback control which only reduce the green split at the approach. In this study, a signal control system utilizing the imagery information from ITS roadside equipment is developed for operation of oversaturated intersections. The strategy calculates the saturation ratio based on the queue length extracted from ITS RSE, and designs the signal control variables according to the saturation ratio. The signal control strategy is divided into two phases: oversaturated and supersaturated. In oversaturated conditions, timing plan for main approach is optimized by the queue length. In oversaturated conditions where spillback might occur, the signal timing is designed in order to avoid the spillback. To increase field adaptability, the strategy is designed to adjust the split length, all-red-time, and clearance time, and keep the major signal control variables intact. The result of the simulation shows that in oversaturated conditions, the improvement is similar to the real-time signal control system. In case of, oversaturated conditions, however, the effect of the strategy is superior to that of a real-time system.Key words : Oversaturated, Signal Control, Spillback, Queue, Image detection† 본 연구는 국토교통과학기술진흥원 연구과제(11교통체계-지능01) 지원에 의해 수행하였습니다.* 주저자 : 서울연구원 교통시스템연구실 연구원** 교신저자 : 서울연구원 교통시스템연구실 연구위원† 논문접수일 : 2013년 06월 13일† 논문심사일 : 2013년 07월 22일† 게재확정일 : 2013년 08월 01일