Study On The Methods Of Urban Traffic Signal Control For Congested Condition

The urban traffic signal control system plays a key role in the urban road transportation developing process; it improves the order and efficiency of road transportation. The method of signal control originated from isolated fixed signal timing has been adaptive network signal timing.At present, the most difficult problem for urban traffic signal control system is hard to control congested traffic flow. In order to improve traffic operation efficiency and relieve traffic congestion, it's necessary to identify traffic conditions and adopt an available signal control method for different traffic condition.This dissertation studied the methods of urban traffic signal control for congested conditions. The main innovative works conclude:(1) In order to meet the need of traffic signal control, novel methods are presented for identifying traffic conditionsThe definition of traffic condition is presented from qualitative and quota angle in this dissertation. On the basis of real-time traffic data, a traffic evaluation index system for urban road network is set up. Moreover, according to analyzing saturation and LOS, real-time identification methods for judging urban road traffic conditions are presented based on dynamic data which are gathered from different traffic detectors. The presented methods will overcome the deficiency that present traffic signal control system is hard to identify traffic condition, and will provide technological support for traffic signal control system to identify traffic congestion and switch traffic signal control method.(2) Proposed an available traffic self-organizing signal control method for traffic congested conditionIn order to relieve traffic congestion, an available traffic self-organizing signal control method is proposed, which is an unusual signal control way, no signal cycle, no fixed phase and phase order. The novel signal control way will overcome the deficiency of the present signal control way for controlling congested traffic flow.(3) Designed a self-organizing signal control method for isolated congested intersectionA novel signal control method that is self-organizing signal control is proposed based on the self-organizing signal control way. The method can ease the congested traffic flow of a congested intersection.(4) Developed a new method of traffic self-organizing signal control for congested arterial intersectionsTo make up for the lack of traditional arterial signal control in congested conditions, a method of traffic self-organizing signal control for congested arterial intersections is proposed, and a searching algorithm of available bandwidth is proposed to decide the switch time for different arterial signal control method.(5) Proposed a novel method of traffic self-organizing signal control for congested district intersectionsAccording to the key congested intersection, a novel dynamic method for partitioning traffic control sub-area in congested conditions is proposed, and a congested control strategy and detailed congestion signal control method are presented.Based on VISSIM4.2 and Visual Basic6.0, the experiment platform UTC-CI, Urban Traffic Control for Congested Intersections, is developed, and methods presented in this dissertation are verified under UTC-CI. Results show that traffic condition identification method and traffic self-organizing signal control method presented in this dissertation can identify accurately traffic congestion and control effectively congested traffic flow.