Research On Optimization Control Method Of Intersection Under The Condition Of Local Congestion

With the development of economy,progress of society and gradual improvement of urbanization process,people have increasingly high requirements for transportation.The contradiction between traffic supply and traffic demand intensifies rapidly,which leads to the fact that problems such as traffic jam happen frequently.Traditional traffic control technology cannot meet people's requirements for quality of commuting.The increasingly mature intelligent traffic control technology provides new method for urban traffic control.Fuzzy control is one of the intelligent controls.It can deal with complex and uncertain problems and does not need to establish accurate model for research object.Some specialists and scholars have researched how to use the method of fuzzy control to solve problems of traffic control.Fuzzy control is suitable for traffic authority to control and command traffic signals and provides effective solution to solve the problem of traffic jams.This article adopts fuzzy control method to solve problem of intersection congestion.In order to better put forward corresponding strategies to solve problem of intersection congestion,this article divides the traffic congestion at intersection into two states,namely traffic jam and traffic overflow to analyze according to order of severity of traffic jam.Traffic jam refers to the state that vehicles move slowly when traffic demand of certain entrance road is greater than the traffic capacity of road section,and the intersection is in the state of local congestion;traffic overflow is a baneful influence of traffic jam and refers to the queuing phenomenon of vehicles at the road segment because of traffic jam.The queuing length will increase with the increase of traffic flow.Vehicles occupy the entire road section.This article puts forward two kinds of control measures for two states of traffic jam.For local congestion at intersection,this article firstly designs correlation model of intersection to carry out optimization control of intersection.This model gives full consideration to the influence of upstream and downstream intersection on traffic condition of the current intersection and analyzes influencing process of traffic flow at correlation intersection.Give fuzzy control algorithm for correlation model of intersection and design fuzzy controller.Fuzzy controller mainly includes two modules: phase sequence optimization module and delay module of green light.Phase sequence optimization module refers to getthe next release phase according to passing need degree of red light phase and degree of congestion at upstream.Delay module of green light refers to give a delay time for green light according to queuing length before the completion of green light phase.The determination of green time has relationship with traffic condition of downstream section.Correct the delaying time of the current green light according to traffic condition of downstream intersection,and then confirm the delaying time of green light,and finally give corresponding release measures for traffic lights according to phase sequence optimization module and delay module of green light.For the overflow state at intersection,this article bases on characteristics of overflow state at intersection,fully considers adjusting phase difference of upstream and downstream intersection to control and designs fuzzy controller of phase difference of traffic overflow as well as simulates experience of traffic authority to control traffic lights.The input of fuzzy controller includes two aspects.On one hand,it refers to the time anticipated for congestion dissipation.On the other hand,it refers to the ratio of length of queuing vehicles on the road to road length.The output of fuzzy controller refers to phase difference of upstream and downstream intersection on the road section of traffic overflow and relieves the condition of traffic overflow through setting reasonable phase difference.