The Study Of Traffic Flow Control And The Secondary Accident Fore-warning Technique Of Expressway

The growing demand of traffic on expressway makes it easier for some sections,bottleneck sections in especial,to become more and more congested,leading to greater traffic safety risks for affected vehicles.At the same time,the growth trend of highway accident isn't going well.The traffic environment and the road traffic capacity will be effected to some degree when accident happens.It will expand the scope and severity of accident,if drivers haven't handled issues properly or traffic environment have changed sharply,etc.,which will cause the happening of secondary accident.This may make the consequence incalculable.Therefore,the traffic flow data,provided by the roadside traffic information gathering equipment and based on the considering of expressway traffic flow theory,is analyzed.In order to reduce the traffic speed deviation rate,ease congestion a nd bring down the safety risks caused by uneven traffic density,the dynamic control unit on the freeway segmentation management is established and the traffic flow control model is put forward.Based on VISSIM simulation platform,the model's validity is verified by taking travel time as the index and a section of Jinan-Qingdao Expressway as the research object.The conclusion of simulation also indicates that the traffic flow larger,the control effect is more obvious.From the standpoint of the expresswa y secondary accident generating theory and the accident fore-warning in ordinary state,the methods of measuring and calculating fore-warning index and setting threshold interval are proposed and the secondary accident fore-warning index system is established.In the paper,BP neural network is used to classify the levels of secondary accident,and traffic management strategy under different fore-warning levels is put forward in the end.