Research On The Traffic Control Strategy Of Expressway In The Dense Urban Area Under The Condition Of Saturated Flow

The expressway in the dense urban area has the characteristics of small spacing,frequent traffic and complicated traffic flow.With the increasing number of motor vehicles and the increasing frequency of interregional traffic,the hub,interflow of the expressway in the dense urban area have appeared frequent traffic jams and traffic jams under abnormal conditions.It is of great significance to study the traffic control strategy of dense urban section under the condition of saturated flow to improve the safety and efficiency of expressway operation.The characteristics of road network in the dense section of expressway are analyzed,the threshold of saturated flow is determined,and the traffic characteristics and traffic accident characteristics are revealed in the dense section of the expressway in the saturated state.The formation and diffusion mechanism of congestion in the dense section of expressway in the saturated state is studied,and the overall traffic control target is "safe,smooth and orderly" in combination with the operation and management requirements of the expressway.In view of the influence range of three traffic congestion,"point","line" and "face",the traffic control strategy system of urban expressway in saturated state is constructed.The implementation conditions of ramp control,main line control and road network induction shunt strategy are studied,and the optimization model of the ramp coordination control is constructed.The average running speed and density of the main line vehicles and the maximum line length of the ramp are selected as the evaluation indexes.The implementation effect of the ramp control strategy is verified by Aimsun simulation.The speed control model determines the corresponding minimum,maximum speed limit and lane control measures for different types of vehicles.The screening method of induced shunt node and shunt path in expressway network is studied,uses Aimsun simulation software to establish road network model,carries out parameter verification,and the operation index of expressway network under the condition of strategy and without strategy is compared and analyzed.Under the condition of highway network operation indicators,evaluates the implementation effect of road network induced shunt strategy.Taking the Wuxi section of Shanghai Nanjing Expressway as an example,the ramp control strategy,the main control strategy and the induction shunting strategy are applied to the Wuxi section practice.The main measures include releasing traffic guidance information through the variable intelligence board to control the entrance flow of the toll station and control the remittance of the ramp on the toll station through the physical isolation.Big data measure is used to publish speed limit in real time;Formulates detailed schemes for induced diversion and dynamically publishes traffic guidance information in real time.And the effectiveness of traffic control strategy is comprehensively verified from the two aspects of road network efficiency and traffic safety.