The Control Strategy Of City Traffic Occasional Congestion And Sub-region Dynamic Partitioning Based On Graph Theory

With the sustained increase of urban population and vehicle numbers, the urban traffic facilities planning and construction can’t keep up with the change of traffic demand. And the conflict of urban traffic between the supply and the demand is becoming increasingly acute. Traffic congestion has become one of the city’s main problems. In addition to the common jam in peak hours, some traffic incidents are also easy to cause accidental congestion in the urban road network.For the non-recurrent traffic congestion, where and when it takes place is random. The control evacuation is complex. On the one hand, due to the randomness of the location of congestion control. The traffic capacity of the adjacent intersections and roads and the traffic flow characteristics are different. And the second, because of the randomness of time, traffic flows in different periods also have different characteristics. The optimum control project for the normal traffic flow does not apply to the evacuate control. Therefore, to complete the evacuation control of the non-recurrent traffic congestion, the first important problem is how the control region is partitioned. Usually the dynamic partitioning of the control areas is to merge the adjacent intersections that the correlations are stronger into one larger control area. And different control area has different control strategies. The control system implements the real-time control. Based on this, this article focuses on the evacuation control strategy which is used to solve the non-recurrent traffic congestion. On the basis of the existing research results, the article makes the following several aspects mainly:(1) This article summarizes the congestion area dynamic partitioning methods at home and abroad, and the current state of the evacuation control strategy which is used to solve the non-recurrent traffic congestion research. At the same time, it summarizes the basic knowledge about dynamic partitioning in the non-recurrent traffic congestion. It also analyzes the static road parameters, dynamic traffic flow parameters, the signal control parameters and dynamic partitioning parameters in detail.(2) The non-recurrent traffic congestion is random. From traffic incident leading to the congestion to the jam disappearing completely, the congestion zone is changing. Using real-time traffic flow density parameter, Graph theory and the related theories, and the Kruskal Algorithm, it analyzes the dynamic evolution process about the traffic flow blocking area, transition area and normal area. It provides the basis for the evacuation control strategy selection in the urban road accidental congestion. A numerical simulation is performed by using MATLAB, and the result confirmed that the method is feasible.(3) The ban on vehicles and traffic signal control is two common methods to realize the congestion area evacuation strategy. In terms of vehicle ban, this paper practices the vehicle ban in the blocked area and normal area at the same time. Drawback of diamond control strategies is used in the blocked area to limit the vehicle to drive into the accidental event center and to prevent the regional internal collapse.