Traffic Evacuation Algorithms Design And System Implementation Based On Dynamic Flow

With the pace of urbanization development unprecedented speeding up, the growth of cities size, urban security risks constantly increasing, under the conditions of paroxysmal disasters the traffic emergency evacuation has been attracted more and more researches. In order to reduce the traffic evacuation time under the conditions of the sudden disasters, as soon as possible evacuate vehicles in the affected regions, and enhance utilization of evacuation resources, this thesis studies dynamic models of vehicles, framework of traffic evacuation system, traffic evacuation key algorithms, evacuation-oriented traffic guidance model and algorithms, as well as the evacuation traffic system design, implementation and testing.The thesis not only introduces the characteristics of the current famous traffic evacuation systems and traditional evacuation models, but also analyzes their shortcomings. According to characteristics of the emergency traffic network flow and the actual road network, this thesis puts forward the storage structure that can shows these characteristics, and analyzes the dynamic process of moving of traffic flow in the road, calculates the traveling time according to the attributes of roads and intersections. Based on these studies, the thesis designs the framework of evacuation system facing to emergency.Base on the introductions about multi-objective optimization which are pursued by traffic evacuation algorithms, this thesis brings up evacuation algorithm under the conditions of dynamic traffic flow. This thesis uses the traditional minimum time path algorithm to evacuate traffic, and uses contraflow to improve the evacuation algorithm. This thesis applies heuristic search to the field of traffic evacuation avoiding blind search, and improves the estimate function enhances the evacuation algorithm efficiency.The thesis puts forward evacuation-oriented architecture of emergency traffic guidance and analyzes how to intelligently and automatically generate traffic guidance information, and puts forward the release / subscribe engine under emergency conditions to publish guidance information. This thesis brings up a guidance region dynamic division method based on turning ratio of intersection, and based on cellular automaton model uses SWARM simulation platform to simulate traffic flow in order to test the efficiency of the method, the testing results show that the dynamic regional guidance algorithm have the average travel time reduced by 20% to 25% than using static guidance regional algorithm, and makes the average waiting time reduced by 4% to 10%.According to the network storage structure, the vehicles traveling dynamic model, the framework of the system, the traffic evacuation algorithms and guidance algorithms designed by this thesis, the thesis divides the evacuation system into modules and has designed and implemented each modules of the emergency traffic evacuation system. Finally, the system is tested based on the flood spread model designed by this thesis. Test results show that the system can give evacuation routes dynamically according to the changes of disasters. Also the results show that the system has made use of the shelters at high utilization rate, and quickly evacuate vehicles in the dangerous regions.