Study On The Methods Of Traffic Organization Optimization For Emergency Evacuation

Large-scale natural or man-made disasters can have devastating impacts in terms of loss of life, human injury and property damage. Evacuation from dangerous areas is one of the most common protective actions that can be taken for disasters. Recent natural or man-made disasters around the world have provide compelling evidence that transportation system plays a crucial role in the emergency evacuation and have stressed the need for effective evacuation traffic organization to maximize the utilization of the transportation system and to minimize fatalities and losses. However, evacuating a large population exposed to immediate or foreseeable life-threatening danger in the shortest time is an extremely complicated and difficult challenge, which is primarily dependent on careful planning and effective organization.In recent years, it shows the trend of frequent disasters in China. Even through an emergency evacuation plan promptly launched by authorities played a positive role, However, Practice shows that relying solely on qualitative emergency plan is not enough. On the whole, the study on sudden disasters and emergency evacuation in China starts lately. Traffic management in the emergency evacuation mainly takes executive orders and departmental interaction supervise rescue. Without strong support of traffic organization optimization technology including rapid traffic planning, real-time traffic control and traffic information guidance, emergency evacuation traffic management are becoming lack of the optimal strategy to respond whenever necessary with flexibility, coordination and speed, thus leading to the road traffic is one of the bottlenecks in emergency evacuation. Therefore, it is of great significance to research on the methods of traffic emergency evacuation organization optimization for improving the capability of emergency traffic organization.This dissertation studies the methods on traffic organization optimization for emergency evacuation from the following aspecets, and obtains the corresponding creative relults.(1) Proposes a novel method to identify the key nodes and critical routes of road network for emergency evacuation based on information centrality.In order to identify the key of traffic organization and management for emergency evacuation, this dissertation proposes the concepts of the key nodes and critical routes of road network. Moreover, based on the basic principle of information centrality, presents a method to determine the efficiency key nodes, the connectivity key nodes, the comprehensive key nodes and the critical routes of road network for emergency evacuation. Finally, proposes the method to identify the potential bottleneck of emergency evacuation routes. This method helps determine the focus of traffic management for emergency evacuation, improve the effectiveness of traffic plans, and can effectively reduce the complexity of traffic organization for emergency evacuation.(2) Presents a real-time dynamic traffic assignment method for emergency evacuation on the basis of CCRP algorithm.Due to the highly dynamic and uncertain natures involved in the process of emergency evacuation, this paper, on the basis of the Capacity Constrained Routing Planning (CCRP) approach, proposes the real-time traffic assignment method for emergency evacuation aiming at improving the efficiency of traffic assignment. In order to overcome the shortcomings that CCRP algorithm does not take into account the safety and access quality requirements of evacuation routes, and can not solve the sudden congestion in evacuation, the presented algorithm, based on the real-time information, introduces the penalty function in the calculation of link travel time to generate high quality routes and bypass the danger zone. Moreover, the sudden congestion points are taken as temporary virtual origin. Thus, the proposed algorithm can effectively complete real-time route optimization and redistribution of traffic flow as an ideal reference point for signal control and information guidance program for emergency evacuation. This method can effectively improve the speed of the dynamic traffic assignment, further improve the effectiveness of emergency evacuation, and provide technical support for transportation planning of emergency evacuation.(3) Proposes a traffic signal control method for evacuation corridor based on mixed integer linear programming, non-linear quadratic programming and human-simulated intelligent control.In order to meet the requirements of oversaturated corridor, real-time and contingency, this dissertation, aiming at maximizing the efficiency of traffic corridor for evacuation corridor, for one thing, proposes a two-step phase-oriented real-time traffic signal control algorithm by combination of a mixed-integer linear programming and a non-linear quadratic programming to maximize evacuation throughput, fully utilize storage capacity of the road, and provide reasonable service to the transfer inflow and outflow at the key intersections; for another, enhancing the real-time efficiency of ramp, this paper, based on the human-simulated intelligent control, proposes a novel traffic signal control algorithm of ramp metering of urban freeway and expressway for emergency evacuation. The former not only improves the efficiency of emergency evacuation, but has the necessary contingency ability for evacuation corridor; the latter fully utilizes the capacity of urban freeway or expressway and reduces the interference to the operating flow in the main corridor. (4) Presents a method of traffic information guidance strategy and program generation for emergency evacuation on the basis of fuzzy decision.In order to improve the effectiveness of emergency evacuation route guidance information, this paper takes into account the subjective and fuzzy factors of driver’s route choice behaviour in emergency evacuation, based on the actual Stated Preference (SP) investigation, uses concepts from fuzzy set theory and approximate reasoning and proposes the driver route choice behavior model in the presence of traffic information. On this basis, this paper reveals the important factors for drivers to accept the recommenden path, and presents the method of route information guidance strategy and program generation.Taking a capital city and surrounding road network consisting of high-grade roads as research objective, this thesis realizes the above methods through programming and simulation using programming software MATLAB2007, SQL Server2005, and traffic simulation software TransModeler2.6as tools. The results show that the proposed methods of traffic planning, signal control, and information guidance can effectively improve the efficiency of traffic organization for emergency evacuation, help to rapidly generate traffic organization optimization scheme for emergency evacuaion, thus effectively to enhance the rapid response and real-time adjustment of the transportation system in critical situations.The research contents, methods and conclusions are useful exploration for the traffic organization optimization methods under disasters, and provide a theoretical basis and engineering reference to real-time road traffic organization and management for emergency evacuation.