Bus-led Urban Emergency Traffic Evacuation Research

Emergencies may trigger large-scale regional evacuation,resulting in emergency traffic evacuation.The goal is to quickly and safely transport rescue forces to the place where the emergency occurs,and evacuate people within the scope of the emergency to the refuge in a safe and orderly manner place.To formulate an emergency evacuation traffic organization method that takes into account the efficiency of rescue and evacuation,which is the key to solving the mergency traffic evacuation problems,ensuring the successful completion of rescue and evacuation tasks and reducing casualties and economic losses caused by emergencies.Taking public transportation as the leading role,supplemented by other means such as private cars,evacuation of people within the scope of compulsory evacuation in emergencies can not only help the evacuation of people with low mobility,but also is particularly in line with our national conditions,and can efficiently use the urban road network to complete emergency evacuation.Based on this background,this paper develops a segmented multi-modal bus emergency evacuation traffic organization method to solve large-scale regional evacuation problems.Firstly,read the literature to determine the definition,type,level,characteristics of emergencies,traffic and crowd characteristics of emergency evacuation,and limit the scope of the study.Then,a segmented multi-modal bus emergency evacuation theory considering emergency rescue and evacuation is constructed,and the functional structure of segmented bus emergency evacuation,which considers emergency rescue,is divided into golden rescue stage and rescue mitigation stage;and the organization of multi-mode bus emergency evacuation,which considers urban conventional rescue and transportation system.And carry out the overall design of the emergency evacuation of segmented multimode public transport,clarify the required basic data and data sources,study evacuation area and the method of dividing evacuation zones,and provide fundamental guidelines for formulating the emergency evacuation plan of segmented multi-mode public transportation.Secondly,carry out supply and demand analysis,summarize and analyze the types of rescue needs and evacuation needs and their corresponding supply sources,and determine the estimation method and change law of the scale of evacuation needs.It is clear that the public transport evacuation assembly points and shelters as the public transport evacuation demand collection and distribution center are the key points of the evacuation demand,and the qualitative and quantitative analysis are made: quantify the alternative principles of the public transport evacuation assembly point,and construct an optimization model for the selection of public transport evacuation assembly points was constructed,aiming at the shortest total walking time of public transport evacuation demand and the least total number of collisions between people and vehicles,and with the constraints of the number of assembly points,assembly point capacity,maximum walking time,and evacuation demand,and design a solution algorithm,so that it can effectively reduce the walking time of public transport evacuation needs,which indirectly reduces the travel time and number of routes of public transport evacuation vehicles,improves the overall evacuation efficiency,and reduces various losses;determine the comprehensive evaluation method of refuge places,which is used to establish a candidate set of shelters,and build a shelters selection model with the goal of minimum total cost.Then,with the goal of minimizing the total travel time of emergency rescue vehicles and bus evacuation vehicles and the total cost of shelters,an integrated optimization model for vehicle deployment and path planning-shelters(referred to as "integrated optimization model")is constructed: according to the golden rescue stage and the rescue mitigation stage,divide several evacuation time periods;determine the evacuation network optimization architecture method based on graph theory,formulate traffic control measures to eliminate conflicts and reduce delays,and convert them into quantitative constraints;determine the allocation method of emergency rescue vehicles and bus evacuation vehicles,according to the evacuation time period,reflecting the dynamic nature of emergency evacuation;determine the objective function expression and the calculation formula of road section travel time considering the degree of danger,and based on evacuation safety,economy and reliability,analyze the mathematical expressions for constraints such as node flow,available bus evacuation vehicles quantity,arc flow,capacity of shelters,service coverage of shelters,and road network management and control measures;using none-dominated Sorted Genetic Algorithm II to solve the integrated optimization model to achieve simultaneous optimization of vehicle allocation,route and shelter selection,formulate the emergency rescue and bus evacuation traffic organization plan,directly reduces the evacuation time,reduces the evacuation risk,controls the evacuation cost,and ensures the overall optimization.On the basis of the results of the integrated optimization model and the urban rail transit road network,the rail transit evacuation plan with the smallest total cost of the refuge is determined;the on the basis of the results of the integrated optimization model,topology of the evacuation network is reconstructed to determine the private evacuation traffic evacuation plan.Finally,taking the emergency evacuation in some areas of Zhongshan District and Xigang District of Dalian City as examples,the emergency evacuation plan for rescue needs and evacuation needs is formulated,and the traffic organization method,model and algorithm of the segmented multi-modal bus emergency evacuation traffic organization method proposed in this study are verified.And briefly supplement the emergency evacuation traffic management strategy to improve the emergency evacuation strategy.