Study On Route Selection And Vehicle Allocation Algorithm Of Bus Emergency Service

With more and more people in our big cities and more and more complex transportation networks,Residents’ travel is characterized by high concentration and diversified modes.In recent years,the number of urban emergencies continues to increase,the scope of influence continues to expand,there are many difficulties in traffic evacuation.First,urban vulnerable groups cannot start rapid evacuation by themselves;second,private car evacuation is of low efficiency,high randomness and high vulnerability.In order to improve the efficiency and reliability of emergency evacuation,this thesis studies the planning method of emergency evacuation based on bus and special lane system,which provides reference for urban traffic emergency management in China.Taking the residents of the affected areas in urban emergencies as the research object,the location of available rally points and the design of evacuation routes for public transport have been studied,the assembly point location model and the evacuation path optimization model have been set up,the method of model parameter calibration and effect evaluation have been put forward.First,the thesis analyzes the characteristics of emergencies,studies the intensity and influence range of different types of emergencies,and classifies and grades them.The influencing factors of bus evacuation were studied,including site layout,event category,regional scale,passenger flow,road network structure,etc.,and order relationship analysis method(G1 method)model of alternative assembly point was established.Considering the walking distance of residents to the alternative rally point and the reliability of the alternative rally point,a multi-objective optimization model of the available rally point based on the p-median was established and the model parameters were calibrated.Secondly,according to the indexes of disaster resistance,accessibility,and the completeness of refuge facilities,a G1 method based refuge point model was established,and the number and location of the refuge points were screened by the model.On this basis,the thesis studies the bus evacuation route between the available rally point and the refuge point,and obtains the travel time of the section by using the road resistance function model of the bus lane.In this thesis,the shortest path algorithm was combined to calculate the time of each evacuation path,and the maximum timeconsuming path of the bus emergency evacuation path was taken as the goal,and the number of evacuees,the number of vehicles and the capacity of the refuge point were taken as the constraint conditions to build an evacuation route selection and bus distribution model.The genetic algorithm was used to solve the model,and a reasonable and effective scheme was obtained.Finally,this thesis takes a central urban area as an example,assumes the attribute information of the emergency and the scope of the event,and makes a public evacuation plan.The results show that: 1)the number of evacuees in the affected area and the capacity of the refuge point have an impact on the number of bus trips;2)the evacuation number of the alternative rally point and the distance to the available rally point have an impact on the site selection of the available rally point;3)In this thesis,the evacuation route scheme of bus lanes is considered to improve evacuation efficiency in emergency.