Research On Bus Evacuation Optimization In Urban Local Disaster Environment

All kinds of sudden disasters occur constantly and they have affected human society deeply.In order to reduce the casualties and property losses caused by disasters,it is necessary to formulate an emergency evacuation plan to evacuate people and important properties in the affected area as soon as possible.With the acceleration of the urbanization process,in order to alleviate the problems of urban traffic congestion and high travel costs,the government has made great efforts to develop public transportation,so buses can be found all over the city.The number of buses is large,the bus capacity is large,and they are easy to dispatch.They can undertake the task of evacuating car-less persons when disasters occur.However,it is necessary to carry out scientific evacuation planning so that the role of buses in the evacuation process can be effectively played.Therefore,this paper establishes evacuation optimization models based on public bus under the urban local disaster environment.According to the characteristics of disaster evacuation,this article divides it into two types of evacuation activities: early warning disasters and no-warning disasters.In a no-warning disaster environment,because the evacuation time is very short,it is necessary to evacuate as many trapped people as possible in a short time.So we consider a small amount of evacuees with strong mobility walking in a short distances between pick-up points,then add it to the bus evacuation model to improve evacuation efficiency.A simulated annealing algorithm is designed to solve the model in order to get the best evacuation plan as soon as possible.In an early warning disaster environment,people have some time to prepare for evacuation.So first,establish a pick-up points selection model.This model can reduce the number of evacuation pick-up points and thus reduce the scale of the problem,and also facilitate evacuation management and vehicle scheduling.Then establish a vehicle allocation and route selection model.The model allocates evacuated bus vehicles to each space-time pick-up point to evacuate all trapped people as much as possible,and at the same time obtain the bus flow and evacuee flow on each arc.In the end,the article selects a representative local area in Haidian District of Beijing as an example to verify the practicability and effectiveness of the model in the two disaster environments.The results of the example analysis show that in the early warning environment,the optimal evacuation plan obtained by using the model established in the article can successfully transfer all evacuees to the shelter within the evacuation time.In the no-warning environment,because of a small amount of evacuees with strong mobility walking in a short distances between pick-up points,the optimization model greatly improved the evacuation efficiency and reduced the number of victims.It is hoped that the model established in this paper can provide emergency evacuation plans for evacuation decision-makers and provide a basis for organizing evacuation actions,thereby improving the evacuation efficiency and minimizing personnel casualties and property losses.