The Modeling And Simulation Of Passenger Flow Evacuation In Rail Transit Hubs

The urban rail transit system is the main skeleton of public transportation,carrying most of the urban residents to travel.With the increase of rail transit lines,the network is becoming more and more complex,and the rail transit hub has become the most important node for passengers to transfer and improve the transportation efficiency.The rail transit hub is the gathering point of multiple traffic lines and the distribution center of various types of passenger flow,with the continuous increase of passenger flow,combined with its closed environment,densely intertwined passenger flow lines,and complicated transfer lines,it’s low passenger evacuation capacity is likely to led to a bottlenecks,affecting passengers’ transfer efficiency and increasing internal safety hazards.Therefore,identifying the bottleneck in the hub,finding the optimal route for large passenger flow evacuation,ensuring the normal and orderly use of the hub and the evacuation efficiency of the passengers in the station have become an urgent problem to be solved.This paper takes the typical rail transit hub station in Chongqing as an example to carry out field investigation and data collection.Use the SPSS software to conduct descriptive statistical analysis of the surveyed passenger flow related data,to study the layout of facilities in different areas of the site,to summarize the passenger flow characteristics during peak hours and to draw passenger flow diagrams.According to the characteristics of passenger flow,the evacuation demand of large passenger flow in the peak transit time transportation hub site is proposed from the four aspects of passengers,station structure,guiding signs and train operation conditions,through the weighted Gray Relational Analysis,the evacuation ability evaluation model of the orbital hub station is established according to the gray relational degree between all the influencing factors,so that the evaluation result is more objective and accurate.The Ant Colony Optimization is selected to optimize the passenger flow evacuation path.It is improved from the three aspects of heuristic function,pheromone concentration update and state transition rule,and the optimal evacuation path model of passenger flow at the orbital hub station is established.Firstly,in order to use the internal structure of the rail transit hub to express the heuristic function more accurately,define the evacuation channel pass coefficient.So that,the heuristic function is proportional to the pass coefficient and the channel width of the evacuation channel formed by the two nodes,what’s more,it’s also inversely proportional to the distance between the two nodes.Secondly,in order to make the nodes that frequently appear in the optimal path get enough pheromone enhancement,the global update rule is set to update the ant path that gets the optimal solution in each loop only.Then,the dispersion is defined by the distribution on the path during the ant exploration process.When the dispersion is large,the distribution of ants on all paths is relatively scattered,in order to improve the efficiency of exploration,the node with a large pheromone concentration is directly designated as the next node of the ant exploration path.Otherwise,the distribution of ants on the path is concentrated,in order to prevent the algorithm from premature convergence,the node with the highest pheromone concentration is removed,and the next exploration node is selected according to the random selection rule.Finally,combined with the example,based on the improved passenger flow optimal evacuation path model,use the MassMotion pedestrian simulation software to simulate the passenger flow evacuation,which provides a reference for the passenger flow evacuation design and daily safety management of the rail transit hub.