Research On Evacuation Capacity Of Urban Rail Transit Stations

Urban rail transit is favored by travelers because of its large capacity,punctuality,and quickness.However,operational safety issues are gradually exposed.Because urban rail transit stations are mostly underground confined spaces,and there is a large amount of passenger volume.Once an emergency occurs,the evacuation of trapped persons will be likely to have potential problems which would cause secondary accidents.It is the premise of safe and efficient evacuation that the evacuation capacity of urban rail station can meet the demand of passenger flow.Therefore,it is of great significance to study the evacuation capacity of related stations in advance to reduce the accident rate in the evacuation process and to improve the passenger evacuation speed.Firstly,this paper analyzes the relationship between passenger flow speed and density at the facilities,and establishes the passenger flow queuing model in the facilityies,then analyzes the interaction of the parameters of the facility queuing model between the adjacent facilities to construct the station evacuation queuing network,and combines the evacuation equilibrium to construct the node probability selection model.The model is used to calculate the related indicators of station evacuation capacity and evaluate the network evacuation capacity of stations.Then use AnyLogic to verify the algorithm,and propose suggestions about the improvement and optimization of station facility geometric attributes and evacuation flow line optimization.The specific research content is as follows:(1)Clarify the definition of urban rail transit station evacuation capacity;analyze the influence factors of the evacuation capacity of the station network from three aspects:the station evacuation network structure,the structure of the facility junctions,and the capacity of facilities;Formulate survey plans for the geometrical properties of station facilities and passenger flow behavior of each facility under different scenarios;aimed at different busy-level Beijing urban rail transit stations,conduct investigation of passager flow behaviors during morning and evening rush hour.Based on this,analyze the characteristics of passenger flow aggregation and walking behavior of each facility.(2)Based on the characteristics of passenger flow at different facilities,build the queuing model of passenger flow at passages,stairs/escalators and gates under different capacity limits of the entrances.Determine the corresponding indicators of passenger flow at each facility,the average travel time of passenger flow,and the passenger traffic congestion probability and the number of passengers in the queues,etc.Analyze the relationship between the parameters of the queuing model with previous and subsequent connections,and building passenger evacuation queuing network in the station.(3)Propose an evaluation framework for station evacuation network capabilities;use K-shortest-paths algorithm to search for feasible evacuation routes and stores them into a feasible path set;introducing evacuation time reliability,based on the Logit model,setting the optimization goal of evacuation equilibrium to construct the node probability selection model in station evacuation network.The station evacuation queuing network and the node probability selection model are considered synthetically and then the evacuation capacity calculation procedure based on the rigorous capacity restriction feature of the queuing model is given.(4)Take the example analysis of Beijing Urban Rail Transit Station-Jianguomen Station.Three different types of scenarios are established.The calculation of the passenger flow density,facility saturation,and path evacuation time are performed using the scenario with the largest evacuation volume as an example.Based on this,the bottlenecks are identified.The simulation software AnyLogic is used to set the corresponding scenario and make a comparation.Verify the effectiveness of the model with the results of the passenger flow density of the facility and the evacuation volume of each outlet.Based on the results,the suggestions for improving the evacuation capacity of the Jianguomen subway station are proposed.