Optimizing The Transportation Capacity Of The Urban Rail Transit Lines Under The Operation Mode Of Express/Local Train

Due to the characteristics of large volume,fast speed,safety and punctuality,urban rail transit has become the main mode of public transport development in major cities,and also the preferred means of transport for more and more travelers.With the aggravation of population density in the central urban area,a large number of people pour into the urban fringe groups and peripheral areas,making the urban rail transit lines gradually extend to the periphery.The unbalanced spatial distribution of such lines and the long distance between stations lead to the low matching degree between train capacity and passenger flow,which reduces the line capacity and leads to the decrease of passenger travel efficiency.As an important means to improve transport capacity in recent years,the operation mode of express/slow train has attracted more and more attention.In this context,it is of great theoretical significance and practical value to carry out the research on the optimization method of urban rail transport capacity under t the operation mode of express/slow train.The paper analyses the general calculation method and influencing factors of urban rail transit line capacity,among which the main influencing factors are fixed equipment,mobile devices and vehicle organization scheme.Comparing and analysing the influence of three train organization schemes,namely,train multi-routing mode,train multi-marshalling mode and train stop scheme,on line capacity.The passenger flow conditions and line conditions of the operation mode of express/slow train are analyzed.The passenger flow conditions are as follows: the line passenger volume is medium level,the unbalanced coefficient of passenger flow section distribution is greater than1.5,and the proportion of middle and long distance passenger flow in the total passenger flow is higher;The line conditions are as follows: the total length of the line is more than 35 km,the average passenger transport distance is more than 1/4 of the bus route length,the station spacing is between 1.5 and 5 km,and the crossing station is set as the double island four-line station.A bi-level programming model for line capacity optimization under the operation mode of express/slow train is established.The upper model aims at minimizing passenger travel time and train stopping cost,and takes the ratio of fast and slow train running,train departure interval,fast train stopping and overtaking station selection as decision variables.Based on the behavior analysis of passenger path selection,the lower model is based on Logit stochastic passenger flow assignment model.Finally,the particle swarm optimization algorithm is used to solve the model.Taking Guangzhou metro line 14 as an example,this paper analyzes the line background of line 14,brings its line and passenger flow data into the model to solve the optimization scheme,obtains good optimization effect,and verifies the validity of the model.