Analysis And Calculation Method Of Transportation Capacity Of Urban Rail Transit Network

With the rapid development of social economy,the demand for travel has increasingly grown,and the scale of urban rail transit network has been expanding,and the huge passenger flow pressure has brought unprecedented challenges to construct and manage urban rail transit.In this context,how to accurately calculate the current urban rail transit network transportation capacity to guide the planning,construction and operation of the network has become an important research topic.This paper studies the calculation method of urban rail transit network transportation capacity from the perspective of transportation supply and demand matching.The main contents are as follows:(1)The connotation of urban rail transit network transportation capacity was clarified,and the calculation method framework of urban rail transit network transportation capacity was proposed.Based on the analysis of existing research,the connotation of the urban rail transit network transportation capacity studied in this paper is defined,and the main factors affecting the transportation capacity of the urban rail transit network are analyzed from four aspects:network characteristics,passenger flow characteristics,service level and operational organization.Based on this,an urban rail transit network transportation capacity calculation framework based on pressure test that can adapt to the specified passenger flow structure is proposed.It is pointed out that the integrated optimization of passenger flow distribution and train timetabling is the core module of transportation capacity calculation.(2)An integrated optimization model for urban rail transit passenger flow distribution and train timetabling was constructed.Firstly,by analyzing the characteristics of passenger flow distribution and train timetabling problems and the relationship between them,an integrated modeling idea based on multi-commodity flow model is proposed.Then,the foundation of the space-time network that can fully describe the passenger traveling and train running process is constructed.This paper present a multi-commodity flow-based binary integer programming model to optimize the integrating problem of passenger flow distribution and train timetabling,and the objective function is to minimize generalized time cost of the system.(3)The algorithm for solving the transportation capacity of urban rail transit network was designed.Firstly,aiming at the characteristics of the integrated model and the requirements of large-scale calculation of urban rail transit network,an algorithm for solving the optimization model of passenger flow distribution and operation diagram based on Lagrangian decomposition is designed.Through relaxing the coupling constraint and difficult constraint in the model,the primal problem is decomposed into two kinds of independent space-time shortest path sub-problems about train flow and passenger flow,and each sub-problem is coordinated by updating the Lagrange multiplier in a specific order.On this basis,according to the framework of the pressure test method,the calculation method of urban rail transit network transportation capacity is given.(4)The correctness and effectiveness of the calculation method of urban rail transit network transportation capacity were verified.Firstly,based on a simple example,the correctness of the model and the algorithm are verified by comparing the results of the CPLEX model with the results of the proposed algorithm.Then,based on a small-scale network,the validity of the urban rail transit network transportation capacity calculation method is verified.The statistics of the full load rate of each section of the transit network are analyzed,and the bottleneck of the transit network capacity is analyzed to provide a theoretical basis for optimizing the matching relationship between transportation demand and transportation resources.