Adjustment And Optimization Of Urban Conventional Public Transportation Network Based On Two-stage Method

With the development of cities,the development direction of most cities is gradually planned from single-center to multi-center.Under the premise of increasing economic and living standards of residents,the characteristics of residents’ travel needs are gradually changing,and new needs are constantly changing.Therefore,in the context of vigorously developing the "transit city",the existing urban public transportation system’s service capacity and level are required to have matching or even advanced high-quality development.The rapid development of rail transit puts forward new requirements for the positioning and route layout transformation of urban conventional buses,that is,the gradual adjustment of urban conventional bus routes to achieve the goal of "the integration of the two networks,coexistence and growth".Starting from the coordination and integration of the overall line network layout of the urban public transportation system,this paper analyzes the basic theories of urban rail transit and conventional public transportation,the characteristics of the line network,the spatial topological relationship between the two,and the competitive and cooperative relationship.A two-stage optimization and adjustment method for urban conventional public transport network based on rail transit lines is proposed.In the first stage,urban conventional public transport lines are screened from two perspectives of spatial relationship,and the set of lines to be adjusted is obtained and the principles and methods of line optimization and adjustment are analyzed.In the second stage,a mathematical model is established to optimize the city’s conventional bus lines to be adjusted.Considering that changes in the bus network will affect the changes in passengers’ travel strategies,a bi-level planning optimization model is established,and the upper level is based on the total travel time of passengers in the system.The minimum is the goal for the layout of the bus line network,and the direction layout of each bus line in the research area is determined.The lower level distributes the bus passenger flow based on the principle of user balance and uses genetic algorithms to solve the problem.Finally,an empirical study is carried out based on the public transportation network in Dalian,and the sensitivity analysis is carried out on the vehicle speed,line departure frequency and comfort parameters respectively.The empirical optimization results show that when the common line sections of conventional bus lines affected by rail transit lines are truncated and canceled to varying degrees,and connection modes are created at the common station sites to increase the proportion of commuting passengers,the system will be in the new equilibrium state and the passenger travel time has decreased to a certain extent;and a moderate increase in conventional bus line vehicle operating speed,departure frequency and adjustment comfort will reduce the total travel time of passengers from different angles,and increase the attraction of public transportation to passengers.