Research On Coupling Optimization Design Of Urban Rail Transit And Local Bus Transit Network

With the rapid economic growth and the acceleration of urbanization,the car ownership of urban residents is also increasing year by year,and the traffic congestion caused by these problems also need to be solved urgently.As an indispensable part of urban transportation,public transport system plays a great role in regulating the contradiction between travel demand and travel supply of urban residents.At the same time,the use of public transport can also alleviate urban road congestion and reduce carbon emissions.Rail transit and local bus are the two most important modes of travel in the public transport system.The coordinated development between them can improve the operation efficiency of the overall urban transportation network.However,due to the construction of transportation infrastructure,a series of problems such as overlapping service scope of rail transit and local bus,poor connection during transfer,unreasonable station spacing or departure frequency will inevitably occur,and cause the waste of public transport resources,thus affecting the transportation efficiency.Considering the strong randomness and uncertainty of passengers’ travel demand and the extremely irregular road network in the actual environment,this thesis needs to build a regular road network structure to facilitate the construction and solution of the model.This thesis carries out the coupling optimization design of urban rail transit and local bus based on the ideal Square Road network,and takes into account the various route choices of passengers according to the differences of station types,A double-layer mixed integer optimization model is constructed to solve the departure time distance of subway and conventional bus,the line spacing and station spacing of conventional bus.The upper model is a continuous approximate model aiming at minimizing the total cost of the system,so as to find the balance relationship between passengers and operators,and deduce each cost in detail.The sequential quadratic programming algorithm is adopted,and the convex algorithm is used to envelope the nonconvex problem.The lower layer is the path allocation problem considering the distribution according to probability,and the traffic of each path is weighted.Considering the non convexity of the analytical form of the problem,the heuristic method is used to solve it.In order to verify the feasibility of the model,this thesis takes two actual subway bus line networks in Futian District of Shenzhen and Jianye District of Nanjing as examples for case analysis,and gives the optimal network design parameters under different average travel distance and passenger flow density.The results show that with the increase of average travel distance of passengers,the departure frequency of conventional bus can be increased,the distance between conventional bus stops can be reduced,and the distance between conventional bus lines can be appropriately increased,These optimization methods can effectively reduce the travel time of bus passengers and improve the competitiveness of public transport.At the same time,it is found that with the increase of transportation distance,the optimized rail transit departure frequency has a fluctuating trend of first decreasing,then increasing and then decreasing.In the case of congestion,the optimized rail transit departure frequency is higher than that in the case of non congestion.The extent of saving the total cost of the system by this optimization method increases with the increase of passenger flow density.The saving proportion of the total cost of the system finally shows an increasing trend with the increase of travel distance.On the whole,the saving proportion of time cost is also higher than that of the total cost of the system.This study can provide theoretical support for the design of urban subway bus network in China,and is of great significance to accelerate the integration of rail transit and conventional bus network.