Study Of Bus Network Optimization And Adjustment At The Beginning Of Urban Rail Traffic Operation

With the rapid development of China’s national economy,the motor vehicles population in urban has increased drastically,and the problems of urban traffic become more and more serious.In order to solve them,the priority development of urban public transport construction has been paid much more attention.It is an urgent need to develop the mode of rail transit thanks to its unique nature.However,the development of rail transit started late in China,and its network degree keeps low,so that building a reasonable integrated rail transit-bus network has become quite vital.In the actual rail transit construction process,because its feature of time-order,the conventional bus adjustment and optimization should be considered in advance in the early stage,so as to maximize their effect in the urban passenger transport.The above topic is the very point of research in this paper.Firstly,the function and position of each transportation mode are analyzed,beginning with the system of urban public transport.Meanwhile,the influence scale of traditional bus network is studied with the target of getting benefits at any passenger flow level.Thus the reasonable attraction scale of rail transit is defined.Besides,the method of designing overall feeder bus network is discussed combined with the existing researches.Secondly,the adjustment of existing bus network is studied after putting the rail transit into operation by defining the reasonable attraction scale of rail transit.Furthermore,the significant influence factors are selected,which can reflect the relationship of cooperative-competition between them.These factors are dealt with by SPSS statistical software.The classification method of input condition of K-Means cluster analysis is put forward to avoid the subjectivity,and the adjustment strategy of existing lines is worked out.Thirdly,regarding an integrated rail transit-bus network as the goal,the selecting method of feeder stations is given based on the reasonable attracting scale of rail transit.Also,the layout and assignment of new feeder bus routes are proposed at the beginning stage of rail transit operation.Then,a bi-level programming model is built to optimize feeder bus network,which takes maximum the direct passenger flow density and the revenue of operating company in upper model,and the takes minimum the cost of passenger travel in lower model as objective,considering benefits of social,operating company and passengers.In addition,corresponding algorithm is designed to solve the bi-level programming model and genetic algorithm is used in upper model,a new label method based on the optimal travel strategy is used in lower.Finally,the adjustment method,the optimization model and the algorithm are tested by a concrete example of the rail transit line 1 in Lanzhou.The results show that the adjustment method of the existing bus network is reasonable and effective.Additionally,the bi-levelprogramming model is more effective than the upper one by comparing their Pareto solutions.Therefore,the practical value and significance of this paper are verified.