Urban Public Transit Network Optimization In Consideration Of Transfer Time Composition

The development of Chinese urban public transit now has such problems as unreasonable network layout,which has severely lowered the service level of the urban public transit and the travel efficiencies of its passengers.In order to improve the overall travel efficiency of the passengers,this study newly develops an optimizing model to analyze the influence of the transfer time composition of an urban public transit network upon the travel efficiency of the passengers,and accordingly optimizes the urban transit network layout.Unlike the existing modeling research simply considering the transfer time of a public transit trip as a constant value,this study takes the average transfer time of public transit trips as a variable that consists of an average transfer walking time and an average transfer waiting time.The transit network in the urbanized area of a city in our country has been studied as example.The value of the variable is determined with the statistical survey of the time costs of all the trips with transfers on the transit network.The proposed model is established on purpose of minimizing total travel time of all the passengers.It is assumed that the numbers of the transit lines and the transit stops on the public transit network are unchanged,the passenger travel demands and the travel time between the stops are stable,the passengers transport capacity supply can meet the corresponding travel demands,and each passenger choose the least time-consuming travel route on public transit network.This study optimizes the routes and lengths of the transit lines.Given the prior global search abilities of the Genetic algorithms,this study designs the corresponding Genetic algorithm to solve the new optimizing model.Finally,this work applies both the transit network optimization model with transfer time as a constant and the newly developed model with transfer time as a variable to optimize the same public transit network,and analyzes their optimization results in comparison.The analyzing results show that the transit network optimization model newly proposed in this research is able to determine more rationally the value of the transfer time.In addition,it is found that the newly proposed model can effectively reduce both the public transit trips with too many transfers and the time-consuming transfers.This would be more realistic as to improving the travel convenience of the passengers,and improving the overall travel efficiency of all the passengers on a public transit network.