Measurement And Optimization Of The Connectivity Of Bus Network Based On Travel Impedance

The connectivity of bus networks is the main index for evaluating the capacity of bus service.Previous researches have been based on the topological structure of the bus network,measuring bus network connectivity from the perspective of bus service providers.This paper presents a method to measure and optimize network connectivity from the perspective of bus travelers.The proposed bus network connectivity measurement method integrates both the bus travel impedance(BTI)and the passengers' recognition degree to BTI(i.e.connectivity threshold)into the measure of bus network connectivity by exploiting bus Global Positioning System(GPS)data,bus network geographical data,and the data of passenger questionnaire survey.Bus GPS data and bus network geographical data are used to calculate the BTI.And the passenger questionnaire survey data are used to determine the connectivity threshold.On this basis,the method determines whether a station pair is connected or not based on comparing the BTI of the station pairs and connectivity threshold,then establishes the first-order connectivity matrix to describe the connection state of station pairs in network under the non-transfer condition.The k-order connectivity matrix can be used to describe the connection state of all the station pairs in bus network under(k-1)-time transfers,which is obtained through the matrix self-multiplication of the(k-1)-order connectivity matrix.Finally,a bus network connectivity-statisfied index is proposed to measure the degree of statisfaction of passengers to the network connectivity provided by the bus service providers.Further,establish a new bus network optimization method that is aimed at improving the degree of statisfaction to the network connectivity on the base of the proposed connectivity measurement method.Firstly,the first step of the method is to determine the sequence of bus lines that need to be optimized according to the impact of bus lines to the bus network connectivity.Further,the target bus lines that need to be optimized are judged,and then,building the bus network connectivity optimization model based on the bus departure frequency,and by adjusting the bus frequency of the target lines to promote the satisficing of passengers to the network connectivity.In the end,the proposed measurement method and optimization method of this paper are applied to improve the degree of statisfaction of passenger to the network connectivity of Ping Fang District of Harbin.The results of the case show that the proposed connectivity measurement and optimization method of this paper can be used to measure the connectivity of bus networks from the passengers' perspective,and improve the degree of statisfaction to the network connectivity.In addition,the proposed bus network connectivity-statisfied index can be used to analyze the time variation characteristics of bus network connectivity;and the proposed bus network connectivity optimization method provide a new view to improve the bus network connectivity,that is,it can improve the degree of statisfaction of passengers to the bus network connectivity provided by bus service providers from the perspective of bus dispatching.