Research On Public Transport System Efficiency Based On Multi-layer Network

The city changes a process to be accelerated increasingly,city population and the number of private cars increases dramatically,so that the problem of traffic congestion is becoming more and more serious.Public transportation system takes on the biggest passenger volume in the city,so it can enhance its appeal to the travelers,increase the carrying capacity of public transportation and ease the urban congestion by optimizing the route of public transport and improving the efficiency of public transport.In this paper,the multi-layer complex network theory is applied to study and solve the efficiency of urban public transport.However,there are still three difficulties in applying it to the study of urban public transport system: 1)how to establish multi-layer public transport network;2)how to set up the indicators and weights of public transport network to accurately represent the topological structure and functional characteristics of the network,of which the most interesting and challenging is how to represent the inter layer;3)how to improve the efficiency of the public transport network and optimize the network structure by the analysis results,that is,the optimization of routes.This paper mainly focuses on the efficiency of urban public transportation,aiming to build a set of relatively complete network indicators and models that conform to the characteristics of the transport system,so as to analyze the internal characteristics of the public transport network and the relationship between the sub-systems.By optimizing the application of public transport lines,the efficiency of public transportation can be improved.The main contents of this paper are as follows:(1)this paper proposes a structural representation method of aggregation point graph,which is a simplified structure of public transport network.Aggregation point can simplify the urban public transport network by aggregating some stations with similar geographical space into a node,which can not only display the framework of the urban public transport network,but also greatly reduce the computational complexity Degree.(2)This paper constructs a three-layer network model of urban public transportation.Firstly,L-space representation is used to abstract the structure of urban public transport network into a traditional single-layer network structure and simplify it into an aggregation point graph.In order to connect bus layer with subway layer,we add a middle layer.The relationship between the two modes of transportation is transfer,so we extract bus stations within a certain distance around all subway stations to form a middle layer,a three-layer network model of urban public transportation is constructed with bus layer as the foundation layer and subway layer as the core layer.(3)We give a definition of nodes and edges weights.The definition of the nodes weight is helpful to identify the nodes that have important roles on both bus layer and tram layer as well as integrated multi-layer network.By considering the topological and structural characteristics,a new definition of edge weight is proposed,which reflects the efficiency of bus lines and is of great significance to solve the problem of public transportation efficiency.(4)Combining with the example of the Changchun public transport system,this paper analyzes the status quo of public transportation network of Changchun City,excavates the important lines in the urban public transportation system based on the above-mentioned definition of weight,optimizes these public transportation lines through genetic algorithm(GA),improves the efficiency of urban public transportation,and proves the rationality and effectiveness of weight definition.