Accessibility of urban agglomeration integrated passenger transport network considering travel impedance

To clarify the multi-layer spatial structure of urban agglomeration integrated passenger transport networks and enhance their functional attributes, a new model is proposed that considered urban transport transfer from a novel perspective of coupling. The impedance accessibility of the network is analyzed in terms of travel cost and time. Firstly, the highway subnet and the railway subnet are constructed using the Space-P modeling method from complex network theory. Passenger stations within the urban agglomeration are represented as nodes in the network and are assigned numerical identifiers. The edge weights are calibrated based on travel time and fare. Secondly, the central urban area of each city within the urban agglomeration is designated as a traffic district. Coupling edges are added between nodes connected by urban public transport, walking, or other transfer modes to create coupling subnets. Thirdly, the highway and railway subnets are integrated into a comprehensive network through these coupling subnets. The traditional network efficiency index is refined to develop a weighted impedance efficiency index, which evaluates the accessibility of nodes and networks. Finally, using the Chengdu-Chongqing urban agglomeration as a case study, the results indicate that: (1) the coupling of multiple nodes enchances the impedance accessibility of these nodes, demonstrating that urban transport transfers are a crucial factor in the study of integrated passenger transport network; (2) compared to the highway subnet and the railway subnet, the impedance accessibility of the integrated network improves by 83.4% and 28.5%, respectively, indicating that the coupling of highway and railway passenger subnets significantly enhances the impedance accessibility of the urban agglomeration passenger transport network; (3) promoting the coupling and coordination between stations or across multiple transportation modes is essential for reducing travel costs and time for passengers, thereby facilitating the development of a more convenient integrated passenger transport network within urban agglomerations.