Abstract In recent years, the increasing segregation and fragmentation of transport service provisions, evidenced between urban and rural areas, and between different administrative divisions, has been concerned in metropolitan areas. The analysis of the spatial configuration of urban bus networks is important to understand the spatial problems and relevant mitigation solutions. Previous studies have regarded the station as the nodes in bus network analyses, while few studies have constructed bus lines as nodes through the complex network analysis. In this study, we highlighted the value of bus lines and their network types for analyzing urban bus network pattern. We developed a novel ‘line–line’ network to examine the spatial characteristics of cross-administration bus lines in a case study of Nanjing metropolitan area, China. The results suggest that the bus network exhibited a consistently bimodal node distribution in both line-line and line-node network types, though their internal mechanisms are different. By evaluating the importance of network nodes, administrative divisions were found to impact the bus network integration in the metropolitan area negatively. Community detection results further revealed that the geography of some subnetworks was affected by administrative divisions, with some exhibiting complex spatial characteristics. These insights would inform strategic development policy to improve the spatial equity and efficiency of public transport provisions in urban China.

Highlights • The spatial fragmentation of transport networks is concerned in metropolitan areas. • A novel ‘line–line’ network was developed to examine cross-administration bus services. • Urban bus services were analyzed through three network types in Nanjing metropolitan area. • Administrative divisions had a negative impact on the metropolitan bus network integration.