The spatial structural patterns of commuting trips by bus and metro in Beijing, China: Complementary or competing?

Public transport in many cities has become increasingly multimodal. How to better integrate various transit services and routes in accommodating daily travel needs requires particular attention. However, few studies have investigated the spatial structures of transit trips and how such structures may differ or coincide between transit modes. Drawing on Beijing, China, as a case study, this research performs a suite of geo-spatial analyses to investigate the spatial clustering patterns of commuting trips via bus and metro. A refined spatial similarity index is also employed to examine the spatial relationships between commuting trips via the two transit modes. Through community detection, the results indicate that the spatial clusters are more identifiable for short and medium durations (0–20 and 20–40 min) than for longer trips (40–60 min and above). In addition, potential competing and complementary relationships between bus and metro services are identified, especially in and around some established locales with a more balanced provision of employment and housing. For prolonged commutes (40–60 min), greater spatial similarity between bus trips and metro trips is found for some inner-city areas, suggesting a potential mismatch between residences and working places. Implications are derived to inform the coordination of bus and metro services to better accommodate commuting demands of varying lengths.