How far to allocate feeder transport to metro effectively? An empirical study in Xi'an, China

Metro construction has encouraged transport emission reductions in the recent decade. Analyzing access/egress distance to station is crucial for transport planning and implementation. In the recent contexts of fast metro construction and advancing information and networking technologies, various feeder transport emerged and access/egress distances to metro extended a lot, but few studies modeled metro mode share variation by access/egress distance. To determine the focus metro catchment area for effective feeder transport allocation, this study explores the threshold range of access/egress distance by walking, biking, bus and park-and-ride. The data comes from a sampling survey of household travel in Xi'an. The results show that, within a 3-km radius of the stations, metro mode shares decrease quickly from 16-23 % to 2–3 %. Beyond this distance, the decreasing rates become quite small. The bus-metro transfer distance can be extended to 6 km in the suburbs. For the effective and economical feeder transport allocation, a 3-km radius of the station is the focus area. The average elasticity of access/egress distance to metro mode share is −0.644 and −1.445, respectively in the central urban area and the suburb, indicating a larger variation compared with the result of −0.29 in North America. The number of parking lots within 50 m of the station is a critical factor for park-and-ride. We recommend providing diverse feeder bus operations and allocating the dedicated and human-oriented walking/cycling lanes within a 3-km radius of the station. In the suburbs, feeder buses can be extended to a longer range, about 6-km radius of the station according to the local demands. We suggest providing park-and-ride facilities within 50 m of the station and simultaneously encouraging shared parking lots. These planning suggestions can promote an efficient access to metro station pattern, optimize urban transport system's performance, and ultimately, obtain the low-carbon and sustainable transport development goal.