Understanding passengers' intermodal travel behavior to improve air-rail service: A case study of Beijing-Tianjin-Hebei urban agglomeration

Uneven utilization of airport clusters is a widespread problem, yet China is still planning to build more airports. Intermodal Passenger Transport Service (IPTS), the most typical of which is the Air-Rail Integration Service (ARIS), is one new way to solve this problem. Although some service products have been derived, intermodal travel services are still in their infancy due to problems such as long transfer time and inconvenient connectivity arising from the fact that those products fail to take into account the complexity of transfers between multiple hubs, resulting in a low penetration rate of intermodal services. Therefore, this study constructs a universal Hybrid Choice Model (HCM) framework that includes mode choice and city choice based on an online stated preference (SP) survey about multi-hub intermodal transportation in the Beijing-Tianjin-Hebei urban agglomeration, and introduces travelers' concerns about travel security, comfort, convenience and reliability as attitudinal variables, which expands the research on IPTS. Then the willingness to pay (WTP) for travel service is evaluated to demonstrate intermodal travelers' preference for shorter transfer time, transferring in the metropolis, more reserve time for air than rail, and the impact mechanisms of luggage through-handling service and mutual recognition mechanism of security checks. Last but not least, through scenario testing, we find that the excessive concern for security and comfort among high-educated and high-income passengers with a low tolerance for transfer time will reduce the market share of air-rail. These findings can assist relevant departments and businesses in making more humane plans for intermodal travel and infrastructure construction.