Mitigating the Vulnerability of a High-Speed Railway–Air Network by Optimizing the Location of Integrated Transportation Hubs

High-speed trains and flights are the backbone of interregional transportation. A coupled high-speed railway–air transportation network (HRATN) allows these two modes of transportation to substitute for each other when the HRATN is threatened by extreme events. During train and flight operations, the area of influence and occurrence of extreme events are difficult to predict. Reasonably selected integrated transportation hubs can mitigate the vulnerability of HRATNs to extreme events. Optimizing the locations of integrated transportation hubs makes full use of the transport resources of both modes and facilitates the transfer of passengers, thereby decreasing the losses caused by extreme events. In this research, a tri-level model is established to reduce the potential worst loss by optimizing the location of the integrated transportation hub. The column-and-constraint generation algorithm based on duality is used to solve the model. For an illustrative example case, the enumeration method and sensitivity analysis show that building more integrated hubs can mitigate HRATN vulnerability but decreases unit investment income. This trivial conclusion verifies the validity of the model constructed in this paper. For a real-world case, comparing the corresponding models that do not consider extreme events reveals that the proposed strategy does not conflict with the decision-making in the normalized situation, thus verifying the usability of the present research.