Three-level multimodal transportation network for cross-regional emergency resources dispatch under demand and route reliability

Global emergencies, ranging from natural disasters and public health emergencies to terrorist attacks, have been more frequent of late. In the face of large-scale emergencies, it is difficult for an intra-regional emergency resource dispatch mode to meet the subsequent requirements. Essentially, the interruption of local routes leads to uncertainty in resource demand and transportation time. In light of this, this study defines route reliability to describe the possibility of interruption and establishes a functional relationship between route reliability and delay. We further propose a model, using an ant colony optimization design, as a solution to the problem. Using the 2008 Wenchuan earthquake in China as a numerical experiment, the target value of generalized cost was calculated to be 0.3819, which was 9.53% lower than that obtained by a two-level transportation network and 5.71% lower than that obtained by a three-level single transportation network. Additionally, dispatch plans with different route reliability were compared. In the case of pessimistic route reliability, the resources transported by highways were found to shift to railways for long distances and to aviation for short distances. In contrast, for optimistic route reliability, highway transportation with moderate cost and speed was preferred.