Split-demand multi-trip vehicle routing problem with simultaneous pickup and delivery in airport baggage transit

In this study, we focus on the routing and scheduling of multi-carriage transit trains for airport baggage transit. It is modeled as a vehicle routing problem with cross-route dependencies caused by side constraints, including split demand, multiple trips per vehicle, and simultaneous pickup and delivery. Besides, some other practical constraints such as time windows, baggage release time, baggage waiting time, and priority of unloading are taken into account in the implementation. The joint consideration of these characteristics brings a unique challenge to determine the start time of each service for aircraft due to the interdependencies across vehicle routes. Thus, we adopt topological sort to construct the directed acyclic graph and then derive the flight service time. Based on that, we develop an Adaptive Large Neighborhood Search (ALNS) algorithm. Moreover, in order to examine the moves quickly, a two-stage solution evaluation method is proposed, where the single tour is checked based on the segment-based evaluation method in the first stage, and the complete solution is checked using the topological sort in the second stage. The results demonstrate the superiority of our algorithm in computational time and solution quality. In addition, some insightful conclusions are drawn through detailed analyses.(c) 2023 Elsevier B.V. All rights reserved.