Improving the Initialization and Repair Heuristics to Effectively Solve the Pickup and Delivery Problems with Time Windows

Pickup and delivery problems with time windows (PDPTW) are challenging yet realistic scheduling problems in which each delivery vehicle is assigned to handle different pairs of pickup-anddelivery requests. Our previous work successfully adapted the push forward insertion heuristic (PFIH) for initialization, and proposed a new swap operator to effectively solve PDP-TWs. In this paper, we improved our adapted PFIH to efficiently obtain a better initial solution. Moreover, we proposed an adaptive swap (AD-Swap) operator that can flexibly revise its neighborhood size for iterative improvements. Our improved search prototype achieved remarkable results against those of a tabu-embedded metaheuristic search or our previous work on a set of modified Solomon’s test cases. More importantly, our improved heuristics can easily be integrated into many search schemes to solve other scheduling problems.