Enhanced Branch and Price and Cut for Vehicle Routing with Split Deliveries and Time Windows

In this paper, we study the split delivery vehicle routing problem with time windows (SDVRPTW) that is a variant of the well-known vehicle routing problem with time windows (VRPTW), where each customer can be served by more than one vehicle. We propose enhancement procedures for the exact branch-and-price-and-cut algorithm that was recently developed for the SDVRPTW. In particular, we introduce a tabu search algorithm to solve the column-generation subproblem, extensions of several classes of valid inequalities, and a new separation algorithm for the k-path inequalities. Computational results show the effectiveness of the proposed enhancements.