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.