Integrated planning for multimodal networks with disruptions and customer service requirements

Multimodal carriers are third-party logistics providers who utilize multiple modes of transportation to deliver timely door-to-door services to their customers. Notwithstanding frequent service disruptions, customers have ever-increasing expectations for on-time deliveries, posing significant challenges to tactical planning. Inspired by the operations of actual carriers, we study the tactical decision planning of multimodal freight networks, considering operational disruptions, timetabling restrictions, and explicit customer service requirements. Despite our focus on tactical planning, our models integrate long-term commitments by penalizing deviations from strategic goals with last-minute operational planning decisions, which are recourse actions aiming to accommodate service disruptions. After improving the dual bound of our initial formulation, we provide reduced-sized models for the special cases of nonpropagating delays and nonreactive last-minute decisions. This latter formulation is utilized to construct scenario-based and trip-based heuristics, which we combine in a hybrid search loop. Our computational study illustrates that our approach attains high-quality solutions for real-sized instances that are otherwise unsolvable by off-the-shelf optimization software, and a significant improvement over a nontrivial rolling horizon benchmark.