Near Optimal Solution for Continuous Move Transportation with Time Windows and Dock Service Constraints

We consider a pickup and delivery vehicle routing problem (PDP) commonly found in the realworld logistics operations. The problem includes a set of practical complications that have received little attention in the vehicle routing literature. There are multiple vehicle types available to cover a set of transportation orders with different pickup and delivery time windows. Transportation orders and vehicle types must satisfy a set of compatibility constraints. In addition, we include some dock service capacity constraints as required in real-world operations when there are a large number of vehicles to schedule. This problem requires to be attended on large scale instances: transportation orders ≥ 500, single-haul vehicles ≥ 100. Exact algorithms are not suitable for large scale instances. We propose a model to solve the problem in three stages. The first stage constructs initial solutions at the aggregated level relaxing time windows and dock service constraints of the original problem. The other two stages impose time windows and dock service constraints within a cut generation scheme. Our results are favorable in finding good quality solutions in relatively short computational time.