A Continuous Time Model of Multi-vehicle Routing Problems: A Column Generation Approach

In this paper, we propose a column generation heuristics to a continuous time model of conflict-free pickup and delivery vehicle routing problems. The transportation system is divided into several regions with regular intervals. A network model of conflict-free multi-vehicle routing problem with acceleration and deceleration motions is developed. A column generation heuristics is used to find a near-optimal solution. The pricing problem for each vehicle routing problem is formulated as a resource constrained shortest path problem, which is effectively solved by a labeling algorithm. Computational results demonstrate the effectiveness of the proposed method.