Branch and Price for Service Network Design with Asset Management Constraints

We address the service network design problem with asset management considerations for consolidation-based freight carriers. Given a set of demands to be transported from origins to destinations and a set of transshipment facilities, the objective is to select services and their schedules, build routes for the assets (vehicles) operating these scheduled services, and move the demands (commodities) through the resulting service network as efficiently as possible. We propose a first branch-and-price framework for the mixed-integer formulation of the problem with integer cycle design and continuous flow-path variables. The proposed method includes particular column generation subproblems for dynamically constructing these cycles and paths, as well as an acceleration technique to identify integer solutions rapidly. The computational study shows that the proposed method finds better solutions for large network instances than reported previously.