New Formulations for the Scheduled Service Network Design Problem

We propose a new approach to formulating the Scheduled Service Network Design Problem (SSNDP) that involves modeling with enumerated consolidations of shipments routed on the physical network. This is in contrast to the classical approach of capturing the synchronization of vehicles and shipments needed for consolidation with a time-expanded network. The proposed formulation has both a stronger linear relaxation and is less symmetric. We present multiple speed-up techniques and with an extensive computational study illustrate that the consolidation-based formulation is much easier to solve with an off-the-shelf solver than the classical formulation based on a time-expanded network.