Planning interrelated voyages with separation requirements in roll-on roll-off shipping

Abstract

We consider a new problem of planning interrelated voyages with separation requirements along a single trade in roll-on roll-off shipping. Along a given trade with a sequence of port calls, there is a number of contracts for transportation of cargoes between the different port pairs, where each contract states its service frequency as well as that these services should be evenly separated in time. Instead of visiting all ports every time a trade is serviced, as closely resembles current planning practice, we aim at determining the sailing routes of each voyage along the trade, i.e. which ports to visit when, which contracts to serve, and the sailing speeds, so that all contract requirements regarding frequency and separation are satisfied at minimum cost. We propose and compare two novel mixed integer programming models for the problem, both including a new way of modeling the contracts’ separation requirements. Then we show through a computational study on a set of realistic test instances that significant gains can be obtained compared to current planning practice.