Routing and scheduling for deployment of vessels for one of the world’s leading RoRo carriers

Transportation of cars by sea is mainly performed by specialized vessels. These vessels are purpose built for transporting cars and trucks, but some also transport other rolling equipment (high and heavy) and non-containerized cargo (break bulk). In this paper we introduce a routing and scheduling problem for deployment of the fleet of roll-on roll-off (RoRo) vessels. This problem is based on a real-world problem faced by Wallenius Wilhelmsen Logistics (WWL), one of the world’s leading RoRo carriers. WWL operates more than 60 RoRo vessels, and transports more than 2.3 million vehicles, rolling equipment, and static cargo each year to destinations around the world. Maritime planning problems are also often divided into three modes of operation: liner, tramp, and industrial shipping (Lawrence, 1972). In liner shipping the ships operate according to a published itinerary and schedule similar to a bus, and the operator tries to maximize their profit from cargoes lifted. Tramp shipping resembles taxi services, where the ships follow the available cargoes and the operator tries to maximize the profit from mandatory and optional cargoes. Industrial shipping operators usually own and control both the cargoes and the ships, and the objective of the operator is usually to minimize transportation cost (Christiansen et al., 2007). Traditionally, planning is divided into three classes based on the length of the planning horizon: strategic, tactical, and operational. Strategic problems are long term planning problems, which in shipping usually means 5 to 20 years. Fleet size and mix, network design, and contract evaluation are all typical strategic planning problems. Problems with a planning horizon length of a few weeks up to 18 months are usually referred to as