A Shortest Path Heuristic for Evaluating the Quality of Stowage Plans in Roll-On Roll-Off Liner Shipping

Abstract

Abstract. Roll-on Roll-off shipping companies transport rolling cargo, such as cars, trucks and large construction machines. When sailing, this type of cargo must be attached to the deck using chains, to prevent damaging the cargo. For each voyage including multiple port calls where the cargo is loaded/unloaded, an important decision is to decide where to place each vehicle (or unit), such that the time used on shifting is minimized. Shifting means temporarily moving some vehicles to make an entry/exit route for the vehicles that are to be loaded/unloaded at a given port. As the vehicles are securely fastened to the deck, shifting is a time-consuming procedure. We present the stowage plan evaluation problem which is to determine the optimal vehicles to shift at each port call, such that the time spent on shifting is minimized. Given a set of alternative stowage plans for a voyage, the results from the stowage plan evaluation problems are used to determine the best among these stowage plans. We present a shortest path based heuristic for solving the problem. Computational results show that the solution method is a powerful tool for comparing stowage plans, due to its fast computing times and high success rate, i.e. its ability to determine the better of two stowage plans.

An adaptive large neighborhood search heuristic for the planar storage location assignment problem: application to stowage planning for Roll-on Roll-off ships

“…In their work, heuristic rules are used to guide the placement of the vehicles. To determine the true objective value of a solution, an additional optimization problem must be solved, namely the stowage plan evaluation problem (SPEP) introduced by Hansen et al (2017). In this work, we extend the original stowage model defined by Hansen et al (2016) to account for shifting explicitly, building on the ideas of Hansen et al (2017).…”

“…In this case, however, an optimization problem must be solved to provide the value of c(X ), namely the Stowage Plan Evaluation Problem (SPEP). We solve this problem by using the shortest path solution method proposed by Hansen et al (2017). Given a stowage plan X , the method decides which vehicles to shift at each port such that none of the loading/unloading vehicles are blocked, by solving several shortest path problems.…”

“…Given a stowage plan X , the method decides which vehicles to shift at each port such that none of the loading/unloading vehicles are blocked, by solving several shortest path problems. Hansen et al (2017) show that the method is effective in determining the better of two stowage plans, which is what we intend to use the method for in this work, i.e. to compare the shifting cost of the temporary stowage plan c(X ) with the shifting cost of the current one c(X ).…”

“…Even though the method presented by Hansen et al (2017) is computationally effective, the time spent evaluating the shifting cost of different solutions make up a substantial amount of the overall runtime of the algorithm. Hence, as mentioned in Sect.…”

A branch and bound approach for large pre-marshalling problems

“…We highlight the Container Relocation Problem (CRP) that just differs from the CPMP in that containers are successively removed from the bay as the CRP is solved (Tanaka and Takii, 2016;Tanaka and Mizuno, 2018). Other related problems are: the loading of vehicles on a "roll-on roll-off" ship (Hansen et al, 2017); the stacking of steel coils (Tang et al, 2015); stack loading problems for train cars and assembly lines (Boysen and Emde, 2016); and the work of Galle et al (2018) that considers the CRP when deciding where to store containers in the yard. The blocks world problem from the AI community is also similar to the CPMP in that a set of blocks (containers) ought to be manipulated from above without height or stacks number constraints (Slaney and Thiébaux, 2001).…”