Combining Optimization and Simulation for Designing a Robust Short-Sea Feeder Network

Abstract

Here we study a short-sea feeder network design problem based on mother and daughter vessels. The main feature of the studied system is performing transshipment of cargo between mother and daughter vessels at appropriate locations at sea. This operation requires synchronization between both types of vessels as they have to meet at the same location at the same time. This paper studies the problem of designing a synchronized feeder network, explicitly accounting for the effect of uncertain travel times caused by harsh weather conditions. We propose an optimization-simulation framework to find robust solutions for the transportation system. The optimization model finds optimal routes that are then evaluated by a discrete-even simulation model to measure their robustness under uncertain weather conditions. This process of optimization simulation is repeated until a satisfactory condition is reached. To find even better solutions, we include different performance-improving strategies by adding robustness during route generation or exploiting flexibility in sailing speed to recover from delays. We apply the solution method to a case based on realistic data from a Norwegian shipping company. The results show that the method finds near-optimal solutions that offer robustness against schedule perturbations due to harsh weather. They also highlight the importance of considering uncertainty when designing a short-sea feeder network with transshipment at sea.

An Adaptive Heuristic for Feeder Network Design with Optional Transshipment

“…Main problem characteristics Approach Fleet Cargo Time window Speed Transshipment Fagerholt (1999) Homogeneous MILP Sambracos et al (2004) Homogeneous Metaheuristic Fagerholt (2004) Heterogeneous MILP Karlaftis et al (2009) Heterogeneous P&D ✓ Hybrid GA Santini et al (2018) Heterogeneous P&D ✓ Branch-and-Price Holm et al (2018) Mother & Daughter P&D Specific locations at sea MILP, Medbøen et al (2020) Mother & Daughter P&D Specific locations at sea Simulation-Optimization Akbar et al (2020) Mother & daughter P&D Specific local ports MILP Msakni et al (2020) Heterogeneous containers between services until they reach their final destinations. According to World Shipping Council (2020), there are around 500 liner shipping services operated around the world by more than 6,000 ships.…”

“…A critical operation to consider while creating the routes is that synchronization has to be ensured to guarantee that both mother and daughter ships meet at the same location at the same time at sea for the transshipment. This problem was later extended by Medbøen et al (2020) with a simulation engine embedded within the optimization algorithm to handle uncertainty in sailing times. A similar study is performed by Akbar et al (2020) with the same mother and daughter route structure.…”

Legal Disputes under Time Charter in Connection with the Stranding of the MV Ever Given

“…However, in the case of a standard international time charter, as there is no such explicit provision, it is necessary to determine the subject of the liability for damages, or whether the time charterer or shipowner will bear the expenses based on the detailed clauses of the time charter. For example, with regard to the Ever Given, Evergreen (the time charterer) is responsible for expenses such as the necessary pilotage fees, towage fees, canal tolls, and fuel costs, based on the conditions of the contract, for which the shipowner would have paid to complete the navigation based on the command (navigation) authority including the right to command the captain if the shipowner actually operates the vessel [85]. On the other hand, SKK is responsible for the salaries of seafarers and repair costs for the vessel, which are necessary to guarantee the vessel's seaworthiness.…”

Evaluation of an autonomous, short sea shipping feeder-loop service through advanced simulations

“…The study in [4] addresses liner shipping network design and determines optimal routes and daughter vessel sizes. An extension of the problem introduced in [4] is found in [5], where uncertain sailing times is taken into consideration in the synchronisation between routes such that mother and daughter ships (see AEGIS [1] ships in Figure 1) meet at the same location at the same time for transhipments. They introduce the combination of optimisation and discrete event simulation to find optimal routes and evaluate them in terms of robustness under uncertain weather conditions.…”