Cyclic Planning: A New Approach to the Maritime Inventory Routing Problem

Efficiently planning vessel routes and managing inventory levels is a critical challenge in the maritime industry, addressed by the Maritime Inventory Routing Problem (MIRP). Traditional MIRP models have provided valuable insights but fall short in capturing key operational nuances. In particular, these models often neglect the effects of vessel speed and load on fuel consumption and inventory levels. Additionally, they suffer from “end-of-horizon effects,” where short planning horizons result in suboptimal and impractical solutions.

To overcome these limitations, the authors of a recent study propose an innovative approach: cyclic planning for MIRPs. This methodology ensures that the system’s state at the end of the planning horizon matches its state at the beginning, effectively eliminating end-of-horizon effects. By doing so, cyclic planning provides more realistic and robust solutions for maritime logistics.

Key Contributions

1. Introducing Cyclic Planning for MIRPs: The cyclic planning approach redefines the problem by aligning the start and end states of the planning horizon. This cyclical perspective eliminates distortions caused by arbitrary horizon boundaries and enhances solution reliability.
2. A New Mathematical Model: The authors present a refined mathematical model tailored to cyclic MIRPs. This model incorporates variables such as vessel speed and load, ensuring a more accurate representation of operational costs and inventory dynamics.
3. Demonstrating Effectiveness Through Computational Experiments: Through rigorous computational experiments, the study demonstrates the superiority of cyclic planning over traditional approaches. The results highlight its potential to deliver cost-effective and operationally feasible solutions.
4. Exploring Industry-Specific Applications: While cyclic planning offers significant benefits, such as predictability and cost reductions for upstream supply chain stakeholders, the authors recognize its limitations. Industries with highly variable demand patterns or those without a need for regular schedules may find it less applicable.

Benefits of Cyclic Planning

• Predictability: Cyclic planning fosters regularity, aiding in better resource allocation and scheduling.
• Cost Reductions: By mitigating end-of-horizon inefficiencies and optimizing fuel consumption, this approach can lower operational costs.
• Sustainability: Incorporating vessel speed and load effects aligns MIRPs with environmental goals, promoting greener maritime operations.

Conclusion

The introduction of cyclic planning marks a significant advancement in addressing the Maritime Inventory Routing Problem. By tackling the challenges of traditional models, such as end-of-horizon effects and oversimplified assumptions, this approach provides a practical and forward-looking solution for the maritime industry. While not universally applicable, cyclic MIRPs offer promising opportunities for industries seeking predictable, efficient, and sustainable supply chain operations.