Hybrid optimization strategies for terminal-oriented container stowage and relocation in large port operations

Efficient container stowage planning in large port operations is paramount for ensuring vessel stability, navigational safety, and overall terminal efficiency, especially under the growing demands for smarter and greener maritime logistics. Port operators must meticulously arrange thousands of containers, adhering to preliminary plans from shipping lines while optimizing for critical factors such as weight distribution, minimization of container relocations within the yard, and seamless integration with dynamic terminal operational processes like twin-lift handling and quay crane workflows. This study proposes an optimization framework to generate complete stowage plans for large vessels from the terminal’s perspective, distinguished by its ability to identify and eliminate complex relocation patterns involving multiple containers. An efficient solution methodology is designed, integrating mixed-integer programming models for initial bay allocation and subsequent slot positioning, followed by an advanced neighborhood search algorithm. This search algorithm incorporates a novel graph-based relocation detection technique, utilizing matrix exponentiation to identify and minimize complex k-cycle relocation patterns. Based on operational data from a major international terminal (Yangshan Port), extensive numerical experiments and a real-world case study were conducted. The results validate the framework’s capability to produce robust, high-quality stowage plans for large vessels about 10 minutes, leading to a 16.8% reduction in container relocations and enhanced terminal efficiency, thereby offering valuable managerial insights for advanced stowage planning.