Rehandling-aware stowage planning for RoRo ships using exclusive subgraph modeling and affinity-based cargo ordering

Area of Science:

• Maritime Logistics
• Operations Research
• Computational Science

Background:

• Roll-on/Roll-off (RoRo) ships facilitate efficient wheeled cargo handling.
• Cargo stowage on RoRo ships presents the NP-hard RoRo Ship Stowage Problem (RSSP), characterized by potential cargo path blockages.
• Rehandling, the relocation of other cargoes to access specific ones, incurs significant costs and operational inefficiencies.

Purpose of the Study:

• To develop an effective algorithm for minimizing rehandling in the RoRo Ship Stowage Problem (RSSP).
• To reduce cargo handling costs and improve operational efficiency in RoRo shipping.

Main Methods:

• A backtracking-based algorithm is proposed for the RSSP.
• Key components include a disjoint subgraph ship model, a cargo ordering strategy considering inter-cargo relationships, a Conflict Free Block (CFB) selection strategy, and a post-processing strategy for rehandled cargo partitioning.

Main Results:

• The proposed method achieved up to a 65% reduction in rehandling instances compared to existing methods.
• This translates to an approximate 18% reduction in the total number of cargo handling operations.

Conclusions:

• The developed backtracking-based algorithm effectively minimizes rehandling in the RSSP.
• The findings offer a practical solution for reducing costs and enhancing efficiency in RoRo shipping operations.