A Direction-Constrained Space-Time Prism-Based Approach for Quantifying Possible Multi-Ship Collision Risks

Maritime collision risk prediction is crucial for the safety management of ocean transportation. Previous studies have primarily focused on near-miss collision risk of ship pairs, yet the risk due to congestion caused by multiple ships is significant. This paper proposes a novel space-time geographical approach for addressing multi-ship near-miss collision risk based on vessel motion behavior. The direction-constrained space-time prism is used to characterize the interaction possibility of ships, enabling potential collision risk to be evaluated. The advantage of direction-constrained space-time prism in analyzing ship movements is that it accounts for direction limitation thereby eliminating unreasonable estimation associated with the assumption of arbitrary changes in sailing direction through the classical space-time prism. This paper uses the trajectories of ships traveling the southeast coast of China to investigate the viability of the proposed approach. In comparison to the fuzzy quaternion ship domain model and closest point of approach-based methods, the proposed approach is capable of identifying hierarchical near-miss collision risks for different ships to improve risk evaluation. This is essential for ship path optimization that accounts for changes in the speed and course of ships. This work supports maritime collision risk forecasting, but also provides detailed insights for actionable steps to reduce risks.