Operationalizing COLREG exemptions and equivalents: Data-driven evidence via association rule mining and network analysis

While the International Regulations for Preventing Collisions at Sea (COLREG) establish universal design and operational standards to ensure maritime safety, the practical implementation of legal flexibility through exemptions and equivalents remains a critical yet under-examined aspect of regulatory compliance for modern and specialized vessels. This study investigates how these mechanisms are operationalized by analyzing official notifications submitted by national administrations to the International Maritime Organization (IMO). A structured dataset of 1,281 verified COLREG-related cases was extracted from 12,834 notifications spanning 2012 to 2025 using a hybrid pattern-mining and text-normalization method. The data were then analyzed using a methodological framework comprising association rule mining, network analysis, and statistical tests to uncover structural, relational, and temporal patterns. Findings reveal that notifications concentrate within a few frequently coupled rule sets, with issues varying systematically by vessel type and over time. Rather than isolating individual clauses, the evidence points to coordinated adjustments reflecting practical design constraints, administrative practices, and evolving technologies. The resulting data-driven framework exposes structural regularities in vessel design conflicts, providing insights to inform survey practices, support consistent decision-making, and facilitate future policy development.