Metocean Exposure and Underway Transit-Time Reliability in Coastal Maritime Traffic: An AI S-Based Fixed-Effect Analysis

Abstract

Evaluating metocean effects on arrival-time reliability is essential for maritime traffic management, port-call planning and coastal logistics. In coastal waters, however, the sea state experienced by a ship is already shaped by route geometry, traffic structure, port approaches and operational speed management. This paper proposes an open-data hindcast framework that separates ship-encountered metocean exposure, within-vessel speed response, and underway transit-time reliability using point-level Automatic Identification System (AIS) data, ERA 5 wind and wave reanalysis, and Copernicus Marine surface currents. The framework analysed 12,022 Class-A cargo and tanker transits in the Pacific Northwest, New York Bight and South-East Atlantic during October–November 2025. Ship-encountered maxima were 5.0–6.0 m, whereas the South-East Atlantic regional field reached 11.1 m during a hurricane-influenced window. Vessel-fixed-effect regressions yielded positive point estimates in all six region-months, with four segment level 95% confidence intervals excluding zero and fitted within-vessel speed-loss contrasts of 3–9  percentage points between significant wave heights of 0 and 3 m. The modelled metocean component accounted for 0.5–15.8% of transit-time deviation variance; the remaining variation was dominated by the operational/model residual and interaction effects.