Empirical Analysis of Ship Anchor Drag Incidents for Cable Burial Risk Assessments

Subsea cables are critical infrastructure for the global economy but are vulnerable to the risks of anchor strikes from ships, causing significant damage and interrupting global telecommunications or power networks. Whilst methodologies have been proposed to aid decision makers with optimal routeing and mitigation strategies for these cables, such methods require definition of drag probabilities which thus far have not been empirically validated. In this paper, we present a framework through which anchor drag probabilities can be calculated through analysis of historical vessel traffic data and environmental conditions. Drag distances, probabilities and causal influences of conditions are shown through comparison of three million hours of vessel anchoring exposure. We show that the wind speed and wave height are the most significant factors for calculating the likelihood of anchor dragging, but other factors omitted in this study may also be influential. The results show that the method can improve the validity of Cable Burial Risk Assessments, supporting navigation authorities and developers with mitigating the risks to subsea cables.