Quantitative Risk Assessment of a Periodically Unattended Bridge

A periodically unattended bridge is a likely use case, often cited with regards to Maritime Autonomous Surface Ship (MASS) technologies. The German-funded B ZERO project aims to develop and demonstrate capabilities which are needed for navigating a cargo ship for up to 8 hours within a predefined operational envelope. From a risk perspective, MASS technology, and thus the implementation of B ZERO must be as safe as conventional technology, which is why a safety assessment of the B ZERO concept is executed according to the International Maritime Organization Formal Safety Assessment guidelines. This paper outlines the results from the hazard identification and risk analysis executed along the Bow-Tie Model. The risk analysis focuses on quantitative methods such as Fault and Event Tree Analysis Modeling, for relative comparison of conventional (attended) bridge and unattended bridge instead of qualitative expert-based ratings in risk matrices. It includes insights into how risks associated with MASS can be modeled by identifying reasonable probabilities from literature.