Testing Implicit Safety Science Assumptions in Maritime Waterway Risk Control Options: An Empirical Analysis of PAWSA Reports

Abstract

Maritime waterway safety remains a critical concern due to the severe human, environmental, and economic consequences of shipping accidents. The Ports and Waterways Safety Assessment (PAWSA) method relies on expert judgment to propose and evaluate Risk Control Options (RCOs), including their perceived Risk Reduction Effectiveness (RRE). This thesis analyzes an empirical dataset of 50 unique RCOs extracted from 21 PAWSA reports (2016–2023) using content analysis and a tailored Strength-of-Evidence (SoE) framework. Results show substantial variation in RRE and SoE, with many RCOs lacking strong empirical support and only a small subset demonstrating both high effectiveness and strong evidence. Further analyses examine RCOs across actor groups, hierarchy of controls, and risk management phases. Findings indicate that expert judgments only partially align with common safety science assumptions. This study contributes to understanding how expert judgment reflects underlying safety concepts and supports more evidence-informed decision-making in maritime risk management.