Hierarchical modeling of perceived collision risks in port fairways

Abstract

Navigational collisions are one of the major safety concerns in many seaports. Despite the extent of work recently done on port navigational safety, little is known about harbor pilots' perception of collision risks in port fairways. The study described in this paper used a hierarchical ordered probit model to investigate the associations between perceived risks and the geometric and traffic characteristics of fairways and pilot attributes. Perceived risk data, collected through a risk perception survey of Singapore port pilots, were used to calibrate the model. The intraclass correlation coefficient justified the use of the hierarchical model rather than an ordinary model. The results show higher perceived levels of risk in fairways attached to anchorages and in those featuring sharper bends and higher traffic operating speeds. Lower levels of risk were perceived in fairways attached to the shoreline and confined waters and in those with one-way traffic, a traffic separation scheme, cardinal marks, and isolated danger marks. The level of risk was also found to be perceived higher at night.