Risk analysis for RoPax vessels: A case of study for the Strait of Gibraltar

The Strait of Gibraltar (SOG) is one of the principal navigation areas in the world. The maritime traffic registered in the area is approximately 110,000 ship movements per year, where thirty-three per cent of total traffic involves roll on/roll off passenger (RoPax) ships which run scheduled voyages between ports in the area. There are presently many accidents involving this type of ship being reported. Although these incidents have serious consequences, both based on a financial scale and regarding human safety, there is no formal maritime risk analysis study for this area carried out to date. The aim of this paper is to present the results of a risk analysis for RoPax ships operating in the SOG, based on accidents statistics covering the period 2000-2011. The work has been performed using the two first steps of the IMO Formal Safety Assessment methodology: Hazard Identification and Risk analysis. To identify the hazards and their associated scenarios and quantify, their frequencies and consequences, the Historical Accident Data Analysis and Expert Judgement techniques were used. A risk matrix has been drawn up to calculate the risk indices of the identified hazards. A comparative study of the accident frequencies obtained from similar previous studies is also presented in the paper. A high-level model risk for collisions was established through the elaboration and quantification of an Event Tree, calculating the individual and social risks. The conclusions of this study could serve as recommendations to be used in a subsequent decision making process.