This paper examines the applicability of formal safety assessment to the passenger ships. This is followed by an analysis of passenger ship characteristics and a proposed formal safety assessment methodology. Five interlocking steps are described to construct a safety model including novel risk assessment, cost-benefit analysis and decision-making approaches. A case study is carried out in order to demonstrate the proposed methodology. Further development in formal safety assessment in the context of passenger ship safety is finally discussed in detail.

The quantitative evaluation method of the safety management cost was suggested to prevent a gas accident as a major industrial accident. In a gas governor station, process risk assessments such as the fault tree analysis(FTA) and the consequence analysis were performed. Based on process risk assessments, potential accident costs were estimated and the cost-benefit analysis(CBA) was performed. From the cost-benefit analysis for five classification items of safety management cost, the order of the cost/benefit ratio was estimated.

Cost-benefit analysis was investigated to propose the analysis method of the effect of investment and the optimum investment level of safety management cost for preventing gas accident in the B governor station. From five classifications of safety management costs consisting of cost items with similar characters and potential accident costs calculated by risk assessments(FMEA/HAZOP), we found that the order of the benefit(the reduction cost of the potential accident cost) was the instrument increase and repair cost > the safety checking and inspection cost > the labor and training cost > the safety equipment and corresponding cost > the research and development cost. As the benefit was increased with increasing the investment cost, the effect of investment was increased with decreasing the Investment cost. As a result, the optimum safety management cost was estimated and the investment level was analyzed by the model of optimum investment level.