Pierre C. Sames

Elements of Risk Analysis for Collision and Grounding of a RoRo Passenger Ferry

Newly developed software was applied to study the effects of damages due to collision and grounding. The annual risk of collision and grounding was computed for an example RoRo passenger ferry. Collision frequency was evaluated for a specified route taking into account traffic data. Grounding frequency was calculated for an artificial obstacle located close to the traffic route. The consequences of collision and grounding scenarios were estimated by introducing damage criteria that link the calculated distribution of damage size and damage location to monetary units. Loss of human life and reputation was not considered. It was shown that the main part of the calculated annual risk is caused by capsize of the vessel after severe damage.

A Risk Model for the Operation of Container Vessels

Commercial shipping of containerized goods involves certain risks for human safety and environment. In order to actively manage these risks, they must be identified, analyzed, modeled, and quantified. This requires a systematical analysis of design and operation of container vessels. Within the EU-funded research project SAFEDOR, a Formal Safety Assessment has been applied to establish the current safety level of generic container ships and to identify potential cost-effective risk control options. This paper describes a structured approach to develop the underlying high-level risk model. It is structured as risk contribution tree consisting of a series of fault trees and event trees for the major accident categories. Statistical analysis of casualty data is used to estimate the probability of occurrence. Finally, the summation overall individual risk contributions yields the current risk pro file for the operation of container vessels is presented as FN-curve.

Towards Environmental Risk Acceptance Criteria

Risk evaluation criteria related to safety of human life have been available in the maritime industry for some time. However, only recently these criteria became formally accepted by including the CAF and ALARP-boundaries into the Formal Safety Assessment guidelines of the IMO. Risk evaluation criteria related to the protection of the environment are not yet agreed. A proposal for a cost effectiveness criterion related to accidental oil spills called CATS was suggested by the project SAFEDOR. However, a societal risk acceptance of environmental damages from shipping is not yet proposed. And, to effectively apply a cost-effectiveness criterion related to environmental protection, societal risk acceptance and the associated ALARP area need to be defined. To contribute to the ongoing discussion on environmental risk evaluation criteria, this paper presents a societal risk acceptance criterion related to oil spills of tankers which can be used within risk-based ship design and approval as well as for rule-making. The presented work adds to SAFEDOR’s contribution to risk evaluation criteria for the maritime transport in providing an ALARP area for risk assessment of oil transport by tankers. The paper first presents the current state of oil transportation by tankers and continues with providing suggestions how the ALARP boundaries may be derived in this context.© 2008 ASME

Introduction to Risk-Based Approaches in the Maritime Industry

Methods of risk and reliability analysis gain more and more acceptance as decision support tools in engineering applications. Integration of these methods into the design process leads to risk-based design. Ship safety is well regulated at United Nations’ level by the International Maritime Organization (IMO) and a tendency to move from prescriptive to goal-based regulations is seen today. In parallel, advances in technology and the need to develop ever more economic maritime solutions drives innovation and risk analysis is becoming a central element for the development of novel ships. Therefore, an enhanced ship design process integrating risk analysis was conceived over the last decade and appropriate additions to the regulatory framework were recently developed. Today, all main elements of risk-based ship design and approval are being developed and early applications demonstrate their feasibility in practice.

ASSESSMENT OF SLOSHING LOADS FOR TANKERS

This paper presents a new procedure to assess sloshing loads for tankers. It is applied to a sample tanker. Starting with computed ship motions and fluid motions inside partially filled tanks, critical fill levels were identified. Simulation of fluid flow was performed with a finite volume method for each critical fill level. Two- and three-dimensional flow computations were employed to predict pressure loads for panel sized patches of tank walls. Time traces of pressure were analyzed and resulting maximum loads were compared for all critical fill levels to determine overall maximum loads. Results generally agreed favorably with current rule based values.