The current risk and vulnerability analysis in complex socio-tecnical systems should be enhanced as regards to the

• overall effect of risk factors
  efect of risk reducing measures
• SINTEF are developing improved analysis methods based on influence diagrams og Bayesian networks.

The methods have been successfully applied in risk and vulnerability analysis of helicopter and ferry transport.

In risk and vulnerability analyses it is often an essential task to identify risk influencing factors (RIFs). The RIFs may be arranged hierarchically in influence diagrams to demonstrate their interdependence and effect on the risk. This approach is often applied for complex sosio-technical systems, when the objective is to carry out overall holistic analyses, taking all relevant aspects into account (i.e. technical, human, as well as organisational factors). It is a central aspect of this approach to model the effect of risk reducing measures and changes. Further, risk indicators may be used for assessing the actual status of the RIFs, and thereby the actual risk.

The influence diagrams are used both as a means for communicating the model between various categories of "experts", further as an aid in accident analyses, and also in the qualitative evaluation. The influence diagrams are further used in the quantitative analyses, and have the advantage that various types of data can be utilised (e.g. statistical data, expert judgments). There exist data programs for carrying out the quantifications.

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