The safety of risk or the risk of safety?

Safety is nowadays one of the main items on the agenda during the planning, realisation and management of most large-scale projects, particularly in infrastructure and building projects in intensively used areas such as multiple use of land projects. It is vital that safety aspects are properly assessed at an early possible stage of the project. In this paper relations between safety and risk are suggested. In order to quantify the safety in objective terms, risk (analysis) is used as an important tool. However, definitions of risk vary from global and informal to objective variants and consists both psychological and mathematical elements. When a risk analysis is performed, one has to consider these definitions. In this paper, both psychological and mathematical risk definitions are mentioned and their interrelation is described. An essential element in risk assessment is risk evaluation. When a risk analysis is performed, it is also important to realise that decision making about risks is very complex and that not only technical aspects but also economical, environmental, comfort related, political, psychological and societal acceptance play an important role. Finally, a recommendation has been made for narrowing the gap between deterministic and probabilistic approach by use of Bayesian Networks. It appears that these networks are also useful in order to integrate psychological and mathematical definitions of risk.