Optimizing Risk Analysis Relating to External Safety in The Netherlands

Risk analyses in The Netherlands have been optimized so that they now express risks in a numerical form suitable for comparison to national safety standards. This factor is more important to national government than to local authorities; other factors relevant for local authorities are given less emphasis or even completely omitted from the results of the analysis. From a comparison of 16 risk analyses carried out during the last decade, it became clear that in the last 5 years the methods of risk analyses related to external safety have become unified. Results are now presented in terms of individual risk contours and in terms of F‐N curves (accident frequency vs. exceeded number of fatalities). This unification seems to be a result of government policy. First, the implementation of the post‐Seveso‐directive (501/82/EC) in The Netherlands obliges a number of industries to provide the authorities with a quantitative risk assessment. Second, the government has set standards for the maximum permissible risk in residential areas. A unified type of risk analysis is a tool to achieve both these policies. From interviews with local government authorities, however, it has become clear that they need and use some quantitative risk information that is not provided by the unified analysis. They feel they need figures that provide insight into the effects of incidents and into the way effects may change as a result of safety measures. Ultimately, government policy may mean that local officials receive less information than before.