The safety chain: A delusive concept

Various governments have defined a so-called safety chain to structure their efforts in the field of risk management for low-probability disasters. The safety chain typically consists of the following components: proaction, prevention, preparation, repression. While the terminology suggests that the safety chain should be interpreted a series system, the safety chain more closely resembles a parallel system. This has important implications: the safety chain is not as weak as its weakest link; unreliable links need not always be strengthened as it will often be more efficient to rely on a few layers of protection, or just one. To avoid misguided efforts caused by the confusing terminology ‘safety chain’, we propose the use of the term ‘layers of protection’, as is currently the case in the Dutch flood safety policy. Furthermore, we show that imperfect preparedness for low-probability disasters is often perfectly defensible or rational, given the differences between the cost-effectiveness of investments in prevention and disaster preparedness.