Improvement principles

The improvement principles are a group of safety principles whose central message is that no risk level above zero is fully satisfactory, and that we should therefore always strive to improve safety. The major safety principles in this group are: as low as reasonably achievable (ALARA), best available technology (BAT), the substitution principle, vision zero, and continuous improvement.

This article investigates their similarities and differences, the ways in which they can incorporate compromises with objectives other than safety, and the difficulties that may arise in their application. A particular emphasis is put on comparisons with two major competing groups of principles, namely acceptance principles, which draw a sharp line between acceptable and unacceptable states of affairs, and weighing principles such as CBA that search for an optimized compromise between safety and other objectives.

In comparison to their main competitors, the improvement principles have the important advantage of consistently encouraging safety enhancements. However, some of the problems in their application can probably best be tackled by including them in a combined approach that also makes use of acceptance and/or weighing principles. Two such combined approaches are proposed. The choice between them should be based on the underlying value structure of the decision problem. Practical applications: Guidance is given for the choice of safety principles and for the combined use of more than one such principle.