Scenarios in the design process.

The Safety Science Group of Delft University of Technology has developed a method by which the input of safety in the design process is structured through the application of use-scenarios and hazard patterns. The approach is illustrated with case studies in the field of agricultural equipment (pneumatic pruning shears, power chain saws and power-take-off shafts). Use-scenarios and hazard patterns result from safety problem analyses and give structure to the problem space and assist in the explanation of accidents. Selection of solutions is facilitated by a matrix scheme which links technical design options and measures of a social and organisational nature into a set of coherent measures. In the evaluation of designs, the application of use-scenarios and hazard patterns is helpful as a predictor of residual risks. Incorporating safety in the design process is a dynamic decision-making process. The decisions involved and the role of the safety expert in this process are discussed. Application of the method to the design of tools and consumer products seems very promising, although several problems remain. Valid accident data for use in the method are scarce; the technique for the translation of safety requirements into design specifications is still not fully developed and the first projects are only now being carried through to the implementation stage.