The contribution of design to accidents

This paper gives the results of a study of the proportion of accidents that have their root causes in design. In particular, it investigates the validity of the claim that 60% of the root causes of accidents arise in the design stages.The study reviewed available accident and incident data from the aviation, railway and nuclear industries. Where the data indicated that design was a root cause, this was taken as adequate evidence. Where the data or reports did not give root causes, or where the root causes were investigated or categorised in a way that precluded the possibility of identifying design as a root cause, a judgement was made.The results show that for the accidents and incidents in the aircraft and nuclear industries, about 50% have a root cause in design. This is close to the claim of 60%. The proportions for the aviation and nuclear industries (51% and 46%, respectively) are remarkably similar. For the railway industry, quantitative analysis was not possible. However, design was a significant contributor to recent major accidents.Types of design error are cited, as are indicative incident and accident synopses that show the role of design in incident and accident causation in these three industries.