Representing causal mechanism of defective designs: a system approach considering human errors

Reducing design defects by proactive actions requires comprehensive understanding of how and why they happen. To achieve this, it is necessary to know the causal relationships of inherent factors, by which design defects arise. This paper represents a causal mechanism of defective design occurrence by considering interactions of underlying factors in designing process. The mechanism draws on the system approach to human errors to describe defects in design caused by designers' active failuresand failures of design reviews as defences to catch defects. It portrays the causal process of the failures with workplace factors and organizational factors as influencing factors. Workplace factors arise from designers' working conditions and include internal and external factors to the actors. Organizational factors comprise elements due to client and designer company's conditions. Then, two failure pathways are discussed to show how the factors lead to design defects. Two case studies are presented in this paper to clarify and explain the mechanism.