The systematic integration of Human Factors into safety analyses: an integrated engineering approach

The performance of the human reliability analysis (HRA) and integration of its outcomes into quantitative risk assessment schemes remains quite a difficult and complex task to perform. Even worse is the assessment of organisational reliability assessment. The reasons of this difficulty mainly lay on the absence of a generically accepted paradigm that enables engineers to include systematically human and organisational factors (H&OF) into the analysis. Broadly speaking, engineering approaches very often account for error of omission forgetting the errors of commission (EOC), and, on top of that, they do not make any macro distinction between pre- and post-initiating human failures. This paper offers a paradigm on how to integrate H&OF into safety analysis by means of the recursive operability analysis (ROA), which has been adapted to accommodate H&OF, and renamed integrated recursive operability analysis (IROA). By means of a practical example, the method will illustrate how to account for H&OF in a systematic and consistent manner using an engineering approach. The paper will even provide a paradigm for the construction of integrated fault trees consistent with the IROA framework.