A New Method for Human Reliability Assessment in Railway Transport

Even though human factors have a great influence on railway safety, the assessment still follows traditional and inadequate approaches. In railway engineering practice, the error probability of every human action, regardless of its complexity, is often rated with the fixed value 10-3. Improving this reductionist approach, e.g. the in Germany well-established method by Hinzen distinguishes three classes of human behavior. However, this method incorporates the contested statement that skill-based actions are generally less error-prone than rule-based ones and rule-based actions are less error-prone than knowledge-based ones. Moreover in classic approaches the human being is considered as a weak point despite its flexibility to react on unspecified system conditions. In the project SMSmod funded by the German Research Foundation (DFG) a new method for an adequate human reliability assessment is being developed. The internal human processing is modeled by a cognitive processing loop together with cognitive couplings classifying the cognitive demands associated with a particular task. Thereby the focus is on the human’s ability to adapt to and recover from hazardous situations (resilience) instead of human errors. This paper gives an overview of the project so far and focuses on the importance of performing shaping factors (PSFs). The approaches of a CAHR analysis and a detailed PSF analysis which are pursued in parallel are presented and their expected importance for the project is shown