Estimation of safety requirements for wayside derailment detectors

BP-Risk is a semi-quantitative approach for railway risk assessments, which has been published and validated. Semiquantitative methods are a combination of qualitative and quantitative approaches. They can be defined as "qualitative, model-based´ risk assessment methods. This means, that for semi-quantitative risk assessment methods, numerical (quantitative) values are assigned to qualitative scales. This article shows how a semi-quantitative risk assessment method can be applied for the estimation of safety requirements for wayside derailment detectors. Wayside derailment detectors were recently developed as a part of modern wayside train monitoring systems to guarantee operational safety in centralised and remote controlled railway operation.