Safety is a major concern for both automobiles and railway vehicles. The related standards provide definitions of the same concepts such as Risk, Harm, Hazard, etc., which we consider here as the core concepts. However, related conceptual models existing in the scientific literature either are inconsistent or do not cover the core concepts comprehensively.We modeled the core of these safety concepts ourselves both in meetings and with tool support, based on the definitions given in the related standards. As a result, this paper presents a small core ontology of safety risk concepts for reconciling the scientific literature with standards. Since it matches the terminology of the related standards, it may serve as a reference model in the future. In fact, we already used it ourselves for systematically studying where human error may compromise safety.