There are specific cases of control system applications in which the control system is required to fulfil its control, as well as safety functions. The control system that meets this criterion is usually referred to as a safety related control system (SRCS). The control systems in railway applications fall into the SRCS category. Safety functions are, together with a tolerable hazard rate, determined by a risk analysis and implemented via technical measures. Technical measures ought to decrease an amount of risk related to specific hazards. If the SRCS is meant to be approved, a lone implementation of the safety measures is not enough. A proof that related risk has been decreased to an acceptable level is mandatory. Each individual user of a service (of a railway transport for instance) should take a risk that is the same everywhere, independent of a country. The process of making risk analyses objective is, together with the definition of system safety requirements and safety evaluation, very problematic nowadays.