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Dr. Holger M Becht PhD, BInfTech(Hons)

Safety & RAM Manager; Ansaldo STS, Brisbane

In virtually all safety-critical industries the operators of systems have to demonstrate a systematic and thorough consideration of safety. This is generally done through the application of safety standards as part of the development of safety critical systems.

Many safety assurance standards (like EN50126 [1], IEC 61508 [8], DEF (Aust) 5679) [6] are very prescriptive. They require specific techniques, approaches or measures to be applied to achieve the safety objective without allowing the users to select a suite of techniques and measures best suited for their application and development environment. The application of prescriptive techniques can work well for some systems but can be a hindrance for others.

There has therefore been an increasing trend in many industries to demonstrate safety by assuring certain goals have been achieved, rather than simply following prescriptive standards.

Goal-based standards do not specify the means of achieving compliance but sets goals that allow for alternative ways of achieving compliance. Goal-based safety standards are now a reality and applied in the medical industry and defence; examples of such standards are the UK Defence Standard 00-56 [5], and the UK Railway Safety Standard The Yellow Book [11].