Technical Safety Requirements are at the heart of a safe technical design.
Yet there’s no set formula for writing them. The ISO26262 standard does not prescribe any specific method for specifying technical safety requirements or TSR’s, and therein lies the dilemma. How does a safety engineer know he has covered enough fault scenarios or whether he has over specified?
Part 4 of the ISO26262 standard talks about Specification of Technical Safety Requirements. In many ways TSR’s are the strong foundation on which functional safety is built. The TSR’s form the basis from which specific hardware and software safety requirements are derived. They also play a key role in testing the functional safety achieved by the electronic control unit. Like functional requirements, constant revisions and late changes can easily derail project budgets and schedules.
A method for systematically deriving the bulk of technical safety requirements using well known safety analyses techniques is discussed in the SAE paper “Writing Good Technical Safety Requirements”, authored by kVA. Readers are encouraged to critique and share their experience with alternate approaches to writing well defined technical safety requirements by visiting this link: Writing Good Technical Safety Requirements.