The twentieth century saw a remarkable increase in the capability, reliability and safety of engineered products. This is true in many areas of engineering, but perhaps most obvious in the area of road transport. In the early days of automotive engineering safety was given little consideration. The middle of the century saw the beginnings of a systematic approach to safety, initially investigating the safety of finished products, e.g. by the use of crash testing. Nowadays safety is a significant design driver, as witnessed by the provision of sophisticated active and passive safety systems such as anti-lock braking and air bags. Indeed we have moved from the situation where safety was not a major consideration to one where many automotive manufacturers use it as a key strand in their approach to marketing. Similar trends have occurred in other industries such as air and rail transport, chemical processing and factory automation. However, in parallel with the increases in product safety there has been a number of countervailing trends.
First, the size of the market for engineered products has grown enormously. Pragmatically, this means that the acceptable rate of occurrence of technical failures which can give rise to accidents must be extremely low. Further, the products must be designed to be safe when operated by people of enormously varying skills and experience, and in widely varying circumstances.
Second, the capability of products has grown to a remarkable degree. Whilst the sophistication of modern systems gives opportunities to include safety mechanisms, it means that the engineering challenges of designing safe products are amplified enormously. Further, much of the sophistication is provided by computer systems, and these introduce new concepts and failure modes which are outside the scope of traditional safety engineering.
Third, public perceptions and tolerance of risk have changed substantially. Risk perceptions change over time, and with knowledge: one need look no further than the attitude to cigarette smoking for evidence of this. In general, society seems to be becoming less tolerant of risk, and more prone to sue in the event of accidents.
The discipline of System Safety Engineering (SSE) has developed over the last half of the twentieth century. It can be viewed as a process of systematically analysing systems to evaluate risks, with the aim of influencing design in order to reduce risks, i.e. to produce safer products. In mature industries, such as aerospace and nuclear power, the discipline has been remarkably successful, although there have been notable exceptions to the generally good safety record, e.g. the Chernobyl and Ariane 5 accidents.
However the trends mentioned above pose challenges for traditional approaches to SSE. For example, classical hazard and safety analysis techniques deal poorly with computers and software where the dominant failure causes are errors and oversights in requirements or design. Thus these techniques need extending and revising in order to deal effectively with modern systems. Also, in our experience, investigation of issues to do with safety of computer systems have given some useful insights into traditional system safety engineering, e.g. into the meaning of important concepts such as the term hazard. This is the sub-discipline of Safety-Critical Systems Engineering (SCSE) for computer based control systems.
These modular courses are designed to prepare students for work in this demanding field by exposing them to the latest science and technology.