A Protocol Triumvirate - Risk Assessment and Risk Reduction

Ralph L. Barnett^1,

¹Mechanical and Aerospace Engineering, Illinois Institute of Technology, Chicago, Illinois

Cite this paper:
Ralph L. Barnett. A Protocol Triumvirate - Risk Assessment and Risk Reduction. American Journal of Mechanical Engineering. 2020; 8(3):127-143. doi: 10.12691/ajme-8-3-5

Abstract

Scientific laws are introduced to engineering students in the various disciplines, for example, Ohm’s law in electrical engineering; Newton’s law in mechanical engineering; Boyle’s law in fluid mechanics; Entropy in thermodynamics; Avogadro’s constant in chemical engineering; and the Mass - Energy Equivalence (E = mc²) in physics. Ask someone to cite some of the laws in safety engineering! Indeed, ask a safety practitioner to define safety. Will he explain that the technical definition of safety is the reciprocal of Risk which is defined almost everywhere as a combination of hazard severity and hazard exposure? This challenged definition of safety is really a description that has been replaced by the safety community with Risk Matrices developed through consensus not research. It has, nevertheless, been incorporated into guidelines for conducting Risk Assessment and Risk Reduction which is the subject of this paper. Generally, if we characterize a contrivance, the protocols for its risk assessment and risk reduction include five building blocks: Hazard Identification, Definition of Risk, Risk Acceptance Criteria, Hierarchies of Control, and Control Management. The value of these protocols for defining safety and improving safety, derives from the fact that the combination of building elements includes the concepts of Design and Safeguards which are supported by the classical engineering disciplines. In addition, users of the protocols are introduced to the full safety toolbox together with an enlightened presentation covering most of the significant historical safety observations. On the other hand, these building blocks have never been validated by research and the protocols have not been compared to risks computed from actual statistical data. The protocols are critiqued in this paper primarily through the lens of their authors. With time, the risk protocol that was originally presented as a guideline has undergone a metamorphosis into a faux-safety theorem by virtue of its introduction into a variety of consensus standards and safety reference books. It has achieved ubiquity and currently carries the mantle of a gold standard for determining Tolerable Risk. Notwithstanding its value, it remains an art form that does not contribute to the basic underpinnings of safety technology. Protocols present in three different forms. The most advanced are directed toward products that reflect critical mishaps such as aircraft design and weapon design; these protocols contain an extra building block, Validation and Documentation, together with Risk Acceptance Criteria that include independent authority outside the purview of the design team. An intermediate level protocol that is championed by ISO/IEC deals with non-critical mishaps that also include the extra building block, Validation and Documentation, without the requirement that Risk Acceptance Criteria embrace independent scrutiny. Finally, a very popular protocol of a type recommended by ANSI for non-critical mishaps, has no validation requirements and uses Risk Acceptance Criteria for the determination of tolerable risk that reside in the discretion of the designers.

Keywords:
risk hierarchies of control risk matrix mishaps system safety

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