Current Efforts to Rewrite the History of the Safety Hierarchy and Obviate its Purpose
Authors: Munsell William P. 
Published: February 2024

The duty on the part of manufacturers to incorporate features in equipment for the sole purpose of protecting workers and bystanders from injury grew out of the advent of worker’s compensation legislation in the second decade of the twentieth century. The new legal landscape suddenly made safe design an issue that impacted the bottom line of industrial employers through reduced insurance premiums. This was the impetus for the newly formed National Safety Council in 1913, which drew its members primarily from industry. The real sea change, however, can be traced to a paper published in the ASME Journal two years later by Carl Hansen, titled “Standardization of Safety Principles”[1]. In it, Hansen proposed the novel idea that it was the responsibility of design engineers to address the hazards their machines presented. His proposal was not made in a vacuum. The responses of leading figures in engineering, the insurance industry, and worker safety were published in the Journal as well, and the unanimous consensus was agreement with Hansen’s new ethic.

In Hansen’s proposal can be found almost all of the basic concepts of the Safety Hierarchy as it was presented in the 1955 edition of the National Safety Council’s Accident Prevention Manual for Industrial Operations [2]. This states that a manufacturer has a duty to evaluate and address foreseeable hazards, including those related to human error, by design first and foremost. Only if no feasible design solutions can be found may the manufacturer rely on methods that control exposure of the hazard to users and bystanders, such as guarding. Only if no feasible design or exposure-control solutions can be found may the manufacturer rely on personal protective equipment. Since that time the hierarchy, only slightly modified, has penetrated every industry and has come to define the modern basis of safe design in the United States.

In 2000, a lobbying group called the Association for Manufacturing Technology sponsored a technical paper which resulted in the promulgation of ANSI B11.0-2020 Safety of Machinery – General Requirements and Risk Assessment [3]. This standard represents a radical departure from established safety principles in that it inserts an undefined process by which manufacturers or purchasers can unilaterally decide the risk associated with any given piece of machinery is acceptable, and thereby opt out of the requirements of the safety hierarchy. The threshold of ‘acceptable risk’ is left uncodified and can be calculated based on a host of factors as vague as ‘culture’ and the ‘context of their own circumstances’. The effect of this approach on the stakeholders who would suffer the most dire consequences, the injured workers, is not considered. I argue that ANSI B11.0-2020 and its related standards are retrograde in their effect on safety in the workplace, and cannot be reconciled with the last 108 years of safe design principles as developed in the United States. This paper will provide a historical review of safe engineering design principles and analyze the provisions and implications of ANSI B11.0-2020. The basis for a revised ANSI B11.0 will be presented.