A Comparison of Machine Risk Acceptance Results Among Trained Users of ANSI B11-TR3

Abstract

The ANSI guideline on machine risk assessment, B11-TR3, describes risk assessment as an iterative process. This implies that protective measures of varied levels of technology can be successively evaluated until a risk that is acceptable is attained. The theories of risk acceptance are many. Reducing risk to a level that is agreed to be 'as low as reasonably practicable' (ALARP) is said to give focus to making a decision about when risk has been adequately reduced. Main (2004) says that "Although the concept of acceptable risk is becoming more commonly adopted throughout the world, a single level of acceptability cannot be universally applied. Acceptable risk is a function of many factors, and is specific to a company, culture, and time-era." Fischhoff et al. (1981) have argued that "the risk associated with the most acceptable option is not acceptable in any absolute sense. One accepts options, not risks, which are only one feature of options." This paper describes risk assessment groups in five manufacturing workplaces and discusses training that led to acceptable risk decisions for a hazardous machine system in each workplace. The composition of the five teams in this study ranged from a team with just a single engineer to teams involving several workplace personnel. The applied preventive measures ranged from measures that were tailored to meet corporate safety goals to measures that evolved from the local risk assessment team's ingenuity. The paper concludes with suggestions on how to make the risk acceptance concept meaningful in the training of future machine risk assessment teams.