A company conducted a fatigue risk assessment study to estimate the fatigue levels of approximately 9,000 shifts and the risk of incidents occurring because of operator fatigue. The findings provided an insight into the likelihood of fatigue and the risk of errors or incidents occurring for approximately 9,000 shifts of control-panel operators working on a 4-day 12-hour shift pattern. The results presented in this paper are limited to the assessment conducted for day shifts in order to demonstrate the methodology.
The study compared different shift patterns in order to identify shifts with higher fatigue levels and identify control measures to reduce operators’ fatigue levels and risk of incidents to as low as reasonably practicable (ALARP).
The lowest fatigue and risk levels were identified for the current 4-day shifts compared with 7-day and 28-day shift cycles followed by other companies. In order to lower the risk to ALARP, additional control measures such as training and ergonomic assessments and key performance indicators such as tracking incidents by fatigue levels are being rolled out.
This approach is a combination of a qualitative and quantitative fatigue risk assessment methodology and has widespread applicability, prospectively in terms of shift design and the prevention of incidents caused by fatigue-induced impairments and for incident investigations retrospectively.
This study fosters proactive occupational health management by promoting employee health and preventing or reducing fatigue. It thus plays a vital role in the prevention of sickness absenteeism and illnesses associated with chronic fatigue.
Fatigue is defined as the progressive reduction in mental or physical performance that results from prolonged exertion or insufficient quantity and quality of sleep.
Investigations into catastrophic incidents such as the NASA Challenger explosion, the Exxon Valdez oil spill, the Bhopal gas tragedy, and the Three Mile Island nuclear incident have revealed that fatigue was an underlying factor. When a technical fault occurs, operators need to be at the peak of their mental performance to mitigate an incident. However, if an operator is fatigued, the event can be escalated by poor decision making.
Fatigue is known to decrease the electrical activity in parts of the brain responsible for problem solving, alertness, and mental calculations, and chronic sleep debt has been linked with ill health. Clinical evidence correlates chronic fatigue and sleep debt with a higher risk of developing diabetes, obesity, cardiovascular diseases, gastrointestinal diseases, and increased susceptibility to infections.
Companies, therefore, need to manage fatigue in order to prevent accidents, maintain good performance, and promote the health of employees.
The quantification of fatigue is a challenge in the absence of medical tests; however, it is important to quantify fatigue because that which cannot be measured cannot be managed.
International methodologies such as the UK Health and Safety Executive’s Fatigue and Risk Index for quantitative fatigue risk assessment and the International Association of Oil and Gas Professionals’ Fatigue Task Sensitivity for qualitative fatigue risk assessment were used for this study.
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