An experimental method to study the effect of fatigue on construction workers' safety performance

Fatigue is believed to have a negative effect on workers' safety performance. The current fatigue studies in construction have relied on questionnaire or interview survey, and due to certain limitations of such research method, the changing patterns of errors and the types of errors associated with different levels of fatigue are not well understood. By viewing an unsafe behavior as a cognitive failure, this research proposes an experimental method to study the effect of fatigue on construction workers' safety performance. First, the research designed a typical manual handling task to simulate the actual construction work. The participant's fatigue level could be measured by a Fatigue Assessment Scale for Construction Workers (FASCW), and the participant's safety performance could be measured by monitoring the participant's errors when performing the tasks. Second, a pilot study was conducted to show that the experimental tasks could induce fatigue effectively, and workers made more errors in a fatigue state. Third, the formal study found that the fatigue level of 20 was a critical point from where the effect of fatigue began to emerge. When a worker's fatigue level exceeded 20, there was a linear relationship between fatigue levels and error rates. In terms of error types, when at a relatively low fatigue level above 20, a worker's errors were mainly due to the failure of hazard perception. But as fatigue accumulated, its impact on the worker's capacity of motor control became significant. Relevant implications derived from the experimental findings for safety management are also discussed.