This study explored the links of fatigue on hazard recognition skills in construction.
155 electrical power transmission and distribution line workers in the US were included in the sample. Psychomotor vigilance testing was utilised to represent fatigue impairment whereas construction scenarios were used for hazard identification.
Providing background, it’s noted that:
- Hazard recognition training has patchy evidence and doesn’t necessarily result in improved hazard recognition skills
- “other research shows that much of this [hazard recognition] training is broadly ineffective” (p307)
- Hazard recognition has been shown to be affected by 1) selective attention or inattention to certain hazard types, 2) unknown potential hazard set and 3) the perception that certain hazards impose low threat levels
- Fatigue can affect functionality in the prefrontal cortex, thereby impairing basic and complex cognitive functions that control ability to concentrate and assimilate new information, plan, communicate and react to stimuli (p307)
- Some work has shown that a single night of sleep deprivation can decrease cognitive performance by 30% and this reduced an additional 30% during the second night of sleep deprivation; stabilising at 40% decrement after 48hrs sleep deprivation
- Several studies have found that the hazard recognition performance of construction workers “remains insufficient”
Results
A moderate negative correlation between the fatigue level of an individual and their ability to recognise hazards was found (r = – 0.21), thus “indicating that the more fatigued a person is, the less able to recognize hazards” (p311).
No significant correlation was found between years of experience and recognised hazards, supporting other work that more training or years’ experience won’t necessarily improve hazard recognition.
They argue that “the lack of correlation between years of experience and the number of hazards identified suggests that safety performance does not share a monotonic relationship with safety knowledge” (p312), and perhaps suggests that a paradigm change in the way hazard recognition knowledge transfer is approached is needed in the industry.
In discussing the findings, the authors draw on Rasmussen’s dynamic safety model. They note that motivation for higher levels of productivity pushes performance towards the edge in terms of their exposure to hazards.
This push is amplified in the electrical field due to pressures for restoring power and often during disrupted schedules of work and sleep. Further aggravating this matter is labour shortages, weather and other factors which drive additional overtime to satisfy sporadic demands – increasing fatigue risk factors.
Thus, these findings suggest that fatigue can reduce the hazard recognition skills of workers, making them more vulnerable to harm.
Of further interest is that cognitive performance wasn’t statistically different between the start and end of shift. This may be due to a range of factors. One is that fatigue is influenced by more factors than just the shift-related activities/structure and influenced by accumulating factors over days.
The result may indicate that the time-off between two consecutive shifts wasn’t enough to achieve full recovery for the workers.
In concluding they note that a limitation of the study was the sample size and that the width of the confidence interval leaves a fair bit of unexplained variability.
[** My thoughts are that these findings also support other guidelines that high-risk, monotonous, high consequence planning or new/novel work should be minimised during the highest fatiguing conditions or times of the day.]
Authors: Techera, U., Bhandari, S., Hallowell, M., & Littlejohn, R. (2020, November). In Construction Research Congress 2020: Safety, Workforce, and Education (pp. 306-314). Reston, VA: American Society of Civil Engineers.
Link to the LinkedIn article: https://www.linkedin.com/pulse/impact-worker-fatigue-hazard-recognition-skills-ben-hutchinson
SafetyInsights.org 
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