This conference paper explored the impact that fatigue (physical & mental) has on productivity of a construction crew in a dam construction project in Queensland. The calculated economic impact of the lost productivity was also calculated.
A sample of concrete crew members were monitored over a working week. This involved:
1. Psychomotor vigilance task (PVT) testing over the working day (a reaction time test that also records lapses/missed signal detection. This test is a validated instrument to measure fatigue and sleep loss impairment on performance)
2. Subjective fatigue surveys
3. Productivity assessments using the Labour Utilisation Factor. This involves a series of one-minute observations during shifts throughout the day and a formula that calculates a final productivity percentage.
The working arrangements was a minimum of 10-hour shifts, 5 days a week. Saturday was common, raising weekly work hours to >60 hours.
Results:
Survey results indicated that the majority of the concrete team experienced mental or physical fatigue over a standard working week – with 8 out of 12 concreters experiencing high levels of fatigue through the week.
It’s said that the survey “showed that most workers in this crew were affected by mental fatigue for the past 6 months or more, indicating that the stresses of the job had accumulated over time” (p999). Heat, repetitive tasks and sleep loss were the main causes of fatigue in this crew. Further, 65% of the crew were affected by heat during the work shift, 55% affected by sleep loss and 58% affected by repetitive tasks.
For the PVT reaction time tests, reaction times were seen to increase considerably from the start to the end of the shift – ~21% worsening of objective performance over the shift.
For productivity, it was found to start relatively low at the start of the day, peaked in the late morning and then dropped off towards the end of the day. The authors note that “It is also apparent that the reduction of productivity after lunch time is highest on Friday” (p1000).
PVT performance had a statistically significant and negative relationship with productivity, such that higher fatigue was associated with lower productivity.
When calculating the lost productivity for a standard 10-person crew on this project, it was found this was around $50,000 annually in losses based on the labour utilisation factor survey. (As far as I can tell there was no control or comparison group, so it’s difficult to read into this finding too much.)
Authors: O’Neill, Conor, Panuwatwanich, Kriengsak, 2013, Proceedings of the Fourth International Conference on Engineering, Project and Production Management
Study link: http://hdl.handle.net/10072/60153
Link to the LinkedIn article: https://www.linkedin.com/pulse/impact-fatigue-labour-productivity-case-study-dam-ben-hutchinson
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