Measuring and evaluating physiological demands of construction work

Construction craft work is physically demanding. Physically demanding work leads to physical fatigue that leads to decreased productivity and motivation, inattentiveness, poor judgment, poor quality work, job dissatisfaction, accidents, and injuries. In the 1950s and 1960s, there was a surge of interest in applying work physiology to investigate the physiological demands of construction work. Since then, the workforce has changed to include more women and more older workers, and the work itself has changed. Recent advances in computer and microprocessor technology enable scientists to efficiently measure the physiological response to work. In this research, physiological measures of energy expenditure, including oxygen uptake and heart rate data, were collected for 100 construction workers performing 130 actual construction work activities in 12 trades. The average oxygen uptake for the measured construction activities was 0. 82 liter · min -1 (±0. 22 liter · min-1). The average heart rate for the measured construction activities was 108 beats · min-1 (±17 beats · min-1). This research also considers relative physiological workload, the ratio of absolute workload expressed as mean oxygen uptake (VO2) and individual work capacity expressed as maximum oxygen uptake (VO2max). Determining VO2max is rather impractical, and may even be dangerous for unfit construction workers. Alternatively, a Time Series Analysis based statistical technique was developed to predict the relative physiological workload from sub-maximal oxygen uptake data collected in-situ. The new technique was validated on eight subjects. The standard errors in predicting %VO 2max and VO2max are ±3. 2% and ±0. 28 liter · min-1, respectively, which is much better than using the standard VO2-HR method. Using the new technique developed in this thesis, the average relative workload for the 100 construction workers was predicted to be 26 percent (i.e. , 26%VO2max ±6 percent). The lowest and highest average predicted relative workload were 15 and 48 percent, respectively. The absolute and relative workload data was evaluated against published guidelines for acceptable levels of physical performance in industrial settings. The findings of this research reveal that based on two physiological indicators of work load: oxygen uptake and heart rate, construction work is classified as moderate to heavy work. Moreover, evaluations of both absolute and relative workloads reveal that a significant number of craft workers (20 to 40%) routinely exceed generally accepted physiological thresholds for manual work. By using the methods developed and results advanced in this research and by promoting and applying concepts of work physiology at the workplace, many improvements will find their way to the occupational health and safety of the construction workforce. The methods described in this research have widespread applications in identifying excessively demanding construction tasks so the work can be better matched to the abilities of the workers. This thesis has developed the foundation for further research and practical applications regarding the physical demands of construction work.