Measuring and evaluating physical strain to improve construction workforce productivity

Anecdotal evidence suggests that there is a reciprocal relationship between physical strain and workforce productivity and safety performance. Hence, a monitoring technology able to assess physical strain through the analysis of workers' physiological parameters may be an important step in improving safety and productivity. However, clear relationships between physical strain, safety, and productivity have yet to be determined. Moreover, previous studies showed limitations regarding the monitoring of physiological parameters. Innovative monitoring devices, called Physiological Status Monitors (PSMs), have overcome the past limitations enabling real-time monitoring of workers' physiological parameters. Thus, this research evaluated PSM suitability for construction workforce monitoring by investigating the construction industry's perspective through a questionnaire survey. Moreover, three off-the-shelf PSMs were tested to assess their validity in monitoring physiological parameters during dynamic activities similar to construction workforce's routine activities. Ten subjects participated in the experiments for a total of over 35 hours of recorded data. This research also analyzed the physical strain vs. productivity relationship by adopting heart rate and breathing rate as predictors of physical strain. Thus, productivity, heart rate, and breathing rate data of nine subjects performing a four-hour, simulated construction task (i.e. , over 30 hours of recorded data with sampling frequency of 1 Hz) were used to generate 160 regression models. The analysis of the regression models showed that breathing rate is not a significant predictor while heart rate is a significant predictor with a strong parabolic relationship with productivity. Therefore, this research provides evidence of the physical strain vs. productivity relationship and, for the first time, proposes a mathematical formulation of such a relationship. This research project significantly contributes to the advancement of knowledge about physiological monitoring of workers. The methods and results proposed in this research coupled with concepts of ergonomics at the work place can foster not only enhancements in productivity management, but also improve construction workers' wellbeing and safety.