Simulation-based assessment of workers' muscle fatigue and its impact on construction operations

Construction workers are frequently exposed to excessive physical demands due to repetitive lifting and material handling while performing tasks. Consequently, many construction workers suffer from a significant level of muscle fatigue that may negatively impact a project's performance. Thus, evaluating the level of muscle fatigue prior to work and implementing appropriate interventions to reduce physical demands will help to prevent adverse effects of workers' fatigue on construction operations. Even though several research efforts have suggested methodologies to evaluate muscle fatigue, the extent to which workers' muscle fatigue would affect construction performance has not yet been fully studied. To address this issue, a simulation-based framework is proposed to estimate physical demands and corresponding muscle fatigue, and thus to quantitatively evaluate the impact of muscle fatigue during construction operations. Specifically, physical demands from a planned operation modeled using discrete event simulation (DES) are estimated through biomechanical analyses. Then, the proposed dynamic fatigue models estimate the level of muscle fatigue of each worker as a function of the estimated physical demands. Workers' strategies to mitigate muscle fatigue, such as taking voluntary rests, are, in turn, modeled in the DES to understand how muscle fatigue affects time and cost performance of the planned operation. As a proof of concept, a case study on masonry work was performed to demonstrate the usefulness of the proposed framework, describing the need for taking into account muscle fatigue for operational planning due to possible excessive physical demands. The results from the case study indicate that excessive physical demands beyond workers' capabilities result in reduction of time and cost performance. The proposed framework helps to better understand workers' response to physical demands by adding workers' capabilities as changing variables into traditional DES approaches, enabling pro-active management of human resources. Ultimately, the framework, which combines conventional interests on optimized operations in terms of time and cost with those of ergonomics, provides opportunities to take into account both workers' health and work performance in early design stages.