Modeling construction labor productivity

This paper presents a philosophical argument for new construction labor productivity models based on actual factors affecting productivity. The paper reviews various work-study models that have been borrowed from industrial engineering. These are the delay, activity, and task models. Using research data, these models are shown to be inadequate and unreliable productivity models. It is suggested that these models emphasize work methods, and that the best opportunity to improve productivity is to focus on the factors that management can control. Two reliable productivity models validated specifically for construction situations are presented. These are the factor model, which accounts for project, site, and management factors affecting productivity, and the expectancy model of motivation, which describes why a crew exerts an effort to perform and how this effort relates to productivity. The essential features of the models are described, and it is suggested that the models can be integrated into a single comprehensive model to quantify the factors affecting productivity and to forecast performance.