Determination of construction process duration based on labor productivity estimation: A case study

Monitoring labor productivity and how to decrease construction costs are the key issues in the planning process of a construction project. The CONTEC automated system combined with statistical methods assists in predicting the amount of time required to complete construction works according to the specified number of deployed work crews, technological processes, and labor required for certain production in person-hours. This study applies statistical analyses and probability theories for plastering work, which represents a labor-intensive construction process. The goal of the research is to determine the probability of completion of the construction process based on monitoring the mean value of performance. By application of statistical analyses a decrease in the performance standard has been proved compared with the planned values given in the CONTEC database. The decrease in performance, which was also caused by the number of days with unfavorable climatic conditions and demonstrated by performing interval estimates based on the collection of statistical data, was later confirmed by a relative frequency test. The measures taken were in terms of establishing the required number of personnel capacities for complying with the construction schedule.