Monte Carlo simulation of labor performance during overtime and its impact on project duration

Labor productivity, which is the greatest source of variation in overall construction productivity, is the critical factor for determining the project performance in terms of time and cost, especially during scheduled overtime when extra time and cost are invested. Since scheduled overtime causes continuous deterioration of labor performance over its duration, it needs to be planned and scheduled in advance in order to benefit from the extra investment of time and cost. However, traditional construction scheduling methods like Critical Path Method (CPM) can not handle the variability of labor productivity. This research suggests Monte Carlo simulation modeling of labor performance during scheduled overtime as a solution. After the variability and pattern of labor performance deterioration during scheduled overtime were modeled for simulation, the simulation model was integrated with a commercial CPM scheduling software package to assess and analyze the impact on total project duration. Furthermore, correlation between the durations of construction activities is incorporated into the simulation model in order to represent the system more accurately and realistically. Since the simulation model quantifies the variability of productivity during scheduled overtime, the estimation of time to complete the activities using scheduled overtime is more realistic and reliable. Also, because the simulation model is integrated into a project schedule network, the assessment of the potential impact of the scheduled overtime on total project duration is clearer and more accurate. The simulation model provides more reliable and realistic information to a project manager's decision making in an effort to complete the project on time and within the budget using scheduled overtime. It is concluded that simulation analysis of scheduled overtime presented in this dissertation can provide the knowledge to make the right decision as well as the tools to communicate risk and uncertainty involved in scheduled overtime to the owners and other project team members.