Linear Optimization Model to Minimize Total Cost of Repetitive Construction Projects and Identify Order of Units

This study developed a linear optimization model for scheduling repetitive construction projects with varying quantities of work in repetitive units. The model provides new capabilities that enable planners to identify an optimal/near-optimal schedule that minimizes project total cost and number of times crew work is interrupted. It is capable of identifying the optimal/near-optimal order of executing repetitive units to achieve further reduction in project time and cost. The model was developed in three main phases: (1) identifying input data such as quantities and crew productivity rates; (2) optimizing the construction schedule of repetitive units by identifying decision variables, formulating objective functions, and constraints, and executing model computations; and (3) visualizing the generated optimal/near-optimal schedule, crew interruption, project duration and cost, and order of executing repetitive units. Two case studies of 105 and 6 repetitive units were analyzed to evaluate the model performance. The model resulted in 0.13% and 4.2% additional reduction in project total cost and indirect cost, respectively, for the optimal order of repetitive units compared with the best model in the literature. (C) 2021 American Society of Civil Engineers.