Multiobjective optimization model for planning repetitive construction projects

Minimizing the duration of repetitive construction projects such as high-rise buildings and highway construction often requires interrupting the work continuity of construction crews and/or utilizing overtime hours. Available scheduling models for repetitive construction projects can generate optimal trade-offs between minimizing project duration and crew work interruptions; however, they are incapable of minimizing the use of overtime hours. This paper developed a novel multiobjective optimization model for repetitive construction projects that is capable of generating optimal trade-offs among project duration, work interruptions, and overtime use. The model was developed in three main phases (1) a formulation phase that identified all relevant decision variables and formulated the three objective functions of the model; (2) an implementation phase that executed the model computations using multiobjective genetic algorithms; and (3) a performance evaluation phase. The results of this performance evaluation confirmed that the model outperforms existing models in minimizing the use of overtime hours, and generating optimal trade-offs among project duration, crew work interruptions, and overtime use.