Multi-objective Resource-Constrained Scheduling in Construction Projects

The resource-constrained scheduling problem (RCSP) is one of the most challenging problems in project management. It is a combinatorial optimization problem with multiple and contradictory objectives (resource allocation within resource availability levels, project completion prior to a given deadline, resource leveling throughout the project length) and constraints (precedence constraints between activities) while its complexity grows as the number of activities increases. In this study, the objective function includes a number of sub-objectives that result from practical considerations of actual construction projects. These are the cost of daily resources exceeding the resource availability, the cost from the day-by-day resource movement in and out of the project work, and the cost of prolonging the project duration or exceeding the project completion deadline. Due to the large solution space size (even for a small-sized project), genetic algorithms are employed in this study to develop the optimal or a near-optimal solution. The model is applied to a case study project and tested for different constraints and goal scenarios, in order to provide insight regarding the effectiveness of the method in different optimization criteria and project management priorities. Evaluation results indicate that the proposed approach can effectively approximate the optimal solution in all cases.