Ensuring quality in resource constrained project scheduling

Abstract

This study constitutes an initial effort for modeling and solving resource constrained project scheduling problems with the objective of maximizing quality. Two mixed integer formulations of the problem are introduced. The first formulation assumes integral activity durations and completion times. These assumptions are relaxed in the second formulation. In both formulations the quality of a project is measured by the amount of rework required and the corresponding additional cost incurred. These quality measures are expressed in a common unit of measure and incorporated into the objective function. The second mixed integer formulation is found to be more efficient and thus computational results are reported based on that model. A set of resource constrained scheduling problems are solved using the quality objective and traditional objective functions from the literature. In general it is found that the schedules obtained when maximizing quality outperform the schedules obtained with minimizing makespan or maximizing the net present value of project cash flows objectives in terms of makespan, cost and computational times.