An innovative two-stage method for balancing time, cost, quality, and additional objectives in multi-mode resource-constrained project scheduling: A case study of a food product packaging production line project

This paper presents a novel two-stage approach for optimizing the scheduling of multi-objective construction projects, validated through a real-world case study of a food product packaging production line. Beyond the conventional objectives of time, cost, and quality, five additional factors—risk, scope creep, environmental impacts, stakeholder satisfaction, and safety—are quantitatively incorporated based on expert judgment and normalized performance ratings. In the first stage, a TOPSIS-based similarity index is calculated for each execution mode of the project activities, aggregating the additional objectives into a single comparable criterion derived from the weighted expert assessments. In the second stage, a four-objective optimization model is formulated to balance project makespan, cost, quality, and the similarity index. Integrating the similarity index ensures simultaneous consideration of both traditional and supplementary objectives. The multi-mode resource-constrained project scheduling problem (MRCPSP) is solved on small instances using the epsilon-constraint method, and for medium- and large-scale problems, two metaheuristics—NSGA-II and MOPSO—are employed. Computational results and sensitivity analyses conducted on the case study demonstrate the model’s capability to produce a diverse set of high-quality Pareto-optimal solutions within reasonable computational timeframes. The proposed framework’s flexibility makes it suitable for projects with varying objective priorities, offering a comprehensive and practical decision-support tool for project managers aiming for more balanced and precise scheduling decisions.