Title: Time-cost trade-offs in resource-constraint project scheduling problems with overlapping modes

Authors: François Berthaut; Robert Pellerin; Nathalie Perrier; Adnène Hajji

Addresses: Jarislowsky/SNC-Lavalin Research Chair in the Management of International Projects and CIRRELT, Department of Mathematics and Industrial Engineering, École Polytechnique de Montréal, 2900 Edouard-Montpetit, P.O. Box 6079 Station Centre-ville, Montréal, Québec H3C 3A7, Canada ' Jarislowsky/SNC-Lavalin Research Chair in the Management of International Projects and CIRRELT, Department of Mathematics and Industrial Engineering, École Polytechnique de Montréal, 2900 Edouard-Montpetit, P.O. Box 6079 Station Centre-ville, Montréal, Québec H3C 3A7, Canada ' Jarislowsky/SNC-Lavalin Research Chair in the Management of International Projects and CIRRELT, Department of Mathematics and Industrial Engineering, École Polytechnique de Montréal, 2900 Edouard-Montpetit, P.O. Box 6079 Station Centre-ville, Montréal, Québec H3C 3A7, Canada ' Department of Operations and Decision Systems, Faculty of Business Administration, Laval University, 2325, de la Terrasse, Québec, Québec G1V 0A6, Canada

Abstract: In companies, overlapping is commonly regarded as a promising strategy to accelerate project execution. Overlapping consists in executing in parallel two sequential activities by allowing a downstream activity to start before the end of an upstream activity based on preliminary information. However, overlapping can entail reworks in downstream activity, caused by information updates until finalised information is available, and additional coordination and communication, which both require additional time and costs. In this paper, we present a model for the resource-constrained project scheduling problem with feasible overlapping modes. The makespan minimisation and the gain maximisation problems are formulated as linear integer programmes. Time-cost tradeoffs between project duration and overlapping costs are also discussed. An example of a 30-activity project is provided to illustrate the utility and efficiency of the model. Our results highlight the closed interaction between resource constraints and overlapping modes and suggest the relevance of jointly considering them.

Keywords: activity overlapping; concurrent engineering; project management; project scheduling; resource constraints; time cost trade-offs; project execution; downstream activities; upstream activities; preliminary information; finalised information; information updating; coordination; communication; RCPS problem; resource constrained project scheduling; feasible overlapping; makespan minimisation; gain maximisation; ILP; integer linear programming; project duration; overlapping costs; overlapping modes; simultaneous engineering.

DOI: 10.1504/IJPOM.2014.065259

International Journal of Project Organisation and Management, 2014 Vol.6 No.3, pp.215 - 236

Published online: 31 Oct 2014 *

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