Time/cost trade-offs

Time/cost trade-off problem in project scheduling

Branch-and-bound procedure

The paper of Demeulemeester et al (1998) discusses new results for the DTCTP in project scheduling. The optimal solution is determined by a branch-and-bound procedure, which employs convex piecewise linear estimations.
  • Demeulemeester, E., De Reyck, B., Foubert, B., Herroelen, W. and Vanhoucke, M., 1998, “New computational results on the discrete time/cost trade-off problem in project networks”, Journal of the Operational Research Society, 49, 1153-1163.
  • Download the project data of this paper here.


Three extensions to the DTCTP are discussed in the paper of Vanhoucke & Debels (2007). A heuristic solution procedure is proposed for the time-switch, work continuity and net present value extensions.
  • Vanhoucke, M. and Debels, D., 2007, “The discrete time/cost trade-off problem: extensions and heuristic procedures”, Journal of Scheduling, 10, 311-326.
  • Vanhoucke, M., 2015, "Generalized discrete time-cost tradeoff problems", in C. Schwindt & J. Zimmermann, eds. Handbook on Project Management and Scheduling Vol.1. Springer, pp. 639–658.

Time/switch constraints

The DTCTP with time-switch constraints, which force periods of inactivity in the project activities, is handled by Vanhoucke et al (2002).  The paper of Vanhoucke (2005) builds on the previous research and proposes new computational results for the DTCTP with time-switch constraints.
  • Vanhoucke, M., Demeulemeester, E. and Herroelen, W., 2002, “Discrete time/cost trade-offs in project scheduling with time-switch constraints”, Journal of the Operational Research Society, 53, 741-751.
  • Vanhoucke, M., 2005, “New computational results for the discrete time/cost trade-off problem with time-switch constraints”, European Journal of Operational Research, 165, 359-374.

Business Game

The well-known Project Scheduling Game is a game to optimize time/cost trade-offs in a dynamic setting. It is used at universities and business schools, and has been the foundation for several research papers.

  • Vanhoucke, M., Vereecke, A. and Gemmel, P., 2005, "The project scheduling game (PSG): simulating time/cost trade-offs in projects", Project Management Journal, 36(1), 51–59.
  • Vanhoucke, M. and Demeulemeester, E., 2003, "The application of project scheduling techniques in a real-life environment", Project Management Journal, 34, 30–42.

Payment models

The net present value variant of the DTCTP is applied to three payment models in the work of Leyman et al (2015). Different metaheuristics and solution representations are applied to the three models.
  • Leyman, P., Van Driessche, N. & Vanhoucke, M. (2015), "Metaheuristics for the discrete time/cost trade-off problem with net present value optimization and different payment models", currently under submission.
  • Download the created value data of this paper here.