New computational results for the discrete time/cost trade-off problem with time-switch constraints

Recently, time-switch constraints have been introduced in the literature by Yang and Chen (2000). Basically, these constraints impose a specified starting time on the project activities and force them to be inactive during specified time periods. This type of constraints have been incorporated into the well-known discrete time/cost trade-off problem in order to cope with day, night and weekend shifts. In this paper, we propose a new branch-and-bound algorithm which outperforms the previous one by Vanhoucke et al. (2002). The procedure makes use of a lower bound calculation for the discrete time/cost trade-off problem (without time-switch constraints). The procedure has been coded in Visual C++, version 6.0 under Windows 2000 and has been validated on a randomly generated problem set.