Linear programming based approaches for the discrete time/cost trade-off problem in project networks

In project management, the activity durations can often be reduced by dedicating additional resources. The Time/Cost Trade-off Problem considers the compromise between the total cost and the project duration. The discrete version of the problem assumes a number of timesol;cost pairs, called modes, and selects a mode for each activity. In this paper, we consider the Discrete Timesol;Cost Trade-off Problem. We study the Deadline Problem, that is, the problem of minimizing total cost subject to a deadline on the project duration. To solve the Deadline Problem, we propose optimization and approximation algorithms that are based on the optimal Linear Programming Relaxation solutions. Our computational results from large-sized problem instances reveal the satisfactory behaviour of our algorithms.