Time-cost optimization model considering float-consumption impact

The main objectives of construction projects are completing the project on time and within budget. Typically, there is a trade-off between time and cost. Time loss is costly and time savings can provide benefits to all the parties involved in the project. Time-cost optimization is essential for construction projects. The objective of time-cost optimization is to determine the optimum project duration corresponding to the minimum total cost. This is accomplished by shortening the duration of critical activities to reduce the overall project duration. Time-cost optimization techniques result in reducing the available total float for noncritical activities, and thus, reduce the schedule flexibility. This paper presents a nonlinear-integer programming model that is developed to solve the time-cost optimization problem taking into account the impact of total float loss. The model uses What'sBest solver to find an efficient solution to the optimization problem while incorporating the total float-loss cost calculated according to the float-commodity approach. The results are significant and allow project managers to exercise new trade-offs between time, cost, and flexibility, which will ultimately improve the chances of achieving project objectives.