Time-Cost-Quality Trade-off in Project Scheduling with Linguistic Variables

3 Abstract: Time, cost and quality are among the crucial aspects of each project. In recent years, the demands of project stakeholders regarding reductions in the total cost and time of a project along with achieving the acceptable quality of the project have risen significantly. This leads researchers to developing models that incorporate the quality factor to previously existing time cost trade-off models.We develop a model for discrete time-cost-quality trade-off problem. For each activity, an execution mode can be selected from a number of possible ones. The time and cost of each mode are assumed to be crisp but the quality of each mode is a linguistic variable. Therefore, in this paper, fuzzy logic theory is employed to consider affecting uncertainty in project quality. Project manager can have different solutions which are dependent on his measure of accepted risk through applying -cut methods in fuzzy logic theory. To solve the model, a new metaheuristic algorithm called NHGA is developed. By presenting a case example, the efficiency of the proposed algorithm for solving the model and its flexibility for project managers' decision making is demonstrated. The proposed algorithm and classic genetic algorithms are prepared by the analysis of variance (ANOVA) method.