Incorporation of Fuzzy Sets and Earned Value Management into a Cost-Time Trade-off Model

Time-cost trade-off (TCT) problem is a well-known subject in the project scheduling contexts. None of previous studies in this area of research emphasize on the incorporation of the TCT problem into the started project’s performance in order to present a comprehensive model for scheduling and controlling the project in its whole life. The aim of this paper is to provide a novel control mechanism which includes scheduling the project prior to start date، monitoring the project’s performance through the execution، predicting future performance of the project، determining the necessity for re-scheduling، and providing an approach for re-scheduling of the project. In the proposed model، several options with specific time and cost have been considered for the initiation of each activity. These options make different paths for the construction of the project. Due to vagueness and imprecision presented in real case projects، the time and cost behavior for each option has been presumed as fuzzy numbers. Earned Value Management (EVM) has been then utilized for measuring project performance and ultimately، statistical modeling has been also employed in predicting the future trend of EVM’s indices. The model has resulted in selection of the best path for implementation purpose among all available paths. Moreover، the proposed model provides the advantage of assessing the possibility of rescheduling process. An illustrative case has been studied to analyze the application of the proposed model.