Fatemeh Moazami Goodarzi - Department of Industrial Engineering, Amirkabir University of Technology, Tehran, Iran
Seyed Mohammad Taghi Fatemi Ghomi - Department of Industrial Engineering, Amirkabir University of Technology, Tehran, Iran

Estimating project time and cost is a challenging task for project managers and planners. The reliability of these estimates is very low and far from reality due to the risks in the projects. This paper, argues that this reliability can be improved using the concept of stratification to calculate the time and cost of a project more accurately and closer to reality, and to implement this concept in a dam construction project. This concept, received less attention in studies, describes a system transmitted through a number of modes to reach the target mode. Modes that have related inputs (risks) and outputs (project correction time and cost) gradually categorized based on their distance from the target set. This provides a unique structure that is able to take into account the risks that may occur during a project, thus increasing the reliability of estimating the time and cost of completing projects.