Fuzzy critical chain risk management for quantifying impact of variation in non-critical activity duration on project duration

Abstract

This paper develops a method for quantifying and minimising risks causing variation in critical and non-critical activity duration which influences a project completion time. The method employs a critical chain concept using buffer penetration rate to control risk affecting activities in construction projects. Uncertainty associated with the risk assessment and variation in activity duration is represented by fuzzy numbers. The buffer of several types is sized based on the variation in activity duration which is in direct proportion to the assessed value of risk magnitude. The proposed method shows relationships of the scheduled buffer, consumed buffer and project completion time which helps tackle variation in both critical and non-critical chains and reduce the impact of the non-critical chains on the critical chain. It provides a design chart for a project manager for developing an as-planned schedule with a consideration of risks. During project execution, the proposed method concentrates on the penetration level in the project and feeding buffers and dynamically updates an as-built schedule based on actual progress, which can be also used as a schedule control.