A new approach for buffer sizing in critical chain scheduling

The direct application of the theory of constraints (TOC) in project management is known as critical chain project management (CCPM) which is introduced by Goldratt. It is considered to be one of the popular approaches to project management. One of the most significant shortcomings in CCPM is the lack of mathematical analysis. Specifically, in buffer sizing step, Goldratt suggests using of 50% of critical chain lengths as a project buffer. Recently some approaches have been introduced to overcome this problem in CCPM. The fundamental research issues we address in this paper are the use of lognormal distribution for tasks completion time and integrate the risk of tasks in order to determine the parameters of distribution. In the next step a new method is proposed to size the buffer based on Root Square Error Method (RSEM) approach.