Critical Chain Method

Posted on August 7, 2009 by


The Critical Chain Method, developed by Eliyahu M. Goldratt, is a schedule analysis technique that is listed in the fourth edition PMBOK®’s Develop Schedule process. Although similar to the Critical Path Method, this method emphasizes resource limitations and buffers. After building a project schedule network diagram, any necessary changes are made to the schedule based on resource limitations. For example, the original schedule could have four simultaneous paths that each has a certain type of specialist working full-time on that path’s activities. However, the organization may only be able to obtain one specialist, and that person cannot work four full-time jobs at once! So the schedule in this case would be lengthened so that the specialist can do all the work within normal full-time hours.

The Critical Chain Method also inserts buffers, which is a length of time without scheduled activities that can be used for activities that may last longer than expected. For example, if everything goes as planned, a project could take 11 months to complete, but an extra month is scheduled at the end whose days can be used for activities that take longer than expected. This is called the project buffer. Buffers throughout the project are called the feeder buffers.

Critical Chain does not place as much emphasis on finding the shortest possible critical path, as it recognizes the high element of uncertainty in the duration of project activities. Also see the earlier postings of Critical Path Method Explained with Cookies (posted August 6, 2009), Develop Schedule Process (March 10), and Project Schedule Network Diagrams (posted June 24, 2009).