The Critical Chain Method (CCM) is one of the methods used to perform Schedule Network Analysis that takes into account task dependencies, limited resource availability and buffers. It’s used to prepare the project schedule when limited or restricted resources are available. The goal of CCM is eliminating project schedule delays due to uncertainties, overestimation of task duration and wasted internal buffers.
In this method, the Program Manager (PM) usually schedule all or most of the high risk or critical activities in the earlier stage of the project schedule. This allows the critical tasks to be completed early as well as gives buffers to handle unexpected problems if arises. Also, the PM will combine several tasks in to one task and assign one resource to handle all.
The six (6) steps involved in the CCM are:
- Identify all activities and dependencies
- Construct a Schedule Network Diagram
- Define constraints
- Determine critical path
- Determine buffers
- Apply resource availability
The CCM has three (3) different types of Buffers which are:
- Resource buffer: is inserted just before a critical chain activity where a critical resource is required. It’s used to remind the project team that a resource is needed and to finish up prior activities.
- Feeding buffer: is inserted as a safety margins in the non-critical chain of a network schedule. It’s placed where the path feeds back into the critical chain path.
- Project buffer: the summation of all the internal buffers added to each project task or activity.
AcqLinks and References:
-  Defense System Management College “Scheduling Guide for Program Managers” – Oct 2001
- DoD “Integrated Master Plan and Integrated Master Schedule Preparation and User Guide” – 21 Oct 2005
- CDC “Project Scheduling Best Practices/Guide” – 30 Jun 2007
- GAO 12-120G “Schedule Assessment Guide: Best Practices for Project Schedule” – May 2012