Critical chain project management (CCPM) is a method of planning and managing projects that emphasizes the resources required to execute project tasks.

It was introduced in 1997 by Eliyahu (Eli) M. Goldratt. CCPM addresses issues related to project timing, increased costs, performance and under-delivery, versus traditional methods, such as critical path, where the emphasis is placed on tight scheduling and ordered tasks.

The critical chain project management technique is very effective in organizations which do not have evolved project management practices. But this technique does not advocate multi-tasking, and in projects with complex schedule networks, the results of implementing the critical path methodology have proven to be a deterrent to the overall project schedule.

Critical chain project management uses buffer management instead of earned value management to assess the performance of a project. Some project managers feel that the earned value management technique is misleading, because it does not distinguish progress on the project constraint from progress on non-constraints.

Buffer in CCPM:

CCPM planning aggregates the large amounts of safety time added to tasks within a project into the buffers—to protect due-date performance and avoid wasting this safety time through bad multitasking, student syndrome, Parkinson's Law, and poorly synchronized integration.

CCPM relies on Buffers to ensure that the chain doesn’t break and tasks are completed to ensure on-time delivery. (Buffers are basically strategic safeguards inserted into the critical chain to ensure a project continues to run smoothly, and any unforeseen circumstances don’t disrupt the project delivery date.)

There are 3 types of buffers used in CCPM:

• Project Buffer: Project buffer are placed between the last task and the project completion date, and it acts as a contingency for the Critical Chain activities.

• Feeding Buffer: Feeding buffer are inserted between the last task on a non-critical chain and the Critical Chain. They are added to a feeding chain to ensure that any delays on a non-critical chain don’t affect the Critical Chain.

• Resource Buffer: Resource buffer are placed on the Critical Chain to ensure appropriate resources. These buffer are available whenever needed. Resource buffer acts as a trigger point for the resource, indicating when the critical path is about to begin.

Fig: Buffers in CCPM: