Project Management guide · Project management fundamentals
Critical Chain Project Management (CCPM) Explained
Critical Chain Project Management (CCPM) is a scheduling method developed by Eliyahu Goldratt, based on his Theory of Constraints. It focuses on resource constraints and protects the project deadline with shared buffers rather than padding every task.
Key takeaways
- CCPM schedules around resource constraints.
- Safety time is pooled into project and feeding buffers.
- Progress is tracked through buffer consumption.
The problem it addresses
- Padded estimates: people add safety time to each task.
- Student syndrome: work starts late because there seems to be plenty of time.
- Parkinson's law: work expands to fill the time available.
- Multitasking: switching between projects delays all of them.
Together, these mean individual safety margins are wasted while projects still finish late.
How CCPM works
- Estimate tasks aggressively, without individual safety margins.
- Identify the critical chain: the longest chain of dependent tasks, taking resource availability into account.
- Add a project buffer at the end of the critical chain.
- Add feeding buffers where non-critical chains join the critical chain.
- Use resource buffers or alerts to make sure key people are ready.
- Avoid multitasking; work on one task at a time and pass it on as soon as it's done.
Buffer management
Progress is tracked by how much buffer has been consumed relative to how much of the chain is complete, often on a fever chart with green, yellow and red zones. Managers act only when buffer consumption gets ahead of progress.
Critical chain vs critical path
| Critical path | Critical chain | |
|---|---|---|
| Considers | Task dependencies | Dependencies and resource constraints |
| Safety time | In each task estimate | Pooled in shared buffers |
| Tracking | Task dates and float | Buffer consumption |
See critical path method.
Free templates for this topic
Frequently asked questions
Who created CCPM?
Eliyahu M. Goldratt, who introduced it in his 1997 book Critical Chain.
Where is CCPM used?
In engineering, manufacturing, construction and organisations managing many resource-constrained projects.
What is Critical Chain Project Management?
A scheduling method that accounts for resource limits as well as task dependencies, removes safety time from individual tasks and pools it into shared buffers.
What is the critical chain?
The longest chain of dependent tasks in a project, taking resource availability into account.
What is the difference between critical chain and critical path?
Critical path considers task dependencies and keeps safety time in each estimate; critical chain also considers resource constraints and pools safety time into buffers. See critical path method.
What is a project buffer in CCPM?
Pooled safety time added at the end of the critical chain to protect the project's finish date.
What is a feeding buffer in CCPM?
A buffer placed where a non-critical chain joins the critical chain, so delays on the feeding chain do not delay the critical chain.
What is a fever chart in CCPM?
A chart that tracks buffer consumption against chain completion, with green, yellow and red zones that tell managers when to act.
What is student syndrome in critical chain project management?
The tendency to start work late because there seems to be plenty of time, which wastes the safety margin built into estimates.
What is Parkinson's law in critical chain project management?
The observation that work expands to fill the time available, so padded estimates rarely lead to early finishes.
How is CCPM related to the Theory of Constraints?
CCPM applies Goldratt's Theory of Constraints to projects, treating the critical chain as the constraint to protect.