Critical Chain Project Management (CCPM)
Goldratt applies his Theory of Constraints (TOC) to project management and presents the “critical chain” scheduling approach. ScienceDirect
1. Background & Context
- TOC: Every system is limited by a few key constraints.
- Goldratt extended TOC to project management; CPM often ignores resource limits.
- In 1997, Goldratt introduced the “Critical Chain” method (CCPM).
2. Core Concepts
2.1 Critical Chain Definition
- The “critical chain” is the longest sequence of tasks considering both task dependencies and resource constraints.
- CPM looks only at dependencies/durations; CCPM adds resource limits.
2.2 Key Differences from CPM
- Traditional schedules pad each task for uncertainty, leading to “student syndrome” and Parkinson’s Law.
- CCPM uses shorter, more aggressive durations and protects the schedule with buffers.
- Multitasking is discouraged; focus on one task at a time for critical resources.
2.3 Buffer Management
- Project Buffer: at the end of the critical chain, protects the finish date.
- Feeding Buffers: where non-critical paths join the chain, protect against delays.
- Resource Buffers: ensure resources are ready for critical tasks.
2.4 Monitoring & Control
- Monitor buffer consumption, not just task deadlines.
- Focus is on protecting the chain and finishing on time.
3. Implementation Steps
- Define scope & build a task network (WBS).
- Estimate realistic task durations (remove padding).
- Assign and level resources; avoid multitasking.
- Identify the critical chain.
- Insert project, feeding, and resource buffers.
- Execute and monitor buffer consumption.
- Review and improve for future projects.
4. Benefits & Challenges
4.1 Benefits
- Handles resource constraints better.
- Can reduce project duration and improve reliability.
- Reduces multitasking and context-switching.
- Focuses on overall schedule protection.
4.2 Challenges
- Requires cultural change and buy-in.
- Needs accurate estimates and resource planning.
- May not suit all project types.
- May require new tools and practices.
5. Summary Table
| Item | Description |
|---|---|
| Critical Chain | Longest sequence of tasks considering dependencies and resources. |
| Buffers | Time protection at project end, feeding paths, and resource readiness. |
| Resource Leveling | Avoids over-committing critical resources. |
| Monitoring | Focuses on buffer consumption, not just task deadlines. |
| Goal | Reliable, fast project completion by protecting the chain. |
| Primary Source | Goldratt, Critical Chain, 1997. |
6. Suggested Further Reading
- Globerson, S. “PMBOK® and the Critical Chain.” PM Network, vol. 14(5), May 2000. PMI
- “Research on Critical Chain Project Management”, PM World Library. PM World Library
- “The Basics of Critical Chain Project Management” (Asana blog). Asana
7. Sources
- Goldratt, Eliyahu M. Critical Chain. North River Press, 1997.
- Rand, Graham K. “Critical Chain: The Theory of Constraints Applied to Project Management.” International Journal of Project Management, vol. 18, no. 3, June 2000, pp. 173–77. ScienceDirect
- Ghaffari, Mahdi, and Margaret W. Emsley. “Current Status and Future Potential of the Research on Critical Chain Project Management.” Surveys in Operations Research and Management Science, vol. 20, no. 2, Dec. 2015, pp. 43–54. PM World Library
- Wikipedia
- marris-consulting.com
- critical-chain-projects.com
- Asana
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