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Critical Chain Project Management

The Theory of Constraints applied to projects: size the constraint as the longest chain of dependent, resource-contended steps, and pool safety time into shared buffers instead of padding every task.

[!todo] Seed note. A starting point, not a finished note yet.

Critical Chain Project Management (CCPM) is Goldratt’s 1997 application of the Theory of Constraints to project scheduling. The constraint is the critical chain: the longest sequence of dependent tasks once resource contention, not just logical sequence, is accounted for. CCPM attacks safety time that gets wasted rather than saved through Parkinson’s Law (work expanding to fill its estimate) and student syndrome (starting late so the pad is gone before trouble hits). It strips per-task padding down to roughly 50% confidence estimates and pools the removed safety into shared buffers, a project buffer at the end plus feeding and resource buffers, then manages the project by watching buffer consumption instead of task milestones. Because task fluctuations are partly independent, the pooled buffer can be smaller than the sum of the pads it replaces. Seeded from Theory of Constraints.

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