The critical chain, in project management, is the sequence of both precedence- and resource-dependent terminal elements that prevents a project from being completed in a shorter time, given finite resources.
If resource availability is not a constraint, then a project's critical chain becomes the same as its critical path (just like Einstein's theory reduces to Newton's under conditions of low speeds and gravity).
It is an alternative to critical path analysis. The main features that distinguish the CC method from the critical path are:
- The use of (often implicit) resource dependencies. Implicit means that they are not included in the project network but have to be identified by looking at the resource requirements.
- Lack of search for an optimum solution. This means that a "good enough" soulution is enough because:
- as far as I know, there is no analytical method of finding an absolute optimum (i.e. having the overall shortest critical chain)
- the inherent uncertainity in estimates is much greater than the difference between the optimum and near-optimum ("good enough" solutions).
- The identification and insertion of buffers:
- project buffer
- feeding buffers
- resource buffers.
Critical chain project management uses buffer management instead of earned value management to assess the performance of a project. The earned value management technique is thought to be misleading, because it does not distinguish progress on the project constraint (i.e. on the critical chain) from progress on non-constraints (i.e. on other paths).
So far, none of the major project management software packages directly support critical chain planning and monitoring, although add-ons are available.
See also: project planning