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critical chain

См.: критическая цепь.



critical chain

critical chain - The longest sequence of dependent events through a project network considering both task and resource dependencies in completing the project. The critical chain is the constraint of a project.

Usage: The project duration is the total of the critical chain task times plus the project buffer.

Illustration: The project below has eight tasks and one unit of each of five resources (B, C, M, O, and Y). Tasks M16 and M10 require resource M at the same time, an example of resource contention. One option is to start task M10 earlier to eliminate the contention. Once this is done, the critical chain becomes M11-Y4-O6-M10-M16-C20. This sequence of tasks plus the project buffer (PB) of 33 days determines the critical chain duration of 100 days (although see the Caution below about the length of the critical chain).

Caution: Internal organization functions (e.g., resource managers, project managers, software developers) use the term critical chain to describe the unbuffered or unprotected chain of dependent tasks/resources. In contrast to this usage, sales, marketing and other functions that deal directly with clients use the term critical chain to describe the total project duration, which includes not only the total task time on the critical chain but the project buffer also. This total project duration provides the

basis (adjusted for starting date) for promising project completion dates to clients. Goldratt, in his summary in Session 3: Project Management and Engineering of the Goldratt Satellite Program, uses the terms critical chain and protected critical chain to describe the internal and external uses of the term, respectively.

See:critical chain project management, protected critical chain.