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Critical path
In project management, a critical path is the sequence of project network terminal elements with the longest overall duration,
determining the shortest time to complete the project.
The duration of the critical path determines the duration of the entire project. Any delay of a terminal element on the critical
path directly impacts the planned project completion date (i.e. there is no slack on the critical path).
A project can have several, parallel critical paths. An additional parallel path through the network with the total durations just
shorter than the critical path is called a sub-critical path.
Originally, the critical path method considered only logical dependencies among terminal elements. A related concept is the critical
chain, which adds resource dependencies.
The critical path method was invented by the DuPont corporation.
Critical chain
In project management, the critical chain 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 aggregates the large amounts of safety time added to many subprojects in project buffers to protect due-date performance, and to avoid
wasting this safety time through bad multitasking, student syndrome, and poorly synchronised integration.
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).
Concept developed by Eliyahu M. Goldratt as an application of his theory of constraints.
So far, none of the major project management software packages directly support critical chain planning and monitoring, although add-ons
are available.
Related Topics
Risk Management in Project management
Scheduling & Project Scheduling
Project Management Tools - PERT Chart and Gantt Chart
Project Definiton | What is a Project
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