CCPM

Critical Chain Project Management (CCPM) is a project scheduling methodology developed from the Theory of Constraints to improve delivery reliability and reduce project duration. Introduced by Eliyahu M. Goldratt in the late 1990s, CCPM shifts focus from individual task encumbrances and optimistic estimates to resource constraints and buffers that protect project due dates.

Core concepts include identifying the critical chain, the longest path through the project network when considering resource dependencies and constraints. Unlike traditional CPM or PERT, CCPM emphasizes resource availability and multitasking reduction. Safety margins are removed from individual task estimates and consolidated into buffers: a project buffer at the end of the chain and feeding buffers where non-critical paths converge with the critical chain. The aim is to shorten completion times while ensuring on-time delivery through buffer management rather than status reports of percent complete.

Implementation typically involves mapping tasks and dependencies, identifying the critical chain with resource constraints, shortening task estimates to reflect realistic durations, and placing buffers to absorb delays. Execution focuses on protecting the project buffer, reducing multitasking, and monitoring buffer consumption as a measure of project health rather than tracking progress of each task.

Benefits claimed for CCPM include faster project completion, reduced schedule risk, and improved reliability in delivery dates. It is commonly applied in environments with high uncertainty or scarce resources, such as construction, manufacturing, and software development. Limitations include the need for organizational buy-in, cultural change, and disciplined buffer management; effectiveness depends on accurate resource data and consistent progress reporting.