This is not a summary of an article per se; but it summarizes the description on how to build a Critical Chain as it was published in
Rand, Graham K.: Critical chain – the theory of constraints applied to project management; in: International Journal of Project Management, Vol. 18 (2000), No. 3, p. 173-177. http://dx.doi.org/10.1016/S0263-7863(99)00019-8
The Theory of Constraints was outlined by Eliyahu M. Goldratt in his book „Theory of Constraints“, which subsequently Goldratt applied to project management in „Critical Chain“, which interestingly is a novel similar to Tom DeMarco’s Deadline. Anyway, the basic idea of the Theory of Constraints is according to Wikipedia
[…] every organization has – at any given point in time – at least one constraint which limits the system’s performance relative to its goal. These constraints can be broadly classified as either an internal constraint or a market constraint. In order to manage the performance of the system, the constraint must be identified and managed correctly […] (from Wikipedia)
The Theory of Constraints outlines a 5 step process to tackle the whole problem
- Identify the constraint
- Decide how to exploit the constraint
- Subordinate everything else to above decision
- Elevate the constraint
- If constraint has been broken, go back to (1) and never allow inertia to cause a system’s constraint
So what is the constraint on a project? Of course it is the time of critical resources. What is the problem with them? They do suffer from something called student’s syndrome – no matter how much buffer they get, the work is only done in the last few days.
The solution? Exploit the constraint – then elevate it. In other words: finish task on time before trying to decrease total time.
How can one exploit the constraint? Remove all buffers into a big one at the end of the project. All tasks or streams which are not on the critical path get a feeding buffer right before they feed into the critical path again.
How do I manage it? Project Management needs to ensure that no time is lost on hand-overs. Furthermore if the time comes everything must be dropped and everyone works on tasks on the critical chain only. Never ever shall multi-tasking occur!