Moving Beyond the Triple Constraints

Filed under Misc | Posted by PMStudent


Dave Garrett recently wrote on the concepts expressed by Aaron Shanhar in his book, Reinventing Project Management. The gist is that the common triple-constraint model of managing cost, schedule, and scope is not enough. As I like to put it and in Goldratt’s words, necessary but not sufficient.

I have not yet read Shanhar’s book, but have a few initial thoughts based on Garrett’s description.

The notion feels right. I have observed a few specific behaviors that may come about because of the framework of incentives set up by the traditional approach. First, quality assurance seems to be an afterthought or necessary evil in many projects, if it happens at all. I agree with the notion that the triple constraints are efficiency-focused. They set up incentives to meet the requirements, even if those are the bare minimum. Many times, scope is reduced as a result of cost cutting efforts, and they are looking for whatever will provide barely satisfactory results. Activities are dropped without a thorough analysis of what the impact on quality, team morale, etc. might be.

Second, I have known many project managers to define success as sticking to the requirements, even if they are very bad requirements. There’s no incentive to put a lot of effort into quality requirements if a project manager knows they will still have met scope, schedule, and budget. In other words, you can have a failed project which meets all three constraints. Interesting….doesn’t sound like success criteria.

I agree we need a better model with which to think about projects holistically. I look forward to reading Reinventing Project Management, and learning more.


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