The Project Management Triple Constraint – do you manage it or does it manage you?

Project Management is ultimately about getting and using the right team, tools, and techniques to get the job done. One of the traditional ways to measure whether a project’s objectives are being met is the Triple Constraint. I’ve seen it defined a number of ways:

scope|cost|schedule
scope|resources|quality
time|cost|quality
time|cost|resources

…an equilateral triangle that has to remain equilateral as elements are adjusted over time.

Actually, the first time I heard it explained was when a former co-worker—after hearing a long wish list of bells and whistles an exec team wanted in an upcoming trade show booth—said, "We have to deal with certain limitation realities, especially with regard to timing – as the show will happen whether we’re ready or not. So, you want it good (the bells and whistles), you want it fast (in time for the event), and you want it cheap (of course). Pick two, ’cause that’s all you get."

His outlook is valid in some situations, but I don’t think it shows the whole picture; the triangle should be viewed as another tool in a PM’s arsenal to help gauge that a project is running efficiently and to help keep it on track, not the only tool; the use of PPM software can help monitor this. But a good PM knows better than to focus solely on the elements of the triangle, causing the triangle to manage the project manager. As a work management tool, the triangle should act more like a red flag.

While it’s true that when one of the three elements changes the others must change as well, it’s necessary to the ultimate success of the project to include a number of other factors into the mix: quality/operability (is it right; does it work), risk, customer satisfaction, executive satisfaction, and team satisfaction. What it seems to come down to is communication (again).

If the client decides to change or add to the features list, it’s up to the PM to make it clear to all the stakeholders that other things may either have to change or suffer. A lot depends on the initial agreement, the change control process, the relationship with the client, and how much wiggle room was included in the original estimates, but in any project based work, a shift in one piece will likely cause a shift throughout. By letting the client know right away that their request might effect the delivery date, the cost, or the quality, you put any trade-off decisions squarely into their hands, with known consequences.

Bottom line: Manage the Triple Constraint Triangle, don’t let it manage you!