Executive Summary: There’s an adage, fast/cheap/good, pick any two. This relates to the Project Management Triple Constraint. It also has other names like Iron Triangle and Project Triangle.

The Triple Constraint. A common teaching in the project management world is the Triple Constraint. This is represented by the simple triangle shown.

All projects are constrained by three factors: scope, cost, and time. Each of these three constraints exists while the service provider is simultaneously meeting customer quality requirements.

The logic of the triangle follows using three typical scenarios. If an owner makes a change in any two of the three, then the other two cannot be maintained. For example,

1. If an owner wants to increase the scope, (s)he cannot have it at the same cost and/or at the same time.
2. If an owner wants the project done in less time, (s)he cannot have the full scope or at the same cost.
3. Finally, if the owner wants the project at a lesser cost, either the scope or time must change.

Owner education. The Pick Two adage is something that owners conveniently ignore or forget when it comes down to project negotiations. Owners need to be reminded that they contracted for a set scope, time duration, and cost. Changing any of the three factors is possible, but they must be willing to acquiesce on one of the other two or even both.

My story. Although this triangle is industry-recognized and accepted, I don’t agree with it. I believe more in a diamond approach where quality is one of the major factors in construction. I think that cost, time, scope, and quality make a diamond or square the more appropriate shape.

On the flipside, walking into a client meeting and telling them to pick any two sure sounds simple and direct. It makes negotiation simpler for both parties (the contractor and the owner).

An aside. The Project Management Institute is an organization which discusses this topic and many others. You can find a constraints article here on their website: [QR]