The Triple Constraints–How they are Handled Differently in Traditional and Agile Project Management

In John Stenbeck’s book “PMI-ACP® and Certified Scrum Professional Exam Prep and Desk Reference”, in the second chapter “Introducing Agile Project Management”, he has a section called “Agile Planning and Estimating” where he has an elegant explanation for one of the most frequently asked questions about Agile, namely, “how do Traditional and Agile Project Management differ in their approach to project management”?

He does this by showing how the two approaches differ with respect to how they manage the “triple constraints” on a project, namely, scope, time and cost, which are represented by the triangle below.


1.Traditional PM Assumptions

In traditional project management, your first assumption that the scope needs to be as well-defined as possible.    Once this is done, then the planning process consists of estimating the cost and time it will take to complete that well-defined scope.

So in traditional PM, the archetypal problem for project managers is “scope creep”, meaning uncontrolled or continuous scope.   Because the changes in one constraint normally affect a change in the other constraints, this means that the resources required to complete the project will be ever expanding as well.    Of if you are not allowed additional resources by management, you will have to do more and more with less and less, which creates an undue burden on the project manager and the project team.

2. Agile PM Assumptions

In agile project management, your first assumption is that the customer has a well-defined date and cost constraint in mind in the very beginning.    Here, the planning process can be flexible with regards to the slope, and the object of the project team is to prioritize those features which add the most value to the customer.

How is this done?    By using agile techniques to get the customer involved in the process so that the plan can reflect on external realities which may change during the course of the project.

Because the focus is on a fixed cost and time, and a variable scope, rather than a fixed scope, and a variable cost and time constraint, agile can be seen as literally turning traditional project management on its head.    It uses as its starting point the throwing out of the first assumption of traditional project management, namely, that the scope can be well-defined in advance of the execution of the project.    By giving up trying to capture such a mythical creature as a “well-defined scope”, agile project management looks at scope in a much more realistic way, as subject to negotiation between the customer and the company.

This explanation shows how different the traditional and agile project management methodologies differ.   The two approaches differ not just in methodology, but terminology as well.    In the next post, I will discuss the way that agile management differs from traditional project management when it comes to executing and controlling a project.


One Response

  1. very well written and informative. thanks

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