Project Constraints Redefined
By: Ray Myers, Jr., PMP
Traditionally, project managers have managed projects using the triple constraints of scope, time, or cost, where scope refers to what must be done to produce the project deliverables, time refers to the time available to complete the project, and cost refers to budget allocated to complete the project. These constraints are called the project triangle.
Scope, time and cost are competing constraints because a change to one of the three often throws the other legs of the triangle out of balance. For example, increasing scope may increase the cost or time needed to complete the project.
Many project managers when asked if they could make changes to the project assumptions, would typically respond with something like, “we have scope, time, and cost, choose 2, you can’t have all 3,” or “which two do you want.”
Quality, a fourth constraint, was added to the triangle and refers to how closely the project deliverables conform to the documented scope. So the project triangle became four-sided and would usually be drawn something like this:
Figure 1 The Project Triangle
The long-established project triangle has now been redefined by the Fourth Edition of the Project Management Institute’s Guide to Project Management Body of Knowledge, commonly called the PMBOK.
The PMBOK asserts that there are actually six competing project constraints. The new list includes, but is not limited to: scope, quality, schedule, budget, resources, and risk. Then the newest edition of the PMBOK continues and potentially expands the list even further by stating, “The specific project will influence the constraints on which the project manger needs to focus.” Stated another way, each project has its own set of unique constraints which should be investigated, documented, and managed.
This recent addition to the project triangle certainly changes how we look at the project constraints landscape. The project manager will have more things to consider when asked to make adjustments to one or more of the project constraints. I wonder what the project manager will say now when asked to make a change to the project constraints, maybe, “choose 5, but you can’t have all 6.”
By the way, how would you draw a triangle with 6 sides?
About the Author: Ray Myers is a PMP certified project manager with over 2o years experience planning and managing technology projects.
Copyright © 2009 Ray Myers, Jr. – All rights reserved
This document may be freely copied and distributed, provided that: this copyright notice is included, the entire body of text is included, and the textual content of this document is unchanged.
For written permission to use portions of this document in other publications, send email to info@pmservicesnw.com
