Fear Not! Managing Your Project Constraints is as Easy
as Managing the Lowest Level of Your WBS

By Ulohomuno Eze Afieroho, MBA, PMP

As project managers, we often talk about cost, time and scope – the triple constraints and the major limitations for any project delivery. A project manager I know once described the triple constraints as “the metrics for measuring projects and project managers’ performance.” I quite agree with him. We work hard as project managers to ensure that projects are delivered according to scope, within budget and on time.

Cost, time and scope are so closely knitted that a slip in one will affect at least one of the others. Juggling between these triple constraints is our major challenge as project managers. But are they difficult to manage? How can project managers effectively manage these constraints?

My experience in project management has taught me that managing these triple constraints is easy if we understand our project Work Breakdown Structure (WBS) and monitor and control its lowest level – the work package. This article focus on how to manage the triple constraints by looking at your project’s WBS as the key to handling the difficulties of managing your project scope, time and cost.

The Relationship between the WBS and the Triple Constraints

Take a good look at your project and you will likely discover that the project time, cost and scope are symptoms of your WBS. How accurate your project WBS is and how effectively you have managed each activity in your WBS will determine the success of your project

PMI’s A Guide to the Project Management Body of Knowledge (PMBOK® Guide) defines the WBS as “a deliverable-oriented hierarchical decomposition of the work to be executed by project team, to accomplish the project objectives and create the required deliverables.” It goes on to say that the WBS organizes and defines the total scope of the project. Simply put, this means that the work or activities not included in your project WBS are outside your project scope.

What about cost and time? How do they relate to the WBS? Recall that we defined the WBS as a hierarchical decomposition of work. The WBS subdivides the project work into smaller, more manageable pieces of work, with each descending level of WBS, according to the PMBOK® Guide, representing an increasingly detailed definition of the project work.

The planned work contained within the lowest- level WBS components, called the work package, forms the basis on which project schedule (time) and budget (cost) are estimated. These estimates form your project time and cost.

Two Fundamental Steps to Keep in Mind

Managing your project triple constraints with your WBS requires two fundamental steps. Though quite easy, they do require determination.

1. Understand the uniqueness of your project WBS. This first step requires sincerity. If it is done wrong, the next step will be fruitless and managing your project constraints through your WBS will be a mirage.
   
   It’s critical to remember that all projects are unique. If you don’t understand this you will be tempted to use a WBS of similar project or templates to create your project WBS, and that would be the first step to failure. Instead, seek to understand your unique project preliminary scope statement, which is the high-level definition of what is to be done and not to be done to create your project’s unique product or service. Then, leverage on past experience and/or templates to create your project’s detailed scope statement and WBS.
   
   
2. Create your project’s WBS. Once the first step is done right, the road is cleared for a smooth ride. Creating your project WBS requires the following procedures:
   • From the scope statement in step one, develop a high-level WBS (level 1) for the project and pass each high-level WBS to a Subject Matter Expert (SME) or functional manager to coordinate the development of the more detailed WBS ( from level 2 to the work package level).
   • Then submit the detailed WBS for review and use it to estimate the project duration (time and schedule) and cost, and to verify the project scope and update the scope statement, if need be.

If you follow these steps in creating your project WBS, your project scope will be well defined and understood by the project team. You will also avoid the “failure of estimation”--one of the main reasons for project failure. Implementation then becomes easier.

Managing the Triple Constraints with Your WBS

Recall that the work package is the lowest level of your WBS. The work package is not only used for estimating project cost and time but, most importantly, it breaks down the project work into more manageable pieces of work that can be effectively monitored and controlled. This is exactly what we mean when we say “managing your project triple constraints through your project WBS.”

By doing so, you ensure that each work package fulfills its performance target in terms of scope, cost and time. And, when the performance requirements of all work packages are complete, those specific WBS-level performance requirements are automatically fulfilled as well. This translates to the next high-level WBS performance requirement and, finally, the project.

Essentially, what we’re doing is focusing attention on a part rather than the whole. This makes it easier to assign performance measures and controls. In practical terms, you are ensuring that all activities in each work package are performed according to the project requirements. This is easier and better than monitoring and controlling the “whole.” Even better, you are using less effort to get an incremental success that produces the desired “big picture.”

This approach also allows the project to be easily steered back on track in terms of time, cost and scope if a performance requirement slip occurs. Scope change can also be effectively managed, since you have a detailed WBS that is unique, with an estimate of each work package. You can easily determine the effect such a change will have on your project time, cost and scope and make a case for approval or rejection.

Conclusion

Ultimately, if we understand that projects are unique and learn to assign performance measures and control to our project’s lowest-level WBS, we are on the right track for excellent project delivery in terms of time, scope and cost.

The challenge is to get it right from the start by following the two fundamental steps and then continually monitoring and controlling each work package to ensure that the performance requirement for each is met.