Work Breakdown Structure - Why one is necessary
There are many discussions on the need for, value, and detail in a work breakdown structure (WBS). So, what is a WBS and why would you have one? How does it relate to a product breakdown structure (PBS)? What are the benefits?
If you look at any item – a pen for example – you can break it down into its components. Suppose it’s a Biro. There is the casing, the part that you hold; there is the ‘ball’ for the ballpoint; the part that hols the ball in place; the tube containing the ink; and the ink; and the cap to close the end when the pen is not in use.
But this only defines the parts that make up the pen; it does not describe them in any detail; nor does it describe the work required to create one, or what is required to manufacture them. Nor does it include the extended work required for a batch of pens, or for delivering them to the customer. This work includes aspects such as quality assurance, material composition, timing, testing, staffing, maintenance of equipment, and packaging. A WBS for a project needs to embrace all of these.
For any common tasks we will all have, in our minds, a process for achieving the task, and we could create a WBS for it. But we would not usually write this down. So what would happen for a project? If you were the project manager, to what extent would you expect people to provide a WBS for their own work? You have a team of experts carrying out key tasks for the project and you trust them. You know they are the best available and that they can deliver. Would the absence of a WBS bother you?
But what would happen if they became unavailable? How would you transfer their work to someone else? And suppose, thinking further ahead, at the project review or for some future project, you or your client had the same broad requirements, how would you capture the work required to reuse rather than have to reinvent. Without a WBS you would not have the facility to understand and convey potentially vital information.
My view is that wherever possible there should be a WBS although the detail required is always a matter of judgment. As project manager you need to be sure that the work is defined and described in terms that are sufficient for the immediate purpose, meet your requirements for reporting purposes, can be replicated in enough detail for someone new to take on, and adequately describe the requirements for review and for future projects.