Chapter 8. Creating the Work Breakdown Structure

If you've got a project charter and an excited customer, why go to the trouble to build a work breakdown structure? After all, aren't you a software engineering professional? The work breakdown structure (WBS) is the heart of a project plan, as most of the other parts of a project are built from it. The WBS is the tool used to document all the work that must be done to develop and deliver the software in a satisfactory manner. Although it may seem that the information that it contains is redundant with some of the other various documents that a software development project generates (scope of work, software requirements specification, design document, etc.), it serves to consolidate information from many sources into one place and into an organized format, convenient for planning, estimating, and tracking.

A WBS serves as a framework around which to build the project schedule. It helps you move from the top-level activity of the project (the do it activity) down through a set of simpler, smaller activities designed to build the software product deliverable, until the activities become small enough to manage well. It helps everyone understand the relationships of tasks and activities to each other in an illustrated way. It helps ensure that all the work is represented and that no work steps have been omitted. It also helps the project team divide the work to be done into small, well-defined tasks and activities. Of course, the WBS also facilitates planning, estimating, and scheduling, and it is a basis for monitoring the project and for historical data collection. (See Figure 10-3 for an illustration of how building the WBS is part of the big picture for software estimating.) It allows us to dismiss, “We're 90% done,” and replace it with, “We've completed 97 of 234 planned activities.” Weighted tasks and activities become meaningful and can be associated with a cost estimate.