Director's Corner

16 February 2006


Barry Barish
Work Breakdown Structure (WBS)
The second meeting of the Reference Design Report (RDR) group leaders was held at Fermilab this past week. The primary purpose of this second RDR organizational meeting was to establish links between the RDR "Area Groups" and "Technical and "Global Groups", clarifying the work plan and methodology for obtaining the design and costs. The area groups are organized around accelerator subsystems (e.g. the main linac, positron source, etc), the technical groups cross subsystems (e.g. magnets, vacuum, cryogenics, etc) and the global groups cross subsystems and also have some elements outside subsystems (e.g. conventional facilities). Our plan is to do the design and costing of the ILC baseline by area (or subsystem) with the relevant costing inputs coming from the technical and global groups.

To organize the effort into a methodology that will capture all the costs for each subsystem, we will employ a "Work Breakdown Structure." At the Fermilab meeting, Peter Garbincius gave a talk entitled, "ILC Construction WBS," that described a draft WBS for the RDR that Wilhelm Bialowons developed.

Garbincius’ talk illustrates our transition from activities primarily focused on conceptual issues to ones more concerned with project issues. This change is necessary to enable us to specify the baseline ILC design details and costs. As a result, we are beginning to use standard project management techniques, and that includes using a Work Breakdown Structure (WBS).

Work Breakdown Structure (WBS)
An example of a Work Breakdown Structure (WBS)

So, what is a WBS and why do we use it? The concept underlying a WBS is not so foreign. Although we don’t use such terms, we naturally organize our lives using a work breakdown structure. If we need to get some task done, we often make a to-do list to organize our work, or even more informally in our everyday life we perform a set of tasks that enable us to do the activities of the day (we get up, have breakfast, drive to work, etc). In other words, we breakdown our day into small "work packages."

For large projects, the purpose of using a work breakdown structure is to organize a hierarchical structure that breaks down the work, starting from well-defined small work packages in a way that all add together to achieve the total project. The origin of using a formal structure, such as a WBS system, for organizing projects comes from the U.S. Department of Defense. They have documented the process in MIL-STD-881B (1993) and later updated it in MIL-HPBK-881 (1998). These documents define the process as,

"A product-oriented family tree composed of hardware, software, services, data, and facilities. The family tree results from systems engineering efforts during the acquisition of a defense materiel item. A WBS displays and defines the product, or products, to be developed and/or produced. It relates the elements of work to be accomplished to each other and to the end product."

The key idea in this methodology is to organize a project into hierarchical deliverable-oriented project elements that when "rolled up" result in the total project. This might seem like an obvious way to organize the work, but in fact we are much more inclined to organize our work around tasks, rather than deliverables. And it takes planning and discipline to organize the work for a project around deliverables. Ideally, the same WBS structure can be used to obtain costing, to manage the work and to bring the deliverables together into the overall project.

Although it may not be obvious from the descriptions of the WBS that I gave above, such a methodology can be employed from the earliest stages of project planning and that is what we are now doing to develop costing for the RDR. This underlying methodology will be used to organize much of the activities that I will be describing as we develop our reference design and costs this year.