"Breaking down" the Work Breakdown Structure: the WBS is the beginning of everything else in the acquisition process - Program-Project Management

Program Manager, March, 2002 by James J. Clark, Philip D. Littrell

A WBS is a product-oriented family tree, composed of hardware, software, services, data, facilities, testing, and everything else resulting from a system engineering process. Whenever an organization has a large project to manage--whether organizing a picnic for several hundred people or developing a major weapon system--breaking down the effort into manageable parts is the first step.

DoD and large commercial contractors use a specific format, called a Work Breakdown Structure (WBS), to organize the breakdown of work into small areas and parts. Organized as a hierarchical structure, the WBS depicts a relationship between the largest and the smallest elements.

WBS Types

There are two types of WBS: Program WBS and Contract WBS. In the Program WBS, the government develops Levels 1 to 3. In the Contract WBS, the contractor develops all levels below Level 3. Developed prior to program initiation, the Program WBS encompasses the entire overall effort (big picture) of the program. To illustrate, Figure 1 represents a very simple WBS--a diagram of a new house (to be constructed).

Level 4 and below would represent the beginning of the Contract WBS. The Contract WBS is developed by the contractor and covers all of the products and services that the contractor is responsible to produce and perform. Contractors will take the government's Program WBS and extend the effort down (in the form of the Contract WBS) to whatever level they believe is necessary to make a realistic bid on the contract and manage the work effort on the program. They will break each element down into further levels of detail until they reach the level of work packages, which are portions of the project that will determine cost accounting data in each area within the organization. Work packages typically range from 80 hours to 60 days of level of effort. Details of the process are described later in this article.

Within the acquisition process, the WBS is used on several occasions throughout a system's life cycle. Regardless of the life cycle model, the WBS applies to all acquisition models. Early in the acquisition process, the WBS is a "strawman" of a proposed program WBS. As the program develops and other documents provide further guidance, the WBS takes shape into a real object. A notional design for an early prototype eventually evolves into a refined engineering effort. The WBS creates this notional structure to help the manufacturer work toward a design and eventually prepare for production.

In certain instances, depots will bid on a contract and also will be required to submit a Contract WBS. Depots would be expected to generate the same level of information as any other contractor to realistically bid and manage the work effort.

The Contract WBS usually starts off with a Level 3 element from the Program WBS to ensure continuity For example, in our Program WBS for the house (Figure 1), one of the Level 3 elements was the framing. The Contract WBS would divide the framing into components (such as the wall framing, ceiling framing, floor framing, and interior framing). Each of these areas would be further subdivided into smaller and smaller parts. The program and contract WBS must be consistent with one another; and any revisions to one must be reflected in the other.

Obviously, Figure 1 does not show everything used in the construction of a house--the drawing would be too massive for this page. So, realize that all entities of the house (e.g., blueprints, labor and materiel cost, paint, nails, subcontractors' work) are actually shown in a WBS, but not for this particular illustration. Now, consider a Program WBS for an aircraft system (Figure 2). Like our WES in Figure 1, the aircraft system has three levels in a Program WBS. Directly below the Program WBS appears a Contract WBS.

At the top (Level 1) is the overall project--the aircraft system. Level 1 is usually directly identified as a major program; a PPBS [Planning, Programming, and Budgeting System] program element; or as a project or subprogram within an aggregated program.

The second row (Level 2) is a general breakout of the parts and activities associated with the aircraft system. Level 2 elements are major elements of the defense materiel item; for example, the vehicle itself (the prime mission product, which includes all hardware and software elements), aggregations of system-level services (e.g., systems test and evaluation, system engineering, program management), training, and data.

The third level (Level 3) further breaks down the components into more detailed levels. Level 3 element are elements subordinate to Level 2 major elements such as airframe, propulsion, and fire control type of service (e.g., developmental test and evaluation, contractor technical support), or types of data (e.g., technical publications). Level 3 elements are generally common across similar programs. Lower levels follow the same process.

In rare circumstances, the Program WBS can extend below Level 3. However, these circumstances would be in cases where the government believes that a critical management effort is necessary to control the program. Otherwise, dictating a contractor to go below three levels could result in litigation against the government if the development goes poorly.