THE DIVISION BASES

To put things in the proper perspective, the transition from each level of WBS to the next level may be on any one of the following bases:

Deliverable-Oriented

   —Product

   —Functional system

   —Physical area

FIGURE 2-1 Work Breakdown Structure

Schedule-Oriented

   —Task or activity

   —Sequential

Resource-Oriented

   —Discipline

   —Administrative unit

   —Budget account.

There is some overlap in definition and usage between the items of a subgroup of these eight bases, i.e., between product, functional system, and physical location. It is possible for one person to divide the project on the basis of product and, depending on the nature of the project, someone else might view the division as having been on the basis of physical location.

The product basis refers to those cases where the project is divided into individual distinct components that ultimately comprise the project, such as hardware, software, physical structure, south wall, north wall, concrete foundation, or steel roof. The functional basis refers to the functional systems that provide a particular facet of the infrastructure for the project deliverable. Functional systems are usually interwoven into the product. Examples of functional systems include the electrical system, the mechanical system, or the skeleton of a building. The physical area basis highlights the geographical or physical locations of the deliverable (e.g., south side, north side, top floor, entrance). It is important to note that the most useful, and admittedly the most difficult, procedure for developing a WBS is to use the deliverable as the basis of breakdown of the project.

Task or activity basis refers to things that project team members do toward the goals of the project, such as excavating, pouring, forming, polishing, programming, testing, etc. Sequential basis reflects the order in which activities are performed, such as Phase I, Phase II, Phase III, etc. The sequence is often dictated by administrative constraints and may be somewhat arbitrary. Use of these two bases is akin to importing the project schedule into the WBS. Ideally, the WBS should be used to develop the schedule—and not the other way around.

The administrative unit basis is an infusion of the OBS elements into the WBS and indicates the administrative or organizational division lines. Examples include work done by employees of division A, division B, or the contract office. The budget account basis is an infusion of the RBS into the WBS and will follow the organization’s financial structure, such as activities paid by federal funds, state funds, charge account A, or fiscal account B. Here again, the WBS should be used to develop the costs and resource assignments, and funding procedures should not influence the nature of the project.