The concept of utilizing a Work Breakdown Structure (WBS) has been around for over 50 years. It can and should be utilized for all Projects, regardless of scope or scale. The term “Work Breakdown Structure” is often confused for a task list or a set of action items. However the most common misinterpretation of a Work Breakdown Structure is for a project schedule; this association is always incorrect. A Work Breakdown Structure should always be produced first, and is one input into creating a project schedule. A Work Breakdown Structure is a hierarchical decomposition of deliverables (or products) which will be constructed throughout the duration of a project. It can, in some instances, resemble a project schedule without calculated start and end dates. Technically, a WBS in proper form will only utilize nouns, verb usage is incorrect. The main reason for this is that we are not decomposing tasks or activities, the product is being decomposed into its components. A side benefit to this approach is the decreased likelihood of Scope Creep. Since we are decomposing the product, and not tasks, the Project Team and Stakeholders are less likely to “add” unnecessary components. A proper WBS will also have a unique numbering system associated with it as well, an example is as follows:


1.1    Powertrain

1.1.1    Engine

1.1.2    Braking System

1.1.3    Exhaust System

1.1.4    Suspension System

1.1.5    Steering

1.1.6    Transmission

1.2   Exterior Body

1.2.1    Body Panels

1.2.2    Windows

1.2.3    Doors

1.3   Interior

1.3.1    Trim Panels

1.3.2    Seats

1.3.3    Audio System

1.3.4    Airbags

In the example above, the Automobile (WBS ID 1.0) is the major deliverable to be produced as part of the project. The major deliverable, Automobile, is then decomposed into lower level deliverables (such as the Powertrain, Exterior Body, and Interior). In this case, the Exterior Body deliverable (WBS ID 1.2) requires the following Work Packages to be complete:

  • Body Panels (WBS ID 1.2.1)
  • Windows (WBS ID 1.2.2)
  • Doors (WBS ID 1.2.3)

In terms of Project Management, Work Packages are generally the lowest level which will be tracked and proactively managed. It is this granular decomposition which enables the Project Manager to be effective when calculating estimates.

In simple terms, a Work Breakdown Structure is a decomposition of tangible deliverables produced by a Project. Usually, timescales (in terms of man hours), are added to each level of decomposition. A Work Package is the lowest level of a WBS, a timescale between 8 and 80 hours is the rule often cited. That is, a Work Breakdown Structure is always decomposed to the Work Package level, which is usually associated with a timescale parameter of between 8 and 80 man hours to complete; anything over 80 man hours to complete is usually decomposed further. At this point activities may be identified, logically sequenced, resources are allocated, and ultimately a schedule is produced (with calculated start and end dates).

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