Work Breakdown Structure (WBS)

What is a WBS?

A WBS defines the objectives of a project at all levels of detail (hierarchical) and is essentially a map of the project i.e. visual representation of all parts. It can only be formed once the scope and deliverables have been identified.

How is a WBS constructed?

The WBS begins with the project as the final deliverable. The higher elements are used to identify deliverables at different phases in the project and to develop status reports during the execution stage of the project life cycle. Major project work deliverables are identified first; then the subdeliverables necessary to accomplish the larger deliverables are defined. The process is repeated until the subdeliverable detail is small enough to be manageable (top management deals primarily with major deliverables while first-line supervisors deal with smaller subdeliverables and work packages). This subdeliverable is further divided into work packages which is the lowest level of a WBS. Work packages are basic units used for planning, scheduling, and controlling the project (Figure 1). Since the lowest subdeliverable usually includes several work packages, the work packages are grouped by type of work e.g. hardware, programming, testing. 

Why is a WBS constructed?

• Helps to assure project managers that all work elements are identified therefore they can be easily monitored & tracked
• Determines a project timeline and develops a schedule
• Assigns responsibilities and clarifies roles
• Integrates the project with the current organisation - offers an ongoing view for management and team members into how the entire project is progressing
• Establishes a basis for control - accurate estimation of effort, duration, resources and cost
• Offers an ongoing view for management and team members into how the entire project is progressing
• Minimizes the chance of adding something outside the scope of work or forgetting a critical deliverable
• Helps make planning consistent and provides for effective project execution

How can it be used to identify risks?

• WBS helps controls scope creep and prevents work from slipping through cracks. Unnecessary work or anything not seen in the WBS can be eliminated thus it helps the team to focus on the project scope only.
• WBS enables project managers distribute the project budget into defined packages linked to the tasks and check to make sure that the task costs in total don't exceed the total project cost
• WBS ensures no overlap and no gaps in responsibility or resources

Figure 1

WBS example - Structure for building a house (w= work)