Work Breakdown Structure WBS by Steven Macdessi

WORK BREAKDOWN STRUCTURE (WBS)

WHAT IS MEANT BY THE TERM “WORK BREAKDOWN STRUCTURE” (WBS)?

A complex project is made manageable by first breaking it down into individual components in a hierarchical structure, known as the work breakdown structure, or the WBS. Such a structure defines tasks that can be complete independently of other tasks, facilitating resource allocation, assignment of responsibilities, and measurement and control of the project.

This logical subdivision of all the work elements is easy to understand and assimilate, thus helping the project participants to quantify their responsibility and position in the overall project. Work not in the W.B.S. is outside the scope of the project.

As with the scope statement, the W.B.S. is often used to develop or confirm a common understanding of project scope. Each descending level represents an increasingly detailed description of the project elements.

MEANS OF SUBDIVISION
The overall process of construction can be divided and sub-divided for management purposes into various elements or groupings,
Trade or Sub-Contractor Groupings,
Building Element (Product),
Location on site,
Material Types,
Sequence, (recognizing dependencies)
Organizational
Contractor's contractual responsibilities,
Cost Centre (Cost Planning Quantity Surveyors)

This division and subdivision process is referred to as “decomposition”
Decomposition involves the breaking down of major project deliverables into smaller more manageable components until the deliverables are defined in sufficient detail to support future project management actions, planning, executing, monitoring/reviewing and attendance where needed.

ADVANTAGES OF WBS
a) provides for easier monitoring of work definitions,
b) allows work to delegated in coherent packages,
c) enables work to be managed progressively,
d) enables the enhancement of cost effectiveness, productivity & process improvement,
e) allows for Risk to be managed effectively,
f) provides a system for training,
g) demonstrates objective evidence of planning.

DISADVANTAGES OF WBS
a) Requires active management of the interfaces created,
b) Management functions increased with each definition, e.g., planning, organizing, monitoring and reviewing/changing.
c) Risk of demarcation problems with every interface created.

HOW MUCH DETAIL?
There is always a question with WBS as to the amount of detail to be shown.
Too much detail and it becomes unmanageable and expensive, but too little detail does not permit the accurate estimation of time, cost and resources, as well as the practical management of tasks.

The manager must rely on judgment and experience when deciding the appropriate amount of WBS detail.

WBS ROLL-UP
The roll-up process is used to roll back up project activities for management overseeing purposes. By initially suitably arranging the WBS, re-combining of the boxes can produce an overview of the project.
This roll up technique lends itself to anything that flows in the project, such as costs, duration, man-hours, productivity, resources (such as materials), etc. Any of these could be planned, tracked and controlled using W.B.S.



References

PMI (2008), A Guide to the Project Management Body of Knowledge (PMBOK Guide), 4th Ed, Project Management Institute, Newtown Square, PA.