An Insight into Work Breakdown Structure

A work breakdown structure is a tool generally used in Project Management to define and group a projects distinct work elements or fundamentals in a way that helps define the work scope of a project. The element may be a product or data or service or a blend of these. It provides the essential framework for comprehensive cost estimation and control along with assistance for schedule development and control.

This is a tool that is under the control of the project manager and revised and updated by him with additional input from project team members. A Guide to the Project Management Body of Knowledge 3rd Edition defines WBS as ‘A deliverable-oriented hierarchical decomposition of the work to be executed by the project team to accomplish the project objectives and create the required deliverables.’

The concept of the WBS developed with the Program Evaluation and Review (PERT) technique that was introduced in the United States Department of Defense in the 1950’s. In 1987, the Project Management Institute (PMI) documented the development of these techniques across non defense organizations.

In general the approach followed in Work Breakdown Structure is by starting with an end goal, dividing this into manageable components in terms of size, extent and accountability example; sub systems, sub tasks etc and which includes all steps required for achieving the goal or objective. This is the basis for breaking down work into definable increments from which the statement of work is derived.

The WBS is centered on the products or planned outcomes of the project instead of the work that contributes to it. A well designed WBS makes it easy to assign each activity of the project to a corresponding element of the WBS. It helps to chart the requirements from one level of system specification to another.

One of the key design principles of the Work Breakdown Structure is called the 100% rule. This rule states that ‘The WBS includes 100% of the work defined by the project scope and captures all deliverables – internal, external, interim – in terms of the work to be completed, including project management’.

This rule also holds true regarding the activity level of the project. This rule ensures that the WBS does not include any work or activity that falls outside the scope of the project. The best way to adhere to this rule is to define WBS in terms of outcomes. In addition to the 100% Rule it is important to follow the Mutually exclusive elements concept which states that there is no overlap in elements of a work breakdown structure.

To create the WBS effectively it is necessary to get all the key stakeholders together. Then it is necessary to launch into the process of decomposition or breakdown. This is the task of breaking deliverables into small chunks of work that needs to be completed for achieving a level that can be realistically managed by the Project manager and also completed by the resources who are assigned the task. This level of breakdown and detail is called as Work Package.

The 8/80 Rule states that no work package should be less than 8 hours or greater than 80 hours. Instead of 8 hours duration sometimes the rule of thumb followed is that no activity should be longer than a single reporting period. A Work Package is a task that can be realistically and confidently estimated, cannot be broken down further in a sensible manner, produces a deliverable that is measurable, is in the formation of a unique package of work that can be outsourced or contracted out.

A terminal element is the lowest element in a WBS that cannot be further sub divided. It is also sometimes referred to as a Work Package though both terms are not synonymous.

Normally the WBS is created by using a hierarchical tree structure where each level of the structure breaks the deliverable or objective to more specific or measurable element. This structure helps to do resource allocation and gives more clarity to the deliverable. It allows to double check that all specifics are neither missing nor overlapping. Besides the tree structure, Mind Mapping methodology is also used