Project Work Breakdown Structure (WBS) is a hierarchical listing of the individual work elements of a project. Breaking up a project into smaller components facilitates project management. Preparation of a WBS is one of the key steps in project planning.
In order to create a WBS, list the objectives of the project and decide upon the tasks to be done to accomplish each goal. Start with the various phases that the project will go through during its life cycle. For example, we can have “initiation, planning, execution, control and hand-off” as the top level items in the WBS hierarchy. They can be termed as tasks or phases. For each of these tasks, specify the sub-tasks or phase-entries. For example, the “Execution” phase can be further broken down into “documentation of requirements, system design, development (coding), testing, installation and user training”. These sub-tasks form the 2nd level in the WBS hierarchy. The “testing” sub-task can further be broken down as “prepare test plans, unit testing, integration testing, regression testing, and user acceptance testing”. These form the 3rd level in the WBS hierarchy and they are called activities or work packages. Likewise, we can come up with a tree structure showing all the activities involved in the project. For each item on the last level (leaf nodes) of the hierarchy, the schedule, budget and man power are estimated.
The upper levels in the Work Breakdown Structure indicate major milestones or deliverables. The lowest level of the WBS indicates the work to be allocated to individual team members. The WBS captures all deliverables, internal (items such as test plans and code review documents used internally by the project team as part of standard procedure) and external (to be delivered to the client as part of the final product). WBS follows the 100% rule. The percentage of work done to complete each of the activities in the WBS will add up to 100% of the work to finish the whole project. At any point in time, the project completion percentage can be easily determined if each individual updates the percentage of completion of the activity assigned to them.
The WBS can be represented graphically as a tree structure, in tabular form or textually with numbered bullets showing the level of each item.
Benefits of creating Work Breakdown Structure
- Cost, effort and schedule estimates for the project are more reliable since they are calculated as the sum of the estimates for the individual components in the WBS. Estimation of resources is more accurate for a smaller chunk of work.
- The development team gains better clarity about the tasks involved in the project.
- Easier allocation, accountability and tracking of project work.
- Helps to define project scope effectively.
- Helps to monitor and control the project.
- Helps to identify dependency between tasks. Completion of some tasks may be a prerequisite for starting other tasks. Alterations to the specification of one task may affect another.
- Redundant / repetitive tasks can easily be identified.
Care should be taken to break down the project into a proper number of detail levels. Having too many levels will result in micro-management of the project, which will cause resentment among the developers and over-burden the team leaders. Having too few levels in the Work Breakdown Structure will make activities too large to control effectively. Ensure that each activity / work package spans less than a week in order to facilitate project management.