The Work Breakdown Structure (WBS)

Abstract

Successful project management relies on thorough planning. This begins by defining the project objectives with sufficiently detailed information. The Work Breakdown Structure (WBS) is an effective technique based on decomposing a project into hierarchical deliverables. Each one of the deliverables corresponds to a specific outcome that must be accomplished to complete the project. In other words, the WBS provides a clear view of the project’s scope, by schematically showing all the objectives that it englobes and the relations between them. A well-designed WBS that presents information at the appropriate level of detail and in formats and structures meaningful to those performing the work is an invaluable tool in project management.

The following article has been created in order to provide all the information needed to create the WBS of a given project. The first part of the article contains a detailed description of the WBS, together with an explanation of its purpose. After this, the wide benefits the WBS provides to a project during the totality of its life cycle are presented and it is explained how doing the WBS for a project enhances the likelihood of its success. Also, it is shown how the WBS looks like and the specifications its structure must accomplish. The second part of the article presents how to create the WBS, where several methods are proposed. Also, it is indicated in what specific moment of the project’s life cycle the WBS should be created. Moreover, some of the most usual mistakes committed when designing the WBS are specified to anticipate and avoid making them. In the third part of the article the limitations of the WBS are discussed and some advice in order to counteract them is given. The fourth and last part of the article, includes an annotated bibliography where several references with additional information are proposed.

Big idea

What is the WBS

The Work Breakdown Structure (WBS) is a hierarchical decomposition of the total scope of work to be carried out by the project team to accomplish the project objectives and create the required deliverables. The WBS organizes and defines the total scope of the project and represents the work specified in the current approved project scope statement.

The WBS' purpose

The Work Breakdown Structure (WBS) is used with the purpose of defining the goals and delimiting the scope of a project. The WBS assists project leaders, participants, and stakeholders in the development of a clear vision of the end products or outcomes produced by the project. Successful projects plans are built on the foundation created by an effective WBS. Developing a WBS is an essential step during the initial project phases. Work Breakdown Structures are useful not only for projects, but for programs and portfolios as well. The WBS for a program or a portfolio is performed in the same way as a project. These differ only in the breadth of the content (scope).

The WBS's structure

The deliverables of the WBS are decomposed following a hierarchical structure. Decomposition is a technique used for dividing and subdividing the project scope and project deliverables into smaller, more manageable parts. As the work is decomposed to greater levels of detail, the ability to plan, manage, and control the work is enhanced. The level of decomposition varies in between projects, but it usually depends on the degree of control needed to properly manage the work that has to be achieved.

Each one of the deliverables of the WBS corresponds to a specific outcome that must be accomplished to complete the project. Every descending level of the structure includes the deliverables that must be carried out in order to fulfil the outcome located in the level right above. Each WBS element belongs to only one parent WBS element. It is important to note that the deliverables must be outcomes, not actions. That is because outcomes are final products or results that can be precisely predicted, whereas the actions and procedures followed to obtain them cannot always be anticipated. Project activities are not listed, as these are components of the project schedule, not the WBS.

The WBS is a process required to ensure the project includes all the work required, and only the work required, to complete the project successfully. This is achieved thanks to the application of the 100% Rule. The 100% Rule is a principle which states that the WBS includes 100% of the project’s scope and 100% of the deliverables that form it. The rule also applies to each one of the levels within the hierarchy. All the deliverables that form a descending level must equal to 100% of the work needed to complete the outcome stated in the previous level. The lowest levels should roll up to the higher levels so that nothing is left out and no extra work is performed.

The deliverables that belong to the lowest level of the WBS are named work packages. For the work packages it is possible to do an estimation of the cost and duration of the activity that must be conducted in order to achieve them. The level of detail for work packages will vary with the size and complexity of the project. Nevertheless, the work packages must always follow the 8 to 80 rule, which states that the amount of hours dedicated to achieve that outcome should be bigger than 8 hours and smaller than 80. There is no need to have all work packages at the same level. Additionally, not all legs of the WBS must be symmetrical in terms of the number of levels developed.

Why the WBS

The WBS enhances the chances of success of a project, thanks to the several benefits to a project throughout its life cycle. Some of those benefits are the following:

Provides clear scope and objectives:The key benefit of this process is that it provides a framework of what has to be delivered. The WBS assists project leaders, participants, and stakeholders in the development of a clear vision of the end products or outcomes produced by the project.

Makes work more approachable: The project is organized in deliverables which are subdivided following a hierarchical structure with the intention of simplifying the work and making it more manageable.

Eases the next steps: It facilitates other project management processes such as estimating, scheduling, resource allocation, risk analysis, and measurement and control of the project.

Aligns team expectation: Since it gives a clear vision of the scope of the project and the goals are defined, the whole team is aware of the reach of the project and the expectations of all the members are aligned.

Relieves the project manager: It also has the added bonus of shortening the process and engaging the team in the work, which will lighten the load on the project manager.

Improves the communication with stakeholders: The WBS facilitates the communication between the project manager and the stakeholders. The WBS establishes the foundation that the project stakeholders use as the basis to creating their project schedule with project activities; network diagrams to sequence work; budgets for estimating and managing costs; and for making all decisions to objectively manage scope creep. Whenever work is logically structured, easily identifiable, and clearly within the capabilities of individuals, project stakeholders can confidently expect that objectives associated with the work can and will be achieved.