(WBS) - Work Breakdown Structure

The WBS (work breakdown structure) is a process used in project management to identify the scope of a project and all the associated tasks that must be done to complete the project as defined. For this purpose, a results-oriented hierarchical decomposition of the work is carried out. This technology not only makes the work more accessible and manageable. It also enables the monitoring of different processes of a project, the estimation of costs and schedules and helps with team building. This led to WBS becoming one of the most important project management tools.

In the following, the author presents the different structuring techniques of a work breakdown structure. Furthermore, he describes the process of creating a work breakdown structure, the different forms of presentation as well as the advantages and limitations of a work breakdown structure and will illustrate these with examples

Backgroud

As part of the U.S. Navy's fleet ballistic missile program (Polaris), the Program Evaluation and Review Technique (PERT) program was established in 1957 to address backlogs in planning. The program was designed to find a solution that would generate all the necessary tasks and efforts for the project based on its outcome. In 1962, the Department of Defense (DOD) and NASA published the first description of the work breakdown structure (WBS) with PERT as a model and later adopted it as the standard for the entire DOD product line. However, the first naming took place only in 1968. Beginning in 1987, the work breakdown structure (WBS) was first introduced by the Project Management Institute (PMI) with the PMBOK as a standard procedure for non-military operations, e.g., for applications in companies and other organizations and has been further developed by means of the introduction of a project charter since 1999.

WBS in Project Management

A project is characterized by being temporary and providing a unique product, service or result. As each project in its entirety has never been done before, it involves a certain degree of uncertainty and risk. To counteract this, it is important that a project is planned comprehensively. This planning includes costs, resources, schedule, risks and the project scope with its specifically defined goals, objectives and deliverables. The WBS helps the planning team reduce the extent of uncertainty by breaking down the entire scope of the project into a series of smaller components making it more manageable and less overwhelming.

According to PMI, a WBS is defined as follows: "The 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 is used to explicitly describe the project scope, the deliverables and the outcome of a project. It answers the question of the "what ?" of the project. The processes that lead to the results, the "how ?", as well as the schedule witch determines the exact time of the production of a deliverable, the "when ?", are not answered by using a WBS. .

By using a WBS, the consistency and completeness of scope can be verified and duplicates of work or deliverables can be avoided. Furthermore, a WBS functions as a communication mechanism that helps to communicate the scope of work to all stakeholders involved in the project and create a shared understanding. Because project management communication has been proven to be one of the biggest influences on project success, the use of the work breakdown structure is an essential part of any project planning process, regardless of the project type, industry, project deliverables, or project life cycle type. After the creation of a WBS, the defined outcome can be used as a basis for defining further planning processes, such as defining activities, estimating costs and activity resources and identifying risks. Moreover, WBS establishes frameworks for the controlling and execution of the project's work. Poorly executed WBS, on the other hand, can also lead to adverse project results including scope creep or unmanageable, frequently changing scope, unclear work assignments, ongoing, repeated project rescheduling and extensions, budget overrun, missed deadlines and unusable new products or delivered features.

WBS Structure

The structure of the WBS consists of a multi-level framework, whose elements are organized and represented graphically, presenting the deliverables and their component parts in a logical relationship. A project component is more precisely defined or subdivided at each descending level.

• On the first level of the WBS the project name, product name or initiative name appears.
• The second level represents the project phases or the major project deliverables.
• The third and levels below include all decomposed deliverables that are necessary to create the respective deliverables of the previous level.
• The Components of the last and lowest level of the WBS are called work packages.
• The number of levels depends on the size and complexity of the project.

Figure 1: Work Breakdown Structure. Click for a clearer picture

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Fundamentals of the WBS

• Packages
• Control accounts
• Levels & coding
• WBS Dictionary
• 100% Rule

• MECE Structure

Representation of WBS

• WBS List
• WBS Tree Diagram
• Gantt Chart

Phase-Based WBS

• Build around the project life cycle phases

How to Create a Work Breakdown

• Top-down
• Bottom-up
• Yo-Yo approach

Benefits and limitation of WBS

Benefits

• Detailed illustration of scope
• Monitor progress
• Cost and schedule estimates
• Build project teams