Work Breakdown Structure

It is beyond any reasonable doubt that the Work Breakdown Structure (WBS) is an exceptionally useful tool for planning, estimating, scheduling and controlling any kind of project. The term WBS describes the procedure of subdivision of the project deliverables and workload into smaller more manageable segments. More specifically, “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.” (PMBOK® Guide-Fifth Edition, 2013, p. 126)

The purpose of this wiki-article is not only to thoroughly describe the capabilities and restrains of this method but also to provide guidance to project managers concerning the techniques that can be used for the effective implementation of project Work Breakdown Structures.

Big Idea

Historical Retrospection

The initial forms οf the Work Breakdown Structure (WBS) were developed by the U.S. Department of Defence (DoD) and the National Aeronautics and Space Administration (NASA) at the mid-1960s with a view to regulating projects which had the ultimate goal of enhancing military and space systems respectively. Moreover, the management of these projects was undertaken by a central administration office and many different industrial contractors were recruited in order to contribute to the accomplishment of the huge variety of tasks. So, the WBS tool was used to “…ensure that the total project is fully planned and that all derivative plans contribute directly to the desired objectives” (NASA, 1962). After two decades; namely in 1987 the Project Management Institute introduced the Project Management Book of Knowledge (PMBOK) which provided the necessary guidance on how work breakdown structures could be applied in any kind of project.

Work Breakdown Structure Definition

The WBS process is characterized by the disintegration of the project into separate segments with the aim of managing it in a more efficient and effective way. Furthermore, this practical tool facilitates many other project management procedures like scheduling, efficient resource allocation, monitoring and control of the project. Also, the Work Breakdown Structure provides a complete and clear view of the project scope and deliverables. In addition, it presents with clarity the total workload as determined by the scope statement of the project and analyzes the planned work at the lower levels, also known as work packages. With the help of work packages, the activities that contribute to the planning, assessment, supervision, and control of operations are grouped together.

Work Breakdown Structure Framework

The Work Breakdown Structure (WBS) consists of several layers and which are grouped at the upper and lower levels. Below the composition of a typical WBS is described. To begin with, the content of the WBS levels may vary depending on the type of project and the industry involved. More generally, the main areas of the project are included at these levels. Then we have the lower WBS elements which mainly focus on supporting specific project management processes such as schedule development, cost estimation, resource allocation and risk assessment. These levels are called Work Packages. The official definition of the Work Package is, “A deliverable or project work component at the lowest level of each branch of the work breakdown structure. The work package includes the schedule activities and schedule milestones required to complete the work package deliverable or the project work component.” (PMBOK® Guide-Third Edition, 2004, p.380). Finalizing WBS is done by assigning each work package to a control account and creating a separate identifier for that work package. With the help of these identifiers, the hierarchical summation of the cost, schedule and resources is achieved. “A control account is a management control point where scope, budget, actual cost, and schedule are integrated and compared to the earned value for performance measurement.” (PMBOK® Guide-Fifth Edition, 2013, p.132). Each control account typically involves one or more work packages while each work package cannot be linked to more than one control account. Additionally, these management control points are associated with more than one planning package, which is part of the WBS under the control account with given work content but without specified detailed activities.

Work Breakdown Key Features

Some of the most important prerequisites for qualifying a WBS as high quality and successful are listed below:

• A key feature of WBS is that it is deliverable oriented. In particular, a deliverable is defined as “Any unique and verifiable product, result or ability to perform a service that must be produced to complete a process, phase or project” (PMBOK® Guide-Third Edition, 2004, p.358). Therefore, the WBS should be aligned with the individual deliverables.
• A functional WBS is a hierarchical decomposition of the work. Decomposition is “a planning technique that subdivides the project scope and project deliverables into smaller more manageable components until the project work associated with accomplishing the project scope and providing the deliverables is defined in sufficient detail to support executing, monitoring, and controlling the work.” (PMBOK® Guide-Third Edition, 2004, p.358). In this way, a clear definition of the project scope is achieved with the use of independent sub-deliverables.
• An effective WBS manages to share the project scope with all the stakeholders.
• The work packages it contains should clearly identify the tasks that need to be performed with a view to delivering the work package deliverables.
• Another important prerequisite is the participation of experienced subject experts (SMEs) as well as skillful financial and business managers in its construction.
• It should follow a common course with the development of the project scope until the final definition of the scope.
• The WBS must be open to continuous improvements that may be needed after setting the project scope. .

Application

Creating WBS: Tools and Techniques

The creation of a WBS can be carried out with the help of a wide variety of methods and tools. Some of the most common and important ones are presented and analyzed below.

Decomposition

With the help of the decomposition technique, the scope of the project and the project deliverables are subdivided into work packages. The greater the difficulty of effectively controlling the project is, the higher the level of decomposition becomes. Also, depending on the size and complexity of the project, the level of detail for the work packages is determined. The process of decaying the entire project into work packages includes the following activities:

• Determine and analyze both project deliverables and work related to them.
• Construction and analysis of WBS.
• Disintegration of the higher levels of WBS to more detailed lower-levels.
• Create and match the identification codes to the corresponding components of the WBS.
• Evaluation of the decomposition rate of the deliverables.

Expert Judgment

Expert judgement is a very useful tool which contributes to the procedure of analyzing the data needed to break down the project deliverables into more manageable pieces with a view to building an effective WBS. Specifically, this method addresses the technical characteristics of the scope of the project and aims to find the ideal way to dissolve the overall scope. The truth is that any group with relevant expertise and experience with a corresponding project is able to provide expert judgment. In addition, the expert judgment is available in the form of pre-defined standards, which are usually of an industrial nature and products of previous project experience. The project manager uses this practical and indispensable tool to arrive at the final breakdown of the project scope into the individual work packages, which in turn will contribute to the effective management of the project’s work.

Top-Down Method

The following steps describe the general top-down process for developing a WBS:

1. Determination of the final products of the project. At this stage, the products that make the project successful are defined. A basic prerequisite for achieving the alignment between WBS and project requirements is the detailed overview of high-level project scope documents, examples of which are the Statement of Work and Technical Requirements.
2. Determination of the project's main deliverables, which are of key importance for the development of the project but are not capable of satisfying the business needs by themselves.
3. Decompose the main deliverables to the point of being easier to manage and control. The set of these independent WBS elements at each level should represent 100% of the work in the upper element. Also, each work package should not include more than one deliverable.
4. Continuous improvement of WBS in order to satisfy stakeholders. In particular, the development of the WBS should be continued until there is a common understanding that the project will be successful and the implementation and control process will produce the desired result.

Annotated Bibliography

Dr Parviz F. Rad, PE CCE. “Advocating a Deliverable-Oriented Work Breakdown Structure”, Cost Engineering - December 31, 1999.

Annotation: This article presents the rationale and methods for modifying the traditional breakdown structure philosophy in order to obtain a WBS that is focused on deliverables.

Project Management Institute. “A Guide to the Project Management Body of Knowledge (PMBOK® Guide)”- Fifth Edition, 2013.

Annotation: This book provides guidelines for managing individual projects and defines project management related concepts. It also describes the project management life cycle and its related processes, as well as the project life cycle.

Eric S. Norman, Shelly A. Brotherton, Robert T. Fried. “Work Breakdown Structures: The Foundation for Project Management Excellence”- John Wiley & Sons, 2008.

Annotation: This book is intended to be a beginning step in filling the information gap that exists between what is currently written about Work Breakdown Structures and what the authors have learned is needed by program and project managers today.

Project Management Institute. “Practice Standard for Work Breakdown Structures”- Second Edition, 2011.

Annotation: This book provides guidance in the initial generation, subsequent development, and application of the WBS. It also includes information derived from accepted project management industry sources.