BACKGROUND OF THE WBS CONCEPT

The WBS is not a new concept in project management. This section provides some background that will assist in understanding the important role played by the WBS in managing projects effectively. This section also provides the basis for a later discussion of more complex aspects of the WBS.

Early U.S. Government Activities

In 1959, Malcolm, Roseboom, Clark, and Fazar published a classic paper describing the successful implementation of a technique called Program Evaluation and Review Technique (PERT). Although the WBS is not addressed directly in the paper, the graphics include a breakdown (Figure 1-10) that shows how the concept for a WBS was evolving.

FIGURE 1-10 Early Polaris Project Work Subsystems

By 1961, the term work breakdown structure was in common use. At that time a sample WBS was included in an article published within General Electric Corporation that explained the importance of a WBS in developing effective management control systems. Part of this WBS for the Fleet Ballistic Missile Maintenance Training Facility is shown in Figure 1-11.

The PERT and WBS concepts spread widely and swiftly. These management tools and their application, as developed between 1958 and 1965, are the basis for much of the project management body of knowledge used today.

FIGURE 1-11 Work Breakdown Structure – 1961

The deliverables include equipment and equipment modification, documentation, trainers, and simulators. The WBS elements of management and installation are cross-cutting or support elements.

In June 1962, the U.S. Department of Defense (DoD), in cooperation with the National Aeronautics and Space Administration (NASA) and the aerospace industry, published a document intended to guide the systems design of the PERT COST system. That document included an extensive description of the WBS that is essentially the same description used today.

In October 1962, NASA published another document that expanded on its earlier discussion of the WBS. NASA stressed at that time that a top-down approach should be used in the development of the WBS to ensure that the total project was fully planned and that the derivative plans contributed directly to end objectives. It also stated that, in any integrated time/cost management system, both cost and time must be planned and controlled from a common framework.

Within the aerospace industry in the early 1960s, several companies were rapidly incorporating the concept of the WBS into their internal project planning operations. The author was using the WBS in his project planning in the Baltimore division, and the Orlando division of Martin Marietta (now Lockheed Martin) published a document that required the development of a WBS in its project planning when using PERT.

In August 1964, the U.S. government published the PERT Implementation Manual, which included a discussion of the WBS. That document was intended for use by government agencies as well as private and public institutions. That document also recommended a top-down approach to developing the WBS so that “detailed plans will not be developed outside a common framework.” The authors stated that while it is apparent that plans, schedules, and network plans can be developed without a WBS, such plans and schedules are likely to be incomplete or inconsistent with project objectives and output products.

The development of a WBS in all the government and aerospace industry documents during this early period typically follows the same pattern. The planning begins at the highest level of the project with the identification of objectives and end items, and those are then broken down into logical elements.

When developing the WBS for large military systems such as those that existed in the 1960s, it became apparent that the top two or three levels were very similar for each family of systems; that is, the end items and the next level decomposition of the end items were the same. For example, all aircraft have wings, engines, a fuselage, empennage, landing gear, and so on, regardless of whether they are transports, fighters, or bombers. A typical WBS or template could be developed for major systems.

Since the time of its first use until the mid-1960s, many different concepts of the WBS existed. As a result, a project might be structured according to the contractor functional organization, contract phases, contract tasks, or other schemes. The DoD performed a special study in August 1965 to establish consistency among system acquisitions and to create a historical database. This effort resulted in the issuance of DoD Directive 5010.20, Work Breakdown Structures for Defense Materiel Items, on July 31, 1968, which was followed by MIL-STD-881 on November 1, 1968. The DoD Directive sets forth the policy, and the military standard provides the guidance for implementing the policy. The latter document made application of the WBS mandatory for all DoD projects estimated to exceed $10 million that used research, development, test, and engineering (RDT＆E) funds.

On April 25, 1975, MIL-STD-881A was published as an updated standard. The use of the standard was mandatory in three areas:

(1) All defense materiel items (or major modifications) being established as an integral program element of the 5-year defense program plan;

(2) All defense materiel items (or major modifications) being established as a project within an aggregated program element where the project is estimated to exceed $10 million in RDT＆E financing; and

(3) All production follow-on of (1) and (2).

In addition, the standard stated: “A work breakdown structure (WBS) may be employed in whole or in part for other defense materiel items at the discretion of the DoD component, or when directed by the Director of Defense Research and Engineering.”

MIL-STD-881B, Work Breakdown Structures for Defense Materiel Items, was issued on March 25, 1993. This standard improved upon the previous edition in many areas, one of the most significant of which was the addition of an appendix containing a user guide. The required application was the same as MIL-STD-881A except that the dollar value minimum was eliminated. Furthermore, the standard stated: “This standard is to be used by both contractors and DoD components (Government activities) in the development of work breakdown structures for the acquisition of defense materiel items.”

Recent U.S. Government Activities

In the mid-1990s, the role of 881B was modified by the Defense Standard Improvement Council, which reviewed the standard as one of many documents for possible cancellation, conversion, revision, or retention. The policy that evolved was that a program WBS was to be developed as outlined in 881B, and attention was directed to the user guide to avoid improper application. After a program WBS was developed properly by the DoD program manager, a solicitation needed to refer to 881B “for guidance only” as a basis for a contractor to develop a contract WBS. MIL-HDBK-881 updated and superseded the MIL-STD-881 documents on January 2, 1998.

MIL-HDBK-881 is still directed at defense materiel items. The WBS templates for the same seven DoD systems that were in the original standard are still included in the handbook. The handbook includes the top three levels of the WBS and the associated descriptions (WBS dictionary) for the following systems:

1. Aircraft systems

2. Electronic/automated software systems

3. Missile systems

4. Ordnance systems

5. Ship systems

6. Space systems

7. Surface vehicle systems

Figure 1-12 presents the ship system WBS as included in the handbook.

FIGURE 1-12 Ship System WBS

Because of a change in DoD philosophy, the NASA PERT and Companion Cost System Handbook was no longer mandatory and could not be cited as a contractual obligation. However, other DoD documents did specify the use of a WBS as a requirement.

The DoD policy in 2002 was based on (1) the requirements of DoD 5000.2-R and (2) the guidelines of MIL-HDBK-881. The DoD 5000.2-R regulation states:

The PM shall consider the following topics during program design and comply with each, as appropriate. C5.3.1. Work Breakdown Structure (WBS). Systems engineering shall yield a program WBS. The PM shall prepare the WBS in accordance with the WBS guidance in MIL-HDBK-881 (reference (cj)). The WBS provides the framework for program and technical planning, cost estimating, resource allocation, performance measurement, technical assessment, and status reporting. The WBS shall include the WBS dictionary. The WBS shall define the system to be developed or produced. It shall display the system as a product-oriented family tree composed of hardware, software, services, data, and facilities. It shall relate the elements of work to each other and to the end product. The PM shall normally specify contract WBS elements only to level three for prime contractors and key subcontractors. Only low-level elements that address high-risk, high-value, or high-technical-interest areas of a program shall require detailed reporting below level three. The PM shall have only one WBS for each program.

The preceding paragraph refers to the work performed in the DoD project office.

MIL-HDBK-881A superseded MIL-HDBK-881 on July 30, 2005. It addressed mandatory procedures for those programs subject to DoD Regulation 5000.2. The Handbook also provides guidance to industry in developing contract WBSs.

The Handbook presents guidelines for effectively preparing, understanding, and presenting a WBS. It is intended to provide the framework for DoD program managers to define their programs’ WBSs and also to be guidance to DoD contractors in their application and extension of the contract’s WBS. Section 1 defines and describes the WBS. Section 2 provides instructions on how to develop a Program WBS in the pre-award time frame. Section 3 offers guidance for developing and implementing a Contract WBS, and Section 4 examines the role of the WBS in the post-award time frame. The Handbook also provides WBS dictionary definitions for specific defense materiel items in its appendices.

The primary objective of the Handbook is to achieve a consistent application of the WBS for all programmatic needs (including Performance, Cost, Schedule, Risk, Budget, and Contractual). The discussion and guidance provided was based on many years of lessons learned in employing WBSs on DoD programs.

Further U.S. government requirements in the use of the WBS are included in Chapter 8 (Part II) of this book.

The Project Management Institute and the PMBOK® Guide

The lead in monitoring and documenting project management practices transitioned from the public to the private sector with the reductions in the space program, the end of the Cold War, and the rapid growth of the Project Management Institute (PMI).

The Role of the Project Management Institute

PMI, a professional association of approximately 300,000 members, through its conferences, chapter meetings, the monthly magazine PM Network®, and the quarterly Project Management Journal®, provides a forum for discussion of the growth and development of project management practices. In August 1987, PMI published the landmark document, The Project Management Body of Knowledge. That document was revised and republished in 1996 as A Guide to the Project Management Body of Knowledge (the PMBOK®Guide). It was updated again in 2000, and the third edition was published in 2004.

The PMBOK® Guide reflects the experience gained in project management since the seminal work of DoD, NASA, other government organizations, and the aerospace industry in the 1960s.

The PMBOK® Guide

The PMBOK®Guide includes proven traditional practices that are widely applied, as well as information about innovative and advanced practices that have seen more limited use but are generally accepted.

The PMBOK® Guide is not intended to be a “how-to” document. Instead, it provides a structured overview of and a basic reference to the concepts of the profession of project management. The PMBOK® Guide focuses on the processes of project management.

The PMBOK® Guide is not as explicit with regard to the development of the WBS as the MIL-HDBK-881A and the other U.S. government documents referenced earlier are. There are some differences, as might be expected with 30 additional years of experience. The PMBOK® Guide addresses a broader audience than the DoD documents and includes all commercial applications. It also describes experience in the field since the 1960s.

In addition to the discussion of the WBS in the PMBOK® Guide, PMI has published Practice Standard for Work Breakdown Structures, which is intended to be more universal in application than the comparable DoD Handbook.

The Practice Standard complements this book in same manner as the PMBOK® Guide complements other books on project management topics. The author recommends that the reader of this book acquire the most recent edition of Practice Standard for Work Breakdown Structures from PMI because the WBS discussion and samples in it are useful.

The PMBOK® Guide uses the same idea of decomposing project work into manageable packages that was used in the early government efforts, which is described in the PMBOK® Guide as “the subdivision of project deliverables into smaller, more manageable components until the work and deliverables are defined to the work package level. The work package level is the lowest level in the WBS, and is the point at which the cost and schedule for the work can be reliably estimated.”

In addition to the standard PMBOK® Guide, there is a U.S. DoD version that was published in 2003, a government version published in 2006, and a construction version that is based on the 2000 PMBOK® Guide. These are all available at www.pmi.org.