PM Network Nov 1991 p. 33 CONCERNS OF PROJECT MANAGERS
Robert Youker
There is common agreement in the profession on what a work breakdown structure is and what it does. The basic Department of Defense definition is:
A typical sample is shown in Figure 1.
Figure 1. Breakdown Structure for Large Communications Project
Source: Managing High-Technology Programs and Projects, by Russell D. Archibald. Copyright 1976 by John Wiley & Sons, Inc. Reprinted by permission of John Wiley & Sons, Inc.
A recent book on project management states:
Formation of the WBS family tree begins by subdividing, or partitioning, the project objective into successively smaller work blocks until the lowest level to be reported on or controlled is reached. This tree like structure breaks down the project work effort into manageable and independent units that will be assigned to the various specialists responsible for their completion, thereby linking in a very logical manner company resources and work to be performed [2].
In practice, however, this seemingly simple partitioning or factoring down process is not so easy. On actual projects the WBS often must be an artistic blend of a breakdown by (1) subsystems or components (product structure), (2) life cycle phases (process structure), and (3) resource units (organizational structure). In addition, the process of preparing a work breakdown structure is an integral part of the overall process of project and objective definition as well as the preparation of a master summary plan and a linear responsibility chart or matrix. This process is usually easier on physical or "hard" projects like equipment or construction and more difficult on "soft" projects like com- puter programming. The term Project Breakdown Structure (PBS) is more descriptive than Work Breakdown Structure and will be used in the rest of this article.
The basic purposes of the PBS are to:
Project Element and Function Mngr Mngr Mrktg Export Cntr Admn Instltn Prepare a proposal Director Line Mngr XXX Proj Engr Cntrlr Mngr Mngr Mngr Mngr Approve proposal Negotiate contract Sign contract Relationship Codes Plan and control project ================== Design and develop prototype A General Responsibility Control product configuration B Operating Responsibility Control product quality C Specific Responsibility Negotiate agreements to perform Project Work D Must be consulted Conduct evaluation meetings E May be consulted Report and maintain contact with customer F Must be notified Conduct design review meetings G Must approve
Source: Managing High-Technology Programs and Projects, by Russell D. Archibald. Copyright 1976 by John Wiley & Sons, Inc. Reprinted by permission of John Wiley & Sons, Inc. groups responsible for the different elements of the PBS.
Figure 2 is a sample project breakdown structure based almost entirely on the phases of the life cycle of the project. There is no breakdown by the various physical units or subsystems or components of the plant. On the other hand, in Figure 1 there is no element in the PBS for assembly of the various parts and components into subsystems and finally into outputs. Both Figures 1 and 2, however, have avoided the common mistake of forgetting final items such as manuals, training and spare parts. Also we can only assume in Figure 1 that system/project management includes the initial preparation of the plan that got the whole project started.
A list of common problems encountered when preparing a PBS are:
DEFINING THE BASIC PBS
The first and most important (and often the only) approach to preparing a PBS is to break the project or system into subsystems or components based on the physical aspects of the project. This is like chapters of a book, fields in an estate or modules in a computer program. It must include all end items of hardware, software, services and information. This is the product structure.
But we have seen that other work on the project must be included also. This could be phases in the life cycle process (process structure) such as planning or assembly or the work of one organizational unit such as legal (organizational structure). Here it is useful to consider the definition of a major element or subproject which is "a series of interrelated activities which are relatively independent from the rest of the project."
For example, on an airplane project the engine could be developed as a separate subproject by a different company once the specifications and interfaces were clearly defined. Legal could either be a subproject by itself or more likely be activities included in various other subprojects. The elements or categories must be mutually exclusive as well as all inclusive The amount of detail (levels of elements) depends on the purposes of the particular PBS.
It is also necessary to look at the existing chart of accounts when developing the PBS, especially its numbering system.
The basic thesis of this article is that the job of preparing a PBS is an artistic blending of the three different structures of process, product and organization into a Project Breakdown Structure or Work Breakdown Structure. Certainly the main approach is physical subsystems, but we must also look at the other structures to ensure that all of the work on the project is included. The PBS must include all of the work on the project.
SUMMARY OF STEPSThe process of preparing a PBS can be broken down into a series of steps as defined below and in Figure 3.
The objectives, nature and scope of the project need to be completely and clearly defined with all of the end items or outputs clearly identified with complete specifications. A hierarchy of objectives is very useful here which shows a complete ends/means chain.
There needs to be some thinking on the various levels of detail of plans that will be required and the number of levels of elements in the PBS.
A chart of the phases of the life cycle of the project should be laid out. (Figure 2, for example.)
The organization chart for the project should include all of the inputs, groups or individuals that will be contributing to the project, including stakeholders in the project environment if necessary. (Project Management is an example of an organizational unit that often becomes an element in the PBS as in Figure 1.)
This is a chart of the breakdown of subsystems or components, including hardware, software, services and information and geographical breakdown if applicable.
The establishment of the coding system for the PBS should be based on the existing chart of accounts of the organization.
The above items are woven together into a PBS similar to Figure 1.
The level 2 or 3 elements of the PBS become the left side of the MSP and the phases of the project (step 3) become the steps from left to right making up the MSP (see Figure 4). This is the summary plan that can then be detailed out in the CPM. Throughout the project the MSP can be used for reporting to top management.
It is useful to analyze the relationships between the elements of the PBS and the organization (see Figure 5 ). The elements of the PBS become one side of the responsibility matrix and the organization chart the other side. Codes can be used inside the cells of the matrix to denote different levels of responsibility of the different actors.
The PBS coding forms the foundation for the project's chart of accounts.
The initial planning in the above ten steps forms the basis for preparation of a detailed CPM plan.
WBS does not include activities, time estimates, resource use nor logic and is separate from CPM planning, which is the next step after the WBS.
The work order system flows from the definition of work packages in the PBS and the organizational responsibilities. Awork package is a convenient breakdown assigned to one organizational unit with clear start and finish points, w*h a budget value, and with a limited time duration. It is a collection of activities for a spe- cific task such as a subcontract for plumbing. This is ideally suited to the issuance of a work order.
At this point it becomes possible to start thinking about the required reporting system to control progress vs. plan.
CONCLUSION
Preparing a project or work breakdown structure is a vital part of the overall process of project definition and planning of project implementation. It is more than just the usual factoring down of the product structure into physical components. It is also necessary to look at the process structure (life cycle phases) and the organizational structure (inputs) to ensure that all work on the project is included. These three structures must be melded with artistic blending into a useful project breakdown structure and developed further into a master summary plan and other tools.
Thanks to Jim Sauter of IBM Education for his insight on the Process Structure.
AUTHOR
Robert Youker is an independent consultant and trainer in project implementation and an adjunct professor of project management in the Engineering Management School of George Washington University.
From 1975 to 1987, he worked at the World Bank, first as a lecturer at the Economic Development Institute and later as a management specialist in the Institu- tional Development Division for Africa. Previous experience includes president of Planalog Management Systems, and analyst with the Xerox Corporation and with Checchi and Company. He is a graduate of Colgate University and the Harvard Business School and has taken graduate work at George Washington University