WORK BREAKDOWN STRUCTURE:HIERARCHIES IN THE PROJECT ENVIRONMENT

1. HIERARCHIES IN THE PROJECT ENVIRONMENT: THE NEED FOR A WORK BREAKDOWN STRUCTURE

Introduction

As discussed in Section 1, the natural division of labor that exists in a functional organization is missing in projects. It is important to divide the total scope of the project (all the work that has to be done in the project) among the individuals and organizations that participate in it in a proper way, a way that ensures that all the work that has to be done in the project (the project scope) is allocated to participants in the project while no other work (i.e., work that is not in the project scope) is being done. A framework composed of two hierarchical structures known as the work breakdown structure (WBS) and the organizational breakdown structure (OBS) is used for dividing the project scope amongst the participating individuals and organizations in an efficient and effective way, as discussed next.

The Scope

In a project context the term scope refers to:

• The product or service scope, defined as the features and functions to be included in the product of service

• The project scope, defined as the work that must be done in order to deliver a product or service with the specified features and functions

The project total scope is the sum of products and services it should provide. The work required to complete this total scope is defined in a document known as the statement of work, or scope of work (SOW). All the work that is required to complete the project should be listed in the SOW along with explanations detailing why the work is needed and how it relates to the total project effort.

An example of a table of contents of a SOW document is given in the Appendix. This example may be too detailed for some (small) projects, while for other (large) projects it may not cover all the necessary details. In any case, a clearly written SOW establishes the foundation for division of labor and integration.

Implementing Division of Labor in Projects

The SOW is translated into a hierarchical structure called the work breakdown structure (WBS). There are many definitions of a WBS:

1. The Project Management Institute (PMI) defines the WBS as follows: ‘‘A deliverable–oriented grouping of project elements which organizes and defines the total scope of the project. Each descending level represents an increasingly detailed definition of a project component. Project components may be products or services’’ (PMI 1996).

2. MIL-STD-881A defines WBS as ‘‘a product-oriented family tree composed of hardware, ser- vices and data which result from project engineering efforts during the development and pro- duction of a defense material item, and, which completely defines the project, program. A WBS displays and defines the product(s) to be developed or produced and relates the elements of work to be accomplished to each other and to the end product’’ (U.S. Department of Defense 1975).

Whatever definition is used, the WBS is a hierarchical structure in which the top level represents the total work content of the project while at the lowest level there are work elements or components. By allocating the lower-level elements to the participating individuals and organization, a clear def- inition of responsibility is created. The WBS is the tool with which division of labor is defined. It should be comprehensive—that is, cover all the work content of the project and logical—to allow clear allocation of work to the participating individual and organizations as well as integration of the deliverables produced by the participants into the project-required deliverables.

Coordination and Integration

Division of labor is required whenever the work content of the project exceeds what a single person can complete within the required time frame or when there is no single person who can master all

the knowledge and abilities required for the project. However, the following two reasons that promote division of labor may lead to the failure of the project:

1. Coordination of the work performed by different individuals and organizations is required because outputs (deliverables) of some participants provide inputs to the work of other partic- ipants in the project. For example, in a construction project, civil engineers and architects produce the design while construction workers perform construction work. However, without the plans and drawings produced by the design team, construction workers cannot do their work.

2. The ability to integrate the deliverables produced by different participants is crucial. Thus, for example, the fact that in a new car development process one team developed an outstanding new body for the car and another team developed a state-of-the-art engine does not guarantee a project’s success. Only a successful integration of the engine with the car that results in a vehicle that satisfies all the requirements and specifications of the project constitutes a success. For example, if the car becomes unstable after engine assembly due to a high center of gravity caused by the location of the assembled engine, the fact that the car body is excellent and the engine performs very well does not make the project a success.

In addition to defining the division of labor in the project, the WBS should support integration and coordination. Properly designed WBS is the tool for division of labor, integration, and coordination.