Work breakdown structure

A work-breakdown structure (WBS) in project management and systems engineering is a breakdown of a project into smaller components. It is a key project management element that organizes the team's work into manageable sections. The Project Management Body of Knowledge defines the work-breakdown structure as 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."

A WBS provides the necessary framework for detailed cost estimation and control while providing guidance for schedule development and control.

Overview

WBS is a hierarchical and incremental decomposition of the project into deliverables (from major ones such as phases to the smallest ones, sometimes known as work packages). It is a tree structure, which shows a subdivision of effort required to achieve an objective, for example, a program, project, and contract. In a project or contract, the WBS is developed by starting with the end objective and successively subdividing it into manageable components in terms of size, duration, and responsibility (e.g., systems, subsystems, components, tasks, subtasks, and work packages) which include all steps necessary to achieve the objective.

The work breakdown structure provides a common framework for the natural development of the overall planning and control of a contract and is the basis for dividing work into definable increments from which the statement of work can be developed and technical, schedule, cost, and labor hour reporting can be established.

A work breakdown structure permits the summing of subordinate costs for tasks, materials, etc., into their successively higher level "parent" tasks, materials, etc. For each element of the work breakdown structure, a description of the task to be performed is generated. This technique (sometimes called a system breakdown structure) is used to define and organize the total scope of a project.