History
The concept of work breakdown structure developed with the Program Evaluation and Review Technique (PERT) in the United States Department of Defense (DoD). PERT was introduced by the U.S. Navy in 1957 to support the development of its Polaris missile program. While the term "work breakdown structure" was not used, this first implementation of PERT did organize the tasks into product-oriented categories.
By June 1962, DoD, NASA and the aerospace industry published a document for the PERT/COST system which described the WBS approach. This guide was endorsed by the Secretary of Defense for adoption by all services. In 1968, the DoD issued "Work Breakdown Structures for Defense Materiel Items" (MIL-STD-881), a military standard requiring the use of work breakdown structures across the DoD. This standard established top-level templates for common defense materiel items along with associated descriptions (WBS dictionary) for their elements.
The document has been revised several times, most recently in 2011. The current version of this document can be found in "Work Breakdown Structures for Defense Materiel Items" (MIL-STD-881C). It includes standards for preparing work breakdown structures, templates for the top three levels of typical systems, and a set of "common elements" that are applicable to all major systems and subsystems.
Defense Materiel Item categories from MIL-STD-881C:
- Aircraft Systems WBS
- Electronic Systems WBS
- Missile Systems WBS
- Ordnance Systems WBS
- Sea Systems WBS
- Space Systems WBS
- Surface Vehicle Systems WBS
- Unmanned Air Vehicle Systems WBS
- Unmanned Maritime Systems WBS
- Launch Vehicle Systems WBS
- Automated Information Systems WBS
The common elements identified in MIL-STD-881C, Appendix L are: Integration, assembly, test, and checkout; Systems engineering; Program management; System test and evaluation; Training; Data; Peculiar support equipment; Common support equipment; Operational and site activation; Industrial facilities; Initial spares and repair parts. The standard also includes additional common elements unique to Space Systems, Launch Vehicle Systems and Automated Information Systems.
In 1987, the Project Management Institute (PMI) documented the expansion of these techniques across non-defense organizations. The Project Management Body of Knowledge (PMBOK) Guide provides an overview of the WBS concept, while the "Practice Standard for Work Breakdown Structures" is comparable to the DoD handbook, but is intended for more general application.
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