Software Engineering

1.5 
Work breakdown structure
The work breakdown structure (WBS) is a project management tool for understand-
ing and establishing the scope of work for a software development effort. The WBS 
is used to decompose the work packages that define the scope of the development 
effort. Each top-level work package involves multiple technical and management 
disciplines that must be involved in performing and controlling tasks. These work 
packages are broken down into the specific tasks, budget allocations, deliverables, 
and milestones for each organization contributing to a task. Each work package 
should identify task dependencies with other tasks making up the WBS. The work 
statements must be evaluated by each contributing organization to determine the 
level of involvement necessary to enable task performance in accordance with estab-
lished policies and procedures. Organizational task estimates should be combined 
and summed up to provide a complete estimate for the work to be performed. The 
top-level work package’s labor, cost, and schedule parameters should be accumu-
lated to provide a basis for establishing project plans, budgets, and schedules.
The top several layers of the WBS provide the project’s skeletal definition of 
work to be performed. The next several layers identify the set of integrated techni-
cal and organizational tasks to be performed. Further layers of WBS decomposition 
should be developed, as necessary, to provide detailed technical and organizational 
task estimates for the work to be accomplished.
The WBS must be developed incrementally as the software architecture is estab-
lished. This permits the WBS to address the technical and project-related work plans 
to properly reflect the software architecture as it is developed. The software engi-
neering IPT is responsible for integrating, controlling, and maintaining the technical 
elements of the project WBS. This is to ensure that the technical WBS conforms to 
the evolving definition of the software architecture and properly reflects the technical 
work to be performed.