The project work breakdown process involves splitting of the project works into its manageable constituents arranged in a hierarchical order till the desired level. The work-breakdown levels are categorized into sub-projects, tasks, work packages, activities and operations. These levels depend upon the plan type, the nature and complexity of the project and the expected degree of control.
The work-breakdown levels for various types of plans are given in fig.



It may be noted that the levels classification is a broad concept and, at times, overlapping of levels may become unavoidable.

The breaking down of task/work package into its constituent activities requires a study of the methodology of execution of the work package. Generally, known by the term method statement, this methodology is evolved by the planning engineer on the basis of his construction experience and discussions with the respective project engineers.

Construction projects are best managed by work packages, which in turn are best planned and monitored by activities. A project planner, uses activity as the common data base for planning projects. Activity duration forms the basis for time planning and scheduling of project work. The inputs of labour, materials and machinery needed for execution of each activity enable preparation of resources forecasts. The activity sale price is used to determine income and cash-flow forecasts. The activity base is vital for monitoring progress of the project work.