The best way to control a large number and a variety of activities of a project, and to identify the specific tools and resources to be used at each step, is to have a coherent, detailed representation of the entire project and its stages. The SPM operational model is based on a process approach which may be said to adopt a three-dimensional perspective. Activities are organized according to their individual contribution to the total project, and the project map represents the basic grid to which they are added before being linked to the levels of time and cost.
WBSPlanned activities are defined and coded in the WBS (Work Breakdown structure), which identifies in the most precise way of all the discrete elements of work and their respective tasks, organizing them into a multilevel structure that allows for easy movement between general and specific information. In a three-dimensional perspective, the WBS can be regarded as the first axis, ordering both planned and completed work, and clarifying the material contents of the project.
PBSThe second axis is the PBS (Process Breakdown Structure), which is used to organize processes, that means all the operations which are necessary to complete the activities classified in the WBS. In this way, it is possible to identify recurring processes and organize the workload efficiently, according to both available resources and project requirements. At the same time, cross reference between the WBS and PBS enables the clear identification and full traceability of documentation, allowing to follow work progress throughout the life cycle of a project.
CBSThe third axis is the CBS (Cost Breakdown Structure), which deals with processed data and operations in respect to planned allocations of time and cost. Thanks to the CBS, we can monitor the development of a project with respect to general objectives and fixed deadlines, so as to evaluate advancement stages, specification compliance and so on. It also marks the contiguity between engineering and project management functions in a new integrated framework.