Work Breakdown Structure and Contracting Strategy

In the application of the systems approach to both the plant and the work there is a step-wise un-hiding of requirements as the partitioning into more detailed elements progresses. This is one side of the manner in which the systems approach handles the complexity of engineering projects. The other side arises from the fact that at each level of the top-down process, the components are not a collection of unrelated components, but interact in a particular way to form a system with a particular structure this system can have properties, the emergent properties we discussed in Sec. A4.1, that are not present in any of the components. As the overall complexity is a combination of the complexity of the elements and the complexity of their interactions, the art of system design is to reduce this combined complexity, not just the one or the other. 

The second difference is that in the case of plants, we can consider what a plant must do, i.e. its functionality, without considering a particular physical realisation a plant has an image in both the functional and the physical domain. That is not the case with work as we mentioned above, work is defined completely in terms of what it does it has only this one image . 

Because of these two differences, the subsequent chapters will focus on exploiting the existence of the functional domain and the consistent application of the system concept in that domain as a means of handling the complexity in designing a plant to meet a demanding set of stakeholder requirements. 

As we saw earlier, the Work Breakdown Structure (WBS) for a project is a hierarchical ordering of Work Packages (WPs), with the whole body of work as a single WP at the top level, and as a set of WPs at whatever level is deemed appropriate for each part of the work. The WPs at this lowest level of breakdown are sometimes called tasks. However, connected to what might look like a simple (but structured) tabulation of WPs is a number of central features of the project. 

This central position of the WBS in the project explains why it acts as the key to the data base that contains the data defining the various types of entities constituting the project. 

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