# Integration of Cost and Work Breakdown Structures in the Management of Construction Projects
## 5 Discussion  
In this study, the importance of project scope management has been endorsed, as it was in previous studies (e.g., [15; 25; 172]). However, we have emphasized that scope management is not just relevant to project planning. On the contrary, poor scope management may have very negative implications in later stages of project execution, mostly regarding project performance. Hence, a clear definition of the project scope is key to successful project scope management. In the construction industry, some tools such as PDRI (project definition rating) [173; 174], DERIS (detail engineering completion rating index system) [175], and FEL (front-end loading) [176] have been implemented to better define the project scope. A clearer definition of the project scope can also be achieved by actively involving stakeholders [137]. Another is obviously by building a consistent and realistic WBS [26]. A good WBS is a hierarchical decomposition, oriented to the project deliverables and the work that has to be actually done to achieve the project objectives [30]. If stated properly, it constitutes the core of project management (PM) [29; 177]. This, because the WBS allows implementing other PM functions such as planning, scheduling, budgeting, resource allocation, and risk management, as well as quality assurance and control. Other authors, however, put the schedule at the centre of the whole project planning and definition stages [178; 179]. In BIM contexts, the WBS has already been implemented for monitoring and reacting to changes in the work schedule [180]. For example, measures to handle design conflicts (configuration management) related to construction components have been already introduced in BIM platforms [181]. Unfortunately, this approach tends to manage time and cost independently, and in it, the WBS is generally not integrated with the CBS [13]. Hence, in those cases, the WBS is used for project time control whereas the CBS is used for budget control. However, if the focus remains on the WBS, project risks can be more efficiently managed, as many authors have also noted [10; 55; 56; 182]. Risk information can be relatively easily managed in BIM environments [183]. For example, risks with their associated project activities in the dynamic process can be considered with a series of linkage rules [184]. These risks that generally derive in non-compliance of project deadlines, budgets and quality requirements, usually arise from incomplete designs, inadequate specifications, and construction procedures, as well as scope changes [185]. However, when the WBS is integrated with the CBS, schedule and cost can be jointly managed [48; 120]. This allows project performance to be more easily measured too [144]. The latter also allows the implementation of project control techniques such as earned value management (EVM) [117]. EVM for example assumes that work packages (WP, from the WBS) and cost accounts (CA, from the CBS) are significantly overlapped. Still, the integration of WBS and CBS is not new in the construction industry, even before the advent of BIM [14]. Unfortunately, the absence of accurate and real-time as-built information has generally made it difficult to integrate and manage those events that produce project variability and uncertainty [186]. Conflicts arise more often, though, when the schedule depends on a WBS, and the budget on a (separate) CBS. Furthermore, there still seems to be no common agreement on which are the best criteria for decomposing the WBS and CBS, nor which is the best methodology to apply [49; 52]. In the construction industry, there have been proposals that have attempted to provide a reference framework. However, although there is a global interest in standardizing processes, through coding systems for instance, the result is still far from satisfactory. Indeed, even after the publication of the ISO 12006-2 and 81346-12 standards (among others), many countries have kept issuing their own new standards.