# Integration of Cost and Work Breakdown Structures in the Management of Construction Projects
## 6 Conclusions  
Project scope management is key for project success. A sound project definition and structure generate fewer changes when project deficiencies are found. Similarly, with the integration of WBS and CBS fewer contradictions will arise and more realistic estimations will be possible at the execution stage. Conversely, poor project definition and structure at the planning stages will surely have performance repercussions at the execution stage. These changes can proceed, for instance, from the task omission, cost overruns, project delays, and/or quality losses. Most construction projects are not created as a whole, but as a collection of parts [45]. In this context, WBS are used for breaking projects down into a number of small pieces that can each be more easily handled by a project manager, on site or in a screen. An early use of the WBS at the project definition stage is critical for the achievement of the project objectives. Likewise, the use of the WBS, as a fundamental tool for the management of a project, is also confirmed with the development of the standard ISO 21511:2018 work breakdown structure (WBS) [190]. Its integration with the CBS also allows both clients and contractors to develop the schedule based on the construction units level (the units of quantity survey contracts). This research has confirmed the importance and advantages of developing WBSs based on CBS in construction projects. By means of a questionnaire distributed among 500 Spanish construction professionals and a structural equation model, direct, significant, and causal relationships between the integration of WBS and CBS have been identified with the achievement of project goals. We have also found that as the competences and training in project management increase, there also is a higher awareness for any factor that facilitates managing the work to be done and implementing the tools that can measure its progress. This individuals' competence and training can be improved through specialist courses, mentoring, professional certification, study of PM methodologies, and gaining experience by participating in complex projects. In summary, according to the results obtained in the survey it can be stated that:  
* The WBS involves structuring the project scope in a hierarchical manner. It is oriented to the deliverables, and avoids both duplication and omission of tasks. * As the project work is defined more clearly, project roles and responsibilities can be assigned to subcontractors and organizational units more easily. This, in turn, also allows to define more representative project schedules and budgets. This research also has some limitations. The survey took place in Spain, a country whose construction sector has no standardized system of coding and construction works classification. Furthermore, in the Spanish construction market, open quantity survey contracts are dominant. This might have partially biased the respondents' perceptions regarding the relationship of project scope, time, and cost management with project success. Moreover, the use of the BIM methodologies is not widespread in Spain. This means, major project stakeholders in this country may not fully grasp (yet) the advantages of standardization and integration of work-related and cost-related structures. To conclude, future research will pursue to quantitatively measure the influence of integrating the WBSs and CBSs with the projects' actual quality, time, and cost performance. It will also be worth asking whether this integration will improve a company's knowledge and change management capabilities.