# Integration of Cost and Work Breakdown Structures in the Management of Construction Projects
## 1 Introduction  
According to the PricewaterhouseCoopers's \"When will you think differently about programme delivery?\" report [1], only 2.5% of companies successfully complete 100% of their projects. Similarly, the Project Management Institute (PMI) in its \"Pulse of the Profession 2016\" report [2], highlights that less than 50% of organizations achieve their objectives when there is not a PM culture in the organization. When there is, more than 70% of companies achieve their objectives instead. It seems project management (PM) is important then. The adoption of PM methods brings multiple benefits to companies [3]. This is why there is a growing number of professional bodies, PM frameworks, and certified project managers [4]. However,in the context of construction, KPMG's \"Climbing the curve\" report [5] reveals the construction sector's low productivity in which less than a third of projects are completed within less than a 10% delay and a quarter within less than a 10% overrun. Construction projects performance is influenced by many aspects (e.g., constraints, specific tasks, project changes) [6]. The project stakeholders need to state the functional requirements at a very early stage [7]. This allows identifying the elements that must be considered in the project definition (scope). The interrelationships among these elements and their relative importance allow the formulation of a first project network structure model. In this regard, scope management constantly assesses and updates this project network structure to carry out the project [8; 9]. This implies the definition of all work a project involves, and also how to break it down into more manageable pieces. Generally, this progressive task decomposition is referred as work breakdown structure (WBS). Eventually, people and responsibilities will also be attributed to the different work packages. This links the WBS to the project and company's organigram. Additionally, but somehow in parallel, companies draft the project budget. They normally resort to another structure where items are classified in chapters, subchapters, and units. This structure is generally referred to as cost breakdown structure (CBS). CBSs may keep some parallelisms (or not) with the WBS. This, as items in the CBS may be grouped according to multiple criteria such as items location, similar construction methodologies, materials, equipment, or resources involved. Still, thanks to these processes, more accurate schedules and budgets can be generated and projects can be controlled (facilitating a comparison of what is actually carried out with what was intended to be executed). Conversely, ill-defined scopes are one of the most frequent causes of project failure [10]. This normally arises as poor project definition, contradictory requirements, important tasks omission, very inaccurate estimates, and inappropriate (unrealistic or overly optimistic) contingencies [11]. In summary, scope management takes care of what must be done in a project, why it should be done, and how it can be done [12]. All these play a key role in project performance. In scope management then, a hierarchical decomposition of all project tasks under the form of the WBS is paramount. However, the CBS is equally important, as it allows to manage the project cost dimension. Hence, both the WBS and the CBS are valuable PM tools as they establish the basis for planning, scheduling, budgeting, resource allocation, responsibility assignment, and information management [13]. In the construction industry, the development of the WBS and CBS allows the implementation of other project monitoring and control techniques that can also handle potential risks [14]. The main objective of this research is to confirm whether a significant alignment between the WBS and the CBS offers additional advantages when managing construction projects. It also investigates how this alignment can positively benefit and facilitate the adoption of BIM and other management tools.