Specialists in different disciplines, e.g., designers and constructors, can examine and view a 3D Model at various levels of abstraction (detail). This helps improve communication and reduce barriers between the upstream (design and engineering) and the downstream (construction) personnel and processes. Specifically the role 3D Models facilitate in better linking the activities among project management, design and engineering, construction, and operation is shown in Figure 2.2 entitled Integrated Design and Construction. (SD-104, p. 10)