In this session, let us quickly go over the development from CAD to BIM. What I would like to show you is that BIM is not a suddenly emerged monster but the road from CAD to BIM is just a natural way to go. In the late 80’s, due to advancement of computer graphics, the AEC industry started to adopt 2D CAD to replace hand-drawing for creating engineering drawings. The fundamental 2D representation of engineering information remained the same but only the tool was changed to 2D CAD software on a computer. So, we can say what 2D CAD did was just digitization of engineering drawings. Later on, when 3D CAD was introduced, an architect was able to use it as a design tool to express his or her design ideas directly in a virtual 3D space. The representation was no longer limited by 2D media. However, for building and civil engineers, the design task is more than geometric shapes. Therefore, 3D CAD was still not a sufficient design tool for engineers although it was helpful. In the 90s, some research efforts initiated from Stanford University started to promote 4D CAD applications. 4D CAD integrates 3D CAD model components with their corresponding time or schedule related information in a AEC project to simulate the construction process. It helps to facilitate team coordination, reduce design and construction conflicts, and support better decision-making with information visualization both before the actual construction work starts and during the construction. Later on, people started to add more dimensions on top of it, for example, adding cost related information to create 5D CAD. Although 4D CAD is very helpful, the construction of a 4D model by linking geometric entities with their corresponding schedules is a very labor intensive and time consuming task. In early 2000, BIM was emerged as a new technology in the AEC industry. It is a model-based approach to provide the industry a better way of managing engineering information needed for collaboration and decision-making throughout the lifecycle of a built asset. With the BIM technology, we can perform virtual construction in the digital space first. Once we are satisfied with the planned process and outcomes, we can then engage in real construction. As you can see here, the real construction should follow very well the virtual construction. In the BIM approach, engineering information are managed in the digital model. This model consists of elements corresponding to unique real objects or components in the physical world. Unlike the information management in traditional 2D drawings, this model-based approach significantly improves the consistency of information management, especially those related to product information. Nowadays, if you modify a 2D drawing, you need to make sure all other related 2D drawings are also modified accordingly to maintain information consistency. This is not an easy task because it is a human task and the relationships of drawings can be quite complicated, especially in a large project. In the BIM approach, the information is managed in the 3D BIM model and all needed 2D drawings are automatically generated by the computer. Therefore, any modification in the BIM model can be easily updated to the related 2D drawings. Since the introduction of construction management in late 80s, management of process information in the AEC industry has been significantly advanced. However, management of product information has long been hindered by the limitation of 2D drawings. Without a better way to manage product information, the advancement of construction management is also constrained. Now, with BIM, there is no doubt a much better product information management is supported and a better process information management will come. To the AEC industry, this development is a new one. But if we take a look at the manufacture industry, we can clearly see that the manufacture industry continues its journey from geometric CAD modeling to BIM-like object-oriented and feature-based modeling in the 90s and beyond. They are now talking about Industry 4.0. In this sense, the AEC industry is following the manufacture industry’s footsteps and that is why I said “BIM is a natural way to go” although we have no control on its pace. Is BIM an evolution or a revolution? I would say BIM is an evolution from the viewpoint of advancement of the AEC industry in adoption of information technology and management technology. And, BIM can be a revolution because it is a paradigm shift and opens a door for revolutionizing the business models in the AEC industry. So, I would say BIM is a “Revolution in Evolution”.
