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Has someone been reading too much Star Trek here? What is 4D modeling? In traditional CAD, a building design is drawn as lines on a computer, rather than directly on paper, but the presentation of the design follows the traditional plans, elevations and sections format. 3D CAD enables the design to then be displayed in perspective, allowing you to "walk around" or "through" the building; this is obviously excellent for presentations to the client, or other interested parties. 3D CAD is often combined with object-oriented CAD, and here the "lines on a computer" are actually designated as the object they represent, e.g. as a wall, and specification details and price can be linked to the object. So with 3D object-oriented CAD, you can "walk through" the design, identify each part of the design (e.g. click on a door and see the type of door, it's size, etc.), and automate the process of producing an estimate. This information source is obviously useful to the designers and the builder, but it can also be extremely useful to maintenance personnel, once the building is complete and occupied.
4D CAD takes this one stage further, and adds the time element, so you can see how the building will look through the construction process. 4D CAD provides the following advantages over traditional CAD design, including:
1. Better comprehension from all parties of the design. Being able to move through the building, if only in a virtual sense, can give a much clearer understanding of the design than from traditional plans and sections, and future users can more easily identify problem areas and beneficial points in the design.
2. The model can identify potential conflicts between design elements (such as an electrical panel and a mechanical duct in the same physical space), leading to better coordination of the design, and consequently fewer change orders. One study indicated that 40% of change orders would be prevented by a systematic application of 4D modeling.
3. The automating of the measurement process, and the linking of costs to the elements of the building, should lead to improved accuracy in the estimates. The time element in 4D CAD also means that it is easier to prepare a projected schedule of payments, which is very important to the developer when arranging financing for the project.
4. The constructability of the design can be better analyzed, when the way the building comes together, over time, can be seen on the computer screen.
5. This same ability to view the construction process can improve scheduling, by allowing the scheduler to see the interaction of different operations.
6. The effects of alternatives, in design, materials, and scheduling options, can be easily assessed.
With these kinds of advantages, why do we not see this technology being used more regularly? Again, there are a number of points to consider:
A. The implementation of 4D CAD would put more work on the architect, and there would need to be an appropriate revision of the fee scale. While there should be compensating savings later in the project, in would mean a higher outlay in the early stages of a project.
B. While this is not a completely new technology, it is one that designers are not using regularly at present, so there would be a learning curve involved.
C. The interoperability of software from different vendors needs to be improved.
The above points of consideration could be viewed as problems on the path to implementing this technology, but they are problems that are being worked on:
a. Companies, such as DPR (www.dprinc.com) have been working with this technology, and successfully adapting contract documents to suit the new roles.
b. Educational institutions, such as CIFE (the Center for Integrated Facility Engineering) at Stanford University (http://cife.stanford.edu) are running courses and seminars to educate the industry about the possibilities of this technology.
c. The BLIS project (www.blis-project.org) is working with software companies (currently over 50 participating organizations) to achieve interoperability between the various applications, by establishing a recognized format to transfer data from one application to another.
Geoff Canham
Atkins Hanscomb F&G, San Francisco |
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