AEC Tech News #95 (April 10, 2003)

9 Apr, 2003 By: Lachmi Khemlani

I devoted a couple of recent issues of the AEC Tech News to exploring the concept of "building information modeling," or BIM--the ostensible successor to CAD in the AEC industry. Issue #90 captured Autodesk's perspective on BIM, advocating change and positioning Revit as its BIM platform of the future. Issue #94 highlighted the contrasting Bentley strategy of not starting over and continuing to use the MicroStation platform to support BIM.

Both these software vendors were recently invited to participate in a debate on BIM, produced and moderated by Jerry Laiserin, editor and publisher of The LaiserinLetter ( Autodesk was represented by Phil Bernstein, VP, Building Solutions Division, and Bentley was represented by Keith Bentley, Co-Founder and Co-CTO. The first half of the two-hour debate had both representatives answer questions posed to them by Laiserin and members of the audience; the second half had them directly field questions from each other. I had the opportunity to watch the webcast of the debate and found that, while nothing fundamentally new was said, many interesting aspects were discussed. Above all, their differences in approach and strategy on BIM were brought into sharp focus. I will devote this and the next issue of the AEC Tech newsletter to capturing the highlights of the debate as well as my analysis of it.

Key Benefits of BIM

Both vendors were in agreement over the importance of BIM and its potential benefits to the industry. In the short term, the use of the model-based approach will lead to faster, cheaper, more accurate, better coordinated, and less risky drawing production, which itself is an incentive to adopt it. There's money to be made right away. The long-term benefits of BIM and business issues, such as who pays for the extra effort and who owns the data, will continue to be debated until they are eventually figured out.

There was also consensus that the benefits of BIM extend well beyond the design and construction phases into the future operation, maintenance, and facilities management of the building as well. A good BIM implementation of a project will lead to substantial savings in the operating costs of a building. Thus, there's a lot more money to be made down the line. We could even have a new profession emerge that continues to manage the information model of a building project after it has been built, a profession for which Keith Bentley coined the interesting term BIM Master, analogous to the term Web Master.

Different Perspectives on BIM

This was about the only aspect of BIM that the two vendors could agree upon. On practically every other issue, there were differences, which can be summarized as follows:

1. Autodesk believes that the building data should be centralized and integrated, whereas Bentley believes the data should not be centralized and will be distributed across multiple applications.

2. The centerpiece of Autodesk's solution is a tool, Revit, while that of Bentley's is a platform, MicroStation.

3. Autodesk is advocating a revolutionary approach to BIM by urging its users to switch to Revit, while Bentley is advocating an evolutionary approach based on its existing MicroStation platform and Triforma applications.

4. With regard to interoperability, Autodesk believes in providing designed interconnections to the building model in the form of APIs, whereas Bentley is advocating open file formats to promote free exchange of building data between applications from different vendors.

Let's look at some of these divergent viewpoints in more detail.

Tool (Integrated Data) versus Platform (Aggregated Data)

The "integrated versus aggregated" data distinction was introduced by Bernstein to explain how Autodesk's approach is different from its competitors'. The centerpiece of Autodesk's BIM strategy is Revit, a modeling application that is designed to be aware of what a building is, has a set of explicit relationships, and lets the architect/engineer interact with the model through the familiar language of plan, section, elevation, schedule, and details, directly connected to the model. The building data is centralized, and therefore, integrated.

In contrast, Bentley believes that the centralized database is not the right approach. Bentley's BIM approach is centered, not on the use of a single modeling tool, but on a platform, MicroStation, that supports an array of different building modeling tools. The building data is therefore, not integrated in one application, but distributed across multiple applications and has to be aggregated. The aggregation must be done intelligently, so that the data cohesively and accurately represents a building. Moreover, this aggregated data must also be managed effectively to ensure that the correct relationships are made, changes get updated in all representations, the most up-to-date version is used, and there is no conflict between components distributed across multiple representations. A managed environment is therefore critical to Bentley's view of BIM.

Revolutionary Approach versus Evolutionary Approach

By urging its customers to switch to a new application, Revit, Autodesk is advocating a revolutionary approach to BIM. In contrast, Bentley's approach is evolutionary: stick with MicroStation and Triforma and continue to improve its modeling capabilities. Given the history of both vendors, this difference in strategy is understandable. Bentley's TriForma has building modeling capabilities that have been in use for several years, so the company sees no reason to adopt a new application. In contrast, Autodesk's in-house application, ADT (Autodesk Architectural Desktop), has been more of an add-on to AutoCAD than a building modeling application in its own right, which is why Autodesk wants to start over with the "state of the art" parametric building modeling capabilities of Revit.

Bentley finds the idea of starting over particularly objectionable and not aligned with the interests of the users. Keith Bentley reiterated this several times in the course of the debate, and one of the questions he directed at Phil Bernstein was why Autodesk cannot build the same capabilities that Revit has into AutoCAD and ADT. He pointed out that MicroStation and Triforma can do everything Revit can. He then provided the analogy of the highly successful Microsoft, which gradually evolved its operating system application from DOS to the current Windows XP, without making any drastic breaks. Can't Autodesk innovate within AutoCAD if it tries hard enough?

This is a critical question, one that I'm sure many AutoCAD users who are not too keen to start afresh are also asking. To this, Bernstein responded by stating quite frankly that AutoCAD is primarily a geometry and drafting engine. Autodesk has made a strategic decision to enable BIM with a new and powerful application that specifically describes a building from the ground up, rather than try and build a solution by transferring existing technologies that cannot fully deliver on the potential of BIM. Autodesk will continue to develop and support both AutoCAD and ADT, but its BIM solution is definitely Revit.

It is a different approach and perhaps a somewhat radical one. Autodesk is undoubtedly taking a risk by staking its future on a yet-to-be-fully-proven technology, while Bentley is playing it safe and continuing with its time-tested and proven technologies. Is the AEC industry ready for a change? Do professionals want to implement BIM seriously? And if so, are they open to using a new application or would they rather use what they have? Only time can tell.

Stay tuned for a further discussion of the issues covered in the debate and my overall analysis of it in the next issue of the AEC Tech newsletter.

Relevant Links

Debate webcast archive and BIM discussion/commentary:

Autodesk's white paper on BIM:

Bentley's white paper on BIM: