The AGC's BIM Initiatives and the Contractor's Guide to BIM

Two weeks ago, I attended the annual Midyear Meeting of the Associated General Contractors of America (AGC) held in San Francisco, California. This is not an event I typically attend; what drew me to it, however, was that BIM (building information modeling) was actually the focus of a couple of sessions at the conference. Also, the AGC was using the meeting to release a brand-new publication called Contractors' Guide to BIM, which outlines best practices for contractors using BIM. This was intriguing, and it was also very impressive to see this kind of initiative coming from the construction side of AEC, considering that BIM has been relatively slow to take off in this sector so far. As I witnessed earlier this year at the Technology for Construction show, there were no BIM solutions on display in the Exhibit Hall, conveying the impression that BIM seems to have made scarcely a dent in the construction industry. But we now have a Contractors' Guide to BIM, well before any such corresponding guides have been made available for BIM in architecture and BIM in engineering. It is not even clear if any such guides are in the making. The construction sector may have been slow to take off with BIM, but the release of this guide and the emerging focus on BIM at the AGC conference should be heartening to those contractors eager to get ahead with this new technological development in the building industry.

This AECbytes Building the Future article provides an overview of the BIM session I attended at the AGC meeting and takes a look inside the Contractors' Guide to BIM.

Session on BIM Presented by the Building Futures Council

The session on BIM at the AGC meeting was presented by the Building Futures Council (BFC), an independent think-tank of building and construction industry decision-makers that identifies and explores critical issues related to the built environment. BIM is one of the emerging issues that the BFC is looking at. It put together the BIM session at the AGC meeting to discuss where the construction industry is currently at with BIM and what to expect in the future. The session was moderated by Michael Kenig, Vice Chairman of Holder Construction in Atlanta, who is actively involved in the AGC. According to him, the GSA's BIM requirement for its projects is one of the main forces driving BIM in construction. His brief introduction was followed by two presentations, one from Tom Faraone of the AISC (American Institute of Steel Construction), who described the BIM developments happening in the steel industry, and the second one from Don Henrich of Graphisoft, who provided the perspective of a vendor developing BIM solutions for construction.

The state of BIM is relatively more advanced in the steel industry, and if this industry can be seen as a microcosm of what is happening in the entire construction industry, then it follows that the rest of the industry can benefit from learning what is happening in the steel industry. That was the premise of Tom Faraone's presentation, and it was mostly centered around discussing the CIS/2 standard, which captures all the information related to the design, analysis, procurement, fabrication planning, fabrication automation, and the erection of structural steel in buildings. CIS/2 can be seen as a subset of the larger, more ambitious IFC standard, which aims to cover the entire spectrum of tasks related to the design, construction, and operation of buildings. I took a detailed look at the CIS/2 standard last year in my article, The CIS/2 Format: Another AEC Interoperability Standard, and therefore, much of Faraone's presentation was a reiteration of content that was already familiar. The only recent update was that the AISC was now working with the AIA Contract Documents Committee to make the amendments to the contract documents needed to make it easier for architects and engineers to work collaboratively using BIM. It follows from the work of the AISC in successfully updating the structural steel engineering Code of Standard Practice (CoSP) with an endorsement of CIS/2 and electronic data exchange, guidelines for the use of this technology, definitions of design model requirements and fabricator responsibilities, as well as a ruling that in the case of a conflict, the design model will rule over design drawings and the manufacturing model will rule over shop and erection drawings. This is a huge step forward in removing the hurdles to BIM implementation, and it is promising to note that the AISC is working with the AIA to take this further across a wider spectrum of the industry.

As of now, Graphisoft is the only BIM vendor that has developed dedicated BIM solutions for construction. Its Virtual Construction suite, comprising Graphisoft Constructor and Graphisoft Estimator, were introduced in 2005 (see AECbytes Newsletter #15); updated versions are expected in 2007. I was a little disappointed that Don Henrich of Graphisoft did not describe these solutions in more detail in his presentation, or present any case studies of how these solutions were being applied by contractors in different projects. Instead, he talked mostly about the IFC standard and referenced the NIST report on interoperability, both of which were again already familiar topics to me (see the AECbytes articles, The IFC Building Model: A Look Under the Hood and The NIST Report on Interoperability). However, in response to a question during the Q/A session, he did talk about the design model versus the construction model, showing that Graphisoft still strongly believes in the separation between the two. As I discussed in AECbytes Newsletter #15, the premise behind Graphisoft's construction solutions is that the building model required for construction is substantially different from the model generated during design, and that in most cases, even if a BIM model has been generated by the architect and engineer, it is not very suitable for construction and will have to be substantially reworked—to the extent that it would be easier to simply start from scratch. This viewpoint has, so far, not been endorsed by others in the AEC industry. But then, we also do not yet have BIM solutions dedicated for construction from the other BIM vendors like Autodesk and Bentley, so contractors may have to go with this theory unless it is proven otherwise. Also, despite being somewhat contentious, at least one positive aspect about this viewpoint is that it encourages contractors to proceed with BIM implementation even if the architects and engineers on their team are still using 2D CAD. Contractors are getting the important message that they don't have to wait to get a design in 3D from the architect before they can go ahead with BIM.

The Q/A session following the two presentations also yielded some additional insights. An inevitable issue that comes up in any kind of discussion on BIM is that of liability, as evidenced by the sessions at the AIA TAP conferences (see AECbytes Newsletter #27); the AGC session on BIM was no exception to this. In response to the liability question, the panelists made an important point—that no one implementing BIM first consults with their attorneys or insurance companies. If they did, they wouldn't be implementing BIM! Another question that was asked was whether owners need to drive BIM adoption, for which the response was that it wasn't necessary. Architects, engineers, and contractors can derive benefits and save money by implementing BIM, and therefore do not need external motivation to do. With regard to the cost of developing a construability model for the use of the contractor, Graphisoft had a pretty exact estimate to share, which is 0.1% of the cost of a project. It was also estimated that it would take 2 to 3 weeks of time to develop the model. With regard to how much time it would take for BIM to become commonplace, a quick poll around the room suggested that in 5 to 7 years, most projects would be done using BIM. The audience, comprising mostly contractors, was cautioned that while the current bottleneck to more widespread BIM implementation are the architects and engineers who are not using BIM technology, very soon, contractors would become the bottleneck, so they need to get up to speed on this technology soon.

The Contractors' Guide to BIM

While I was not able to attend the special session at the AGC event where the AGC's Building Division unveiled the Contractors' Guide to BIM (see Figure 1), I did receive a complimentary copy of the guide from the AGC for the purpose of this article and will provide a brief summary of it here. The guide is free for members of the AGC; non-members can buy it by going to this website. It is a 48 page document co-authored by several contractors based on their experiences with BIM implementation, including Bill Ernstrom of Alberici, David Hanson of Walbridge Aldinger., Damian Hill of the AGC, Joseph Jarboe of Clark Construction, Mike Kenig of Holder Construction, Doug Nies of Turner Construction, Dan Russell of Sundt Construction, and Les Snyder III and Tim Webster of Barton Malow. The objective of the guide is essentially to educate contractors about BIM, including its benefits, tools and applications. The content is organized into five main topics: implementing BIM from a 2D conversion versus a 3D design; the basic software tools that support BIM and the related collaboration; the BIM process and how it is to be conducted; clarification of the fundamental responsibilities of each team member relative to the BIM process; and finally, the main areas of risk management that contractors should begin to think about.

The guide starts by clearly identifying the many benefits to contractors using BIM including the ability to identify collisions (e.g., identifying ductwork running into structural members); the ability to visualize what is to be built in a simulated environment; fewer errors and corrections in the field; higher reliability of expected field conditions, allowing for opportunity to do more prefabrication of materials offsite, which is usually a higher quality at a lower cost; the ability to do more "what if" scenarios, such as looking at various sequencing options, site logistics, hoisting alternatives, cost, etc.; the ability for non-technical people (clients, users, etc.) to better visualize the end product; and fewer callbacks and thus lower warranty costs. The guide also addresses upfront the most commonly asked question of "Who should pay for the model?" by emphasizing that the benefits achieved with BIM, including improvements in productivity, lower warranty costs, fewer field errors and corrections, and a competitive marketing advantage for a period of time will offset the costs of BIM implementation and over time may actually reduce them.

One significant issue for contractors moving to BIM is implementing it on the basis of 2D drawings submitted by the design team (called "2D conversion" for short in the guide) in contrast to using the 3D model developed by a design team using BIM (called "3D design"), and a whole section of the guide is devoted to discussing this issue. For example, the cost of the model is greatly affected by whether it involves 2D conversion or 3D design. Assuming that a contractor has made the initial investment in software and training and is past the initial learning curve, the 2D conversion for a typical project should take between one to two weeks and should cost between 0.1% and 0.5% of the total construction costs. But if the design has been done using BIM software, the guide suggests there is no conversion needed and the contractor's ability to start using the model is immediate and much less expensive. This point directly contradicts Graphisoft's assertion that the construction model is so different from the design model that it would be more advisable for the contractor to create it from scratch rather than re-use the design model. The guide also advises that while 2D conversions can be outsourced to a growing number of third-party service providers, it is a good idea to do it in-house as the firm can benefit significantly from the experience of doing the model.

Another aspect of BIM for contractors that the guide discusses is the issue of the number of models. In all likelihood, multiple models will be produced in different disciplinary BIM applications and these will have to be combined into one composite model for visualization, clash detection, and other tasks (see Figure 2). At the same time, the guide emphasizes that it is not necessary to create all the models to derive the benefits of using BIM on a project. Contractors can make many "partial uses" of BIM such as assisting with scoping during bidding and purchasing, reviewing portions of the project scope for analyses such as value engineering, coordinating construction sequencing (even if just for two trades), demonstrating project approaches during marketing presentations, and so on. Taking BIM in "smaller bites" in this manner, versus creating full blown project models, can be much less overwhelming and has proven to be a great way for many contractors to get started with BIM. But the guide also takes care not to lose sight of the significant benefits of the full BIM approach, where model reviews can be more efficiently conducted in a CAVE (computer-aided virtual environment), shop drawings might be waived in favor of shop models or CNC (computer numerically controlled) fabrication models, and RFIs might become obsolete, or at least significantly reduced in number, and be resolved much quicker if the model is deployed as a jobsite tool.

In addition to discussing the broader aspects of BIM, the guide also provides contractors with several concrete guidelines and suggestions on getting started with BIM including how to set up the team, what project to start with, what to look for in a BIM tool, the cost of software and hardware, and so on. It includes a matrix of "Example BIM Tools" in an appendix that is intended to serve as a starting point for contractors to understand currently available BIM solutions in various categories. For example, the tools under the category "3D Modeling (or 2D to 3D Conversion)" include Autodesk's Revit Building, Graphisoft's Virtual Construction, Bentley's Bentley Architecture, and VectorWorks ARCHITECT from Nemetschek North America, while the "Interoperability" category features primarily NavisWorks applications for combining models and clash detection. Several hardware options are listed as well. I did not find this a very comprehensive or even accurate lists of solutions, as it did not include BIM applications for engineering such as Revit Structure, Bentley Systems, etc., or any estimating and scheduling applications that would be so critical to contractors.

Two other aspects that the guide deals with at length are the fundamental responsibilities of each team member relative to the BIM process, and the main areas of risk management that contractors should begin to think about. With regard to responsibilities, the guide emphasizes that while the use of BIM may well change the ways that projects are conceived, designed, communicated, and built, it will not change the core responsibilities of the members of the project team. Contractors and construction managers will still need to organize and lead the onsite construction effort; there will still be the need for a well-thought-out approach to construction that will allow each specialty contractor to apply its skills in a safe environment; BIM will not replace the need for designers to convey their design intent, nor will it replace the dialogue of the submittal process through which subcontractors demonstrate their interpretation and understanding of the design intent; and owners and code enforcement officials will still need to be afforded the ability to evaluate the cost and adequacy of the various components of the project. BIM technology vendors must ensure that their solutions facilitate the building process and these relationships as they exist rather than attempt to shift the responsibilities of the project team members into a contrived software work-flow process.

While the guide does not attempt to answer all the legal issues presented by BIM, it does discuss some of the concerns and offers some suggestions on how contractors should proceed. For example, it recommends that contractors should do their best to reach an understanding with all parties about the ability and right to rely upon the model. Disclaimers of reliance that some have sought to apply to design documents in electronic format should be discarded. Also, the same risk allocation principles that apply to traditional two-dimensional design should apply to a BIM model. So the architect/ engineer still remains responsible for project design, while a contractor's involvement in, and corresponding liability for, design should not extend beyond that typically associated with constructability issues, construction means and methods, and shop drawings. When a model is used, strict rules should be applied to police the model, so that access rights are reasonably restricted, the ability to change the model is strictly limited to those who are responsible for changes to that portion of the model, outdated versions of the model can be destroyed, and a precise audit trail can be maintained for the various iterations of the model. With regard to the issue of "ownership of the model," it should be worked out through the contract, although it certainly becomes much more complex when the final "model" is a collection of many models to which many parties would have contributed. The issues of design input versus design responsibility will have to be sorted out. Owners need to be particularly aware of the implications of such issues and are expected to play an important role in addressing them.

Analysis and Conclusions

I found that the Contractors' Guide to BIM did an excellent job in introducing the concept of BIM to contractors, summarizing the benefits of BIM as well as the issues, and providing useful guidelines on how to get started. A lot of the content is actually relevant to the entire industry, not just contractors, so it would benefit even architects, engineers, owners, and other building professionals to take a look at it. For example, it cautions that BIM does not automatically guarantee collaboration but it does allow collaborative projects to be more collaborative. This is a very useful insight for the industry at large. To take another example, the guide lists a number of barriers that keep contractors from using the latest technology, including fears (legal/risk fears, fear of change, fear of the unknown, etc.), initial investment costs, the time to learn how to use the software, and perhaps the lack of support from the senior leadership of the company, which may be the biggest barrier for many. This list is exactly what architects and engineers also find themselves up against when it comes to making the move to BIM, so the recommendations the guide makes should be useful to them as well.

This is not to say that the guide is not without some shortcomings. I found that its discussion of software solutions fell far short in giving contractors an accurate and complete picture of what is available. In talking of BIM modeling tools, it listed only architectural BIM solutions, completely disregarding the BIM solutions for structural and MEP engineering, despite that fact that a contractor doing BIM on the basis of a 2D design would have to create all the different disciplinary models and would need to use all the respective modeling applications. While the guide did mention the need to link the data in a BIM model to a scheduling application, it did not follow up by discussing which applications can be used to accomplish this. There was also no discussion of how cost estimating can be done from a BIM model, which is one of the most critical tasks of a contractor, and which BIM has the potential to make a lot more efficient and accurate (see the AECbytes article, Visual Estimating: Extending BIM to Construction). I also found the guide occasionally guilty of some oversimplification, such as "If you are fortunate enough to be given a truly intelligent, 3D design from the design team, using it is as simple as opening the files." It then goes on to immediately contradict this by stating that rarely will 3D design be construction ready and some amount of detail will need to be added to the model, for example, adding pour breaks to a slab object for scheduling its construction sequence. However, it does not even attempt to pose or answer the critical question of which application will be used to add details like pour breaks. Architectural BIM applications will typically not have this capability, and contractors may need to use a dedicated BIM application like Graphisoft Constructor to add construction-specific details. This brings us back to the issue of the design model versus and construction model that came up in the AGC BIM session described earlier. I was disappointed that the guide did not address this contentious issue at all. But considering that this is only the first edition of the guide, some of these limitations should hopefully be addressed in subsequent editions.

With regard to the AGC session on BIM, while I greatly applaud the initiative to bring BIM to the table as a topic of discussion to push its implementation forward among contractors, I did find that the focus on standards at the session was somewhat misleading. While standards and interoperability are an important aspect of BIM, they can be discussed further down the road once BIM implementation is well underway. What is most important for now is for contractors to get started with BIM, and while knowing about IFC and CIS/2 may be informative, it does little to get them on the right track. For now, in my opinion, sessions on BIM for contractors should present more case studies, highlight the benefits that have been achieved by contractors who have been early adopters of this technology, and provide as many implementation guidelines as possible.

About the Author

Lachmi Khemlani is founder and editor of AECbytes. She has a Ph.D. in Architecture from UC Berkeley, specializing in intelligent building modeling, and consults and writes on AEC technology. She can be reached at lachmi@aecbytes.com.