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AEC

How Many Contractors Does It Take to Scale a Wall?

10 Dec, 2006 By: Kenneth Wong

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Associated General Contractors of America releases guidebook offering insight and advice for building industry's adoption of BIM

Les Snyder, executive vice-president of the general contracting and design/build firm Barton Malow, coauthored a guide to help contractors climb over a wall. It's a wall stacked with blocks of fears: fear of legal risk, fear of change and fear of the unknown, to name but a few. To be more specific, they're fears associated with BIM (building information modeling) adoption.

There's no shortage of BIM advocacy literature in the architectural arena, but it's quite a different matter for the contractor crowd. So "The Contractors' Guide to BIM: Edition 1," a 48-page treatise from the Associated General Contractors of America (AGC), may well be one of the earliest efforts by this community to formally advance BIM. As such, this guide is a commendable accomplishment-even if it's anything but exhaustive, by the AGC's own admission.

Deconstructing the Wall
"The new anxieties presented by 3D [a prerequisite for BIM deployment] are not a whole lot different from what happened with computer-aided drafting," Snyder observes. "If we looked back at the conversion from manual drafting to computer-aided drafting, [the design and construction industry] was slow to change and accept it."

Are the concerns legitimate? Some probably are, the guide admits. Take, for instance, the fear of legal implications: What are the liabilities associated with participating and collaborating in the BIM model?

"The emergence of BIM as a vehicle for dramatic change in design and construction occurs in a legal environment that has not fully come to grips with all the risk management implications of the underlying technology of electronic representation, or transmission of documents of any type," acknowledges the guide. "This guide will not attempt to answer all the legal questions presented by BIM, but rather will discuss some of the concerns contractors should at a minimum understand and if possible address. ..."

As one possible solution, the authors suggest the following: "When a model is used, strict rules are 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."

The Contractor's Perspective
"In construction, the more effectively you plan things before you break ground, the more successful and thus profitable the project will be," says Snyder. Nevertheless, good planning is something not consistently practiced in the industry, he admits. So the emergence of BIM, with its emphasis on early collaboration, offers new hope.

"If you use 3D tools to model the construction site logistics -- everything from crane locations to pedestrian walkways to elevator hoists -- you're able to see more clearly than you would in traditional 2D plans," Snyder adds. "Using 3D, you might discover, for instance, interferences with overhead utility lines."

Contrary to popular belief, the guide states, BIM "will not change the core responsibilities of the members of the project team. In a fully integrated 3D virtual construction environment contractors and construction managers will still need to organize and lead the onsite construction effort. No amount of technology will replace the need for a well-thought-out approach to construction. ..."

The authors point out, "Shop drawings, like slide rules and blueprints, may become a thing of the past, but the dialogue between designers and builders that is the basis of the submittal process must continue to be accommodated. Regardless of the medium of communication, it is necessary that the builder and designer confirm that the design intent is correctly interpreted . ..."

What's in the Guide? The principal chapters in the guide are:

• BIM: what exactly does it mean?
• BIM tools
• The BIM process: how is it to be conducted?
• Clarification of responsibilities
• Risk management

These chapters are followed by an appendix with a catalog of some BIM products in the market: hardware, software, training, consulting services and so on. The multipage, multicolumn chart lists each solution's base description, supplier background, BIM application, and approximate cost.

The guide observes that most contractors will probably start off with partial BIM adoption, through visualization, scope verification, collision detection, construction sequencing and so on. The BIM Process chapter discusses a number of practical concerns, including:

• using converted 2D versus 3D designs;
• linking the model to the schedule;
• outsourcing or building the model in-house;
• upkeep of the model during design or during construction;
• the project delivery method/lean construction.

Ready to Climb?
"Owners, architects, engineers, general contractors, subcontractors -- if, at a minimum, everybody just starts using BIM as a tool, we'll move the industry along much faster," Snyder observes. "The American Institute of Architects is doing a great job pushing forward 3D. The owners are doing their part through CURT [Construction Users Roundtable]. We want to do our part."

In the forward, the Collaboration Techniques Tools and Technologies Task Force of AGC of America writes, "This guide is for contractors who recognize this future [of virtual building modeling] is coming and are looking for a way to start preparing themselves so that when the future arrives, they will be ready."

The Contractors' Guide to BIM is available at www.agc.org. Members can download it for free or purchase a hard copy for $25; nonmembers can download or purchase a hard copy for $75.