Page T1.2 . 11 October 2006                     
ArchitectureWeek - Tools Department
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Modeling Rules


Working with BIM

Some AEC firms are already adopting several aspects of BIM. Our experience at Mortenson reaches back nearly a decade. We have applied aspects of BIM across many projects of various size, scope, type, cost, and contract delivery method. For BIM to be successful, it must be championed on every project by advocates who promote collaboration through new tools and processes and, ultimately, integrated delivery.

These BIM advocates work to increase understanding, confidence, communication, quality, and safety, while decreasing cost, time, and rework in construction. They manage and use BIM as a catalyst for communication among the various design and construction professionals, including architects, engineers, and estimators during preconstruction, and superintendents and project engineers during construction.

They use the BIM in preconstruction and construction for design visualization, constructability reviews, design coordination and planning of trades and systems, "4D" construction scheduling and sequencing, "5D" quantity surveys estimating, integrated documents for field layout, prefabrication and modularization, and as-built modeling for facilities operations and maintenance.

To have the greatest influence on integrated delivery, we have found that BIM is especially useful for constructability reviews and for supporting prefabrication.

Especially important for teams seeking new design approaches and construction methodologies, BIM enables builders to provide early feedback about project constructability in ways not previously available. The process promotes an open dialogue about means and methods because these are often implicit in the construction of 3D models.

The software tools obligate architects and engineers to think about the way buildings go together because the model is a simulation of construction, not just a symbolic representation of sections or details. The simulation enables designers to extend their influence on the built work.

Furthermore, a fully coordinated BIM helps project teams rethink the way their projects are delivered and assembled. Entire building systems and rooms can be prefabricated off-site by multiple trades and later installed on site in a predictable building framework.

This prefabrication of building components reduces on-site complexity, labor, and construction time, and increases quality of construction. It can have tremendous implications for the entire supply chain and force builders to think differently about how they procure and install building systems.

Architects and builders must work together early in a project to ensure the success of prefabrication means and methods, and BIM is instrumental in the collaborative effort.

Lessons Learned

Mortenson's application of BIM across a broad range of projects has exposed us to several recurring themes. We've learned lessons from attempting to apply dated practices and discovering that some traditional processes don't work well with new tools. From these lessons, we've developed "ground rules" for engaging a project team new to BIM and suggest that these or something like them should find their way into standard integrated design and construction practice.

Model, don't draft. If a designer models only a portion of the project, then only that portion can reap the benefits of BIM tools. Any portion that is manually 2D-drafted in the documents is not maintained with the model. By developing and coordinating a complete BIM, the team can discover and resolve uncoordinated or incomplete design data early and resolve conflicts before they are exposed in the field.

Model your own scope of work. Each architect, engineer, detailer, and subcontractor is responsible for representing their own work in the BIM, not unlike the responsibilities each has in traditional design or construction documentation. This division of BIM ownership reduces redundancy and the risk or liability otherwise incurred by having one party build a model of someone else's 2D data.

Model it at true size. Traditionally, 2D drawings were not always drafted to match dimensioned or specified information; to this day, standard disclaimers warn contractors not to measure from drawings. But because the BIM has a life beyond design into construction and facilities maintenance everything must be represented at its true size and in the intended location. Critical dimensions should still be noted, but "dimension overrides" and disclaimers should not be used to conceal incorrectly modeled data.

Be "data agnostic." There are too many proprietary file formats and specialized software applications and therefore too many office "standards" in the industry today to efficiently accomplish BIM on a complex project. No one can master every available CAD package. So we recommend that teams adopt and integrate file formats and standards like "Building Smart," IFC, VRML, and X3D into their workflow.

Share your information. Questions of intellectual property and liability often impede adoption of BIM. These valid concerns can be addressed early in a project with proper legal and contract language. The project team aiming for integrated delivery soon learns that, to effectively use BIM, all must be openly willing to share 3D source data with design and construction partners and train them to use each other's project data.

Manage change (or it will manage you). The rapid generation of ideas inherent in schematic architectural design necessitates relatively loose documentation of the evolving changes. In contrast, the current social and legal climate requires a thorough and often tedious documentation of revisions to the work during construction. To effectively use BIM in integrated practice, teams must develop standards and compromises to manage and track design revisions in both design and construction. We should investigate and repurpose revision-tracking tools used by software-development industries, for instance, for our own work.

Future Developments

Despite all the progress the AEC industry has made in using, standardizing, and developing BIM, we still have a long way to go toward its full implementation in integrated practice. We still face challenges and must continue to work towards their resolution.

Most major design and construction projects are unique and elude the economy of mass production enjoyed in manufacturing. We must discover ways to measure the effectiveness of BIM as an enabler of change in our practice despite this obstacle.

We must also develop effective BIM- and integrated-delivery-oriented contract documents to effectively reduce liabilities and manage legal risk. We must address the disconnect between the rich 3D datasets of BIM and the flattened 2D paper documents required by municipalities for review and permitting.

Many standard industry databases do not work with BIM or even acknowledge its existence, so we must strive to efficiently integrate data between modeling, specifications, scheduling, estimating, and facilities maintenance aspects of our industry. To be an effective catalyst, BIM's application must extend beyond its current use.

Using BIM-capable tools to merely manage and deliver 2D drawings will not yield significant change to our fragmented industry. We must seek the full development and collaborative delivery of a single, integrated database beneficial throughout project design, construction, operations, and maintenance.

Yet BIM is not the only tool required. We also need to develop and implement new processes and protections to support full integration. To make a real difference, architects, engineers, and builders will all need to innovate and embrace a new way of working.

Discuss this article in the Architecture Forum...

Dace A. Campbell, AIA is a design manager for the M.A. Mortenson Company. He leads a team of design coordinators who advocate for BIM to achieve integrated delivery in building construction projects. He has been working in the design and construction industry for 17 years, with an emphasis on BIM, new media, and virtual reality technologies.



ArchWeek Image

A building information model (BIM) can be used to study the constructability of remodel work such as this courthouse by Weinstein A/U. Existing foundation conditions are shown in red and yellow and excavation and demolition in orange.
Image: Mortenson

ArchWeek Image

The BIM for a courthouse by Weinstein A/U can be used to study the constructability of remodel work. Here, shoring and underpinning are shown in purple, replacement foundation in green.
Image: Mortenson

ArchWeek Image

A fully coordinated BIM displays building systems and components across all building trades. A portion of a restroom wet-wall in a laboratory designed by Collins Woerman is detailed to include all studs, MEP systems, finishes, and temporary straps.
Image: Mortenson

ArchWeek Image

The wall system being prefabricated in a shop.
Photo: Mortenson

ArchWeek Image

The wall system as seen within the architectural scope of the model.
Image: Mortenson

ArchWeek Image

The wall system as finally built.
Photo: Mortenson

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An electrical room of a laboratory by Collins Woerman is hoisted into the building, its full coordination and prefabrication made possible by BIM technology.
Photo: Mortenson

ArchWeek Image

A portion of a BIM is isolated and detailed to show all systems and finishes for a prefabricated "wet core" of a high-rise condominium by Callison Architecture. All quantities and dimensions were pulled directly from the model and used during fabrication on the shop floor.
Image: Mortenson


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