Builders' Information Modeling (AEC Insight Column)

BIM flows downstream to construction.

Recently, a small but growing percentage of architects and engineers have embraced building information modeling (BIM). However, opportunities for process improvement through BIM automation extend downstream into construction, where construction managers, general contractors, and trade subcontractors all can derive even greater benefits on both projectwide and firm-specific bases.

Additional Resources

Architects and engineers focus on buildings as products — physical objects to be brought into being by others. Constructors focus on building as process — sequences of activities to assemble the physical objects/products envisioned by designers. This difference between building as product versus building as process (noun versus verb) represents differing emphases on space versus time. It also reflects the differing business models and risk-to-reward profiles of architects and engineers versus constructors. Therefore, builders' information modeling differs enough from the rest of BIM to deserve separate analysis.

BIM for Builders

The prehistory of BIM contained seeds of usage for builders' information modeling. In the March 1975 issue of the now-defunct AIA Journal, Charles M. Eastman, then at Carnegie-Mellon University, included among the benefits of his prototype building design system the following:

. . . cost estimating or material quantities could be easily generated . . . providing a single integrated database for visual and quantitative analyses . . . Contractors of large projects may find this representation advantageous for scheduling and materials ordering.

Thirty-three years later, I see this playing out in four categories of applications:

Modeling and remodeling. Builders must create computer models if they are not provided by architects and engineers. Even with architect/engineer–provided models, many builders prefer to remodel projects to more accurately and confidently reflect construction practices. Some builders choose architecture/engineering (A/E) modeling tools such as ArchiCAD, Autodesk Revit, Bentley Architecture, Gehry Digital Project, or VectorWorks Architect; others rely on construction-specific modelers from Beck Technologies, Tekla, or Vico Software.

Estimating and procurement. From quantity takeoff (QTO) to submittals and from pricing to ordering, builders must streamline their material supply chain. Applications in this category include Autodesk QTO, Beck, Gehry, Tekla, and Vico, as well as Design2Cost from Nemetschek, a Revit add-on from Innovaya, and specification-related programs from 1stPricing and e-Specs.

Scheduling and coordination. Sequencing, phasing, staging, potential interference among trades, laydown areas, and site access are among the time-critical elements that constructors must understand before they start to build. Software serving these needs comes from Autodesk (Navisworks), Bentley (Project Navigator), Common Point (Project4D), Gehry (via a Primavera plug-in), Innovaya, Tekla, and Vico.

Workflow and collaboration. Model-based processes offer new modes of interactive and visual collaboration while demanding new kinds of workflow for multidimensional, data-rich project documentation. Offerings in this area range from Adobe Acrobat 3D and Adobe Share to project collaboration networks (PCNs [see "AEC Insight," Cadalyst, December 2007]) such as Autodesk Buzzsaw, Autodesk Constructware, ctSpace, and OpenText LiveLink. Vico 5D Presenter is a construction-specific solution that integrates with the rest of Vico's suite of tools, but Bentley (ProjectWise), Gehry, and Innovaya also play in this space.

For those keeping score, Autodesk, Gehry (figure 1), and Vico appear to have the most comprehensive product capabilities across all areas of builders' information modeling, followed by Tekla, Innovaya, and Beck. Other vendors offer outstanding point solutions in one or two areas, which poses a difficult choice for BIM-curious contractors: adopt a comprehensive suite of products covering all bases or mix-and-match among point solutions when and as needed.

Figure 1. The ability to coordinate architecture, structure, and MEP systems in a single model with associated data is a key element of BIM for builders. This example shows proposed renovations to Alice Tully Hall, Lincoln Center for the Performing Arts, New York, which were designed using Gehry Technologies Digital Project and 3D Strategy software. (Copyrighted image courtesy of Diller Scofidio + Renfro)

Building a Case

An informal survey among contractors using BIM automation or virtual construction (VC), as some prefer to call it, revealed several trends. Adoption of the VC/BIM approach by constructors appears to have initially lagged behind that of designers. Ten years ago, pioneering construction firms began testing schedule simulation, sometimes called 4D CAD. With few contractor-specific modeling and simulation tools available, however, many builders who investigated BIM as recently as five or six years ago still found the technology too immature. The tipping point seems to have occurred at some time between Graphisoft's 2004 launch of its Virtual Construction products (since spun off to Vico Software) and Autodesk's 2007 acquisition of United Kingdom–based Navisworks.

From an industry analyst's perspective, this conforms to typical growth patterns. First, adventurous end users struggle to fill a need by adapting existing tools to new tasks. Then, venture-funded software startups such as Vico emerge to serve the nascent market. Finally, fast-follower tech players such as Autodesk confirm the trend by acquiring key players such as Navisworks.

Thus, VC/BIM adoption among contractors has significantly accelerated in the past two years. As contractors commit to VC/BIM, they quickly move from isolated pilot projects to firmwide adoption. Whether choosing a suite of construction-oriented tools from or revolving around a single vendor — Autodesk, Bentley, Gehry, or Vico — or mixing and matching point solutions from diverse vendors, constructors who scale up their VC/BIM efforts find they must make major business changes beyond adopting new software. For example, significant numbers of staff — as many as 6–8% of total staff — need to become skilled modelers. Whether modeling skills are met through hiring or by retraining current employees, modeling needs extend across all disciplines: architectural, structural, and MEP (mechanical, electrical, and plumbing).

Making Change

Although some contractors might prefer to work with models delivered by architects and engineers, few designers currently deliver such models. Even when contractors know that architects and engineers have created BIM models in-house, the vast majority of A/E deliverables still arrive in the form of conventional drawings and/or 2D CAD files. On the other hand, many contractors say they would remodel architects' or engineers' models even if they were delivered. In part, this procedure is due to lack of interoperability among diverse modeling packages (the designer models in software X, the constructor in software Z, and yet the models cannot be reliably translated). This incompatibility also involves differences in the way architects and engineers model for design intent versus contractors' modeling for means and methods of construction.

Builders also must replace or significantly reconfigure their existing estimating and scheduling software to sync with newly adopted modeling tools. This adjustment requires retraining estimators and schedulers who used the original tools in the old ways. New staff positions likely will be created to manage these efforts. Titles of these emerging positions hint at the responsibilities: virtual construction manager, model manager, BIM manager, and so on. New, computer-centric roles spill over from contractors' offices to job sites, where new personnel may join the project team as VC coordinators or the like, or where incumbent project staff such as superintendents and/or assistant superintendents may take on model-management roles for their respective projects.

Fringe Benefits

Although statistically significant samplings of hard data aren't yet available, the anecdotal evidence among contractors using VC/BIM is that the benefits are sufficient to justify the substantial organizational changes required. Such benefits include reduced waste through more precise ordering and timely delivery of materials, avoided change orders through better coordination and more consistent documentation, and enhanced collaboration with all project partners.