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Laser scanning for a BIM requires close collaboration among team members and an in-depth understanding of the client’s needs.
When the U.S. General Services Administration (GSA) received $5.5 billion through the American Recovery and Reinvestment Act of 2009 to spend on energy-efficiency upgrades and other improvements to properties owned by the federal government, the Minton-Capehart Federal Building in downtown Indianapolis was near the top of the list. Built in the 1970s and named for Indiana Senators Sherman Minton and Homer Capehart, the imposing concrete structure conceived by architect Evans Woollen is Brutalist in design--a term that reflects both its raw concrete construction and rough, blocky appearance. Featuring an inverted-ziggurat shape, with each of its six floors slightly larger than the one just below, the 661,667-square-foot building provides offices for a number of Federal agencies, including the GSA, the Internal Revenue Service, the Social Security Administration and the Federal Bureau of Investigation. Because of its design, the building is considered to have future potential for historic eligibility.
In early 2008, GSA awarded a $35 million contract for a phased renovation of the building to Cincinnati-based Messer Construction Co., a commercial construction firm with offices in Indianapolis. Most of the work was planned to be funded in 2012. However, the 2009 stimulus package moved the project to the fast lane--adding more energy-saving items to the scope and increasing the budget.
Timing is everything, as the saying goes, and that certainly seemed to be the case with the Minton-Capehart project. G.J. Berding Surveying Inc., based in Milford, Ohio, a frequent subcontractor to Messer, had been eyeing the BIM market for several years, but by early 2009 the firm hadn’t yet taken the leap. “It was something we felt was probably a little too large for us to take on alone,” says Tim Schwoeppe, PS, project surveyor for Berding.
Shortly thereafter, Messer contracted Berding to handle the scanning work for the Minton-Capehart project. For Berding, the project was an exciting move into the world of BIM. It was also a natural opportunity to get ARC involved. “Scanning for a BIM is a bit different from a typical as-built,” Schwoeppe says. “The scope of the project--how much detail the client wants to get out of the model--is important. We knew that ARC was skilled in creating Autodesk Revit models for BIM, so we decided to rely on their expertise.”
It was the perfect example of an ideal teaming arrangement. “When we first teamed up with Berding, we were hoping to bring work to them,” Russo says. “But this is one of those instances where a project came to us from their direction. Teaming really does benefit everyone involved.”
Close collaboration among the project partners from the very beginning was key to meeting the client’s needs. Both Berding and Messer were heavily involved in the planning process. “On our first site visit, we walked through the mechanical shaft and took a look at some of the plenum areas, as well. Then we sat down with the client and discussed what they needed to get out of the model, and what they could expect from us,” Schwoeppe says.
Initially, the scanning and modeling work focused on the building’s existing north and south duct shafts. The six-story vertical structures presented more than a few challenges. “The shafts were very tight corridors, and we had to scan and survey in a method that would allow us to register all the data together into one point cloud,” Schwoeppe explains. “The client also wanted to see the relationship of the shafts with the exterior building shell. That produced another issue because the only access to the mechanical room was via elevators or stairwells, and neither of those options was very conducive to running survey control back to the building exterior.”
The Berding crew set up 20 scan targets in specific locations that were visible from each level of the shaft. Each was affixed to the block wall of the shaft with epoxy. Using a Leica HDS3000 scanner, the crew carefully overlapped their scans as they worked their way up the shaft. “We would scan from, say, floor number two and collect a certain number of targets, then go up to floor number four and collect the same targets that we had collected from scan world two. We also modeled physical features, such as piping, to help constrain the registration and check for alignment issues,” Schwoeppe says.
The crew also took numerous photographs of existing features inside the shaft; these would be used to help Berding register the data and would also assist ARC in the modeling process. For the exterior scans, the Berding crew ran their survey control through ventilation vents on the building’s exterior that were also accessible from the mechanical room.
Using both target registration and cloud-to-cloud registration in Leica’s Cyclone software, Berding pulled all of the point cloud data from the interior and exterior scans into a single dataset. Schwoeppe notes that a little extra time was needed to check the registration and ensure that it met the accuracy requirements for the project, but that overall the registration process went according to plan.
From there, the data was transferred to ARC to create the Revit models. This work, too, presented challenges. “Whenever we’re dealing with BIM--going from a point cloud to BIM, basically--there’s always a challenge because of the limitations of the BIM operating tools,” Russo explains. “Most clients want to work in an ortho fashion, and point clouds are real-world--they show all the nuances of what’s there. If you’re going to model a pipe, for example, and that pipe has sag or deflection or is at a weird angle, it’s very difficult to model it exactly as it is in the point cloud using the Revit tools. So there is some custom work involved. Some of that work has been reduced or eliminated with the 2011 version of the software, but that obviously wasn’t available for this project.”
The entire process went smoothly--so smoothly, in fact, that Messer again asked Berding and ARC to provide their services when the construction team needed as-builts of the building’s third-floor plenum area a bit later on in the project. “I was really impressed with the level of detail that was provided from the scans,” Lynch says. “Once the model of the shaft was created, it looked just like the duct shaft and was able to be seamlessly incorporated into the final documents.”
With the help of the Recovery Act, the GSA nearly quadrupled its active construction projects in 2009. Although the Minton-Capehart Federal Building renovation was just one of many projects funded through the initiative, the positive impact of the retrofits will likely be felt far into the future through substantial energy savings. GSA is also looking into ways to use the BIM data to continuously optimize building systems for more-sustainable operation. The renovation work is expected to be completed in 2012.
For everyone involved, the project has underscored the importance of working with strong partners who understand the need for good communication. “There are just so many aspects with BIM that you need to have people from different disciplines and with different areas of expertise involved to pull it all together,” Schwoeppe says. “By working with ARC, we were able to focus our efforts on the performing the scan and allow ARC, who had the software and experience with creating a BIM model, to create the deliverables. The collaboration was an asset to us and our clients. Also imperative was early and open communication on what the client’s expectations were for the model and how they were going to use it.”
Russo agrees. “A true collaboration effort, where everyone is open with their team members really increases a project’s odds for success,” he says. “Being transparent, not trying to control everything yourself, relying on your consultants as experts in what they do, and removing barriers for them so that they can do what they need to do--these are all key.”
Sidebar: Laser Scanning, BIM and the GSAThe primary goal of the GSA’s National 3D-4D-BIM Program is to promote value-added digital visualization, simulation and optimization technologies to increase quality and efficiency throughout GSA project lifecycles and beyond. The long-term objective is to use innovative 3D, 4D and building information modeling (BIM) technologies to complement, leverage, and improve existing technologies to achieve major quality and productivity improvements.
There is a progression from 2D to 3D, 4D, and BIM. While 3D models make valuable contributions to communications, not all 3D models qualify as BIM models since a 3D geometric representation is only part of the BIM concept.
Critical to successful integration of computer models into project coordination, simulation and optimization is the inclusion of information--the “I” in BIM--to generate feedback. As a shared knowledge resource, BIM can serve as a reliable basis for decision making and reduce the need for regathering or reformatting information. GSA is currently exploring the use of BIM technology throughout a project’s lifecycle in the following areas: spatial program validation, 4D phasing, laser scanning, energy and sustainability, circulation and security validation, building elements, and facility management.
Laser scanning is seen as a valuable technology because of its ability to acquire building spatial data in three dimensions with high fidelity and low processing time. In addition to BIM development, the rapid collection of 3D information is being applied to historical documentation, facility condition documentation and construction as-built development. GSA's BIM Guide 03 can be found at GSA.gov/BIM.
Source: U.S. General Services Administration. For more information, visit www.gsa.gov.