Creative New Use for Total Station
Online-only Articles - Online-only 2009
In building the World Market Center in Las Vegas, a contractor found that using a total station proved far superior to older methods for a challenging measuring job.
By Larry Trojak
Once primarily a mainstay of surveyors, the total station has broadened its appeal, finding ready acceptance by other disciplines including concrete contractors, steel erecting firms, and glaziers. Providing far greater accuracy in setting control points than traditional instrumentation, total stations have become a mainstay on many jobsites around the world. This holds particularly true in on-standard construction situations, and Las Vegas-based glazier Embassy Glass drew upon its benefits as it undertook one of its most challenging wall system installations ever. The firm says its total station brought previously unseen levels of efficiency and accuracy and streamlined what seemed a near-impossible process.
The World Market Center (WMC) in downtown Las Vegas is in the mid-phase of a development that when complete will make it one of the world’s largest venues of its type, offering 12 million square feet of upscale home and contract furnishing showrooms and exposition area. According to Steve Pattillo, Embassy Glass’ general foreman, Building C, a 2.1-million-square-foot, 16-floor structure, features an exterior design almost totally without perpendicular lines, particularly on the structure’s east elevation. “We are contracted to install a unitized curtain wall, unitized window wall, and a stick-built tilted panel wall. As with any job, we had to establish control points to work off during the installation process, and the fact that there are so many different angles to deal with made the job unbelievably complex.”
Pattillo says establishing those points not only makes actual installation possible but also helps identify any problem areas that could affect installation. Embassy is working within one-inch horizontal and vertical tolerances, particularly demanding given the nature of the wall system. “The system was manufactured in China,” says Che Hecker, field foreman, “so, returning any individual component because it doesn’t fit is not an option. “We needed to nail down those points, identify any potential problems, and make the needed adjustments.”
The scope of the project on this phase of the WMC alone is impressive, given that more than 1,100 panels have to be lifted into place and secured. Getting there meant establishing in excess of 4,000 individual control points. In the past, Embassy’s crew would have done so using traditional tools—lasers, a plumb bob, and a string line—an imposing task by any standards.
Pattillo suggested an alternative approach. “I’m kind of a technology freak, so I’m always following what’s available to help us do our jobs better,” he relates. “I knew the benefits a total station could bring to our business, so I lobbied hard with our owners to purchase one. We talked to the people at Nevada Transit & Laser here in Las Vegas, purchased the Topcon GTS 235W as well as a Topcon FC200 wireless controller, got enough training on the unit to get us up and running, and immediately put it to work on a smaller job not far from this one.”
“The whole process of establishing our control points was simplified to an unbelievable degree,” Pattillo recalls. “What had been a cumbersome, time-consuming process was now no more than one person with the total station—in this case, me—looking towards one other worker holding a prism pole, making the shot and recording the point into a data collector. Che and I shot 11 floors in a matter of four or five days. Normally, getting that many shots would involve a full crew of six or better working a couple of weeks. The total station is easily ten times faster than shooting it by hand.”
While the speed with which Embassy’s crew could record work points was impressive, the level of data accuracy really impacted their operation. In the traditional large-crew scenario, having additional personnel increases the risk of human error; that was virtually eliminated with the total station, which recorded points accurate to within .03125.” In turn, that accuracy offered them a look at exactly what the slab was doing at any given point and allowed them to adjust accordingly.
“The general contractor took our data and created an overlay to compare our points to what the print said they should theoretically be,” Pattillo explains. “That offered an excellent visual guide for us to deal with making adjustments—a real challenge given the structure’s design. On a normal curtain wall, we can move the whole system in, out, up, or down; that was not the case here. At WMC, particularly on the cantilevered floors, if we moved anything in one direction it meant we would have to move everything because of the angles. It definitely forced us to get creative.”
Those creative solutions included everything from cutting down a portion of any given panel to make it fit to using self-leveling concrete to adding custom clips to accommodate an area larger than the prescribed panel. According to Pattillo, it was the most challenging project they have undertaken.
Because the nature of the new equipment was so foreign to Embassy’s team, they benefited from the support they received from Mike Riley at Nevada Transit & Laser, the local Topcon dealer. “This was certainly a big switch for us, so there was a something of a learning curve,” Pattillo says. The total station was just part of the equation, however; we still had to download the data from the data collector into an AutoCAD program, and that’s where Rich Wilson of CCR Precision Surveying, one of Mike’s customers, came in. He worked with a number of people here to show us how to create overlays and make the data work for us. It has been interesting to say the least, but all these things we’re learning now will benefit us from this point forward.”
As if to underscore the broad role glaziers play in today’s construction, it’s interesting to note that comparatively speaking, Embassy Glass is not dealing with much glass at all at the WMC. The majority of the Zetian metal panel, curtain wall, window wall, and tilted panel system being installed involves galvanized steel back pans that seal and weatherproof the building, followed by aluminum face panels.
“We must have 50 apprentices out here who want to get into the trade but will probably not touch a piece of glass on this job,” says Pattillo. “However, this will be a nice reminder that the glazier trade is far more than just glass, and there is no better opportunity to get exposure to the challenges they will face as they get into this business. I am nearing my one-year anniversary on this project and, while I’m getting anxious to move on, I am also excited about the new technologies we will take with us when we do. For us, using a total station has gone from another possible way to do a job, to THE way to do it. Simple as that.”
Larry Trojak is owner and president of Trojak Communications, a Ham Lake, MN-based marketing communications company. In his 20 years in business, Trojak has written extensively for the construction, aggregates processing, asphalt production, recycling, and scrap processing markets.
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