WEB EXCLUSIVE: High Definition Surveys For Construction Projects
By David Rizzo, D.P.M.
High definition survey (HDS) technology can be an efficient and powerful alternative to conventional surveying for new and existing industrial structures. In the past, manually surveying industrial sites for a facility expansion or retrofit often required hundreds of hours, sometimes over months, and sometimes involved potentially hazardous locations. When as-built infrastructures were hidden or not precisely detailed in original plans, the resulting survey errors usually led to expensive rework or change orders for expansion or retrofit projects.
Today, HDS technology makes it possible for data to be collected from hundreds survey points, with densities and accuracies of 1/8", in a matter or hours instead of days or weeks. Provided by professional specialists, HDS can be used to survey a plethora of industrial projects such as processing plants, refineries, and mining operations and other facilities that plan to make modifications, retrofit, expand, or upgrade key equipment.
HDS technology is based on an imaging laser that collects up to 50,000 survey shots per second, making it easy to provide data that can be used for 2D line work or 3D models. HDS systems also feature an external camera that collects photographic images in a 360°, RGB color values. These image files are later fused to the data points that are assembled as "point clouds," which can then be used for site mapping; project planning; and civil, structural, and MEP design as data is extracted into formats such as AutoCAD, Revit, and MicroStation.
Efficiencies That Lead To Savings
Stan Postma is vice president of Utah based engineering services firm, MWH Americas Inc. (a subsidiary of MWH Global). His firm had recently undertaken the renovation of a hydroelectric power plant that is operated by the City of Logan, UT. "We needed to evaluate some existing structures, including a powerhouse that is about 100 years old," Postma explains. "I knew about HDS type of scanning, and thought it would be a good application for the project. So, we engaged McNeil Engineering’s HDS team to do that for us. This service captured all of the information about the building in a very quick and efficient manner, enabling us to plan around the existing structure with very accurate information."
McNeil Engineering, located in Sandy, UT is a multi-faceted firm that had been performing HDS scanning for the past five years. Postma says that the City of Logan also commissioned MWH to survey an existing dam that is going through some design modifications near the powerhouse site. He says the 3D data the HDS system provided was very helpful in planning that project as well. According to Postma, the data enabled his staff to put the dam in a 3D animation so they could view it from any angle. This provided a precise reference and eliminated the need to send personnel to the site for visual confirmations.
"We’re going to end up with savings on change orders and construction efficiencies all around," Posta says. "Having all the information available in such great detail is going to save money. HDS scanning is very cost efficient tool."
Many design and engineering firms turn to HDS technology because the accuracy of the scans virtually removes the need to work from records that could be somewhat inaccurate, eliminating the need for rework.
Another McNeil Engineering client, Hubbard Engineering in Mesa, AZ used the HDS scanning service for a retrofit project at WestWorld, an open air equestrian center and events arena in Scottsdale, AZ. "The extreme summertime heat was limiting WestWorld use, so the owners decided to enclose and air condition the arena," says Adrian Burcham, P.L.S., director of land survey at Hubbard.
"This was a large retrofit project," he continues. "We scanned the interior because there were no plans available. The HDS technology enabled us to precisely pinpoint the as-builts for design purposes, including the new HVAC system."
Burcham says it took one day to complete the scanning, which he estimates could have taken several weeks with a conventional survey team. "McNeil was able to accurately measure every bolt and column in the original structure," he says. "Also, we got better accuracy on the visible objects in the arena. We were able to map them tighter than you could using conventional tools."
Burcham adds that the 360° photos that McNeil created from points all around the arena were also quite helpful. Used in conjunction with point clouds, the photos made it easier to reference the project visually.
Measure Of Safety
Because HDS scanning is performed from ground level, the technology is unobtrusive, making it unnecessary to interrupt production processes. This convenience also maintains safety, as pointed out by Brian Akers, piping lead at Job Industrial Services, Inc. in Salt Lake City, UT. His company handles retrofit and expansion projects with refineries, mining, and power and gas transmission facilities in Utah and throughout the U.S. Job Industrial Services has had McNeil Engineering team perform HDS scanning at a recent refinery project because the McNeil team possessed state required training certification and other safety related qualifications.
"HDS technology improves on the safety of our personnel because we spend significantly less field time in potentially dangerous environments," Akers explains. "This is the case particularly in the refinery industry, where you may have thousands of miles of infrastructure. If we're doing a retrofit, we can have a service provide laser scans, and with the point cloud information we can do a model a lot more accurately than we can do with conventional field measurements."
Rizzo is a Cerritos, CA based author who has penned three trade books, 200 technical articles, and 500 newspaper columns. In his work, he covers a wide range of topics, specializing in technology, medicine and transportation.
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