Total stations have been the backbone of land surveying operations for the past two decades. Their use has contributed to the nation's framework by providing topographic surveys, construction layout, precision positioning of structural components, and increasingly, machine control on site preparation and finishing jobs. In the construction industry, total stations are essential tools used to determine precise horizontal and vertical positioning for many features: building foundations and anchors, bridge abutments and alignments, sanitary sewers, highways and earthwork operations on very flat grades.
With the escalating trend of GPS technology for land surveying and machine control applications, will total stations become outdated instruments for the land surveyor? Although there could be a case made for this argument, continuing advancements in total station features make them more and more useful every day.
Today's Total StationsTotal stations have come a long way over the years, as Gary Affolter can tell you. Affolter started in the surveying profession in 1965 and has been a licensed surveyor in the state of Illinois since 1973. His 40-year career includes high-profile activities. He spent eight years working as a consultant to Westinghouse at the Department of Energy's Waste Isolation Pilot Plant in New Mexico. This facility is the nation's only underground repository for waste from nuclear weapons production. Affolter, along with a business partner, provided training, project management and other services to Westinghouse's surveying and engineering department. He also spent one month training Russian surveyors on the use of total stations on an oil exploration site at the northern tip of the Caspian Sea. He is now the total station product manager for Topcon (Livermore, Calif.).
Affolter reflects on the vast technical changes that have occurred with total stations during the past 30 years: "The evolution of total station technology took place in the blink of an eye when compared to the measuring tools used for centuries prior to the release of the first total stations. Never in the history of surveying was there such a significant jump in how data is collected and recorded as the jump from tape and transit to what we use today.
"When the first short-range EDMs were introduced in the late '60s, it changed forever the way distances are measured. Coupled with an optical-mechanical theodolite, accurate and precise surveys were being done much faster than with the trusty "chain, plumb bob and transit' method. When electronic technology advanced to where instruments with electronic angle reading sensors were available, the "Buck Rogers' era of surveying had truly begun. When these electronic marvels were "married' to the EDM [either as a co-axial unit or scope/standard mounted EDM], surveyors knew this was just the tip of the iceberg. Manufacturers made data collectors with powerful collection and COGO functions available at the touch of a button. Like computers, things changed so fast you could not afford to wait until the perfect system came along. You had to dive in and hope things did not change too fast before you could afford to upgrade the system."
Surveyors, Affolter remembers, joked about what they thought would never be possible: "I'm waiting for the day I don't need a prism to take a measurement-yeah right!" But by the end of the '80s, EDMs were available to take measurements to objects without the need of a prism. "What's next? A one-man total station?" they asked. And the '90s brought them the "robot" era. Today the profession has robotic total stations that can measure without reflectors.
The advanced features found in today's total stations enable a single worker to quickly complete field tasks that used to require a crew of two or three. Other advances include quick, precise tracking; radio-free optical data communication; onboard computers with advanced operating systems; and wireless communication. These advanced features make the total station an effective and efficient tool for land surveying and construction applications.
Total Stations for Topographic SurveysTopographic surveys can be an expensive part of the design and land development process. Sending a three-man field crew to collect topographic data on a new project site can take several days, even weeks. This essential information has to be precise, as it is used to create base maps upon which buildings are sited, roadways are planned and earthwork quantities are computed. Waiting for mapping of existing conditions and topography can be an effectual kink in the land development process-right at the start of planning when this information is needed most.
Considering the scale and intensity with which land development is now occurring, topographic surveying operations need a boost to respond to this trend. Robotic total stations, for one, now have extended distance measuring capabilities and improved tracking mechanisms that make them ideal for quick and accurate collection of topographic data.
Marcus Kinnee created his company, Benchmark Topographic in Corning, Calif., to specialize in collecting field topographic data. After several years working with a land surveyor, Kinnee realized that under-staffing was a common problem among surveying and civil engineering firms. Since construction and land development cycle through peaks and troughs of activity, firms are hesitant to expand their permanent staffs to respond to the upward swings. Kinnee saw an opportunity to provide field services at a reasonable cost for surveying and civil firms in need. These firms use Benchmark's services to meet peak demands.
His one-man operation is simple: an SUV, trailer, four-wheeler and a Topcon GTS-823A auto-targeting/auto tracking robotic total station. The instrument facilitates his production goal: field work completed in a fast, timely manner-and at a moment's notice. The unit has also allowed Kinnee to extend Benchmark's services to include construction layout. Since he operates in a predominantly agricultural area of California, he provides topographic surveys for farming operations and layout for orchard planting.
Total Stations for Construction LayoutLayout operations on construction sites have their own unique problems. The first and most fundamental issue is safety. Construction equipment operators try to maximize the efficiency of each movement of their machines and aren't always aware of the movement of personnel on the site. The clear line of sight needed for surveying operations constantly changes as components are stockpiled, structures are built and landforms take shape. A bench mark or back sight that is relied on one day may be rendered useless the next day by obstructions or physical changes to a site.
Brian Blevins is the true professional when it comes to surveying with a total station on a construction site-and an example of a surveyor utilizing the advancements offered in today's total stations. He's logged more than 5,000 solo hours in the past three years and specializes in construction layout. Blevins comments on his enthusiasm for his method of operation: "I love to be able to work robotically-two guys working side-by-side [Blevins and his stake setter], instead of one guy at the gun and one guy out in front trying to talk over radios."
A typical job for Blevins includes a mix of surveying tasks: setting precise corners for building pads, centerlines for roadways, offsets for parking lot curbing and cut/fill stakes for site earthwork. Earlier this year, he was involved in layout for a 10-acre high-tech site located in an office park in Lynwood, Wash. He acted as a party chief for Hugh G. Goldsmith & Associates, a land development, consulting, engineering, surveying and planning firm in Bellevue, Wash. Using a Topcon GTS-8203 reflectorless robotic total station, Blevins and his helper kept layout tasks ahead of the construction equipment.
Total Stations for Precision Positioning of Structural ComponentsIndustrial and heavy civil construction projects that include sophisticated structural components, such as bridges, are often located in areas with difficult access. The I-580 Freeway Extension in Reno, Nev., one of the Top Ten road projects currently underway in the United States, is an example of extreme conditions that can present challenges for the layout surveyor. The 8.5-mile route of the new roadway will connect Reno to Carson City and includes five bridges: three conventional spans and two "signature" truss-supported concrete arch spans that will be the longest in the Western Hemisphere.
The roadway traverses some of the most challenging terrain in the United States. The challenges of this tough environment include narrow construction roads that wind down the side of one mountain and up another. On these rocky mountain slopes, real estate for survey equipment and activities is limited, and terrain obscures line of sight. Additionally, the mountain environment brings dynamic and often treacherous weather.
Bob Heavilin, a man with 30 years' experience performing layout and as-built survey tasks for industrial and heavy civil construction projects, is employed by the Colorado Division of Edward Kraemer and Sons in Castle Rock, Colo., as project surveyor for the I-580 project. He is responsible for layout of all structural components for this technically sophisticated bridge project. Heavilin uses a Topcon GTS-821A auto targeting/auto tracking robotic total station to perform structural positioning tasks such as pre-pour check-outs and final adjustments to anchor bolts at the ends of truss spans. This is high precision work; the Nevada Department of Transportation allows a maximum 5 mm tolerance in three dimensions.
Total Stations for Machine ControlRobotic total stations are appearing today on more and more machine control systems. Many of these systems are based on laser guidance. Topcon's GRT-2000 total station is widely used for 3D-LPS (Local Positioning Systems) machine control on motor graders. Site data is transmitted to the instrument from Topcon's Pocket 3D software and a field computer such as the FC-100 or the FC-2000. Using laser signals, the GRT-2000 relays correct real-time horizontal and vertical positioning information to an LS-2000 receiver mounted on a machine.
Besides the traditional use on grading equipment, typically motor graders, 3D-LPS can be extended to new applications. TSD Integrated Controls, a joint venture between Topcon and Sauer-Danfoss, has created technology that enables a curb machine to run without the guidance of a stringline. Crossland Construction Company, based in Columbus, Kan., was the second company in the nation to take advantage of this new application. Last fall, Crossland placed concrete curb and gutter with a Gomaco (Ida Grove, Iowa) GT 3600 at a new Wal-Mart Supercenter in Rogers, Ark.-guided only by signals from a Topcon GRT-2000 total station.
Total Stations: Workhorse InstrumentsTotal stations have played a major role in the development of our nation as we know it today, from precisely locating property boundaries to guiding the placement of infrastructure by machines. Looking to the future, some total station functions may indeed be replaced by GPS technology, but continuous, innovative improvements will extend the use of these workhorse instruments to new and unique applications.
Sidebar: New Total Station Features Create New OpportunitiesJust as combining optical instruments with electronic components brought us the total station, new combinations of technologies are bringing further evolutionary changes to the total station. Topcon recently introduced the GPT-7000i Imaging Total Station that combines digital imagery capabilities with other advanced features currently available.
This hybrid instrument will extend the use of a total station to new applications. Landslides and slope failures can be surveyed for restorative design purposes without risking human safety in unstable areas. Crime scenes can be photographed and surveyed in the same operation, providing legal documentation that can be studied and assessed at a later time. Precise records of the architectural and structural attributes of an historic building can be obtained and recorded from ground level.