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Global Positioning System Revolutionizes Dirt Moving

Wed May 24, 2000 - Northeast Edition
Lori Lovely

Trimble has expanded its Global Positioning System GPS) machine guidance system to use on motor graders. The Site Vision system is already being utilized by bulldozer operators around the world to reduce construction time on large-scale earthmoving projects including golf course development, airport expansions, land reformation, railway and road construction, housing developments and shopping malls.

As Trimble’s senior director of mining, construction and agriculture, Mark Nichol said, “We have already proven that Site Vision GPS can enable bulldozer operators to increase productivity by dramatically cutting construction times. These same benefits can now be realized on the motor grader.”

Jon Casamajor, business development manager for construction systems, said the company is taking its time developing the system for each piece of equipment. “We want to get the machine applications right before we move on to the next one,” he said. Trimble introduced the system for bulldozers last August and has now unveiled the system for motor graders. Casamajor said they have other plans in the offing, but are not prepared to move on yet.

How It Works

The Site Visions GPS system provides operators with real-time graphical information for on-grade and on-line guidance. The system enables operators to bring the site up to consistent and accurate grade that makes finishing faster, more efficient and more predictable. It provides full three-dimensional positional information for earthmoving, achieving horizontal and vertical accuracies better than 3 centimeters (1.2 in.).

“It’s extremely accurate,” Casamajor said. “Depending on the operator and the equipment, it’s accurate to within one tenth of a foot.”

In addition to accuracy, Casamajor said the system brings convenience to projects. “There’s no waiting for control from a third party,” he explained. “It reduces staking, checking and layout.” That means a big savings of time and labor. “You don’t have a million dollar machine waiting on a hundred dollar staker.” Besides, he added, stakes frequently get run over during a job, costing more time and money. “Stakes don’t last long.”

The system includes a 36-channel, dual antenna GPS receiver, two GPS antennas on masts, a wireless data radio, an on-board color display and three light bars for guidance. It’s designed to allow operators to “see” design surfaces, grades and alignments from inside the cab. Machine position versus site plan is displayed on a rugged color monitor, providing quick location of embankments and pad corners. Light bars mounted in the operator’s field of vision guide operators to cut or fill along alignments.

The mapping process is done with an autocad system, creating a two-dimensional design that is blended into a three-dimensional digital control model. Trimble supports the entire process, according to Casamajor. But he added that there are numerous options for those who prefer another avenue. “Some of our dealers are very capable on the data side,” he said. “They’re able to put information from the auto cad onto the machine. But there is a matrix of possibilities out there. Some engineering firms will work on a contract basis, or you can get GPS survey customers.

The data card is inserted into the display unit, which shows a map indicating the machine’s position. Light bars indicate how much the left and right corners of the cutting edge need to be moved relative to the design alignment.

The 5-inch computer interface screen allows operators to select from four views: an aerial view of the plan; a cross-section, or profile; the blade orientation display, showing a picture of the blade position relative to elevation, or design surface; and textual information giving the satellite status and precision factor. With a single key press, the operator can switch between views.


Surveying and grade checking costs are reduced because the operator is able to accurately determine his position from within the cab and control grade.

Jobs are completed more quickly because more earth is moved per day. By placing grade information in the cab, operators are empowered to make fast decisions with minimal supervision.

In-field changes can be made quickly without waiting for grade stakes to be set or repositioned. A new grade or pad elevation can be easily selected from within the cab.

Because the grade is accurately controlled from within the cab, grade is achieved in fewer passes with less rework. The result is better machine utilization and fewer hours per volume of earth moved, which results in lower fuel and maintenance costs.

Because the system reduces restrictions on visibility and site conditions, darkness and weather elements will not slow work schedules and endanger deadlines.

Other benefits include the system’s ability to support numerous design packages such as Infrasoft Ltd. MX products, Intergraph InRoads and InRail, Auto Desk Civil Designs and other third party formats. In addition, the system is easy to install and move between machines.


If there are any drawbacks, Casamajor said, it’s that this is still new technology, and as such, is still evolving. On top of that, he added, it requires operators to learn to perform differently.

Trimble’s dealers perform the training, with assistance from the company. Casamajor said Trimble is in the process of formalizing a training program, based on the feedback received from operators as they learn more about the system and discover what needs they have.

“It’s simple to learn,” he insisted. “At first we weren’t sure how the operators would accept the computer training [necessary to run the system].” But Casamajor concluded that the training time involved in learning this system is less than with any other project he’s worked with. “It’s intrinsic,” he said of the data. “They can see the plan.”

“At first, a lot of the ’old-timers’ were skeptical. They are the masters of operating their machines, and it’s difficult to come in and show them a new method. They have that look in their eyes. But after trying it, they love it! They end up grinning from ear to ear. It gives them the control they’ve never had; they have the entire project in their cabs. So far, no one has rejected it. In fact, our customers are teaching us how to use it now. Engineers can only go so far, you know.”

The Concept

Since the company’s beginning in 1978, Trimble has been an industry pioneer in developing GPS systems specifically designed for industries such as surveying, mapping, agriculture, construction, mining, military, commercial aviation, vehicle tracking and timing. Trimble holds more than 250 U.S. patents on GPS and related technology, partnering with companies such as Bosch, Caterpillar, Honeywell, Microsoft, Pioneer and Siemens. The company’s strength lies in conceptualizing industry requirements and producing products that significantly increase productivity and cost effectiveness.

When a 1996 Presidential Directive allowed civilian use of the GPS designed by the U.S. Department of Defense, Trimble realized its potential. The 24-hour availability of GPS signals, combined with its accuracy, made the system a viable alternative to contemporary construction methods.

The Future

Currently Trimble is marketing the system through independent dealers. Always looking for specialists in the “dirt community,” Casamajor said, “We look for laser and survey companies. But we try to keep thinking out of the box and approach top-quality dealers.”

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