An Underground Revolution


Underground Construction

The way the construction industry moves the earth is being revolutionized. Companies such as Caterpillar, Trimble, Spectra Lasers, and Cashman Equipment are facilitating the revolution by supplying earthmoving machinery solutions with cutting-edge components that provide greater accuracy, higher productivity, and more profitability. Caterpillar's AccuGrade system can provide equipment with built-in GPS technology, while Trimble and Spectra Lasers (a division of Las Vegas-based Cashman Equipment) specialize in aftermarket installations and calibrations on machines such as motor graders, backhoes, track-type tractors (dozers), and excavators.

In the case of Caterpillar, whether a machine comes equipped with GPS from Caterpillar or installation occurs after arrival, the system functions are extremely similar. The AccuGrade GPS and the Trimble GPS are both integrated into the machine to create a control system that allows operators to work with complete accuracy. An excavator, for example, would have two GPS receivers mounted on the rear of the machine, as well as one pitch sensor and three angle sensors mounted on the boom, stick and bucket to calculate exact positioning.

Using machine-mounted components, an off-board GPS base and Real Time Kinematic (RTK) positioning, GPS provides the information necessary for the system to determine exact bucket positioning with extreme accuracy. The receivers then transmit readings from the sensors to calculate precise cut/fill information and send that data to the in-cab display. The operator can see real-time 3-D bucket positioning relative to the design plan or model.

All of this sounds well and good and technologically advanced . . . but what about real jobsite experience? Well, Peavine Construction Inc. can attest to the efficiency and accuracy of the aftermarket system installed and calibrated by Cashman's Spectra Lasers. Making this addition to multiple excavators has enabled this underground construction company to revolutionize its industry in the Sparks, Nev., area.

The conversion began more than six years ago when Cashman's Spectra Lasers division called on Peavine to let them know exactly what his product could do for the company. "We knew this equipment was perfect for them," Cashman employee Rob Eaton recalls. "When you're excavating 10 to 30 feet below ground, you want impeccable accuracy and absolute control."

And that's just what Peavine has now. However, in the beginning, some of that control belonged to others, such as outside vendors who were required to turn the computer-aided design (CAD) files depicting the physical jobsite into computerized models for the company's GPS systems. There were delays in CAD file delivery, lengthy development times and inconvenient revision periods in the middle of a project. "It cost [Peavine] money every time we had to wait for those models to be created or altered. It was unacceptable to us, so Cashman found a solution," explains Bobbie Eaton, Peavine's general manager.

The answer Cashman's Spectra Lasers division produced was in-house model-building software. The new software gave the company exactly what it was looking for.

Peavine needs only a single week to build a brand new model, which can then be saved and referenced for any future jobs in that area. After years of in-house modeling for Sparks projects, Peavine knows exactly what is under the surface of almost the entire city. Some companies believe this means they don't require the surveyors to assist in determining the lay of the land. Peavine disagrees, stating that working with a surveyor as well as the Spectra system avoids liability issues and potentially costly mistakes.

"The surveyor checks us, and we check the surveyor, so we get the job done right," Eaton says.

One of the current jobs Peavine got done right with the assistance of Cashman's Spectra Lasers division is a sewer main installation along Sparks Boulevard. Peavine's Cat 385C excavator — fully equipped with Trimble equipment including two GPS receivers installed on the back and on the boom, stick and bucket — has been removing approximately 3,000 yards of dirt per day and hitting grade every time (i.e., always digging to the appropriate depth, as the 3-D in-cab monitor reveals).

"We get the detailed accuracy we need on these sorts of projects. The potential for human error in depth measurement is much greater at the bottom of a 20-foot ditch like this one. The GPS guidance system virtually eliminates that possibility," Eaton says. The convenience and efficiency of this technology assisted Peavine in placing a 60-inch-diameter pipe in the ground on schedule, with the work completed in April 2008.