...use it already have submitted bids to MNDOT priced lower than expected, Barrett says. On road projects, where contractors are penalized for rough pavement, the agency also sees a difference between finished pavements on GPS and non-GPS subgrades. "Inspectors say they can tell," she says.

Yellow Alert. The U.S. Army is actively testing automatic grade controls (note antenna, at left).

Hardware Wars

In the mid-1990s, GPS-guided machinery was more of a futuristic notion than a reality, but eager mining operators helped manufacturers refine the equipment. The Dept. of Defense also took note, and such military outfits as the U.S. Army Corps of Engineers field tested several automatic grade control units to speed battlefield construction, especially at night (ENR 7/26/04 p. 13).

After more trials, large equipment makers like Caterpillar Inc., Peoria, Ill., urged construction firms to adopt it. "Cat told us that if we didn’t get the ability to grade stakeless, then we wouldn’t grow much more," says Dwayne McAninch, CEO of the firm that bears his name.

Caterpillar’s first GPS controller was called the "Computer Aided Earthmoving System," or CAES, which was developed with help from Trimble Navigation Ltd., Sunnyvale, Calif. Using a color display to show operators where to cut and fill, it still is widely used in the mining and solid waste industries.

Today’s growing popularity in GPS machine control is helping to make the hardware more rugged for construction. McAninch acts as a boardroom advisor for Caterpillar Trimble Control Technologies, a joint venture formed in 2002 between Caterpillar and Trimble. After several years of tweaking the technology, Cat in January produced the world’s first fully-integrated controller, called "AccuGrade." For the first time, automatic grade controls, which used to be after- market items only, could be purchased along with a machine.

No Pressure. Padgett on the job at the soon-to-be Iowa Speedway, in Newton.

With AccuGrade, GPS can move the blade automatically, says Tom Bucklar, a regional manager for Caterpillar’s machine control division. By switching to automatic mode, operators steer the machine while the blade "talks" to local base stations and GPS satellites. Like Padgett’s excavator, this "may turn the operator’s job into a video game," remark authors Robert Peurifoy, Cliff Schexnayder and Aviad Shapira, in Construction Planning, Equipment and Methods (McGraw-Hill, 7th ed., forthcoming).

Trimble is fighting to protect its market share against newcomers like Topcon America Corp., Paramus, N.J., which recently inked a supply agreement with Komatsu America Corp., Vernon Hills., Ill. Deere & Co., Moline, Ill., also plans to start shipping dozers next spring with built-in electronics that are interchangeable with Trimble and Topcon, says Brett Errthum, product marketing manager.

This year, users will install GPS units on 5% of new Deere dozers. By 2015, Errthum thinks that more than 20% of all new dozers will have automatic grade controls. Contractors "will be forced to use these to stay competitive," says Les Scott, Komatsu product manager.

These controls soon will likely incorporate multiple systems in addition to GPS. For example, laser guidance is an older technology that dates back to the 1970s. But engineers are finding that laser and GPS go well together. "GPS by itself doesn’t really give you much vertical tolerance," says Murray Lodge, national sales manager for Japan-owned Topcon. Its newest system, called "Millimeter GPS," uses a laser receiver mounted on GPS antennas to help equipment operators grade down to one quarter of an inch. Just two or three years ago, $50,000 to $65,000-GPS systems could only grade to one-tenth of a foot.

Father. Dwayne McAninch shows a GPS antenna rock guard at a Des Moines fabrication shop.

Now that the hardware is well established, contractors are pushing these methods on owners. Civil designers, surveyors and software companies are caught in the middle. That is spurring new educational demands. "There is a need to have more experienced engineers that understand how to do the data conversion and troubleshoot problems out in the field," says Charles T. Jahren, a professor at Iowa State University. It plans to start a graduate seminar next spring on GPS construction.

Son. Doug McAninch uses his hands to explain GPS grading.

A cottage industry of file preparation consultants has sprung up around GPS. But rather than outsourcing 3D modeling, Dwayne McAninch has built the firm around it. His son, Doug, president and COO, is just as passionate. "We only have 150 working days a year," Doug says. "In August, we can’t be waiting to get stakes." Each machine within the company’s fleet, which is worth hundreds of millions of dollars, works on one-and-a-half to two projects per year. Before it adopted GPS, that was 0.8 jobs per year.

Automatic GPS works best for fine grading. Many firms still do conventional surveying but supplement it with GPS, notes Bill Moyers, project manager for Rea Contracting, Charlotte, N.C. "When you have 20 ft of fill to put in, it really doesn’t do you any good," he says.

Those who "choose not to embrace it are going to get behind, and they are going to get behind quickly," says Dwayne McAninch. How do operators like Padgett feel about GPS? "This takes all the pressure off," he says.

What’s next? More integration and more diversity. Manufacturers are experimenting with GPS controls on paving machines. And states are working to build permanent GPS base towers, so owners, designers and contractors can take location readings and perform quality control on the same network. "It is going to make the whole industry function better," says Schug.

(All photos courtesy of Tudor Hampton for ENR)