More than two years ago, a Global Positioning System (GPS) was just a gleam in the eye of Georgia grading contractor Alan Cawthon. He hadn't bought one, but he was thinking about it.
Then came the day when he had to manually offset some stakes from a road's centerline to one side. His wife watched him start the job, then left and came back when he had finished.
"My wife asked me how long that took me to do," Cawthon recalls. "I told her it took an hour and a half. She said that dozer costs us $450 an hour, and it was sitting idle all that time. So it cost us $675 — nearly the monthly payment on a Global Positioning System (GPS) — to set those stakes manually. That's what opened our eyes to what GPS could do, because we wouldn't need the stakes."
That was more than two years ago. Since then, Alan Cawthon Inc., dba Peek Grading, has fitted two dozers and one motor grader with Leica GradeSmart 3D GPS systems, and he's glad he did — especially in these difficult economic times.
"You can definitely bid projects tighter, and we can tell the customers they don't have to stake roads for us," says Cawthon. "We can work faster with the GPS, and the customer gets a finished product faster."
Cawthon adds, "We're looking at 20 to 25 percent time savings with GPS. A GPS system puts the grading information on the screen, right in front of your face. If you've got stakes, and half of them are knocked over, then you've got to look at the plans to figure out where you're at. You may spend 30 to 40 minutes of unproductive time. Plus it saves rework — the job is done right the first time."
What's more, Cawthon says, a GPS system will make an inexperienced operator into a decent operator — and make an average operator into an excellent operator.
For example, Cawthon tells the story of how Leica Geosystems helped with his first-time demonstration of a GPS system. The project was a 5-acre site for USA Ready Mix, a concrete company in Jackson, GA. It called for moving 40,000 cubic yards of earth.
One of Peek's inexperienced operators was running a Caterpillar D6R with a Leica GPS system to cut a large slope. Cawthon turned the employee loose to grade the slope, left the site, and came back seven or eight hours later. "He had it looking pretty good," says Cawthon. "It kind of took the wind out of my sails, because I saw that we could give a kid a job like that and produce a slope that looked that good. He said he just followed the lines on the GPS screen."
Cawthon says his GPS capability has helped win two recent projects, because he can bid them tighter — even when grading jobs are hard to find and bidding is very competitive.
One of the projects is a commercial site road in Jackson, GA. It's a 40,000-cubic-yard project with about 3,000 feet of road to grade.
"I was able to put together a bid package with a competitive price because I know I can do the grading in a timely manner," says Cawthon. "I definitely think our GPS systems helped us get that one."
The other project, the Village at Westgate, is a large residential subdivision in Ft. Mitchell, AL, near the Georgia border. The estimated excavation quantity is 200,000 cubic yards, and the current phase includes 15,000 lineal feet of streets and 214 new home lots. The project is located near Ft. Benning, GA, and benefits from housing demand created by military personnel. Cawthon reports that the project's developer likes the GPS system because it cuts down on his surveying and staking costs.
For the Village at Westgate, Peek Grading runs two dozers — a Cat D6R and a Komatsu D39 PX, both fitted with Leica GradeSmart 3D GPS systems. Peek also runs a Caterpillar 140G motor grader with a Leica GPS system. All three machines have automated blade control, but one of Cawthon's operators prefers to use only the visual GPS system to guide the grading. The automated blade control is used mostly to finish-grade with the motor grader.
Cawthon says the first step in successfully running GPS systems is to have a good set of plans from the engineer. An outside firm takes the plans and builds a 3-D GPS model of the project. That supplier e-mails to Cawthon the 3-D model, which he receives in his laptop computer in his pickup. The model goes onto a flash card, which fits into the Leica control unit on the dozer or motor grader.
Meanwhile a surveyor has established control points around the perimeter of the site to be graded. The machine operator, or a surveyor using a Leica rover unit, goes around the site and reads the control points.
"Then you've got the site loaded into the control unit and you've got the new design," says Cawthon. "The GPS unit compares the two, and the screen tells you where to cut and fill, and how much."
In learning to use a GPS system, it helps greatly to have a good relationship with your GPS dealer. Cawthon says that both Leica Geosystems and the dealer, Construction Laser, have been very helpful in climbing the GPS learning curve.
Sometimes a GPS system can help resolve a surveying disagreement. That happened for Peek Grading on its first real GPS project — the Manor at Montpelier, a 100-acre residential site with about 7,500 lineal feet of curb-and-gutter streets and three retention ponds.
"The developer was kind of leery about our GPS system, because we said we didn't need any stakes," says Cawthon. "So the surveyor staked it out, working for the developer. Somehow, they got off-line with their total station, and we found that we had to clear some more trees away in a different direction. It was a heavily wooded site.
"I said the road needs to be over here, not there," Cawthon continues. "The developer and I looked at the plans and he said, 'I think you're right.' So we cleared some more trees and he paid us for the extra work." When the surveyor staked the road, his stakes lined up exactly down the center of the cleared area.
"That gave the developer confidence that we knew what we were doing, and it gave us confidence in our GPS system," Cawthon says.
Peek Grading's GPS system helped avoid double-handling of the topsoil at the Rehoboth Road Elementary School project in Georgia's Spaulding County. The project called for moving 140,000 cubic yards of earth on a 40-acre site. Peek's contract included two school building pads, parking lots, a large retention pond, and three athletic fields.
The project called for cutting a large slope next to a parking lot, then undercutting the slope by 4 inches and placing topsoil back in the undercut area. Peek. With GPS systems on two dozers and a grader, Peek cut the slope, the parking lot, and the areas next to the parking lot. The contractor immediately placed the topsoil on the slope and in other areas as needed.
"In the past we would have rough-cut the slope, waited for re-staking, and stockpiled the topsoil to be placed later," says Cawthon. "But with the GPS system we brought the topsoil from another place and put it on the slope right away. We did not have to double-handle the topsoil."
|Ian MacKenzie is a writer who specializes in construction topics.|