The accuracy has proven more than adequate for most jobs at a tenth horizontal and a tenth vertical. “It is real tough to get any closer,” says Martin. “I don’t care who the operators are.”
If closer tolerances are required, the contractor sets up its Topcon laser and mounts the receiver to the same pole that holds the GPS antenna. “Your tolerances are real tight then — as tight as the machine is,” says Martin.
Return on investment depends on the amount of earth moved. “I would say you have to move 50,000 yds. and more to be worth having,” says Martin. He cautions that you may not see a return on your first job. “You have to get used to using the equipment and get familiar with the 3-D systems.”
But time constraints on projects put a premium on the technology. “As tight as the time frames are that we have to work under, you just have to have a couple of guys who can be efficient with using it,” says Martin.
Increased fine grading efficiency
Paul Reed Construction, Scottsbluff, NE, is a general contractor that performs everything from residential to light industrial work. “In the past, we have done a lot of railroad work,” says Ben Ryschon. “Just lately, since we got the GPS, we are starting to take on larger earthmoving jobs, like landfills.”
The company initially purchased its Trimble GPS systems three years ago. It currently has fully automated grade control systems on a Deere 850 dozer and a motor grader. “We have used it pretty solid for the last two years,” says Ryschon.
The accuracy is within a tenth, but Ryschon claims you can get even closer in the right conditions. “With the dozer, it really depends on the type of material you are pushing,” he explains. “If you are pushing in very loose soil, it gets you within a tenth real easily. With a little bit of work in the right material, you can get within about half a tenth.”
But dozers do have limitations when used in solid underfoot conditions. “If you are on really solid ground, we have found you get a lot of movement from the grousers that just shake the whole machine,” explains Ryschon. “Your tolerance goes up. It is going to be around a tenth. In order to get good fine grading, you have to go with the grader.”
The automated GPS has changed the way Paul Reed Construction approaches projects. “Obviously, not all of my equipment has GPS,” says Ryschon. In the big cuts, the contractor does minimal staking to allow the rough cuts to be made with non-GPS equipment. “Once it is roughed in, my GPS equipment comes in. It only takes off the last foot to foot and a half.”
On jobs requiring small cuts, the GPS equipment is often sent out by itself. “If there is only a foot to a foot and a half to cut on a jobsite, I will just use the GPS equipment for all of it,” says Ryschon. “I will not even set a stake in the ground.”
Ryschon is a surveyor/civil engineer tech, so he understands the savings possible with automated grade control. “We don’t need blue tops anymore, other than for a spot check here and there. Right now, we use very minimal staking. If you can eliminate a $20,000 or $30,000 surveying bill, that is a pretty good savings on a job,” he points out.
Eliminating blue tops and hitting grade on the first pass have made Paul Reed Construction a very efficient operation. “We have increased the efficiency of fine grading by 40% to 50%, or even higher in some cases,” says Ryschon. “When you get down to grade, you run your dozer or grader across there and you are done with it. You may have to take a couple of passes to make it perfect, but it is a lot better than having to go out there and pound blue tops.”
The contractor is extremely satisfied with the system. “Of course, it is not cheap,” Ryschon admits, “but we see the dividends it pays out. To be a competitive dirt contractor in the next 10 years, you are going to have to be running GPS of some sort.”