Leveling The Field
March 2012By Don Talend
South Carolina grading and paving contractor slashes costs and improves competitiveness.
Evidently, Charleston, South Carolina-based Banks Construction never got the memo that a severe economic downturn has been underway since December 2007. Four years later, the grading and paving contractor had as much highway and commercial slab work as it could handle in South Carolina. Good thing Banks had purchased both rough and fine automatic grade control systems for several of its dozers and motor graders within the previous couple of years to keep pace with the workload.
One of three concurrent projects that Banks was working on was grading and paving concrete slabs for a 300,000-square-foot manufacturing complex in North Charleston, South Carolina, in November 2011. A Caterpillar D6N dozer and John Deere 750 dozer equipped with a Topcon Positioning Systems 3D-MC2 high-speed Global Navigation Satellite System (GNSS)-enabled automatic grade control system was used on the project.
THE PROJECT DIRT
Banks’ work on the project consisted of excavating 49,000 cubic yards of dirt from a 30-acre site and filling with another 60,000 yards of dirt for three building slabs covering about 303,000 square feet; a 4-acre retention pond area; paving the slabs; a 3,500-foot, 25-foot-wide service road; and a 196,000-square-foot parking area.
Trey Cox, grade control superintendent for Banks, reports that maintaining satellite signals was not a problem during the project, even during the grading of 2:1 and 3:1 backslopes along the edge of the retention pond located at the edge of a pine forest.
Banks acquired the 3D-MC2 system in 2009 for an airport runway project and uses it on most of its highway and commercial work whenever possible, according to Cox. In addition to using automated grade control on the dozers, the contractor uses the technology on three Roadtec RP-195 paver/spreaders, Wirtgen W 2000 and W 2200 cold planers, and a Caterpillar 12H motor grader.
Testing indicates that the 3D-MC2 system can allow grading with twice the productivity of other automated grade control systems, and four times the productivity of grading without the use of automated grade control. Its components include an MC-R3 GNSS controller that works in conjunction with an MC2 sensor that replaces a slope sensor; a four-color, touchscreen, Bluetooth™-capable GX-60 control box; and a conventional GNSS antenna mounted on the dozer blade. The MC2 sensor combines a gyro, compass, and inertial sensor to measure the X, Y, and Z position, as well as the roll, pitch, yaw, and acceleration of the dozer. The technology gives the system the capability to provide blade position readings up to 100 times per second—or roughly five times as many as alternative systems. Additionally, testing indicates that the system yields about three times the grading smoothness of other machine control systems.
A WINNING FINANCIAL PROPOSITION
Cox reports that the 3D-MC2 system had paid for itself on the first project for which it had been purchased a couple of years earlier. “Every time I see Louis Limehouse, our grading manager, he’s grinning from ear to ear because this is a good project,” Cox says. “This project was bid competitively because of the state of the economy. Obviously, we were low bid, but we’re still going to do well. Most of our machine control systems that we have invested in have generally made enough return on the project for which they were purchased,” says Cox.
Without the use of automated grade control, the project would have been a week to 10 days behind the progress that Banks had made by mid-December, according to Cox. This time savings translated into significant financial savings, he adds. “Man hours and machine hours add up pretty quickly,” he says. “Then you’d have a significant amount of additional surveying that would need to be done and, more than likely, you’d have to have more people on the crew because you’d have somebody with a rod checking grade and maybe a shovel taking off more dirt.”
Cox adds that automated grade control allows contractors like Banks to assign workers to operate machines rather than labor-intensive tasks, such as manually checking grade or setting stakes. He estimates that without the use of the technology, Banks would have operated at least three fewer pieces of equipment to allow workers to check grade. “Instead of running a dozer 10 hours a day and moving 2,000 yards of dirt, we can run it 10 hours a day and move 4,000 yards of dirt—that’s where your big savings comes from.”
Use of this technology impacts the utilization of more equipment than just grading equipment, Cox adds. He estimates that, on a typical project requiring 50 triaxle dump trucks to haul dirt per day, a contractor could reduce the number of trucks to 30. “I guarantee that the machines cost $2,000 a day to run, and by figuring an additional 40 hours without machine control, you’re probably saving $80,000 right off the bat.”
Limehouse contends that automated grade control can yield a 400-percent savings in labor on a typical project. “We are doing no surveying whatsoever other than setting control points and building the machine control models from data files that are developed from site plans. If the models are built correctly, just the savings in wood itself is unbelievable. With a rover, a man in the field can verify anything you’re doing out there. This keeps the survey crew from coming out right now; we run two survey crews. At one time, we had four crews. Just that savings in a year helps offset the cost of the unit.” Cox says that the use of automated grade control can allow contractors to bid projects based on stakeless grading and ultimately increase overall sales. “You bid the first job, then you go and buy all of this equipment and you know that you can do this stuff a lot faster, so you start trimming your time and you end up getting more work, and at some point, you know you’re outbidding everybody,” he says. ■
About The Author:
Don Talend of Write Results Inc., West Dundee, Illinois, is a print and e-content provider specializing in covering construction, technology, and innovation.
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