Maximizing Efficiency
The latest generation of machine-control equipment is helping a South Carolina contractor to slash by one-third the time an airport runway project would have taken with conventional survey crews and manual machine control.
Removing old Runway 03-21 and building the new one will take just 200 days—and require only one survey crew—at Charleston Air Force Base, says Brent Evans, project manager for Banks Construction Co. in Charleston. By contrast, it would require two survey crews and take 300 days to do the project with conventional equipment, Evans estimates. Banks is doing the earthmoving and base construction for the project under a $26 million joint venture contract held with two partners, Summers Concrete Contracting of Hahira, GA, and RC Contracting Co Inc. of Greenwood, MS. The general contractor is Northwind Inc. of Idaho Falls, ID.
Work on the joint venture began with the demolition of the old 7,000-foot runway. That involved milling the 8-inch asphalt surface and breaking the concrete under it with a guillotine hammer. Broken concrete was loaded into trucks and hauled to an onsite crushing plant, where it was recycled for base material under the new runway.
For the rough grading, Banks used two bulldozers, both equipped with Topcon’s latest global navigation satellite system (GNSS) machine-control technology, 3D-MC2. The technology automates blade control to maximize the efficiency of the dozer. On the machine, 3D-MC2 uses a rugged antenna mounted to a shock-absorbing pole connected to the blade. A receiver box is mounted in a secure location on the machine.
The joint venture uses an onsite base station to which satellites send positioning data. Satellites also send positioning data to the machine’s receiver. Together, the base station and machine provide real-time kinetic (RTK) position information that reveals the machine’s three-dimensional location on the site. Software compares the machine’s position with the design grade at a given location.
The project’s design firm, A.D.C. Engineering Inc. of Hanahan, SC, had produced a CAD file, which RC Construction used to create a digital terrain model (DTM). Banks then loaded the DTM into two Topcon FC-200 data collectors, and also into the control boxes on the two dozers—one a Caterpillar D6N and the other a John Deere 750J. The control boxes update positioning data and send signals to the hydraulic valves on the dozers. In turn, the valves control the blade, which is automatically positioned for elevation and slope. Other sensors inform the control box of certain machine conditions. For example, dozers are equipped with a slope (tilt) sensor on the blade to measure the cross-slope of the cutting edge. The system can also be run in “indicate mode,” which permits manual control according to position information on a display in the cab.
Evans figures his firm spent approximately $300,000 for Topcon machine-control and survey equipment in connection with the Charleston Air Force Base project. On this and other projects, the equipment will soon pay for itself in reduced surveying costs and improved machine-control efficiency, says Evans. If Banks were building a second airport project like this one, the two projects together would return the investment in machine-control equipment.
Why did the company buy from Topcon? “One reason was local support,” says Richard Rhode, survey superintendent. “We get local support through Carolina Positioning, our Topcon dealer. They give us excellent technical support when we need it.”
100 Times per Second
The primary benefit of Topcon’s 3D-MC2 system is speed, and, therefore, higher production. “A dozer operator running Topcon’s 3D-MC2 can easily double the speed of grading compared to conventional manual control,” says Louis Limehouse, the grading manager for Banks. The 3D-MC2 system uses Topcon’s GX-60 control box, GPS+ antenna, MC-R3 receiver and new 3D-MC2 sensor, coupling them with new controlling software to provide position updates at up to 100 times per second. The sensor combines a gyro, a compass, and an inertial sensor to measure the X-Y-and-Z position as well as the roll, pitch, yaw, and acceleration of the dozer.
Rough-grading for the new runway required moving some 30,000 cubic yards of earth to fills on new safety aprons, one at each end of the new runway. Cuts averaged about 8 or 9 inches in depth. With the two dozers, Banks brought the grade to within one-tenth of a foot of the desired elevation. Compaction followed with a Caterpillar CS 563D single-drum vibratory roller. “We put a lot of compactive effort into the subgrade to meet the required densities,” says Evans.
To fine-grade the subgrade, Banks used a Caterpillar 12H motor grader controlled by Topcon’s latest local positioning system (LPS), a GPT 9001A robotic total station. Richard Rhode, survey superintendent, earlier had surveyed the site with a Topcon GR-3 GPS to establish 34 control points at 200-foot intervals along the runway. So Banks crews simply set up the robotic total station on the control points and loaded the control file into the total station, or “gun” as it is called. To control the grader, the total station automatically tracks a prism on the grader and the blade responds by following the control file’s instructions.
“We used the robotic total station to get the fine grade to within 0.04 foot,” said Rhode. “The Topcon LPS does an excellent job in establishing the desired grades.”
With the subgrade finished, Banks began placing a 5-inch separation layer of crushed concrete that was recycled from the old runway. In similar fashion to the dirt, that material was rough graded with the GPS-equipped dozers to within one-tenth of a foot. The Cat 12H motorgrader, fitted with a prism and guided by the robotic total station, brought the separation layer to within 0.04 foot.
Placing the Drainage Layer
The Topcon LPS also came in handy for controlling the screed on an asphalt paver to place a drainage layer of cement-treated stone. Banks worked with Carolina Positioning to enable the prism to switch from the motor grader to the paver. As trucks unload cement-treated base into the paver, it inches along with its screed controlled by the robotic total station. The drainage layer required compaction with a Caterpillar CS 563D roller, so the paver was programmed with an offset to leave the cement-treated stone about 0.13 foot high, says Doug Brill, assistant superintendent. That number varied depending on the mixture of cement and stone, so Brill would adjust it as required.
Banks set up the robotic total station to work 800-foot-long sections of runway at once. The total station occupied a control point midway in each 800-foot section. Then the paver, working 14-feet wide in each pass, would pave ahead for 800 feet, back up, and repeat the process in the adjacent pass.
Brill was checking grade behind the paver with a Topcon GR-3 rover and FC-200 data collector on the day we visited the project. “It’s working great,” he said. “I just love this system; it’s awesome. We usually spend tens of thousands of dollars to have a bunch of surveyors around, and now we don’t have to do that. This system will put us way ahead of the competition in bidding for work. Plus, there is no guesswork involved.”
“The accuracy of the local positioning system is top-notch,” says Rhode. “It’s just as good as an engineer’s level—the system is operated by a Topcon GPT 9001, a robotic total station with an accuracy of one second.”
The composition of the safety overruns at each end of the runway is somewhat different from the runway itself. Banks graded the subgrade with the dozers equipped with 3D-MC2 and used the dozers to dump and spread base material as well. The base consists of 5 inches of crushed concrete topped with 11 inches of crushed granite. The Caterpillar 12H motorgrader, equipped with Topcon’s Local Positioning System, fine-graded the base stone. When the base is finished, Banks will pave the safety overruns with 3 inches of asphalt.
Advertisement
Banks officials are very enthusiastic about Topcon survey and machine-control equipment.
“What’s really slick about this equipment is that a simple rover can give you cuts and fills anywhere onsite,” says Rhode. “I take the rover pole and just try to find some errors in our grade, and I can’t find any. You don’t see any stakes anywhere on this site. We knew the dirt was on grade, we knew the separation layer was on grade, and we knew the drainage layer was on grade.”
Author's Bio: Daniel C. Brown is the owner of TechniComm, a communications business based in Des Plaines, IL.
October 2009
Maximizing Efficiency
Photo: Daniel C. Brown<br>
An asphalt paver, controlled by a Topcon robotic total station, placed the drainage layer of cementtreated base for the runway.
The latest generation of machine-control equipment is helping a South Carolina contractor to slash by one-third the time an airport runway project would have taken with conventional survey crews and manual machine control.
Removing old Runway 03-21 and building the new one will take just 200 days—and require only one survey crew—at Charleston Air Force Base, says Brent Evans, project manager for Banks Construction Co. in Charleston. By contrast, it would require two survey crews and take 300 days to do the project with conventional equipment, Evans estimates. Banks is doing the earthmoving and base construction for the project under a $26 million joint venture contract held with two partners, Summers Concrete Contracting of Hahira, GA, and RC Contracting Co Inc. of Greenwood, MS. The general contractor is Northwind Inc. of Idaho Falls, ID.
Work on the joint venture began with the demolition of the old 7,000-foot runway. That involved milling the 8-inch asphalt surface and breaking the concrete under it with a guillotine hammer. Broken concrete was loaded into trucks and hauled to an onsite crushing plant, where it was recycled for base material under the new runway.
For the rough grading, Banks used two bulldozers, both equipped with Topcon’s latest global navigation satellite system (GNSS) machine-control technology, 3D-MC2. The technology automates blade control to maximize the efficiency of the dozer. On the machine, 3D-MC2 uses a rugged antenna mounted to a shock-absorbing pole connected to the blade. A receiver box is mounted in a secure location on the machine.
The joint venture uses an onsite base station to which satellites send positioning data. Satellites also send positioning data to the machine’s receiver. Together, the base station and machine provide real-time kinetic (RTK) position information that reveals the machine’s three-dimensional location on the site. Software compares the machine’s position with the design grade at a given location.
The project’s design firm, A.D.C. Engineering Inc. of Hanahan, SC, had produced a CAD file, which RC Construction used to create a digital terrain model (DTM). Banks then loaded the DTM into two Topcon FC-200 data collectors, and also into the control boxes on the two dozers—one a Caterpillar D6N and the other a John Deere 750J. The control boxes update positioning data and send signals to the hydraulic valves on the dozers. In turn, the valves control the blade, which is automatically positioned for elevation and slope. Other sensors inform the control box of certain machine conditions. For example, dozers are equipped with a slope (tilt) sensor on the blade to measure the cross-slope of the cutting edge. The system can also be run in “indicate mode,” which permits manual control according to position information on a display in the cab.
Evans figures his firm spent approximately $300,000 for Topcon machine-control and survey equipment in connection with the Charleston Air Force Base project. On this and other projects, the equipment will soon pay for itself in reduced surveying costs and improved machine-control efficiency, says Evans. If Banks were building a second airport project like this one, the two projects together would return the investment in machine-control equipment.
Why did the company buy from Topcon? “One reason was local support,” says Richard Rhode, survey superintendent. “We get local support through Carolina Positioning, our Topcon dealer. They give us excellent technical support when we need it.”
100 Times per Second
The primary benefit of Topcon’s 3D-MC2 system is speed, and, therefore, higher production. “A dozer operator running Topcon’s 3D-MC2 can easily double the speed of grading compared to conventional manual control,” says Louis Limehouse, the grading manager for Banks. The 3D-MC2 system uses Topcon’s GX-60 control box, GPS+ antenna, MC-R3 receiver and new 3D-MC2 sensor, coupling them with new controlling software to provide position updates at up to 100 times per second. The sensor combines a gyro, a compass, and an inertial sensor to measure the X-Y-and-Z position as well as the roll, pitch, yaw, and acceleration of the dozer.
Rough-grading for the new runway required moving some 30,000 cubic yards of earth to fills on new safety aprons, one at each end of the new runway. Cuts averaged about 8 or 9 inches in depth. With the two dozers, Banks brought the grade to within one-tenth of a foot of the desired elevation. Compaction followed with a Caterpillar CS 563D single-drum vibratory roller. “We put a lot of compactive effort into the subgrade to meet the required densities,” says Evans.
To fine-grade the subgrade, Banks used a Caterpillar 12H motor grader controlled by Topcon’s latest local positioning system (LPS), a GPT 9001A robotic total station. Richard Rhode, survey superintendent, earlier had surveyed the site with a Topcon GR-3 GPS to establish 34 control points at 200-foot intervals along the runway. So Banks crews simply set up the robotic total station on the control points and loaded the control file into the total station, or “gun” as it is called. To control the grader, the total station automatically tracks a prism on the grader and the blade responds by following the control file’s instructions.
“We used the robotic total station to get the fine grade to within 0.04 foot,” said Rhode. “The Topcon LPS does an excellent job in establishing the desired grades.”
With the subgrade finished, Banks began placing a 5-inch separation layer of crushed concrete that was recycled from the old runway. In similar fashion to the dirt, that material was rough graded with the GPS-equipped dozers to within one-tenth of a foot. The Cat 12H motorgrader, fitted with a prism and guided by the robotic total station, brought the separation layer to within 0.04 foot.
Placing the Drainage Layer
The Topcon LPS also came in handy for controlling the screed on an asphalt paver to place a drainage layer of cement-treated stone. Banks worked with Carolina Positioning to enable the prism to switch from the motor grader to the paver. As trucks unload cement-treated base into the paver, it inches along with its screed controlled by the robotic total station. The drainage layer required compaction with a Caterpillar CS 563D roller, so the paver was programmed with an offset to leave the cement-treated stone about 0.13 foot high, says Doug Brill, assistant superintendent. That number varied depending on the mixture of cement and stone, so Brill would adjust it as required.
Banks set up the robotic total station to work 800-foot-long sections of runway at once. The total station occupied a control point midway in each 800-foot section. Then the paver, working 14-feet wide in each pass, would pave ahead for 800 feet, back up, and repeat the process in the adjacent pass.
Brill was checking grade behind the paver with a Topcon GR-3 rover and FC-200 data collector on the day we visited the project. “It’s working great,” he said. “I just love this system; it’s awesome. We usually spend tens of thousands of dollars to have a bunch of surveyors around, and now we don’t have to do that. This system will put us way ahead of the competition in bidding for work. Plus, there is no guesswork involved.”
“The accuracy of the local positioning system is top-notch,” says Rhode. “It’s just as good as an engineer’s level—the system is operated by a Topcon GPT 9001, a robotic total station with an accuracy of one second.”
The composition of the safety overruns at each end of the runway is somewhat different from the runway itself. Banks graded the subgrade with the dozers equipped with 3D-MC2 and used the dozers to dump and spread base material as well. The base consists of 5 inches of crushed concrete topped with 11 inches of crushed granite. The Caterpillar 12H motorgrader, equipped with Topcon’s Local Positioning System, fine-graded the base stone. When the base is finished, Banks will pave the safety overruns with 3 inches of asphalt.
Banks officials are very enthusiastic about Topcon survey and machine-control equipment.
“What’s really slick about this equipment is that a simple rover can give you cuts and fills anywhere onsite,” says Rhode. “I take the rover pole and just try to find some errors in our grade, and I can’t find any. You don’t see any stakes anywhere on this site. We knew the dirt was on grade, we knew the separation layer was on grade, and we knew the drainage layer was on grade.”