The Machine-Control Revolution
Automated controls will pay for themselves quickly.
Automated machine control is sweeping across earthmoving and paving equipment from coast to coast. Granted, it takes some time to learn the process, and the equipment costs money, but the payback is rapid. That’s because machine-control systems will make your earthmovers and pavers more productive. You’ll have next to zero rework. You’ll save materials. Experienced operators will be even better at what they do, and inexperienced operators will learn quickly.
If you don’t believe it yet, check out what these contractors have learned. We gathered four earthmoving examples and two paving projects to show you just what these systems can do.
Minimal Rough Grading
Working under multiple contracts, Vecellio & Grogan Inc. moved about 13 million cubic yards of earth to build a new 9,000-foot runway and parallel taxiway at the Piedmont Triad International Airport in Greensboro, NC. The $29 million Phase 2 grading contract called for moving approximately 6 million cubic yards, says Rick Hertzer, chief engineer for the contractor.
For the Phase 2 contract, the main earthmovers consisted of a fleet of Caterpillar 777 rigid-frame dump trucks that were loaded with a Caterpillar 5110 excavator. A fleet of scrapers and several articulated dump trucks—loaded with a Caterpillar 385 excavator—assisted with the earthmoving. The 100-ton rigid-frame dumps had hauls ranging from 1 mile to 2 miles long, Hertzer says, because the borrow pits were at one end of the runway.
Vecellio & Grogan used two motor graders and a Cat D8 dozer, all fitted with Trimble machine-control equipment, to bring the cuts and fills to within two-tenths of a foot. “When we got close to grade we went through there with the Cat D8 and the graders,” Hertzer says. “We shuffled dirt with a Cat 623 paddle pan.
“The advantage of machine control was that we could bring it to finish tolerance with minimal rough grading at the end,” Hertzer says. “The shuffling of dirt was minimal, and the staking was greatly minimized. I’d say the machine-control systems cut the rough grading crew’s work to about 25% of what it would have been without machine control.”
Thanks in large part to electronic screed controls on an asphalt paver, the contractor achieved excellent asphalt smoothness results in building 16 miles of new four-lane highway in Idaho. For the new section of US 95 near Genesee, Poe Asphalt Paving Inc. used a Blaw-Knox 5510 paver equipped with a Topcon tracker that read a stringline on the first leveling lift of asphalt. For most of the second lift and all of the third, Poe ran two Topcon noncontact skis, one suspended from each side of the paver.
Poe used a stringline for the first lift because the paver had to run on a base of caprock, which consists of 3-inch stones. “We paved the leveling course—and even part of the intermediate course—using a stringline because the cap rock was prone to some movement under the paver,” says Josh Smith, highway division manager for Poe. “That rock has little or no fines to hold it together. It’s designed for drainage.”
John Cushman, Poe’s equipment manager, said the Topcon System 5 works very well to control the paver screed. “We’ve had great results with it,” Cushman says. “And our Topcon dealer has provided us with good support. The Topcon System 5 and non-contact ski is the best system available for achieving maximum smoothness.”
Smith says Poe earned a substantial smoothness bonus for its work on US 95. The International Roughness Index numbers ranged around 45, compared to a target of 60 or less—less is better.
“The versatility of our Trimble equipment is awesome,” says Henry George of AZ Grademaker, an owner-operator of a Caterpillar 140H grader fitted with a Trimble GCS900 machine-control system. “We can do everything from running cross-slope only to using the dual-masted GPS with laser augmentation,” says the Queen Creek, AZ–based owner. “With laser augmentation we can get two-one-hundredths or better accuracy on the grade.
“In the 2D mode, we can run a laser system or tracer to follow a stringline, or just cross-slope,” says George. “And in 3D mode we can run a Trimble ATS 600 robotic total station or the SPS 930 robotic total station.”
Recently, George helped reconstruct a 10-mile stretch of Roan Creek Road near Debeque, CO. It was a remove-and-replace project. American Civil Constructors was the general contractor and did the demolition of the existing road.
With the 140H grader, George placed and graded the granular borrow material and topped that with 6 inches of crushed aggregate base material. For the granular borrow material, placed 2 feet thick, George used the dual 990 GPS receivers with no laser augmentation. “We were able to meet the tolerance without the laser,” he says. “We tried to achieve under four-one-hundredths foot on the grade.”
The crushed aggregage base was placed with the Trimble dual 990 GPS system and finished with the SPS 930 robotic total station. “We did better than three-one-hundredths of a foot accuracy,” says George. The machine-control equipment relies on a digital terrain model of the site that is entered into the control unit on the grader.
“I build all my own digital terrain models,” says George. “A lot of the models we used in the past were not as accurate as we’d like them to be, so I learned to do that myself. I’ve learned it over the past seven years.”
George says he got started building terrain models by fixing the models he got from outside firms. “We would have to do something to the models to make them more grader-friendly,” he says.
“No Problems Whatsoever”
Using a Topcon System 5 with a non-contact ski to control a Blaw-Knox 3200 asphalt paver helped Orlando Paving Co. of Orlando, FL, achieve award-winning smoothness on a mill-and-fill project in Florida.
Located on SR 528, the project covered 66 lane miles and entailed milling up 3.5 inches of asphalt, then placing two structural lifts back—first a 2-inch lift, then a 1.5-inch lift. “We ran a non-contact ski on one side of the paver and used slope control on the other side where necessary,” said Paul Miller, construction manager for Orlando Paving.
“We love the Topcon system,” says Miller. “We’ve had Topcon for several years and we’ve had no problems with it whatsoever. All of our pavers are equipped with Topcon System 5 controllers and they all use non-contact skis.
Smoothness results on the surface course were superb: a 4.17 ride number on a laser profiler, with 5.0 being the best possible score. “The paver moved along at about 30 to 35 feet per minute,” says Miller. “Anything faster would be moving too fast.
“We did a lot of round-robin paving, where the trucks would bring out hot mix for paving and pick up milled asphalt to take back to the plant site.”
The contractor produced and laid 160,000 tons of hot-mix asphalt in just 310 days.
All paving was done at night on the heavily traveled roadway, which carried between 45,000 and 90,000 vehicles per day.
The contractor worked the project between 8 p.m. and 6 a.m. on the mainline and 10 p.m. to 5 a.m. for the ramps. Basically, that left six hours in which to pave, due to the time required to mobilize and demobilize traffic-control devices and to stripe the pavement at the end of the shift.
The Lane Construction Corp. of Cheshire, CT, found success using Trimble machine-control equipment to grade a 16-mile road construction project on US 74 near Lumberton, NC. “We took it from a two-lane road to a four-lane limited access highway,” says Tom Malchak, corporate survey manager for Lane.
Lane crews moved 6 million cubic yards of earth using three Trimble-equipped dozers, and a fleet of scrapers, backhoes and haul trucks. For finish grading, a Trimble robotic total station teamed up with a motor grader to provide four-one-hundredths accuracy. “We could be zero to four-one-hundredths low, but nothing high,” Malchak notes. “They didn’t want anything to throw off the pavement thickness.”
Three dozers were equipped with Trimble Site Vision GPSs to grade the project. Lane set some stakes but not as many as would have been needed with conventional methods. The company is in the process of switching to newer-generation Trimble equipment.
On an even larger project, a $1.4 billion expansion of Interstate 495 in the Washington, DC, area, Lane has formed a joint venture with Fluor Corp. Four lanes will be added to I-495, which is the Capitol Beltway. Launched in January 2009, the project involves 2 million cubic yards of earthmoving and widening, or building 54 bridges.
The joint venture has mobilized four John Deere dozers and three motor graders to handle grading. The four dozers all use Trimble GCS 900 GPS equipment. Two of the graders are equipped with Trimble GPS systems with laser augmentation. One grader works with a Trimble 930 robotic total station.
Special GPS Network
For the Beltway project, Lane set up a special GPS network. Four base stations and three repeaters covered the 16 miles. The overall system is Trimble’s SCS 900 equipment. Plus, the company employed five survey crews to lay out the structures and put in control points for the bridges and drainage structures.
The GPSs allow machine operators to see the project on a display screen. That gives today’s operators a tremendous advantage over the operators of yesteryear.
“It’s like CNN with pictures compared to CNN on the radio,” says Malchak. “We have some very good operators and the GPS systems make them better. Some people don’t have that gift to be able to envision what they’re building, so seeing that grade on the screen is a big advantage.”
The Lane Construction Survey Department in Concord, NC, is building the digital terrain models in-house for the Beltway project. Joint-venture engineers design the plans with Micro Station software, and Lane develops the 3D models with Trimble’s Terramodel software. Lane converts those digital models to a machine file suited for the proper machine.
“We make our own 3D models because we feel more comfortable doing that,” Malchak says. “If there’s a discrepancy, we can go back to the owner or engineer and ask them about it. It’s a QC approach to the construction. We can solve problems before the machine has to sit idle while we resolve a discrepancy.”
As a retired Marine colonel and former Apache helicopter pilot, Spartakoss Valverdini likes speed. Faster is better, in his book. And speed is just what he experienced on a John Deere 750J dozer during a recent hands-on demonstration of Topcon Positioning Systems’ 3D-MC2 machine-control system.
Topcon says a dozer operator can go twice as fast with twice the accuracy of a regular 3D GPS—and four to five times as fast as a dozer without any machine-control system. “Three-D MC2 allows you to go fast all right,” says Valverdini, a member of the Operating Engineers Union and a finish-blade operator versed in the use of laser grade control, GPS. “But that’s just part of the job. More importantly, it gives you the smooth, accurate, finish grade of a grader—with a dozer. I’ve never seen anything like it.”
John Dice, Topcon’s senior training manager, recently put Valverdini behind the joystick controls of the Deere dozer during a demonstration on a football-field-size test site near Topcon’s headquarters in Livermore, CA. Valverdini made a slow pass in manual control, then a return pass at about the same speed, still in manual control. Grading at about 1.8 to 2 mph, his passes were acceptable, he later said.
On the third and fourth passes, he engaged the 3D-MC2 system and ran at about 4 mph. The cuts were definitely smoother…finish-grade quality. On the fifth pass, Valverdini pushed the Deere dozer wide open, running between 6 and 7 mph. The cut, trimmed on both sides by the dozer tracks, was ultra-smooth. A level demonstration showed that it was “on bubble.” “That was something,” Valverdini says. “I have read about 3D-MC2 technology, and I listened to what John Dice said. But until you actually run it, it does not compute what the system can actually do.”
Dice complimented Valverdini’s performance, saying, “He’s a good operator at any speed. But just because he’s a good operator, he didn’t close his mind to the possibilities of what 3D-MC2 can do. If you accept the premise that this machine can make you more productive, thus saving time and money, it’s a natural progression from running with no machine-control system, or even a GPS-only system, to running with 3D-MC2.”
Author's Bio: Daniel C. Brown writes on safety and technology in the construction industry.