Daniel C. Brown
More than 700 contractors and visitors flocked to the Midwest Construction Expo and Field Days, an equipment show held in July at a farm near Melbourne, Iowa, northeast of Des Moines.
Contractors took turns operating the construction equipment - including the latest in GNSS-based machine control systems - used to build a real-world wetlands project. The 14-acre project involved building an earth-fill dam and spillway structure. Wetland grasses in shallow water behind the dam will filter out nitrates and sediment from creek water running across the site, according to Jim Ricken, owner of Ricken Tiling Inc., which has a $125,000 contract with the state of Iowa to build the project.
The hit of the show was the next generation in machine control technology as contractors literally lined up for a hands-on demonstration. Topcon had fitted two bulldozers, a Caterpillar D6R and a John Deere 700J, with its new 3D-MC2 machine control system, which automatically controls the dozer blade. The 3D-MC2 system includes a new Inertial Sensor that works with the GPS system and enables an operator to double the machine's operating speed and accuracy compared to conventional GPS systems.
Plus, Topcon mounted its X63 grade indicator system onto a Komatsu PC 200LC excavator. The X63 system employs two on-board GPS antennas, a receiver, control box, and base station to indicate design grade and bucket position on a display in the excavator cab.
Short return-on-investment time
Attending the show was Jon Thompson, the grading supervisor for Kelly Cortum Inc., an earthmoving contractor based in Norwalk, Iowa. Since last spring, the company has run a Topcon 3D-MC2 machine control system on a John Deere 750J dozer. "We used it on the Carlisle Care Center, a health care facility in Carlisle, Iowa," says Thompson. "It worked really well. The general contractor was so proud of our building pad that he took pictures of it. It was an L-shaped pad with a 1:1 slope down into a basement area.
"Compared to a manual machine control system and stakers, the system saved us a week - and that was probably 25 percent less time to grade that site," says Thompson.
On another project, the Ringgold County Hospital in Mount Ayr, Iowa, Thompson used his 3D-MC2 system for finish grading. Kelly Cortum had done the rough grading beginning in August 2008, and then a contractor built the hospital. Cortum went back to do the finish grading, and found that the footing subcontractor had left extra dirt to move - and so had the plumbing contractor and the pipe contractor.
"We used our system to prove to the general contractor that we needed to get paid for more grading," says Thompson. "When you have multiple contractors like that, everybody blames somebody else for leaving more dirt."
Thompson estimates that his 3D-MC2 system will pay for itself in less than two years. "The savings in survey costs alone are significant," he says, "Not to mention the savings in earthwork that we would have done, and the cost of extra materials."
Excavator GPS system
At the show Topcon displayed - and offered for contractors' use - an X63 GPS system on a Komatsu excavator. Two GPS antennas are mounted on the rear of the excavator. The antennas receive GPS location signals that get recalculated into coordinates of the bucket corners. The data shows up on a control box display in the excavator cab, and the operator can see and read the position of his bucket compared to design grade.
Nathan Whitehead, an equipment operator with Whitehead Farms Construction, says after he tried using the Topcon X63 GPS system, "It's a very slick system," says Whitehead. "You can dig out your trench and see exactly where you're digging relative to your design. It stops you from digging too deep. The arrow tells you up or down and you can move the topsoil faster because you don't have to worry about going too deep, then having to re-do it."