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It´s all about control

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Much has been written about machine control and the  benefi ts it generates in high-volume material situations. And deservedly so, for when hundreds of thousands of cubic metres of material need to be moved, machine control plays a signifi cant role in reining in costs and streamlining the excavation process.

For Kelowna, B.C.-based H&M Excavating it’s the versatility of the technology that’s most appealing. The fi rm tackles a broad range of excavating projects throughout the Okanagan Valley region, and has come to rely heavily on its GPSequipped dozer, grader and excavators. Using machine control, it has boosted productivity by 30 to 40 per cent.

With nearly four decades of experience, H&M is anything but a newcomer to this sector. Over the years, the company has grown to nearly 60 people and has become very good at adapting to change. According to Mark Hayter, the company’s chief surveyor, the addition of machine control was one of those changes.

“We did a good deal of research on the technology, and started seeing what it had done for some of our colleagues who do similar work here in the valley,” says Hayter. “The results were compelling enough for us to purchase our first system, a Topcon 3D-GPS for our Cat D6 dozer. We’ve since added systems to other equipment, as well as four Topcon HiPer+ receivers and have come to recognize machine control as a very powerful resource. We are currently working a number of jobs simultaneously throughout the valley.”

Close quarters

One of those projects is a nine-lot subdivision cut into a hillside in Kelowna. H&M is doing site grading, roadwork and underground utilities.

“The most challenging thing about this project is the jobsite itself; it’s as tight as they come, with lots that step up and down and a 12 per cent grade road leading into it. If this job were to be excavated conventionally, we’d constantly be running over the stakes—it would just be a nightmare. Instead, we have the 3D system on a Hyundai 290 excavator, we started at the back end of the subdivision and are just working our way back out. By the time we get to the other end, all the roads and lots will be sub-graded.”

Hayter adds that the original plan called for H&M to simply rough grade the site, but changes came in asking them to grade the lots as well, and because of their machine control capabilities, they were able to do it.

“When we got the new data from the engineers, I merged the lot grading info into the model that I had, emailed the revised data to the jobsite, they downloaded it to a card and transferred it to the machine,” explains Hayter. “So we were able to go from just rough grading to digging for basement elevations with very little difficulty. Now, because we are giving them finished lots with elevations that will be within one to two inches, the contractor can come right in and start building.”

H&M was also contracted to do some utility work at the Kelowna site, including a combination retention pond, dry well and rock pit at the base of the development. Hayter says he built all the utility work into the model plan and the machine control did the rest.

“That main feature is a huge rock pit with a three-ring dry well in it. Then, to dissipate the water before it reaches the storm sewer, the rock has a small channel that directs an overflow to a creek. I modeled all that in, along with the water lines and sanitary sewer.”

When it came time to excavate for the water line, H&M’s operator would simply flip to that particular model and know exactly where to dig—the pipe crew will just come behind them. “Sanitary and storm crews will then follow up with lasers and stakes of their own, but basically the excavator already has it done for them,” says Hayter.

Hitting the slopes

About an hour to the south of Kelowna in Penticton, B.C., H&M has also been at work on a project called Kaledon Acres. This upscale rural subdivision features 27 residential lots, each measuring from 2.5 to 10 acres, and will offer paved roads, designated parkland, a wildlife corridor and more.

“In addition to laying base for 1.2 km of road, we have some pretty big cut and fill slopes at Penticton,” says Hayter. “Generally speaking, on a huge slope like we have here, we would rely on a slope jig and have to re-stake two or three times to maintain accuracy as we’d work down the slope—all very time-consuming work. Here, using a Hitachi 330 with machine control, we just started at the top and worked our way down—without a stake the entire way.”

Other challenges included cutting a cul-de-sac into an area that was tremely steep. Hayter says the excavator operator had to scrape down to bedrock, then pull himself up just to get started. “The model I created was 1.5:1 slope, but the rock was actually steeper, so we just kept cleaning the rock until we hit the specs from the model, then followed that model. Some projects are fi ne for manual staking; there couldn’t have been a better proving ground for the machine control system than the Kaledon Acres project. We started in early October and, despite the challenging site work and delays due to weather, we will be paving next spring.”

The move to machine control was not without its challenges though, including an initial reluctance to change on the part of H&M’s operators.

“There was an initial fear of the unknown, but that disappeared quickly,” laughs Hayter. “We’ve found, after using 3D GPS for just an hour, our operators never want to go back. And it’s easy to see why; it takes a lot of the stress off them. They know where they’re at all the time, there is no guesswork or eyeballing needed.”

Another unforeseen benefi t that H&M has realized because of the technology, is an increase in the number of engineering fi rms who are now providing them with high-grade surface models. This helps the company tremendously in quantifying project volumes.

“In most cases, the engineers get good tight topo on the original ground, which is what we need; we are almost always tying into original ground. We’re generally paid by the cubic meter, and our quantities are calculated off surface models. So, working directly off those models reduces the chance for confl ict regarding volumes.”

Hayter admits there was a bit of uncertainty justifying the up-front costs of investing in machine control, but has no remaining doubts about the long-term benefi ts now.

“Not only have we been able to justify it, the more we use machine control the more uses we seem to fi nd for it. The fact that we now have it on three different types of machines shows just how well it fi ts into our operation

by Larry Trojak, 2010

Published with permission of On-Site Magazine

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