For nearly 40 years, Thorncrete Construction has been at the forefront of curb and sidewalk paving in the Toronto area, staying ahead of the competition through a combination of hard work, good planning, and a belief in employing the best people and equipment. Occasionally that entailed taking bold steps, such as choosing to add GPS capability to their curbing operation to follow similar moves made by larger customers. Doing so, company officials believed, would make the entire scope of the operation—from clearing to grading to curbing to paving—seamless and, at the same time, increase onsite efficiency. They could not have been more on the money. Today, Thorncrete owns and operates Canada’s first totally stringless, GPS-based curbing machine. Controlled by a system from Topcon Positioning Systems, Livermore, Calif., the company sees it as a way to both enhance its value to customers and maintain a competitive edge.

Cutting the cord

The concept of stringless curbing and paving is fairly new, having only debuted about six years ago. Since that time, however, it has attracted attention and support of some of the biggest players in the industry. It’s not surprising that enthusiasm for the GPS-based approach would migrate northward to Canadian contractors. For Thorncrete, however, it was not a question of simply wanting to get onboard with a new technology. According to Ross Ruscica, vice president and grandson of the firm’s founder, it was a way to improve while better serving one of its biggest customers.

“We regularly subcontract to the ConDrain Group, one of Canada’s largest sewer and water main contractors, and we’ve enjoyed a nice relationship, providing curb-and-gutter services to them for a number of years now,” he says. “They are a very proactive organization and, as such, are in the process of migrating a lot of their equipment and capabilities over to GPS. A little while back, they approached us about doing the same with our curbing equipment. It was a big step for a company like ours.”

With ConDrain moving to GPS, Ruscica says they knew that almost all of the stakes, batter boards, and other materials typically part of the jobsite would be gone. Thorncrete also knew following ConDrain’s lead would allow the company access to surface model files that it could modify and use directly with the new curbing machine it would have to purchase. Weighing the pros and cons, Thorncrete decided to make the switch—in mid-2010 they purchased a Gomaco GT-3600 curb-and-gutter machine.

Getting used to new

The concept of going stringless was a dramatic departure for Thorncrete’s crew. According to Ruscica, there was both a learning curve to overcome and a need to develop a sense of confidence that things were going to be alright. “Without the stringline, you really don’t have a physical point of reference, so you just have to say: ‘Okay, this is where the curb goes, let’s start pouring.’ You have nothing to measure off and that’s pretty scary. But after a short time we got the feel for it. In the past, we always had to make sure the stringline was there, that it wasn’t bent, that it wasn’t crooked, that it wasn’t broken. Now, we have to keep reminding ourselves that this machine can go on its own. Aside from monitoring speed and vibration, the operator can just sit back and watch it do its job.”

Cleaning up the spills

Getting to the point where Ruscica and his crew can have that luxury begins with the base machine itself: a Gomaco GT-3600 curber with a Topcon GPS+ receiver and onboard graphical display. A pair of masts, each topped with a Topcon PZS-1 laser sensor, was added—one to control elevation and the other for steering. Because Thorncrete opted for Topcon’s Milimeter GPS that uses laser-enhanced GNSS technology, a Topcon PZL-1 transmitter is positioned at a control point onsite to track the position of each receiver on the curb machine and relay curb location and elevation data to the Gomaco unit.

“We received a lot of help with installation, setup, and initial operation from Mark Piotto from the Concord office of GeoShack—the local Topcon dealer,” says Ruscica. “Because virtually all the grade on our jobs is now being done with GPS-driven dozers and graders, we simply take that data, modify it for our application, plug it into our machine, and follow the exact same contour. So, for example, if there is a dip and the dozer catches it, so will we; there is no difference between their contour and ours.”

He says that by comparison, with stringline, if a dozer or grader accidentally raises or lowers the blade, the curbing machine will continue to follow the stringline, resulting in spillage.

”Spillage, or an overpouring of concrete, is something all curb companies like ours want to avoid. It is a waste of material and an unintended drain on the bottom line. Because we went to the GPS system, we have all but eliminated spillage,” he says.

Bottom line benefits

Ruscica reports that adding the Milimeter GPS capability to the curbing machine has resulted in an impressive improvement in both accuracy and speed. And with good reason: in terms of accuracy, the already tight ±0.1-foot specifications afforded by GNSS receiver technology are improved to ±0.02 feet when augmented with laser technology as is the case with mmGPS. As to speed, he says his crews report equally impressive numbers.

“It’s really deceiving; it looks like we are moving along at a slow pace, but by the end of the day we’ve accomplished so much more than we would have ever thought. Right now, we are looking at production that is up to two times quicker than what we can get with stringline. Because of the added speed, accuracy, and reduction in spillage, we can get 25% to 30% more production out of this machine than we can from our other curb units. That’s important because it changes the bottom line completely and makes us that much more competitive out in the market.”

He adds that their newfound capability will undoubtedly result in work from other firms around the metro Toronto area whose focus is also on a GPS-based operation—work that, in the past, they’ve generally had to turn down. It also will, he feels, further separate them from the pack.

“I think that this machine will give us the edge that no one else in this region has right now. When it comes time to getting a job done quickly and accurately, customers will know what we can do and will call us. It sure would have been nice to have this 10 years ago, but we’re glad we have it now.”