The Total Package

Well-established proponents of GPS technology, Gehring Construction & Ready Mix recently chose to extend that push to its grade trimming and concrete paving operations with the addition of Millimeter GPS from Topcon Positioning Systems.

Nebraska contractor rounds out full-GPS function with stringless trimming and paving capability

by Larry Trojak

The hallmark of any successful company is its ability to continually strive for improvement. How important is ongoing improvement to a company in today’s challenging business environment?  So much so, that an entire cottage industry committed to just such a goal, has developed around it. Maintaining the status quo, whether it is in methodology, materials used, or technology employed, is generally a recipe for stagnation and an invitation to being overtaken by more-driven competitors. Gehring Construction & Ready Mix learned these lessons long ago and has been active in putting them into practice. Well-established proponents of GPS technology, the company recently chose to extend that push to its grade trimming and concrete paving operations with the addition of Millimeter GPS from Topcon Positioning Systems.  The result of that move has been a measurable increase in efficiency, and the knowledge that when it comes to regional paving companies, they will continue to lead the pack rather than follow the herd.

While the use of stakes and stringline has been the method of choice for pavers since the advent of large-scale slip-form paving machines, the technique is not without its shortcomings.

Looking for a Change
Located in Columbus, NE, about 50 miles west of Omaha, Gehring Construction & Ready Mix is a third generation company which has been serving customers throughout the area for more than 60 years. About four years ago, looking to improve onsite efficiencies, the company added GPS to its operation, then followed that up with machine control in one of its dozers and motor graders. According to Kevin Gehring, paving superintendent and grandson of the company’s founder, the switch to GPS made perfect sense for them.

“We got into GPS because we knew it was a far more accurate and efficient way to do dirt work, allowing us to get the dirt within a tenth of an inch.  That meant that when the time came to trim, we wouldn’t have the usual low spots and high spots, thereby speeding up the grade trimming process considerably. Using survey stakes or blue tops requires both skilled operators and a grade checker, and it is still not as accurate. Add in the fact that the stakes always seem to get run over, prompting a lot of restaking or guesswork on the part of the operator and you can see why we made the move.”

Working through the LaVista, Nebraska office of DK&B Construction Specialties, the local Topcon dealer, Gehring first purchased a HiPer Lite base and rover. He says that move alone showed them the things that could be done faster and better. “But, more importantly, it also opened the door for us to add machine control to the operation, a direction we knew we needed to take in order to be competitive, both onsite and in the bidding process.”

Gehring did, in fact, add two machine control systems to its operation shortly after that initial purchase: Topcon’s 3D-MC2 on a

Installation of components on the GOMACO 9500 Trimmer and the GHP2800 Paver included a pair of Topcon PZS-MC Positioning Zone laser receivers, a GX-60 control box, and the “brains” behind the mmGPS operation, Topcon's MC-R3 receiver.

John Deere 700J dozer and 3D-MC on a Deere 772CH motor grader. “Once we were comfortable with those systems, we started looking onto ways to improve on the traditional approaches to paving: the use of stringline and stakes.  That took us back to DK&B and a look at mmGPS.”

Crossing the Line
While the use of stakes and stringline has been the method of choice for pavers since the advent of large-scale slip-form paving machines, the technique is not without its shortcomings.  Gehring says that, in addition to the headache of initially setting and verifying the stringline itself, other issues have plagued them for years.

“Much of the problem starts after the stringline is already up,” he says. “With it in place, gaining access to the road—necessary for getting in concrete, dirt or crushed concrete base—is tough. In the past, we‘d have no choice but to lower the stringline to allow access. That increased the time it took contractors to move in and move out, often impacting the length of the project. And if you are dealing with a situation in which you have lane closures or a traffic detour, the last thing you want is any kind of delay. We’d heard about stringless paving and knew we had some of the technology under our belt already, so we went to Todd Bachtell at DK&B to see about taking that next step.”

Bachtell agreed that Gehring’s company was an ideal candidate for mmGPS, citing an advantage that seasoned GPS users have when migrating to a related technology.

“This was also a first for us,” he says.  “Prior to Gehring, we hadn’t sold mmGPS to anyone in paving, but we definitely knew it was a good fit for that application.  The fact that they’d been using GPS for a number of years prior to that—both as a standalone instrument and in conjunction with their machine control—and had a good understanding of 3D modeling programs was a real plus. There couldn’t have been a better choice for that technology, so we started coordinating things between Topcon and GOMACO to make it happen.”

Sharing the Wealth
With plans and equipment in place, Bachtell, along with Brian Lingobardo, Topcon’s product manager for 3D machine control

Gehring believes their company is the only one in the Cornhusker State utilizing GPS in a paving operation.

hardware/software, and Matt Morrison, GOMACO’s manager for its 3D Machine Controls Group, met at Gehring’s Columbus location. Over the next two days, the group handled installation of the components needed on both GOMACO products: the 9500 Trimmer and GHP2800 Paver.  Those included a pair of Topcon PZS-MC Positioning Zone laser receivers, a GX-60 control box, and the “brains” behind the mmGPS operation, Topcon’s MC-R3 receiver.

“In addition to the speed and accuracy we were gaining, another real advantage of going with Topcon mmGPS was the fact that both the trimmer and the paver essentially share one single system,” says Gehring.  “Once both machines are set up with necessary brackets, cables and so on, we can use the system on the trimmer, trim the subgrade to tolerances within 1/100 of a foot, and then move it over to the paver. There, after about a five minute switchover, we can work off the same 3D model, set the offset to reflect the

Gehring recently completed a project that involved doing dirt work and paving for a two-lane full-width, 1½ mile section of highway right in Columbus. On that project, Gehring says they saw just how impactful going stringless could be.

thickness of the pavement, and get equally impressive results on the paving. It’s really been working out well for us.”

Highway Bound
Most companies (understandably) boast of the years of experience their operators bring to the jobsite, and Gehring Construction is no exception.  However, Kevin Gehring says the relatively young age of some of his operators actually worked to their benefit when making the switch to GPS-based technology.

“The Topcon systems are extremely user-friendly, so there was not much of a learning curve to start with,” he says. “But the younger guys on our crew were more receptive to the change right from the outset and really caught on quickly to the technology.  We’ve also had outstanding support from DK&B, Topcon and GOMACO which helped us through any initial rough spots. But we paved a small subdivision immediately after the installation, and then a week later moved on to a highway job.”

The project to which Gehring refers involved doing dirt work and paving for a two-lane full-width, 1½ mile section of highway right in Columbus.  On that project, Gehring says they saw just how impactful going stringless could be.

“We were on that job for about three months and having mmGPS probably helped us knock a couple weeks off the overall project length,” he says. “Although the actual trimming and paving time doesn’t really change, there is a savings in not having to go back and correct for high or low spots. However, the real time savings for us came from not having to stake the job or put up stringline; that was huge. And, the fact that all of our Topcon-equipped machines—from those doing site work to those in paving—are working off the same base and the same surface model also improves efficiency and lowers paving costs for us.”

Converts to mmGPS
At this point in time, Gehring believes that their company is the only one in the Cornhusker State utilizing GPS in a paving operation. That fact alone, he says, offers them something of an advantage over the competition that is still “tied up” so to speak with stringline.

“What I find really interesting is the reaction we get from engineers and inspectors on the jobs we’ve done so far with the mmGPS. Because stringline is all they’ve ever seen, they are very concerned about what kind of product we will make without a stringline.  But the technology is so accurate and so impressive, they always come away believers.”

This article appeared in the June 2012 issue of Midwest Contractor

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