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| The Power Curbers and Topcon investment timed well with the start of site work and flatwork at Summit chief Scott Cunningham’s Firefly development. The equipment enabled Summit crews to far exceed daily output typical of prior subcontractors. |
A Power Curbers 5700-C paver running with Topcon Millimeter GPS has shown curb, gutter and sidewalk contractor Summit Industries the productive potential of teaming slipforming machinery and precision controls.
“I don’t make a major capital equipment purchase without first looking into it, seeing what options are available and examining how it will impact our business,” says Scott Cunningham, president and owner of the Summerdale, Ala., company. “We did that with GPS before diving in to it back in 2011, and today have a fleet of dozers, excavators and graders which utilize GNSS machine control technology and give us outstanding results. After researching the possibility, using GPS machine control technology to pour concrete curbs and sidewalks without using traditional string line methods appeared viable.”
Summit used to handle concrete paving through subcontractors, who typically formed up and poured slabs using string line. “I don’t like our job schedules to be at the mercy of a subcontractor,” Cunningham observes. “Regardless of how reliable a company might be, there are always times when you need them and their schedule doesn’t allow it. We operate in an area that averages 68 inches of rain annually. Since concrete pouring is very weather-sensitive, it can be costly to miss our ‘weather windows’ and get rained out, potentially causing weeks of delay on our projects. So we eventually purchased our own curb machine in 2005 which solved that problem for a while.”
Summit was fairly successful running its own curber with string line for about three years, until market conditions changed everything. “We were fortunate enough to make it through the economic downturn without any layoffs,” notes Cunningham. “We were able to diversify and keep busy until things could pick up again. However, we did decide to sell the curb machine since our workload did not allow our crew to stay steady and proficient. After that, we were once again subbing out curb work to the same company we did in the past. That seemed to be the way we would be doing things for the foreseeable future—until [2014], when I started seeing what was developing with stringless paving.”
Millimeter Match-Up
The development to which he alludes is the successful teaming of slipform paving technology with Topcon Positioning Systems’ Millimeter GPS Paver System. It combines the benefits of GPS positioning technology with a zone laser reference to afford contractors like Summit latitude and productivity gains. The potential Cunningham saw in the approach was enough to make him re-think his position on paver ownership.
Summit contacted Power Curbers, Inc. to secure its curbing machine of choice, a Model 5700-C. That decision was based both on the size and volume of jobs typically encountered and those envisioned for the future. During roughly the same time frame, the contractor purchased the Topcon Millimeter GPS system. Representatives from both companies worked together to get key Summit personnel trained and the machine production-ready.
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| After securing the Power Curbers 5700-C control, Summit crews set within 250 feet the Topcon LZ-T5 laser receivers, whose zone-beam technology affords highly accurate elevation details. |
Great Out of the Gate
Any doubts about the impact a GPS paver could have on Summit’s operation were quickly dispelled on the first job: Nearly a mile of curb work at a Daphne, Ala., subdivision. Despite the newness of the technology and a total lack of experience with automated curbing, Summit’s crew, working alongside Topcon and Power Curbers representatives, did an impressive 2,100 feet of curb in two half-day sessions. Working alone on day three, the crew logged 2,600 feet of curb without a single glitch. Cunningham notes that crew members were impressed by what they could do with the machinery and positioning technology, and quickly gained the confidence needed for the next job, a development called Firefly in which he had a special interest.
“This is a low density, low impact development that I own and am developing,” he explains. “Unlike many subdivisions in this area, Firefly will only have 27 lots—ranging in size from one acre to 17 acres—on its 80-acre footprint. That approach has resulted in very little community opposition because of our focus on minimizing the impact on the area. The project includes about 3,000 feet of sidewalk and 6,000 feet of curb and gutter.”
To achieve the most effective coverage in support of the Topcon solution, Summit GPS specialist Jeff McKenzie first established control, then using those points set Topcon LZ-T5 laser receivers at 500-ft. intervals, thereby ensuring that the Power Curbers 5700-C was never more than 250 feet away from a receiver. The LZ-T5 uses zone-beam laser technology to continuously provide high accuracy elevation information, thereby ensuring the highest level of GNSS positioning. “We actually found that range to be effective as far away as 350 feet,” McKenzie observes. “But we wanted to err on the side of caution. We were getting tremendous production from the unit and accuracies were never in doubt.”
“There is a great deal of prep work that goes into getting an area ready for sidewalk, even one using a string line-based curbing machine. There is grading, staking, setting the string, and so on,” he adds. “Pouring sidewalk conventionally, without a machine—in the heat with which we [were] dealing—our subcontractor generally averages about 300 to 400 feet a day. So this 3,000-ft. section of sidewalk could have taken as long as two weeks. Instead, using the GPS-equipped Power Curbers machine, we did it in just about three days. That is an impressive time savings that will allow us to move on to other projects quicker.”
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Power Curbers, Inc., Salisbury, N.C., 704/636-5871, www.powercurbers.com; Topcon Positioning Systems, Livermore, Calif., 925/245-8300, www.topconpositioning.com.