Feature: A Bridge to Efficiency
Professional Surveyor Magazine - July 2011
A Connecticut excavation company brings an end to their base-station saga with one piece of technology.
by Ryan Sweeney
It all started with a robbery. But first...
In 2002, my family’s business, Sweeney Excavation
, a small company based in Hamden, Connecticut, began using machine control with a Caterpillar
D8 using a Trimble
Site Vision system and a semi-permanent base station, with an MS750 as the GPS receiver. Back then, GLONASS wasn’t available with Trimble products, and we were running only one machine and one rover.
Although our use of machine control steadily increased, our company has always required project owners to contract with licensed surveyors to provide our crew with control coordinates surrounding the site, as required for calibration. We typically handle construction layout tasks,
as well as cut-and-fill stakeout and as-built on utilities for our own use, and we supply as-built plans for the owner and all affiliated companies. Today, our company has four machines, three dozers, an excavator, and three full rover setups. And we still use that original base station that started it all. But I’m jumping ahead of myself.
In 2004, business was booming. We made the huge leap (for us) to purchase a second base station. Back then, after our supervisors broke down the base stations at the end of the day, they would throw them in the back of their trucks and take them home for the night, so they had them on site bright and early, ready to be set up.
Unfortunately, when our supervisor woke up one morning in 2008 he found that someone had broken into his truck and stolen the GPS base station. After calling the authorities and soon realizing that we would never see the equipment again, we decided it was in the company’s best interest to try to push forward without the second base station and make do with our first one.
By then the economy was heading south, and we could not justify replacing the base station. It was a nightmare.
It was at this time that a VRS network had just become available from our supplier, Keystone Precision
. For a couple of years, our crew made do by using a cell phone as its VRS base station. But this was good for only one rover. So, we tried to use our VRS connection in more expansive ways. That’s when we discovered the Intuicom
This has turned out, given our predicament, to be the best way we have found to send VRS corrections to our machines and rovers on a jobsite. The Intuicom RTK Bridge streams corrections from the internet over a cellular network, relaying them via radio. It allows us to be very mobile. We currently have it mounted on one of our supervisor’s pickups, and it allows us to receive GLONASS satellites, which we previously weren’t able to do, as our Cat D8 was the only machine we had with GLONASS-capable antennas.
Tom Hogan, the Keystone Precision dealer who has been doing business with my father for years, said, “there’s a huge leap of faith that has to be taken by the user; he’s saying I no longer need a base station.” Getting past that leap, Hogan said “the product sells itself.” He pointed out the product’s “better penetrating capabilities, especially through trees.”
Trying It Out
In June 2010, we put the new system to the test. We started the 100-apartment unit complex, Avalon Bay communities in Wilton, Connecticut, right when the RTK Bridge had become available. Our company was one of the first to put the new unit to the test.
This jobsite was one of our smaller sites; it is about six acres with seven buildings, plus a recycling center and maintenance building. We had about 20,000 yards to export and 50,000 yards total excavation, involving substantial rock drilling and blasting, which also involved state-highway widening and resurfacing.
This project posed quite a few problems when it came to determining where to locate the base station. At the start of the job the main concern was the high-voltage wires directly over one spot on the jobsite where a semi-permanent base station should ideally be sited. After further investigation, we found that it was kind of a crapshoot. No one had a 100% definitive answer; the best we had was, “It shouldn’t affect anything, although we’re not too sure.” This project was on track for a fast pace so we didn’t have time to set up a large, fixed base station and run the risk of relocating it if we found out the high-voltage lines caused interference.
After coming to this conclusion, we found the RTK Bridge was definitely the way to go. With its ease of use and extreme portability, it could be set up virtually anywhere with no extra setup after the initial calibration.
We set up the RTK Bridge in the job site trailer, which proved to be ideal. This enabled us to leave everything connected at night, and the system would spring to life once we started the generator the following morning.
The other issue we ran into was the steep slopes along 200 feet of the job site that caused our guys to lose their radio signal. The RTK Bridge solved this problem. We took it out of the trailer and into the back of the supervisor’s pickup, which took all of 10 minutes. We then drove to where we needed to work and where they were losing signal. As soon as the truck arrived, all the machines were back up, ready to go.
After about a month of using this system, our crew did run into an issue with the RTK Bridge not receiving/sending any signals in the late afternoons. We immediately contacted Keystone Precision, who demonstrated the ultimate in customer service. Keystone visited the job site to try to figure out what the problem was. After quickly realizing they couldn’t solve the riddle, they called Intuicom. A few days later, a company tech arrived on the job site from Colorado.
He spent the day with us, answered many of our questions about the setup, and ultimately discovered that the problem was the cell signal was failing during high commuter times on the highway nearby. A cell signal booster solved the problem. We have been up and running every single day since without a problem (it’s been about seven months).
Our company uses machine control in a variety of areas. For this particular job, we had three dozers doing rough grading and stripping topsoil. And the system is even more beneficial when it comes to grading for building pads and retaining walls. It enables a single operator, using our John Deere 650 dozer (or even our Cat D8 dozer) to push and grade building pads, taking them from rough grade to finished without assistance from a laborer running a laser pole.
Another advantage is quick and efficient utility-trench digging. Sub-inch accuracy enables the jobs to be completed faster and exactly to plan, which the customers always appreciate.
Ryan Sweeney is with Sweeney Excavation, based in Hamden, Connecticut.
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