Rebroadcasting Links Multiple Sites to One Trimble Base Station

By Mike Anderson, Senior Editor | September 28, 2010
Kyle Myers, E.V. Williams

As project engineer and GPS manager with the major Virginia site-prep and heavy-highway contractor E.V. Williams Inc., Kyle Myers has embraced the rebroadcast system idea pitched to him by Trimble dealer Spectra Integrated Systems.

Trimble machine control technology

Miles away from the base station set up at a centralized location, Kyle Myers of E.V. Williams is able to use a rover survey device on another jobsite to collect satellite information and correction factors via a rebroadcast system set up in his pickup truck.

GPS machine control technology

Kyle Myers, project engineer and GPS manager for E.V. Williams Inc., looksover the Trimble SPS 880 base station housed inside a large wood crate.

Trimble machine control

Miles away at one of a number of jobs being served by the base station, Myers sets up the rebroadcast system inside his pickup truck.


Machine control is one thing. Cost control is another, especially these days.

But, as technology-embracing contractors like E.V. Williams are proving, one does not have to come at the . . . well . . . expense of the other.

A site-preparation and heavy-highway contractor based in Virginia Beach, Va., E.V. Williams leverages its Trimble machine control products via use of a “rebroadcast” system.

“We stay within a 50-mile radius of our office, so a lot of our projects are really very close,” explains Kyle Myers, project engineer and GPS manager with E.V. Williams Inc.“So what we'll do is set up a main base station at our bigger project or at our main yard, and we'll calibrate from there. We'll put that base station up on the Internet; it's got an IP address. A rebroadcast system just uses a wireless Internet card, dials up that IP address, and takes the corrections through the Internet to the site it's on, and then you do a site localization — basically check into some control points.

“It saves the need for another $40,000 base station, and it costs about $5,000 for a rebroadcast system, and they're good anywhere from 12 to 15 miles with decent accuracy.”

By decent accuracy, Myers means a rebroadcast system can be used well for rough grade work beyond the six or so miles recommended by the GPS equipment manufacturer for fine work.

“If you stay within 10 kilometers or six miles of that base station, your accuracy is maintained,” says Joe McNamara, vice president and machine control expert with Spectra Integrated Systems, the Trimble dealer in Virginia and the Carolinas.

“With rebroadcast, the idea was: We'd plug the base station up to the Internet at one jobsite, and then we made a little suitcase, if you will, with a WiFi card, a wireless modem and a radio that the contractor could take to another jobsite to call back to the first base station, so they didn't have to push radio signals through cities or subdivisions — standard radios just don't go as far. The rebroadcast site would call to the base station back at Job No. 1, get the corrections, and put it out on the radio so the machines could use it again. So, in essence, we're rebroadcasting from one jobsite to another.”

This is “a perfect solution for people who work close to home bases,” says McNamara.

E.V. Williams has been using the system for the better part of two years now. “Spectra I.S., our local Trimble dealer, came to us and said: 'Since all of your projects are so localized, why not go ahead and try this rebroadcast system?'” says Myers. “Spectra's always been great to work with for us, and they helped us out tremendously on this in particular.”

It's about being a good partner, says McNamara.

“We actually bring it to the attention of most of our users, but only once they get to a certain level of adoption of the technology,” he says. “We're a very high value-add partner to these customers of ours. This stuff is changing very fast, there's lot of options, and they're looking to us to provide them the guidance to save them money, as well as keep them in the latest and greatest technology. We don't sell as many base stations because we went this way, but the theory in our company is that if we're saving them money on that front, that money will get plowed into bulldozers. Base stations do not make anybody any money; bulldozers, motor graders, excavators — the equipment with GPS —make you money.”

E.V. Williams owns four rebroadcast systems and is able to work them all at once off its Trimble SPS 880 base station. Just think of the alternative, says McNamara — five different base stations on five different sites. “It's tough to explain to the owner,” he says, “with that yellow box on that post over there, just how is that making him money.”

And, for contractors like E.V. Williams which concentrate on local projects, they're not giving up anything on fine-grade accuracy, especially within the six-mile guideline, says McNamara. “It's phenomenal. It's as if you had a base station on each of your jobsites. What happens beyond that is a parts-per-million error, with curvature of the Earth, and just over distance the error is going to compound.”

It is possible to work up to a dozen rebroadcast systems off a base station, says McNamara, “but we're not going to see it in my lifetime. The virtual reference stations will come into play before that.”

Within the Spectra I.S. dealership area alone, he notes, the Departments of Transportation in North and South Carolina have set up statewide networks of base stations that can be accessed by contractors.

A downside

Beyond the distance limitations created by the natural curvature of the Earth, there is an additional downside to rebroadcasting, says McNamara.

“The biggest issue we deal with the rebroadcast is Internet. Internet's the key,” he says. “We're replacing the radios with an Internet connection, if you will, to get from one jobsite to the next. And most of these jobsites don't have Internet on it because we're moving earth, so with our systems we moved to the WiFi cards. Probably two or two-and-a-half years ago, the manufacturers came up with a wireless router that you actually stick a broadband card into it, and it's then an Internet hub — a wireless hub. We can take that out, plug it into the cigarette lighter of a truck, and we now have Internet on the jobsite. Since the amount of data that the base station pumps out is very small, we can let it run all day long, and the cell phone companies don't get upset that you're a spammer or something like that.

“But the wireless connection to the Internet is the weak link, if you get into really rural areas.”

And with the Internet, signals can be blocked out, notably so for contractors in Virginia working near military bases, ports and other sensitive government locales.

As rebroadcast systems are used out beyond the six miles recommended for fine-grade accuracy, uses become more general, but not without value, says Myers, “especially if the company needs me to topo and tell them how much material is in a stockpile,” he says. “Well, I just went out there with the rebroadcast system, and I made a false point — 1,000/1,000/100 or something like that — and then I topo'd the stockpile. All the error is relative to that point, so I could give them the exact volume of that stockpile within 20 minutes. It saves a lot of time not having to set up a base at each site.

“That topo I did was something like 20 miles out, but it doesn't matter when the error is relative to itself. If I shoot the ground and it's two inches off, then the top of the pile is two inches off, too.”

It comes down to contractors maximizing utilization of equipment they've invested in, says McNamara.

“We've even seen them push it out 30 miles to just do a stockpile measurement, because it's all relative. We just need a volume not relative to anything else, so they can go out very long distances,” says McNamara. “Some companies might say, 'Alright, we used the rebroadcast at the beginning of the project at 12 miles, because that's where the base is, and when we get into fine grading we'll bring in a local base.' It just gives them flexibility to keep all their equipment utilized and not spend more money until they have to.”

Beyond the networking within a company, the technology is spreading connections externally, too.

“If need be, we'll use it in other areas beyond our immediate area,” says Myers. “If we have a good relationship with a contractor, we'll use their rebroadcast system; and likewise if they come into our area, they'll use ours. It saves the need for having to set up bases in all these different projects.”

McNamara has seen this throughout the Spectra I.S. coverage area.

“We have some contractors who are more dispersed, but they are friends with other contractors. One would put one base station on, let's say, their shop building, and the other one a number of miles away would put one on their shop. When they're working in the other area, they'll use the other company's base station, and when they're working in this area, they'll use their own. They begin to reciprocate. It's an innovative way to deal with the base station issue and keep the cost down.

“These guys tend to be very cooperative with other people who have taken the plunge and spent the money to invest in the technology. I doubt they're going to be real wild about, 'Hey, I just bought a machine. Can I use your base?'”

E.V. Williams has a wide variety of Trimble products, ranging “from the Jurassic yet fully functional MS 750/SNB 900 base station combo with a 13-inch zephyr antenna, to the latest SPS 880 base with Internet and GLONASS capabilities,” says Myers. The company has four rovers in constant use, one of which uses the GLONASS satellites as well. All rovers use the SCS900 software.

Myers builds the majority of his company's digital terrain models in-house using Terramodel. Some more complicated models are subcontracted to Spectra I.S.

E.V. Williams uses GPS machine control on six different earthmovers, including one Caterpillar D6 and two Deere 700 dozers with dual-mast configurations. One excavator and two graders are also GPS-equipped.

Among the contractor's ongoing jobs is a $100-million Virginia Department of Transportation contract as part of the Interstate 64-Battlefield Boulevard interchange construction in Chesapeake.

“It's amazing how much money it'll save you when you don't have to string-line a road and you can put a grader right on it, and it saves you three men and the amount of time it takes you to string-line. The fine grade costs and everything just drops way down,” says Myers. “Everybody who works with the technology and understands it likes it.

“A lot of the older guys like the traditional methods, and there was a little bit of a learning curve. But we've got guys who have been doing this work 30 years running it and now they don't understand that the machines can actually run without it. As soon as it goes down, they're calling.”

E.V. Williams “is one company you can pat on the back,” for leveraging machine-control technology, says supplier McNamara.

“They're very progressive trying to get into this,” he says, “but they are also always trying to get their utilization and knowledge of all the capabilities of it up. Kyle's getting full utilization and maximizing the ROI on this equipment.”

In this regard, machine-control technology is not unlike anyone or anything else on the jobsite: If it's not working, it's not making money.

x
expand_less