GPS technology has significantly increased productivity. Contractors say the impacts on their businesses are positive, as long as they respect the complexity of the tasks that it handles.
Much like a phenomenon that the overall US economy experienced starting in the late 1990s, the excavation and grading profession has seen a quantum leap in productivity thanks to technology in the past decade. Just as the US enjoyed Alan Greenspan’s “dream economy” of low inflation, low interest rates by historical standards, and low unemployment—phenomena due, largely, to office communication and computing technologies that boosted the productivity of service firms—grading and excavation contractors are utilizing powerful global positioning system (GPS) technology to significantly increase their productivity. Evidence of this leap in productivity is a drastically shortened interval between surveying and site preparation.
GPS has two main applications in the industry that shorten this interval: three-dimensional site modeling and machine control. The site-modeling application converts two-dimensional survey data into a 3D schematic that gives the contractor a precise layout of the job site, not to mention a permanent record of the location of features such as utilities for future reference. The machine control application represents a logical next step; construction equipment operators can view an image of the 3D model from inside the cab and adjust the dozer or grader blade, or excavator bucket for slight variations in slope and cross slope for cuts or fills.
GPS site layout systems use a base station that receives satellite signals and transmits the signals to one or more “rover” stations that are used for grade checking on the job site. The satellite signals allow precise marking of grade on the job site, not to mention a much more efficient and less labor-intensive process of laying out a site than the traditional method that relied upon tools such as lasers to measure grade and distance, as well as a staking crew. When the site layout data is incorporated into a 3D model that is displayed inside the cab of earthmoving equipment, the operator has a visual representation of site grading and such features as utilities.
To take the capability of GPS a step further, the contractor can have one or more GPS antennae mounted on a machine so that the operator can mark precise machine location in real time as the antennae receive satellite signals from the base stations. Besides allowing the operator to determine where the machine is located on the job site relative to topographical features, a GPS machine-control system also pinpoints blade or bucket location relative to the desired grade and the operator grades as necessary by adjusting the blade manually, or specially designed software automatically adjusts these attachments during operation.
Grading & Excavation Contractor recently spoke with several contractors who discussed the many benefits of using GPS for site layout and machine control. They also mentioned how using this technology has affected their business and what contractors must do to ensure a successful adoption of it.
Increasing Productivity
Contractors overwhelmingly say that the main advantage of GPS technology is an increase in their productivity, often allowing them to take on and complete more projects with the same human and equipment resources.
Grant Garrett, president of Garrett Excavation in Hot Springs, AR, points out that his three Topcon base stations and three rover stations are used every day, and one individual now lays out a site, a task that used to require two workers. “Before we had the GPS, we had a total station where we would do all of our engineering and layout, and we kept a crew busy doing that pretty much around the clock,” he says. Now the company has equipped four-wheel all-terrain vehicles with rover station pole kits that take readings of various locations on the job site; more precise readings require a stationary range pole. The data gathered by the rovers are compiled into a 3D digital terrain model (DTM) whose data is used in takeoffs and estimating as well as for guidance of Garrett’s dozers and motor graders that have GPS antennas mounted on their blades.
“One, we reduced the amount of layout we had to do right off the bat and two, with the layout we were having to do, we probably increased our production by 300% or 400%,” says Garrett. “It allowed us to take on more work because we could finish more work quicker—instead of taking three weeks fine-grading a job, we could spend 10 days. We were getting done with work quicker, and I had to start getting more work so I wouldn’t have guys standing around with nothing to do.” He adds that initially equipping only half of his crews with GPS technology revealed a significant disparity in productivity between the GPS haves and have-nots. “I thought: This is insane doing it this way when we know we can do it in half the time. I learned really quickly that everyone that I have is going to have to have GPS.”
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| A significant reduction in the time needed for job-site staking can more than justify the costs of GPS equipment. |
Over the past two years, Trimble 3-D models developed by Glankler Data Services LLP have helped Jordan Anglin, project manager, field engineer, and GPS coordinator for Henderson Inc. of Williamsburg, VA, eliminate site layout errors before his dozer, grader, and excavator operators start moving dirt in the field. “The biggest benefit is that it eliminates rework,” Anglin says. When Thad [Glankler] makes a model for us, he calls me and says these garages are back-graded; they’re not going to drain. I’ll call the engineer and let him know that we’re changing the grades, and they’re stupefied—normally, you wouldn’t notice that until you’re pouring concrete or you’re checking grade the old-fashioned way with a stick rule or laser.”
The power of the information in the 3D models turns every worker into a manager, Anglin adds, increasing productivity once metal hits dirt. “We need less supervision for [operators] now,” he says. “Instead of running one job, we can have the superintendent run three jobs with the foreman running the GPS. It takes a lot of the guesswork out of it. It makes an operator into a foreman, basically because he’s got a set of plans in front of him and he can figure things out on his own—he’s not calling the superintendent for what to do next.”
Inside the cab, the operator can view the 3D model and his relative location to site features on a monitor. Of major importance are protected areas in historical Williamsburg, Anglin notes. “It’ll let you know when you go off the job site, which is huge in this area with all the protected areas we have,” he says. “I can flag certain areas with the software so that if they go into a protected area or go out of the limit of the job, they know right away. There’s a real-time icon that looks like the machine that moves with you around the job site and its updating thousands of times a minute. There are three different settings, and you can set the numbers: You’ve got fine grade, medium grade, and rough grade settings, but we get such good accuracy that we keep ours in fine grade all the time.” With this setting, the operator receives a low-accuracy warning when grading is off by more than a preset metric.
A significant reduction in the time needed for job-site staking more than justifies the costs of GPS equipment and 3D modeling services from Dirt Logic LLC, according to Scott Bernhardt, president of Bones Construction in Aloha, OR. Dirt Logic provides a takeoff and uses the data to develop a 3D model that is e-mailed to Bones Construction. “I put it into my GPS system, and I can use it for basic surveying and rough-grading for my sites, and I can also locate manholes for sanitary sewers,” Bernhardt explains. “I have two guys who go around with these GPSs and put in rough-grading stakes. We basically have the site in our rover and in our GPS, and we’re able to walk around the site and tell where all the roads’ centerlines are, where the grades are, where the cuts are, where the fills are, where the lot lines are, and, depending on how much line work we put in, maybe where the sidewalks, where the building envelopes are. That’s something we can do with our guys. I do have two of those systems, so I’ll have one of my grade checkers hit two or three jobs a day.
“In the past, let’s say, I built a new mile of road through a piece of raw land—I would have to use offset wooden stakes and offsets to mark locations of manholes and water valves and maybe particular monuments that I’d want to save,” Bernhardt continues. “I’d have to do that with wood and a tape measure, whereas now once I install the different pipeline systems, I can go through that with GPS and the model and mark exactly where that is, and I can keep that electronic data. I don’t have to offset with a bunch of wood stakes, paint, and markers; I don’t have to go back and find all that stuff because we have all that data electronically—it saves us a lot of time.”
Above all, Bernhardt understands that time is money. Bones Construction’s capability of modeling and staking a job site also makes the company self-sufficient and gives it the ability to better control its own schedule. “There’s also a huge benefit because I’m able to put in my own rough-grade staking,” he says. “It saves me from having to wait 48 hours for the surveyors to come, and it saves my client from having to pay extra money to have extra rough-grade stakes put in. I can just get what raw information I need right away and get my people going. I can also double-check that the engineer’s topographic information is all right and not get surprised at the end and find out that I have an extra 100,000 yards of dirt.
“I still have an engineer do all the standard surveying, but I can basically shoot all the stakes they put in, in case I lose some, which is typical in the industry. I can put them in myself instead of having to call them and have them put in three or four more curb gradient stakes and it costs the owner $1,500 more. I save myself some time and save the owner some money.”
Jeff Hoburg, foreman and superintendent with JH Excavating in Allison Park, PA, has found that the company’s Topcon GPS and 3D modeling from Terrain Modeling Services aid productivity as well as customer service because they streamline the job-site chain of command in regard to site layout when issues arise. “It’s a selling point,” Hoburg says of how customers view JH Excavating’s use of GPS. “If you have a problem, you come see me. If you have additional layout you want, I have that cell phone in my pocket.”
The company uses two site-layout systems and has equipped one of its dozers with a GPS machine-control program. “Anywhere inside the work area [operators] want cut or fill information I can provide it. All of our guys have come to the point where they can pick up [grading with GPS data] and run with it.”
Hugh Brown, GPS coordinator with Beaver Excavating in Canton, OH, adds that the company can pass along cost savings that result by eliminating the outsourcing of restaking tasks, as well as the need for dedicating an individual to grade checking.
More Competitive Bidding
The pinpoint control available to equipment operators also benefits the sales office. Contractors note that GPS data aid in quoting a project, allowing them to submit more accurate, competitive bids.
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Photo: Take-Off Professionals |
| GPS Base stations can send signals to antennae mounted on such machine attachments as dozer blades to inform the operator of blade adjustments necessary to achieve the desired grading. |
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Photo: Glankler Data |
| Rover” GPS stations receive signals from a GPS base station for grade marking. |
Newman Contracting of Glenpool, OK relies upon its GPS equipment and the takeoff and 3D modeling services of Take-Off Professionals out of a realization that these complex tasks are better outsourced to a trustworthy partner. The partnership pays off in accurate bidding, says Trent Newman, project manager for Newman.
“A lot of guys might do their own in-house data, but for us, it comes down to liability and security,” Newman says. “I’ve been doing estimating, project management, our budget and everything else, and that would take up a whole lot more time. [Take-Off Professionals] can do it so fast and so accurately that it saves a lot of time and their files are always really reliable.
“We paid for our GPS on the first job we ever used it on,” he continues. “We basically paid for the system in the amount that we were off on the dirt. It ended up being 160,000 tons of dirt on this job and we originally thought there were 100,000. That’s a lot of money if you’re charging $4 or $5 a yard. If you go the other way, you can overestimate the quantity and you can miss the job because your bid is too high.”
Newman stresses that the cost savings that result from bringing the staking task in-house are passed along to customers.
“We hired a guy with a little bit of survey experience and someone to help him and we went from subbing out 100% of our survey work and paying out the nose for it to doing it in-house,” he notes. “We’re basically operating with the in-house stakeout at about one-third the cost of a subcontractor; those guys are $1,000 a day plus
restaking costs.”
Brown adds that increasing Beaver Excavation’s productivity with the use of GPS also benefits his customers because it allows them to put their projects on a faster track. As a result, Beaver Excavation saves its customers money by saving itself and customers time. “[Customers] think they can get a job delivered more quickly and they set tighter deadlines,” says Brown.
More Reliable As-Builts
This technology gives the contractor the ability to more efficiently and accurately double-check site layout data and as-built data. More accurate as-built data can pay productivity dividends for future projects on the site—and possibly even aid efforts to retain customers who might further develop a site in the future.
“You can record as-builts and not wait for your engineers to come by or surveyors to come by,” points out Mark Gould, owner of Gould Construction in Glenwood Springs, CO. “Also, you can go out and pre-topo a project and make sure you’re comparing the project to the original drawings to make sure that the drawings are correct. Many times, you’ll get surveyors who are plus or minus 2 feet, and that means a lot. Many times, there’s a difference on the job between the recorded engineering drawings and where the water line or sewer line ultimately goes and this is a recording of what’s out there after the fact. All of a sudden for some reason, you’ve got to put an elbow in on a water line and you want to have a recording of where that is.”
Some Caveats
As is the case with using any kind of powerful technology, contractors caution that a user of GPS equipment risks working with inaccurate data unless extreme care is taken to ensure the collection of valid data—and a 3-D schematic is modeled by a competent employee or another organization.
“The young guys love GPS; the biggest problem I have with them is that they trust it too much,” says Anglin. “They’ll just look at the screen and not use their heads as much as they should. There’s no replacement for experience. You can’t just trust the GPS 100%; you’ve still got to use your head to go from Point A to Point B to make things work.”
Also, “We haven’t had it happen in two years, but the machine could get knocked out of calibration,” Anglin adds. “One of the sensors could get knocked out of calibration. If you don’t check in for a while, things can happen. On a job that’s all subgrade and all topsoil stripped off, you can’t tell if you’re half a foot off until it comes time to start laying out your curb and everything else.
“I check the machines regularly,” he continues. “I’ll take my laptop out in the field and check the calibration and the measurements because you’ve got to account for blade wear—I pretty much do that weekly. You can lose two-tenths of an inch off of your blade during the life of it. If you want to go with GPS full-fledged and you have a fleet of equipment, hire somebody to handle [the equipment calibration]. That’s what they hired me to do.
“You’re not going to have a lot of errors with your GPS—that’s not where the problem will be. The problem comes from your data prep. You want the right person with experience in grading and drainage to be making your models. It’s worth the money to pay someone to do your models.”
A strong working relationship and communication between the engineer and the 3D model developer is critical to the success of using GPS, argues Gould, a civil engineer by formal education.
“That data has to be accurate because we are building our model off of their 3D data,” he says of O’Neill Positioning Services, which builds 3D models for Gould. “You have to have some insight into what the engineer was intending because that’s not always clear; there has to be a trust factor.”
Gould adds that the 3D modeler must be someone highly qualified for such a complex task and workers should be trained on how to collect the data using the GPS equipment. “In the beginning, it takes somebody like O’Neill because that’s really the part they help out with is the orientation and getting up to speed so you can use GPS because not every contractor has the in-house capabilities to use a GPS. It’s a computer issue where its garbage in, garbage out. If you put the wrong model in the machine, the machine is going to build the wrong model in the field.”
Tim Priester, vice president with Construction 70 in Phoenix, urges contractors to rely on someone like two former employees to build accurate 3D models if they expect to realize the full benefits of GPS. Two former Construction 70 employees started up their own 3D modeling and takeoff services firm in early 2007 and maintain a relationship with the contractor. “The lasers we used to use were accurate,” notes Priester. “Still, you’ve got to have people who know exactly how we grade out in the field. We still have to get the pads certified, the street certified before we get our final payment.”
Operators Adapt
When it comes to training equipment operators to use GPS-enabled machine-control systems, though, contractors say the learning curve is a fairly short one, a crucial fact that also reduces the payback period for the equipment.
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Photo: Take-Off Professionals |
| Three-dimensional schematics for slope and cross-slope can be viewed by the operator inside the cab. |
“We sent our trainers to the people that we bought our GPS system from [Trimble] and they held two different sets of classes,” recalls Newman. “One was for the guys who would be using the field system for the surveying and layout and staking, et cetera. The other was for the operators. The operator, if there really isn’t much cut or fill—in other words, the dozer doesn’t have to be digging down a foot—he can just drive along and put the blade in automatic mode and just drive and that blade will automatically move kind of robotically and make the cut by itself. If he does have to take an area down by a foot or so, he can turn it down on the computer screen and just add an offset. He can do that entire job without having to touch the blade control lever.”
Adds Garrett: “Our finish grade operators were used to working with all of the magic technology such as two-dimensional lasers, so I’m not going to say that there was a learning curve as far as looking at the computer screen and being distracted, but there was a learning curve because one, now we’ve got a computer in the cab and some of the guys didn’t have computer skills and two, we’ve got antennas, cables and cords and now we’ve got a radio that’s transmitting and receiving a signal. We had to make sure that the information we were receiving was the right information, make sure we had a good radio signal and two, we had a lot of problems with connections and cords going bad that we weren’t used to.”
To Priester, the learning curve inherent in using GPS should be viewed as a positive in regard to professional development. “Some foremen embraced it, others were scared of it,” he says. “The ones who embraced it are the ones they want; you want people to be able to do new things—you take them out of their comfort zone.”
The contractors who spoke with Grading & Excavation Contractor are early technology adopters to begin with, which makes the transition to GPS a relatively smooth one. “There was a little bit of a learning curve, but we’ve been in the laser and [ATS] market for quite a while and our guys have already adapted to using different types of technology, so this was just a software upgrade for them if you want to call it that,” says Brown, adding that Beaver Excavating has used the technology since 2000.
Dabbling in surveying
GPS technology certainly has migrated the capabilities of early-adopting contractors into the outer limits of engineering and surveying. But none of the interviewees said they anticipate complete horizontal integration into that discipline. Surveyors, who have an opportunity to expand their service offerings into building their own 3D GPS models, are the ones who are really impacted by the increasing adoption of the technology.
“Contractually, we require that we are provided with control points to work from, and I flatly refuse to do property-line surveying,” Hoburg argues. “I’m not a registered surveyor, and I have no business doing it, in my mind. If I mess up my work that’s my problem. I’m comfortable with that responsibility because it’s working out.
“I think [surveyors] are all going to have to come to [3D modeling] because if construction layout is their bread and butter, I’m eating their lunch. It’s an opportunity that they almost have to take advantage of or they’re going to be left with very little else.”
Similarly, Newman stresses that the surveyor still has a role in the initial layout of a site. “With the GPS, I might have to localize with a minimum of maybe five points on the job site before we get started and I’ll get those points from a surveyor. We don’t do anything that will make us liable—anything legal, we get from a surveyor. But as far as a surveyor getting paid to do all of our staking for us and do restaking, we can go back out and do that in a matter of seconds.”
Bernhardt agrees but adds that relieving his surveyor or restaking can actually benefit the surveyor. “I think it relieves them of some of the pressures because putting rough grading stakes for me on a big earth site multiple times is really impossible for them to bid to an owner,” he says. “I can do that on my own, but I still have them put in all the pipeline staking, all the original rough grade and staking for the centerline.”