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Software, handheld data collectors, and global positioning system (GPS) base stations are becoming almost as common on earthmoving sites as big chunks of yellow iron. Graders and excavators are likely to sport some version of machine control, and at the other end, where the job gets surveyed and the guys on the ground keep track of what’s going on, things are also changing.
GPS is on its way to becoming the gold standard, and Trimble, Leica, and Topcon have gone into it big. On the other hand, software and equipment from specialized companies expand the options for contractors who may not be ready to jump in with both feet or who need to be nimble to accommodate the kinds of jobs they do.
Digital Cameras on the Job Site
In the category of the Big Three, Topcon has hit the construction market with its new GPT 7000i series, the latest addition to its line of optical instrument products. According to Topcon Product Marketing Manager Jason Killpack, the GPT 7000i is a functional reflectorless total station with fully capable onboard data collection software. A digital camera is incorporated into the equipment and with the unit’s software. The 7000i compiles three-dimensional coordinate data in the same manner as the rest of Topcon total stations, using horizontal and vertical encoders to read angles and a reflectorless electronic distance meter to measure slope distances. What’s different is that the digital camera displays the view from the instrument in real time, and records survey data in a digital picture. This allows the operator to collect all the normal data as well as record the digital picture of every occupation and point collected. By having this real-time image, the unit is able to display known coordinate points inside the live picture streaming from the camera.
“This way the operator can do ground truth imaging with the design points in the field,” says Killpack. “Why try to explain to the project engineer where the mistake is when you can show him?” The image is stored as part of the project file to be archived for additional measurements back at the office or as a historical/legal record of work performed.
Another feature Topcon is touting is the ability to see calculated points that are loaded from the engineered plans into the unit for layout in the field. The site plan coordinates are displayed to the user over the live images that are generated from the camera. This way the user knows instantly if the orientation of the instrument is correct, as well as has a visual reference for where the measurement points are on the ground. The system can be further enhanced with the addition of Topcon’s free translation software, Topcon Link; and a module from Topcon Tools office software can be purchased to edit and manipulate the job data.
“In addition to these unique abilities,” says Killpack, “the unit also has a photogrammetry function. This means that by using it to measure several control points on a project the user can create three-dimensional models from the stereo-paired digital images. Users can capture all relevant data in the field by image, and then measure any of the objects or things contained in the image later in the comfort of the office. No more forgotten points in the field. No more repeat trips out to the field to re-collect data.”
Another camera/instrument pairing comes from Riegl Laser Measurement Systems, USA. Its High Density Calibrated Camera Systems combine a point cloud generated by a Riegl 3D Scanner with the output of a calibrated 6- or 12-megapixel (digital) Nikon camera. This innovative merging of photogrammetry with three-dimensional laser scanning uses the photo and data to provide an existing-condition image of the measured area, which Riegl points out helps users with such post-processing functions as faster feature extraction.
According to Marketing Director Jim van Rens, the scanner can acquire 8,000 points in a second, a hefty increase over 60 points in a day with traditional surveying methods, and is certified eye-safe by the Occupational Safety & Health Administration and the American National Standards Institute. “When you take a measurement with our equipment,” says van Rens, “you generate somewhere between 25 million and 30 million measurement points. This kind of detailed information keeps you from having to come back and re-grade, and you can generate all kinds of dimensional information—how much material has been put down, how much material has been taken off, how much dirt has been moved—in precisely identified volumes. For example, here in Orlando, we built an extension on our trade show arena. The general contractor established a huge common-material pile under agreement with the local contracting authority. But he was obliged to replace that same amount of dirt at the end of the project. If he’d had this kind of technology in place monitoring that pile, it would have saved him a couple hundred-thousand dollars.”
“Where I find this the most helpful,” says Mike Stys, group leader of technology services at Atwell-Hicks LLC, a land development consulting company in Shelby Township, MI, “is to help people relate a site to its context. Reading a two-dimensional plan is sometimes difficult for folks that aren’t accustomed to it. So it’s much easier to illustrate what a site truly looks like in three dimensions like this. With all those millions of points we can more accurately depict what’s going on in the real world.
“It’s a two-step process. Rotating 360 degrees, the laser captures all the points first; then the unit rotates again with the camera to take photographs. It allows us to collect a lot more data with less people in a shorter period of time, so it’s good for projects with tight deadlines. And it’s a lot safer because you can scan a busy roadway without closing a lane or being in a road at all. It’s great for existing-condition surveys. Earthmoving contractors don’t have to wait around for a surveyor to finish before they can continue moving dirt.
“You need an operator who understands more sophisticated software and how it interacts with a piece of equipment, as well as someone who’s comfortable with computers, can solve problems in the field, and has a good understanding of geometry because you have to triangulate your targetry to make it more accurate.”
Taking to the Air
Steve Yurosek, division manager at the Van Nuys, CA, branch of Sukut Construction Inc., uses light detection and ranging (LiDAR) from Airborne 1 Corp. in El Segundo, CA, to verify owner-supplied topography. Sukut Construction takes in $200 million annually grading mostly subdivision developments. “We go the extra mile to verify that the topography is accurate,” says Yurosek. “We’ve compared Airborne 1’s work with what we typically get from owners, and Airborne 1 seems to be more accurate every time.”
LiDAR uses a scanning and ranging laser system developed by the National Aeronautics and Space Administration almost 30 years ago. The laser scanner is mounted in an aircraft and emits high-frequency infrared laser beams. The scanner records the difference in time between the emission of the laser pulses and the reception of the reflected signal. A mirror mounted in front of the laser rotates and causes the laser pulses to sweep at an angle, back and forth along a line. The position and orientation of the aircraft is determined using phase-differenced kinematic GPS. The orientation of the aircraft is controlled and determined by the inertial navigation system.
The round-trip travel times of the laser pulses from the aircraft to the ground and back are measured and recorded along with the position and orientation of the aircraft at the time of the transmission of each pulse. After the flight, the vectors from the aircraft to the ground are combined with the aircraft position at the time of each measurement, and the three-dimensional coordinates of each ground point are computed.
The system can be operated at various scan frequencies and at different altitudes depending on the measurement accuracy required by the client and the regulated eye-safe range of the laser. By accurately timing the round-trip travel time of the light pulses to the surface, it is possible to determine the distance from the laser to the ground typically with a precision of 10 to 25 centimeters. Airborne 1 says typical operating specifications permit pulse rates of 2,000 to 25,000 pulses per second. These parameters yield enough data points to create a highly accurate digital terrain model. Each data point can be classified by type (ground, vegetation, building, power line, or other objects). Once classified, it’s considered simple to manipulate data, remove layers of data points, and create the digital models.
“Airborne 1’s technology gives us more-accurate pay quantities,” says Yurosek. “These days we get paid for more of the work we do.”
Old Friends
These days Trimble’s Site Positioning Systems have become old friends to some contractors, allowing them to track, report, validate, and control workflows from initial design to project completion. The systems use Windows-based SCS900 Site Controller Software to perform the usual job-site management tasks, including initial site measurement and verification of original ground levels, measuring site features, checking finished grade and laid material thickness, basic computing of stockpile volumes, staking out points, lines, and carrying out as-built site measurements. SCS Data Manager companion software allows for automatic transfer and management of data between the field and the office, making it possible for contractors to organize, manage, and track site measurement and stakeout operations for crews on multiple job sites.
Lehigh Valley Site Contractors in Easton, PA, is an all-Trimble shop. “Every thing we use—machine control, robotics—everything is Trimble,” says Survey Superintendent Dave Hubbard. “We used Spectra Precision products, and when Trimble bought Spectra we slid right over.”
Lehigh Valley Site Contractors does residential, commercial, industrial, and heavy highway, and Hubbard says he likes to equip his dirt foremen with SCS900 on Trimble’s TSCe data controller. “You want to keep things simple for them and easy to get into. Volume computations on a day-to-day basis are very important to us, but we also use it to check grade with equipment that doesn’t have GPS on it and for staking utility lines for our drilling rigs. I build everything in Trimble Terramodel, and it goes right into SCS900.
“One of the big benefits is we’re able to manage our material so much easier using this software because we know on a day-to-day basis how much material we’ve moved. Before we used to guess by how many trucks we moved. With this there’s no guesswork.”
Hubbard says the only thing left on his Trimble wish list is more storage capacity for the data collectors. “We have a lot of projects, and a lot of large projects, and that slows down processing. We want more memory, and we want more drive space so we can process things quicker.”
If storage is a problem, get a PC, says Jack Maclean, sales manager at Geologic Computer Systems in Waterford, MI. “Our system is a full-blown computer with a full Windows operating system. You can have an entire job in our memory. Most other systems use smaller storage areas so contractors or surveyors continually have to change TIN [triangulated irregular network] files to utilize data. And as you go from one TIN file jurisdiction to the next, you can skew off, say, seven-tenths of a degree or worse, kink it so your centerline is not exactly on the right plane. The surveyor will come behind you and the points will agree, but the intent of the guy who planned the job was to be on one continuous plane and that’s what we’ll give him.
“There are 10 companies or more involved in two-dimensional management of plot or building sites, but almost everybody is point based. We’re job based. What we’re more likely to be better at is surveying an existing plot, anything from 7 miles of four-lane highway to a 5-acre plot, then designing a pavement surface, which could include milling the surface and replacing the material or controlling the milling machine or controlling the paver replacement service, all within our software. What this means is the plan doesn’t have to be downloaded into a CAD [computer-aided design] file and engineered and then loaded back into the control system to set stakes to have someone build to.
“There are a bunch of survey-based systems that are less expensive than ours. But let’s say you’re an excavating contractor and you want to draw a topographical map of an existing property that’s not in anybody’s CAD system. With our system you can run points, say, every 5 feet at 20 miles an hour and spend two hours. When you’re all done you can then design the parking lot or excavation to come up to finished grade right on your vehicle, right on the screen, right within our software. Then use that data that you’ve designed to set stakes and have somebody do the cut and fill, or actually download the program into an indicator system or machine control system and do the work yourself. You can also offload it onto a DXE [drawing exchange engine] file into a CAD system and have an engineer play with it and then upload it back onto the bike and go back and make any corrections. It’s a real-time design tool.”
“What they’re good at,” says Curt Deibel of Deibel Surveying Inc. in Canton OH, “their uniqueness, is their ability to modify their software to fit your needs. You describe what you want and they tailor their software so you can do it. I had a particular application that I needed for doing an inventory of guardrail in a couple of counties for the state highway department. I needed to keep track of the guardrail in terms of what type, the linear footage, and what the geodetic coordinates were at the ends of the guardrail so that it could be mapped.
“I used GPS and a distance measuring device to keep track of linear footage. I used GPS rather than laser because I could use GPS locations of the ends of the guardrail; plus it was over a countywide area. I got the linear footage by the distance measuring device along curbs and so forth, and I could earmark the ends of the guardrail using GPS. What was important was that I was able to get Geologic Computer Systems to modify their software so I could use the distance measuring device. They’re especially good at integrating other equipment into their software. They’ll set it up for a particular type of GPS or something particular like a distance measuring device or traditional surveying equipment so you can read it into a computer program while it’s working and do real-time mapping. Another major appeal is that they can integrate all different types of equipment so you’re not stuck with one manufacturer.”
From the piece-by-piece automation section of the toolbox, contractors can select RoadEng from Softree Technical Systems in West Vancouver, BC, to get a better handle on material quantities. “Accurate estimates of quantities and material movement can significantly reduce the risks associated with earthwork projects,” says Softree President Craig Speirs. “A good estimate should account for material types, shrinkage and swell, borrow/waste movements, and special treatments. RoadEng allows cross-section information to be digitized from paper drawings or imported from CAD files. Plans, profiles, and cross-sections can be produced and material quantities calculated while accounting for shrinkage and swell. RoadEng also has a built mass haul display that shows balance points along with material movement directions—that is, overhaul, free-haul, and dead-haul.
“If the contractor’s got a total station and he’s doing some surveying himself, he can bring the data in that way. If he has plans and profiles, he can digitize them into the program and use that as his design. He can add the survey information he has to create a model. And if he starts at the beginning with plans from a DOT [department of transportation], for example, he can estimate what his costs are going to be on the job.”
Speirs describes RoadEng as a simpler version of Terramodel. “These kinds of CAD-like programs don’t appeal to a lot of outfits because you have to have a dedicated person to take advantage of them. With our program the contractor can come in from the field, call up a few cross-sections, calculate earthwork quantities, and go back into the field. We can train someone over the phone to use this. We don’t appeal to everyone, but we have the ease of use that is very attractive to a lot of people who don’t have the time or want to bother spending all day in front of a computer.”
“What RoadEng allowed us to do,” says Trent Aver, engineer/technician for the Branch County Road Commission in Coldwater, MI, “is calculate volumes from a survey that would take much more time to do by hand. Another great feature is that you can, say, take an existing road and widen it or add lanes or whatever and make the template for the proposed cross-section and apply it to the existing and you have all the volumes you need. And in the template you can separate it into shoulders, asphalt, base, sub-base, slope material, et cetera.
“The great part of this is that it’s basically built on templates. Softree puts them together for us, and once you have all the templates you need, the project can be very quick. If I have survey data of the existing road or area that’s going to be a road, then I just apply the template I want and basically the entire design is done for me except for geometrics. And the geometrics are pretty simple. You just click and drag points until you get to the specified horizontal or vertical value you want.”
Backing Into the Future
Leica markets Carlson Software’s SurvCE to use with its data collectors as well as for Leica’s machine automation. The software has loaded onto a model of the job site and shares the same files with the machine automation. “A lot of contractors will go out and do a topo of the site with a GPS base station and GPS on a pole or an ATV [all-terrain vehicle],” says Fred Rogers, Leica machine automation sales market director. “You can also collect the data, make a model, and compare it to what an engineering firm supplies you. Sometimes areas are missed by whoever does the topo. Sometimes the topos are three to five years old. Also as the jobs are being built, they can use SurvCE to check progress and for quantities.
“Once a topo is done, the design data can go into the data collector loaded into SurvCE, and they’ll actually see line work on the screen. They can stake out objects, say, a manhole cover. The center of the manhole is given a point number with a northing and easting elevation. They can navigate to that point and stake it out. They can do a stakeout line or an arc and do offsets from that. What this gives you is a one-man operation. Instead of having one man at an instrument and one man holding a rod and another driving a stake in the ground, you’re down to one person. And one of the beauties of the program is that guy out in the field actually doing the stakeout doesn’t need computer experience.”
“SurvCE thinks like surveyors think,” says John Hill, owner of Alphatech Surveyors Ltd. in Virginia Beach, VA. “And that’s because Jim and Dave Carlson have hired surveyors on the staff that write and test the software. That’s one thing; the other thing is I can get ahold of them. I’ve called them from the field with a problem, and in 30 seconds someone’s on the phone working with me. If it turns out it’s something they flat-out can’t fix, I can e-mail them the file. We’re using SurvCE with our Smart Station hardware. It’s 100% seamless.
“I suspect in the next five years everything in contracting will be GPS. I think companies like mine will see a whole lot more of the site prep work. We’ll take the engineering documents from the engineer and we’ll do the conversions necessary to make sure that the three-dimensional files are properly assimilated so they can be downloaded into the cab of the machines, and then we’ll do the base station establishment onsite in accordance with the engineer’s construction documents so the machines are all receiving the proper coordinates—because the contractor is going to have to have a base station established onsite reproducing the “xyz” they’re receiving and translating it into the cut or fill for the design elevations.”
Unless, of course, the contractor subscribes to a GPS base station network like Loyola Spatial Systems RTK-Net, which eliminates the need to set up a base station on the job. “Back in 1999 when Leica’s System 500 GPS was released,” says Brian Daniel, director of Loyola Spatial Systems, which is based in Virginia Beach, VA, “it had the capability of using cell phones for communication between a base and a rover. This eliminated a lot of problems with UHF [ultrahigh frequency] radio, which is pretty much line-of-sight and limited in range. Cellular suddenly opened up the door to covering bigger areas with your equipment. So we decided to take it to the next level and establish permanent reference stations sending data to an IP [Internet protocol] address on the Internet. At the rover end, whether it be a surveyor or a dozer, they have a cellular modem attached. The modem uses the cellular network to connect to the Internet where it goes to a specific IP address and receives the corrections. This real-time data is sold at a subscription price. The network is growing in Virginia with 40 rovers accessing the network on a daily basis, and our game plan includes Maryland and Washington, DC.
“The contractor only has to purchase one rover, which means he can get into GPS surveying at half the cost compared to conventional real-time kinematic [RTK] GPS. A full RTK system with software and training can be upwards of $50,000. We can sell them a rover and they can do the same thing for $22,000.”
Across the country, Clarkson Construction Co. in Kansas City, MO, is a founding partner with its subsidiary, Total Risk Management; and Laser Specialists is an RTK network that serves the greater Kansas City area with 10 base stations, each covering 22 square miles. “The frustrating thing about current GPS is when you arrive on a job site you spend 45 minutes setting up,” says Rodney Tantum, Clarkson Construction’s information technology manager. “Also, at the time we decided to get into this we were doing a job on a 400-acre site and we had some issues with communication between the base and the rover being used by the grade checker. That’s why the network made sense.”
“It’s traditional GPS,” says Brian Phipps of Laser Specialists. “You’re getting the dual-frequency coverage. You’re not walking around with a handheld [device] and using the satellites or a beacon. You’re getting the regular GPS that you would if you set up your own base station and got the dual set of corrections. A lot of contractors are buying a base for when they go out of town, and when they’re in town using the network they get twice the productivity for the same amount of money.” The Kansas City network is not restricted to equipment type. In Virginia, RTK-Net is exclusive to Leica users.
Journalist Penelope Grenoble O’Malley is a frequent contributor to environmental publications.
GEC
- January/February 2006
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