Whether it's GPS, fixed base, or simply laser application, today's surveying technology makes it easier to move earth more quickly and more accurately..

By Joseph Lynn Tilton

For as long as most can remember, getting a site properly surveyed was the second step in preparing a site for construction. The first was getting vegetation out of the way of the surveyor and his assistant. Unfortunately, the task of mechanical surveying also kept machine operators waiting several days, even weeks, before they could get started, only to accidentally blade out the long-awaited stakes. This sometimes yielded finger pointing, especially when deadlines were short. Fortunately, that's all behind us now. Today local positioning systems (LPS) - fixed electronic computer-aided design (CAD) survey systems - make excavation quicker and more accurate, and there are no stakes to run over.

750,000 Yards in 21 Days

When Wal-Mart asked for bids in 2000 for a proposed distribution center in Harrisonville, MO, just south of the Kansas City metro area, Damon Pursell Construction Company won the nod for the 180-ac. site work. But delays at the front end left the company with just 21 days to move 750,000 yd.³ "GPS [global positioning system], with Carlson Software's SurvCadd CES as an engine, has become a very valuable tool to us," declares Gary Sheumaker, estimator and site project manager. "We had 20 scrapers on the site, and one man kept up with them. He used the electronic rover mounted on a Kawasaki Mule. His job provided machine operators instant information as far as location and grade control. He went throughout the site keeping everyone on track."

Final grade tolerances for the grocery warehouse and distribution center included one-tenth of an inch for the parking lot and stormwater retention structure and half of a tenth for all buildings. Still, company reputation helped win the bid. That's because Damon Pursell Construction has been in business since before World War II. It has completed numerous projects in the region, including projects for major railroad companies, the United States Army Corps of Engineers, drainage districts, port authorities, local landfill operations, municipalities, private developers, and Departments of Transportation (DOTs) for Kansas and Missouri. Sheumaker, himself, has 30 years in the industry.

What does he think companies should look for when working with GPS? After admitting that GPS is relatively new with the company, Sheumaker comments, "One of the big things is to have the full plan on the computer in front of you out in the field. That will save you a lot of trips to the office. You can check on any points, such as the corner of the building, and automatically get an update, including how far yet to cut to achieve grade.

"If you do highway work, you'll want GPS that's compatible with AutoCAD and Microstation." He also reports that anyone with a fair amount of experience with electronic instruments will find it takes but a few days to get used to GPS. "Even before you start moving dirt, you're saving time because setup takes just 30% as long as with traditional staking. During the Wal-Mart project, we had no need to set up [again] anywhere on the site - and no stakes accidentally [were] lost because there weren't any to lose."

But they still keep a traditional transit. "That's for when we're having trouble getting satellite reception, such as under a canopy of trees, in a narrow valley, or up near buildings. We'll use it a whole lot less, but we still use it."

Supplier Bruce Carlson, president of Carlson Software in Maysville, KY, notes that software standardization in design files is making the switch to GPS even more affordable to contractors. "For example, in the area of automated grading, the emerging common form is DXS of 3D faces. This format is read by a number of grading products, so it is becoming a de facto industry standard for machine operators." That, in turn, is driven by digital terrain model and a plan view of the site, which automatically drives the grader, dozer, and hydraulics, bringing the site to grade automatically using the total station survey data.

"In staking out projects, surveyors are setting points in the field that correspond to key positions on the plan, such as building corners, center lines, edge of pavements, et cetera. One emerging concept is taking the drawing itself to the field." Carlson points out that the technology is there to handle unexpected field conditions without having to run back to the office to get more numbers.

But he cautions, "What's missing is DOTs and civil engineering companies not making digital TDMs [time-division multiplexers] and sending them to contractors to use and grade with. Instead the contractor must reinvent the wheel. Coordination of information is the biggest missing link in our industry."

So what would happen in an ideal world? Says Carlson, "The digital data for the terrain would flow directly from the designers to the contractor, directly on to motors or graders. Let contractors do what they do best: build it and not have to re-create the design on paper."

Low-Cost GPS

While GPS is new to some, Rod Johnson, survey systems product manager for Thales Navigation in Santa Clara, CA, reports that it's been in use for a quarter-century. "We were around when a GPS system was expensive to build. Now contractors can buy low-cost systems for doing topography, topographic surveying, and control surveying. For as little as $5,000, a contractor can lay the groundwork for a lot of heavy metal very fast."

Furthermore, it's becoming simpler to use. "Someone used to optical equipment can be doing productive work in two to three days. It's designed to be simple enough to learn on your own. You start with the software and follow the avenues that software takes you." Johnson explains.

But, as with heavy metal, the bigger the machine, the quicker it does its job - and the more it costs. "The low-cost system takes some time processing information, but a real-time system, which can run about $30,000 or more, speeds the design field 10 times that of traditional staking."

Bruce Herter, product specialist with Eagle Point Inc. in Dubuque, IA, comments, "What I see happening is the industry already has started going to machine control systems based on GPS so they will need some kind of GPS to give them the control that's there. They can combine it with their machinery and basically have a stakeless job site." But he cautions that contractors should shop around. As in any other industry, there can be a considerable price spread between two systems that essentially are identical.

Accuracy, he reports, is two-one-hundredths to three-one-hundredths on the horizontal and four-one-hundredths to six-one-hundredths on the vertical. "As far as doing layout goes, you double productivity. There's no waiting on the survey or the surveyor. And it seems more and more contractors are adding surveyors to their crews instead of subbing it out. With staking, a survey crew can put in 100 to 150 points a day; with GPS they can easily put in 300 to 400 in a day."

So when it comes to GPS equipment, what's his counsel? "Get something that's accurate, rugged, and reliable; something that can take weather conditions. For example, rain can shut down a job site, but with a rugged system, the contractor can keep on surveying - if he wants do. That's because the receiver and the controlling units are submersible. A rugged receiver sitting atop a 2-meter pole can survive a fall if a sudden strong wind blows it over." With accuracy demands as close as two-one-hundredths to three-one-hundredths, dual-frequency receivers are preferred. Fortunately, a crewmember can learn to use the equipment in as little as an hour, provided he's already familiar with the software. If not, then it takes about a day.

Tom Goodson, vice president of Goodson Construction in Barlingtan, SC, reports that his company went from stakes to GPS two years ago. "We got it from Bruce. We had a job in Myrtle Beach, 5 miles of a six-lane highway, the Carolina Bay Parkway. It was one of the biggest we'd ever taken on. With GPS our tolerances were more accurate, which saved us in time as well as in cost of the granite we put down when we got to grade." Goodson admits that making the change isn't problem-free, that occasional glitches occur, but he wouldn't return to blue, or even red, stakes.

Robotic Staking

Goodson continues to find ways to update his operation. "We've had a robotic station survey system for about three months, which is a lot closer in tolerances than GPS. Our preference is to use GPS when grades do not have to be close, but for fine grading, for base material, a robotic station is preferred. When we had to move 800,000 yards of dirt for an 80-acre paper-mill lagoon last year, GPS was ideal for that. We had to do it in 45 days, and our people put in 12 to 13 hours a day, seven days a week." A drought prompted the emergency because the river was so low that regulations prohibited any direct discharges. Thus, the mill had to find a way to hold the discharge until rainfall recharged the river.

"We brought it in six to seven days ahead of schedule. We got no bonuses, but we had a happy customer," Goodson reports.

Taking GPS to the Air

But what if the terrain is so 3D itself that it's difficult to traverse? That's when project managers, whether private or public, call on Jean Carter, president of Aerial Data Services in Tulsa, OK. Carter, who has been with Aerial Data Services for 29 years, states, "In order to start a big mapping project, you have to have a number of known locations on the ground that are usually government markets. They have to be surveyed in, either through conventional [means] or GPS. We've been using GPS for 10 years. We can give the client a more precise map in a shorter time.

"We had a 10-mile-long highway project in rugged terrain we did with GPS in three days rather than two weeks. We use GPS on the ground for ground points then also have two GPS receivers in the airplane. Every time we take a photo, we have a location of the ground location of the center point. If the site is no more than a mile wide, we will shoot - depending on the ground and accuracy required - 30 to 45 photos. Those are taken from a minimum of 1,200 feet up to 20,000 feet."

Carter continues, "The amount of time in the air is minimal. Everything that needs to be done can be done in two hours. But that's just the beginning of the process. Seven people will touch it, from developing the film to putting it in the software package the client needs." They typically deliver the data on a CD in the language spoken by the client's computer.

She comments, "We're just a contractor. If they have survey crews, then we use our survey crews to work with theirs. If the client is going to do the ground control, then communication is vital. If they don't, then we have people ready to walk the terrain."

But, as with ground GPS info-gathering, ground cover can be a problem, whether it's large trees, high weeds, grass, or even snow. "The majority of the site must be cleared of obstruction before actual aerial mapping is possible. We have a Cessna 310 for aerial work, but we sub out the ground clearing." The only limitation for aerial GPS, Carter explains, is that it is not economical for a job smaller than 80 ac. "We map entire cities, entire counties."

Laser Role in Accuracy

Murray Lodge, national sales manager for Topcon Positioning Systems in Pleasanton, CA, notes that, thanks to something as simple as a laser beam, a contractor can bid farewell to stakes. "The laser guides the machine's hydraulics, giving the blade involved a more sure eye than with an operator. It takes the guesswork out of leveling an area. Now, instead of stubs in the ground every 50 feet, a laser can provide a constant plane up to 3,000 to 4,000 feet in diameter. You don't lose reference points when you bring areas up to grade."

Lodge explains that sonic sensors make grading a road much easier than with stakes. "Sonic sensors will save anywhere from 25% to 35% in time on the project. Sonic string line can eliminate up to three-fourths of the required staking on a road project while at the same time providing a more consistent grade. You must set up at least one run of hubs to establish a physical reference."

He emphasizes that moving from two-dimension to three-dimension helps a contractor know where he is on the job in real time. "You reduce, even eliminate, the chance of moving material more than once, which can be costly. The more difficult the site is to grade, the more productive a three-dimensional system becomes."

So what should a contractor look for in a 3D program? He replies, "Have someone onboard or partner with someone who knows how to create a 3D model. If that person has design software experience, than a half-day seminar can be enough training. The goal is to keep the program as simple as possible."

Meanwhile, the operator sees the job on the screen in front of him in the cab. There is no more getting in and out to look at plans. "But it needs to be flexible for any updates. More and more contractors are going 3D; those who don't soon will be unable to compete with those who have."

3D Contractor

After taking on sonic, then laser, Grading Unlimited Inc. of Hillsboro, OR, has gone 3D with Topcon 3D-MC (Three Dimensional Machine Control) LPS. "We were focusing on state highway projects," reports John Gillett, estimator with Grading Unlimited, "but the industry changes so much that we have gone back to commercial work, such as airports, commercial warehouses, and residential subdivisions. We move where the market is at, and we've replaced people with electronic machine controls on our graders." Think of it this way: the cost of an employee for one year versus the cost of technology machine control that gives you productivity, engineering, and material savings in return; sometimes this is the edge you need to be successful on a project bid.

Gillett recalls, "When we first started operation in 1981, we used red tops and blue tops every 50 feet. Operators weren't supposed to hit them, but they did. Then when you add in tolerances of plus or minus four-one-hundredths for state work and two-one-hundredths for airport work the old way by eye and the seat of the pants, that took an extremely skilled operator."

The Topcon Sonic Tracker II is a versatile tool that combines elevation and cross-slope control in the grader with the help of the Topcon RT-5Sa dual-slope rotating laser. Gillett observes that when they put on a Topcon sonic tracking system on their graders, there was a 300% increase in productivity, a 50% savings on engineering cost, and a 10% savings on materials.

Staying at the forefront of technology has helped this company remain successful. "We used the Topcon Three Dimensional Machine Control System for our graders and contracted the Redmond, Oregon, airport last year, which consisted of two contracts. The first one was for 378,000 square feet for the US Forest Service, and the second contract was for 1,225,316 square feet for the federal government. Both projects were completed without blue tops. The only staking we needed for our grading were control points every 500 lineal feet to 750 lineal feet apart to set the Topcon GRT [geodetic robotic transmitter]-2000 for a stakeless grading surface at designed tolerances or better. The savings on just survey alone was $40,000. The function of the GRT-2000 is simple: A field computer continuously uploads design information to the geodetic robotic transmitter. The geodetic robotic transmitter tracks the grader comparing its position to the actual design grade. Grade information for that exact location is sent to the road grader for the Three Dimensional Machine Control System."

But another aid that Gillett sees with today's technology is how it helps an operator financially. "We're working with the same prices we were 20 years ago. We just have to work smarter and a lot faster for the buck."

After agreeing with the other contractors that adapting to the technology is easy, he points out, "I think the biggest thing to overcome with the new technology is that the owners - being the county, state, and federal agencies - are not aware of it and are passing up a great savings on every project site. Anyone in the civil construction projects also has to be a salesman and a teacher. We have to have the owners understand the new age of grading.

"The Topcon 3D-MC opens avenues for specializing in complex, challenging construction projects for demanding owners giving us greater production, which reduces the construction impacts on scheduling and cost. It creates long-lasting, repeat-business relationships with our clients by serving their needs and by delivering on our promises."

The magnetic-mounted laser receiver provides visual feedback to the machine operator to indicate the accurate grade position.

Gillett reports that when they put on a sonic trapping system, it tripled production and boosted the quality of work. Referring to the airport project, he says, "It was our first job for the year and was a 378,000-square-foot parking ramp for the firefighting planes operated by the US Forest Service. It was a bit of an odd job. We had to pulverize existing asphalt and move it 6 inches from one side to the other to balance it out." They ended up recycling 32,000 ft.² of pulverized asphalt before applying new material.

But 3D is important for bid preparation. Not only does it help to detect mistakes in the original ground survey, it also is a way to help prepare the public for the project. "Many contractors are using the technology, but some prefer to hire others who use our product full-time and so can respond even more quickly," notes Mindy Beiginng, sales and marketing manager for 3D Nature LLC in Arvada, CO. (See sidebar for more information on 3D technology.)

Newer Positioning Systems

And one of the newer systems is LPS. "That's a 3D machine control system that doesn't depend on satellites," explains Gillett. "After all, movement in satellites can vary eight-one-hundredths to sixteen-one-hundredths throughout the day. We're using a GRT-2000 for our 3D control. And the general contractor at that airport project said it saved them $40,000 on their portion of the project, with a total of $100,000 saved on that project alone." Grading Unlimited had gone to LPS (or total station management) just a year ago, after a number of years of using a string line and sonic trapping system.

"We aren't getting reimbursed by the contractor or owner, but we get reimbursed in increased production and greater quality of work. We don't have to go back and redo work that has failed because failures have been eliminated," he points out.

One of the 3D suppliers, also a part of the field of laser level work early on, was LSR Inc., in Ft. Lauderdale, FL. "LSR is short for laser," explains Greg Fearon, vice president and general sales manager. "Our focus is on pipe laser to the utility and excavating contractors, but we're also broadening our focus into new technology to help contractors position exactly where they are. They need to know building corners, how to lay out buildings, et cetera. New technology is coming out all the time."

Fearon emphasizes that while buildings can stand perfectly plumb thanks to 3D technology, "You still have to absolutely rely on the user for accuracy. Users must completely understand whatever system they have so they can get full benefits from using it. Newer technology is easier to use and much less expensive, so a majority of grading and excavator contractors do the surveying themselves. This gives them more control of the project. For example, they're not waiting for someone else to reset a grade stake a motor operator may have knocked over."

Combining Systems

Alan Sharp, segment manager for Trimble Inc. in Westminster, CO, says grading and excavation companies are combining systems, with GPS and total station management being two of the most popular. "Typically in the field today, most GPS use different databases, different facilities. Our goal is to bring the two technologies together to provide a single database and single user interface and to provide base measuring systems to the same level of functionality." This makes it possible for multiple crews to operate on the same site, using the same interfacing, thus speeding up the design portion of the project.

Sharp points out, "It gives contractors terrain models to calculate volumes on-site. There's no need to return to the office and work with charts and graphs. They can spend more time in the field and less time in the office." In addition, contractors can discover mistakes in the prep work as they prepare their bids. This helps reduce bid error so the contracts they win really are winners.

Journalist Joseph Lynn Tilton specializes in land and building issues.

GEC - July/August 2003

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