Wanasek Corp., Burlington, Wis., has found that GPS is adding surprising productivity and increased quality to its already-excellent earthworks operations.
The company began in 1949 when Louis Wanasek purchased a single tractor backhoe to dig a sewer lateral for his own home, then began digging for others. James Wanasek continued to build on his father's success and has directed the company's growth into one of the most recognized and respected excavating contractors in southeastern Wisconsin.
Today, James and John Wanasek direct Wanasek Corp., a diversified excavating company that provides a full range of excavating and related construction services, including: sewer and water construction and repair, grading, site work, trenching, indoor excavating, vacuum truck services, crane services, low-boy and dump trucking, roll-off dumpsters, and asphalt reclaiming.
Although Wanasek still uses traditional stakes, lines and transits for many of its grading jobs, the company increasingly uses GPS to accurately cut, fill, grade, slope, and contour in its earthwork projects.
On some projects, handheld GPS "rovers" are used to accurately place the traditional marking stakes and to verify the accuracy of completed grades and elevations.
On other projects, however, GPS-equipped dozers work the entire job from start to finish without ever needing a single stake.
Wanasek has rapidly increased both its use and inventory of GPS equipment over the past three years, based on the performance results.
Wanasek GPS coordinator Nick Mianecki is a civil engineering technician whose experience includes five years in surveying and several years of operating equipment. He says, "We researched extensively before investing in GPS, then started out by purchasing one basic system, a Trimble, with a handheld rover. When we saw how GPS increased both the productivity and accuracy of site work, we purchased more. We now own two rovers and three dozer-mounted units, all working nearly every day.
"The system programming and operation were fairly easy to learn," he says, "and we've received great educational support from both the manufacturer and our local dealer."
On a non-GPS job, excavating is controlled by stakes, tapes and lasers. A surveyor measures key locations on the job site in relation to fixed reference points, such as roads or buildings, then marks them with stakes that indicate the location, cuts, fills, elevations, and other important information.
If a stake is bumped or moved, the surveyor must re-measure in order to put it back in the correct location. Also, grading at the correct level from one stake to another depends on the skill and eye of the equipment operator. The industry standard of accuracy is 1/10 foot, or 1.2 inches, so getting the elevation and slope just right sometimes takes several finishing passes.
GPS systems locate any spot on a job site to within an inch or less by using signals from satellites and a single base station that can be located anywhere on the site as a fixed reference point.
At its simplest, a GPS system with a handheld rover can be used to position traditional site-marking stakes. In this case, the GPS system replaces the measuring tape and line.
But a more extensive system mounted on a dozer or grader can enable a contractor to finish an entire project without pounding a single stake. A screen in the operator's cab displays all the information an operator needs to cut, fill and contour. In some cases, the GPS system will even control most of the hydraulics on a finish-dozer, adjusting the blade's tilt and depth to make a precise final cut, often in just one pass.
One key to success with GPS is accurate conversion of engineering drawings from the CAD programs used by architects, engineers and designers into the GPS computer's language and memory.
The GPS system uses the CAD drawings to generate a 3-D digital terrain model (DTM) that has contour lines showing elevations, slopes and contours of the finished site — and the work needed to create them.
Mianecki says he typically reviews the DTM to make doubly sure it matches the approved paper prints — which are the only form of drawing approved by municipal governments. "If the DTM is off, the entire project will be off," he says.
To make life easier for everyone working with Wanasek's GPS system, Mianecki has developed a universal color-coded system that puts hard lines like buildings, existing roads and toes of slopes in one color, elevation contours in a second color, and center lines in a third color. The standardized color system enables any operator to climb into any dozer and clearly understand the drawing on the screen.
When the DTM is done, Minaecki loads it into the computer of each GPS-equipped dozer working on the job, and also into the portable handheld "rover" station used to map and check work on the site.
The only manual location required on-site is initial setup of the base station. This unit becomes the reference point for all the other points on the project.
The GPS base station and the orbiting satellites send signals to two receivers mounted at the corners of the dozer blade. The receivers feed the signals to the in-cab computer that compares their actual positions with the correct position on the drawing stored in the computer memory. It then tells the equipment operator how to correct the path in order to make the actual position match the specified position.
One advantage of the GPS system is that it operates by radio waves, so the base station need not have a clear line of sight to the equipment it is guiding. It works effectively over and around hills and other obstructions. Wanasek's system has an effective range of two miles, enabling it to cover a relatively large site. The frequency emitted by the base station can be changed so there is no interference with any other system working on the same site.
Another advantage of the GPS over conventional methods is its ability to work at night. Says Mianecki, "Before GPS, it was difficult to do finishing work at night. Stakes are hard to see and the perspective is different. When we had a two-shift job, we used to do only big cutting and earthmoving on the second shift, so the finishing work could be done in daylight during the first shift. With GPS, we can do finishing work whenever it's convenient, because the in-cab screen guides the operator."
Wanasek put in its first GPS unit at the beginning of 2005. In two-and-a-half years, says Mianecki, there has not been a single day of delay because the GPS system was not working properly.
He also says that the system Wanasek purchased can not only tell a dozer operator where the cuts and fills need to be, but will also tell them how to angle the blade and how much to drop or raise each corner. One of the finish dozers is equipped so the GPS system can actually perform all of the adjustments automatically, without the operator having to touch the controls.
For Wanasek, the GPS system not only increases ease of operation, it also increases quality and speed. Before GPS, operators had to use judgment and feel to cut a level line between stakes. Now, they have a continuous guide on the in-cab screen that tells them when their blade is on line and when it's starting to stray. The GPS guided dozers always meet the industry standard tolerance of 1/10 foot (1.2 inches), and frequently are twice that accurate (5/100 foot, or 6/10 inch).
Wanasek recently demonstrated the effectiveness of its GPS system while enlarging and reshaping the Indian Creek flood-control channel that protects a residential neighborhood in Fox Point, just north of Milwaukee.
The extensive project required Wanasek to install new box culverts for a roadway crossing the creek, to steepen the flood canal's sides, to create bends in the canal's straight path, and to re-make a 6-inch-deep low-flow channel that carries the creek's normal volume.
Although Wanasek got a late start on the project, the company has blazed ahead of schedule, thanks in part to one of its GPS-equipped Caterpillar D6G dozers.
The dozer with the GPS system marks the required contours, and a Kobelco SK330LC hydraulic backhoe excavates the larger amounts of dirt to cut the bank slope close to final shape. The GPS-equipped dozer then forms the 7-foot-wide central low-flow channel, widens the bottom of the larger flood-control channel, and grades the channel's embankments to their final contours and slopes.
Initially, working with stakes and a smaller dozer, the crew was finishing the expected 50 linear feet to 100 linear feet of channel per day. Since switching from stakes and manual measurement to the GPS-guided dozer, Wanasek has been completing nearly 300 linear feet of channel daily. And the grading accuracy has consistently been 5/100 foot — nearly twice the required precision.
Said Mianecki, "This job presented some unique challenges, with a wide range of contours and turns. It would have been very difficult to stake, and the stakes would have had to be moved and re-set constantly. The GPS system lets us work accurately without stakes, which really increases productivity."
Dozer operator Mike Bottoni, a 21-year veteran operator from Operating Engineers Local 139 in Pewaukee, is running the dozer on this job. Bottoni feels that GPS-guided dozers are the future of site work. "I've been running this unit for three years, now, and the GPS takes the guesswork out of the operation. It makes things more accurate and faster. For the final trim, I can run on full automatic and the system's onboard computer controls all the blade functions. An operator still needs to know what is going on, but this system makes the finish pass a lot faster and more efficient.
"When some old-school operators tease me about running an 'automatic' dozer, I just tell them that at the end of the day, I'll have done more work than they have, with better accuracy, at a lower cost. That usually makes them look at things in a different light."
Mianecki concurred, "Certainly, moving into GPS requires an investment. But if a company has enough work to keep the system busy, the productivity gains will make it worthwhile."
Editor's note: The system used by Wanasek is a Trimble. Other major manufacturers of GPS systems include Topcon and Leica.