High-Tech Approach To Pile-Driving
What caught John F. Quinn's immediate attention when he first pulled into the Destiny USA parking lot in Syracuse, NY, wasn't the shopping mall's existing building. It was the immense open area, sun-drenched in July, that had no trees, no buildings or structures of any kind.
"It was a perfect opportunity to use global positioning system (GPS) technology, something I had never done before," Quinn said. As project surveyor on the mall site for Cianbro Corporation, a Syracuse-based construction management company that is one of the largest contractors on the East Coast, Quinn's responsibility was to make sure that more than 1,200 huge pilings were driven down in precise locations for a 300,000-square-foot, first-phase expansion of the mall. When the entire project is finished, Destiny USA's total square feet will be 1.3 million with a 10-acre footprint.
The grid is a 40-foot grid in column lines, Quinn explained. On each column line the majority of the pilings on the job site are three-pile caps, although some are four-, five- or six-pile cap configurations, he said.
"I came on this project by myself," Quinn said, "with no other surveyor to help me. As it turned out, this was a green project from the very beginning, so they were open to my suggestion to use GPS equipment."
In fact, Destiny USA uses an on-site wireless mesh network that provides for real-time communication between architects and people working in the field. The job site is paperless and all vehicles, from trucks to cranes to generators, run off biodiesel fuel, said Quinn. "We run 100-percent biodiesel in the summer, but in winter we have to change the mix to about 80-percent biodiesel with an additive."
If Quinn had used traditional surveying rather than GPS, he explained, he would have had to "set up a gun at an occupational point, then throw a control point down into the job site and constantly keep doing this just to see what's happening several yards away."
All this would have had to be done across a job site where the pilings are horizontally positioned so a crane can drag them across the ground, get them to the desired location and lift them to a vertical position to be driven into the ground.
"These pilings range anywhere from 190 feet to 300 feet," Quinn said. "We cut all our beams to 70-foot lengths. We take two 70-footers and weld them together to make each one 140 feet. Those beams are carried over to where the crane is working. The crane has a vibratory hammer attached to the crane boom, and the crane operator grabs hold of the piling with a regular cable and lifts it. Once the piling is in a vertical position he raises the vibratory hammer above the piling, brings the hammer down and delicately attaches it right to the piling. Once it is clamped on, other arms swing around and holds the piling in place. At that point the vibration hammer drives the entire 140 feet right into the ground. The whole thing takes about 10 minutes," Quinn said.
When all that is done, he said, a second crane comes over, attaches another 70-footer on top of that, which is welded onto the first one. Another crane, equipped with a diesel hammer, seats the piling into the bedrock.
"The mechanical engineers on this site measure the blow-counts. When it reaches the correct number of counts they know the piling has been driven to the point of refusal," Quinn said.
Meanwhile, in the office each desk has two screens sitting on top, Quinn pointed out. "There is a regular laptop, a monitor off to the side and a tablet, which is like a laptop that can be used to take notes on."
During intense activity in the traditional work area, he said, "There are many things in the way and things such as stakes in the ground are always being run over. By using GPS on this project I didn't have to worry about any of that."
Once Destiny USA agreed that utilizing GPS was the way to go, Quinn called in a number of firms to demonstrate their equipment. The company he decided to go with was Topcon Positioning Systems, an organization that he was familiar with from previous jobs. The difference this time, however, was that Quinn had never used GPS before.
Rolf Witt, who is with Admar Supply Company, a Topcon distributor in Rochester, NY, said, "The customer needed a one-man survey system, so we demonstrated and sold him a Topcon GR-3 GPS system."
The GR-3 has access to 72 channels, tracking both GPS and GLONASS constellations as well as the foundation to receive signals from the satellites of the Galileo system that is still in testing, the Chinese Compass system, also in testing mode, and other signals as they become available. That way, Witt said, "You know the equipment you buy today will not be obsolete as more constellations come online."
In the Destiny USA application, no installation was involved. "Survey equipment was all that was needed," Witt noted.
"I bought a base station and a rover," Quinn said. "I have my own control point, which is set up away from all the jobsite activities. Each day I set up the base station, which takes only a couple of minutes, turn on my rover and when it is up and running I have all control points and real time kinematics (RTK) and instantaneous information as to where I am. With the rover you can walk right up to every single point and put a 10-inch spike into the ground, and put a ribbon on it that lets you know which piling it is. If there is existing pavement, I use a magnetic nail with ribbons. You just walk up to the point you want to lay out and stake it. It's quick and easy and great," Quinn commented. "I only have to worry about one control point, although I have others that I check occasionally."
One of the reasons Quinn decided to go with Topcon, he said, was the support technicians. "One of them used to be a land surveyor. He came here with the demonstration equipment and he has been my support person all the way. If I have questions he can relate to them. He helped me set up the positions, showed me how to use the software, how to load it onto my laptop. After that everything has been very simple. All my files are up to date, and I know where the pilings are."
Since Quinn arrived in July 2007 and the pile-driving started in August, one thing has been apparent. "Everything goes at a faster pace. Every firm should be looking at this technology. The Topcon system did everything I expected of it, and I knew up front the savings were going to be tremendous. You eliminate a second surveyor, so you save on surveying costs, you save on materials and you save time."
Although the Destiny USA expansion schedule ran into some delays, Quinn said they are now on target and doing well. The schedule calls for him to leave the work site at the end of April, he said, but if there is a need, "we will accelerate the schedule to make sure that whatever date it is happens."
When he does leave the project, Quinn doesn't know what challenges he will face next. But whatever they are, now that he has tried GPS, he's sticking with it. As he said, "The technology is faster, better and smarter. It's the only way to go."