On Easy Street with Trimble Grade Control
by Jeff Winke
July 1, 2010
A Trimble GCS900 Grade Control System helps the dozer establish grade more accurately on the I-64/Battlefield Boulevard Project.
GPS systems drive early completion of Virginia interstate project
The
project sounds simple enough: widen a couple of roads and clean up an
interchange.
However, in the case of the I-64/Battlefield Boulevard Project in Chesapeake, Va.,
the work posed a challenge. Where the two roads meet, the interstate’s heavy
traffic flows between Suffolk and Virginia Beach, and the
crossover road is a busy local artery.
The Virginia Department of Transportation (VDOT) commissioned the project and
hired the construction-consulting firm McDonough Bolyard Peck of Fairfax, Va.,
to manage it.
“The VDOT project’s goal is improve traffic and reduce congestion,” says Kyle
Myers, GPS manager for E.V. Williams of Norfolk, Va., the primary contractor
responsible for the project.
Beating the Deadline
“We completed all the underground utilities, did all the dirt work, brought in all of the stone and managed the bridge-building and concrete subcontractors,” Myers says. “In addition, we also had a $2 million change order, which was to add a barrier wall on the westbound side of I-64 to separate the collector/distributor lanes from the mainline traffic flow to reduce congestion.”
Using a 24-person crew and six to seven subcontractors, E.V. Williams completed the three-year project, including the additional change order, six months ahead of schedule.
“A key to the efficient production and coordination of this project was our ability to perform dirt work quickly (and) accurately and complete tasks in between the work our subcontractors needed to do,” Myers says. “Our use of GPS grade control technology was major.”
E.V. Williams had acquired Trimble GCS900 Grade Control Systems for its motor grader and several dozers a few months before the I-64/Battlefield Boulevard work began, and all of the Trimble-equipped machines were used on the project.
To make sure the project would go well from the start, E.V. Williams, along with its Trimble dealer, Spectra Integrated Systems Inc., arranged an initial meeting before the project commenced.
“Our Trimble dealer could see a potential train wreck ahead if we didn’t get everyone on the same page,” Myers says. “The surveyor was using a different system from Trimble, and the bridge builder had a third system. So, as the principal contractor we pulled everyone together, including VDOT, and established how we we’re handling the base station, calibrations, site models and the control points. Everyone agreed to it, and everybody matched.”
Shot in the Dark
“The GPS system allows us to work at all hours if needed. We were able to construct one area of our project, the eastbound extension, completely at night, using only a GPS grader. You couldn’t have shot grades in the dark. It just made life extremely easy,” Myers says.
“Here’s another example,” he continues. “We had one of the on-ramp loops completed from virgin ground all the way to the point of blue-top stakes. There was one dozer operator. We backed the dump trucks up to him, he filled it, and he pushed in the slopes all the way out until he boxed in for subgrade. And then, we had our surveyor—just one guy—come in. You can see how much time, personnel and money it saves.”
Myers says E.V. Williams did face a challenge with the location of their base station, a Trimble SPS850 Modular GPS Receiver.
“The project was roughly two miles long, and we were trying to get our radio signals through high-tension power lines in order to reach the entire project,” Myers says. “We ended up erecting a 90-foot tower topped with a high-gain antenna in the lay-down yard about a mile way.”
E.V. Williams used a series of repeaters to reach the project site, and Myers took it a step further by putting the base station on the Internet so the company could use it on a rebroadcast basis for at least four other projects during the life of the I-64/Battlefield Boulevard Project.
Designed to Succeed
When he looks back at the completed interchange—which resembles a Celtic cross with looping on-ramps and exits—Myers says everyone who worked on the I-64/Battlefield Boulevard Project is proud that they were able to keep traffic flowing throughout construction and the finished result is so smooth. The project has received awards for its elegant engineering.
“The rideability is unmatched. When you come down the highway and hit that new section, it’s completely silent in your vehicle; there’s hardly any bumps,” Myers says. “The sub-base is dead on. With the Trimble GPS systems, our average error on each break-point and edge of pavement for four miles of roadway (two miles each way), times five lanes wide, was a quarter inch.”
Using Trimble technology, E.V. Williams was able to take a complicated interchange reconstruction and widening project and make it seem easy.
“It’s unbelievable … how much time and money it saves you when you go from at least a four-man crew, an operator and two workers pulling the string and one checking grade, to one guy on a machine, no stakes,” Myers says. “It’s just uncanny the amount of money that can be saved.
Jeff Winke
Jeff
Winke is an independent construction writer based in Milwaukee. He can be reached through www.jeffwinke.com.
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Title: Great Story
By: Frank Baker
Posted: July 7, 2010 4:07 PM
Machine control is picking up steam. Accounts like this show that it's time for contractors to get onboard to stay competitive.