September 2009

So Much Material, So Little Time

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Photo: Richard Ries
Equipped with GPS, Wright Brothers’ excavators were able to dig to grade, eliminating the need for extensive grading after the material is removed. The time savings were critical on this job.

By Richard Ries

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On July 7, 2008, Volkswagen announced its intention to build a new assembly plant in Hixson, TN, a suburb of Chattanooga. A big assembly plant. A really big assembly plant—three interconnected buildings with 1.9 million square feet under roof. Of the 650 acres on the site not occupied by structures, 240 acres will be made into parking lots. The total investment is estimated at $1 billion and the facility is expected to create 2,000 jobs. Initial production will be about 150,000 cars per year with full production running about 200,000 cars per year. As with any such project, the goal was to get from site announcement to fully operational in as little time as possible so that VW could start production and get some value from its commitment.

Once site selection had been determined, the next step was site prep. The scope of that challenge is revealed with some simple math: 5.5 million cubic yards of material divided by 110 days equals 50,000 cubic yards per day. That’s what Wright Brothers Construction Co. Inc. of Charleston, TN, was up against. And it wasn’t just a matter of volume. The company wasn’t merely pushing millions of cubic yards of dirt over a cliff. No, the resulting area had to be finished to spec. Tolerances were plus or minus 0.25 inches for the building sites and plus or minus 0.5 inches for the parking areas.

When information was gathered for this article, two weeks before the deadline, Wright Brothers was slightly ahead of schedule for the building pads and right on schedule with the overall grading. That’s impressive. More impressive was the fact that the company was beating specs. “In the areas where we’ve used millimeter GPS systems, we’ve held accuracy to one one-hundredth of an inch,” said David “Hootie” Houghton, the engineer in charge of GPS and surveying for Wright Brothers. That’s 25 times tighter than the company’s most demanding spec.

Keys to Success
How did Wright Brothers accomplish this feat? First, the company came with plenty of experience from similar jobs, including the Bridgestone Firestone North American Tire plant in Warren County, TN; the Boeing facility for the manufacture of the Delta IV launch vehicle in Decatur, AL; and the General Mills warehouse in Chattanooga. Second, the timing was right and Wright Brothers was able to bring 70% of its fleet of equipment to this job.

Third, and perhaps most important, Wright Brothers had extensive experience with Topcon Positioning Products technology, including working on five projects using millimeter GPS (mmGPS) in the three years preceding this project. At the Volkswagen site, the company had nine dozers, eight excavators, and a grader equipped with Topcon products. Two of the excavators and one dozer were sporting new 3D machine-control systems bought for this job.

Wright Brothers enjoyed three huge advantages from its extensive use of machine-control systems. First, the learning curve was shallow. “New operators can run our Topcon-equipped machines in a matter of minutes and be cutting grade within a few hours,” said Houghton.

Even seasoned operators found the systems easy to use. Tim Bingham had 22 years in the industry before joining Wright Brothers three days before he was interviewed for this article. Bingham spent more than eight of those 22 years in Florida as a supervisor for a company that used another line of positioning products. “If I’d known then what I know now,” he said, “we would have never used anything but Topcon equipment. It’s so easy to learn and easy to use, yet it has all the features we need.” Bingham was walking the site with a Topcon rover. Wright Brothers used rovers to log its volume to prepare weekly billing, which was submitted on Saturday or Sunday.

Beyond Ease-of-Use
The second advantage was that there were significant time-savings because the first pass was to grade. “There’s no need for rough grading prior to bluetopping,” Houghton continued. “Our first cut-and-fill brought us to the finished grade.” This was true not only with dozers and graders, but also with Topcon-equipped excavators.

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Additional time-savings came from the fact that no stakes were needed for grading. “With nearly 200 pieces of equipment on this site, stakes would not have lasted long,” said Houghton. “We’d have been replacing some percentage of them every day. In addition, we got minor changes every few days and major changes every week to 10 days. With the Topcon Pocket 3D, we loaded the changes and everything was immediately updated instead of resetting 500 to 1,000 stakes every time. Going stakeless saved about 40% of a foreman’s time.”

The third advantage Wright Brothers enjoyed as a result of its proficiency with GPS and machine control was that of production capacity. “Our volume was twice as much as our nearest competitor,” said Houghton, “and that played a big part in landing the job.” Even with the high-volume capability, Wright Brothers worked 12-hour days, six days a week. Next Page >

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