Closing the loop

It was a sunny July 8, 1988 when the then North Carolina governor James G. Martin turned the first spadeful of dirt and announced that a lengthy stretch of new Charlotte freeway – the I-485 “Outerbelt,” as it has been nicknamed – would finally be constructed. “I bet you thought this day would never come,” he said, “but good things come to those who wait.”

Time has passed, Charlotte has grown tremendously, and traffic became more congested. Similar to the I-285 beltline around Atlanta, that first chunk of I-485 has become part of a planned 67-mile continuous loop, which will help traffic skirt Charlotte and travel among its suburbs.

The loop freeway is expected to be fully completed around 2008, at a total cost of $1.1 billion. It has been a longer, more complicated project than what Governor Martin first envisioned.

Another section underway

Currently, a new 5.8-mile section is being built in the northwest quadrant of the loop. This section will have between three to five traffic lanes, both ways. H.B. Rowe & Co., Mount Airy, N.C. was awarded the volume earthmoving and rock blasting, storm drainage, erosion control and finish grading components.

The contractor has six months to complete its share. H.B. Rowe has 57 employees working on this project and anticipates moving 2.3 million cubic meters of soil.

“The project is fairly complex,” stated Gerhard Pilcher, president of H.B. Rowe. “We’re working with 22 different soil types and 150,000 cubic meters of rock. Some of the soil is saturated with ground water, which causes challenges. Plus, 34 structures – culverts, retaining walls and bridges – require special grading for approaches and access.”

In addition to the project’s complexity, the DOT-mandated tolerances on the finish grading are stringent – grade variation should not exceed 2mm. DOT surveyors check and sign off on all completed work. Pilcher emphasized, “We’ve passed every inspection thus far and have had no rework.”

GPS machine control praised

“Three of our machines are equipped with the latest Trimble® machine controls,” stated Pilcher. “The Trimble systems are excellent for complex grading and save us a tremendous amount of time.” Pilcher has a Volvo G726B motor grader, Caterpillar 12H motor grader and a John Deere 750J crawler dozer equipped with Trimble 3D GCS900 Grade Control Systems.

A 4-wheel-drive rover uses a Trimble SCS900 Site Controller System to complement the GPS-equipped machines. It measures cut and fill progress, stockpile material volumes, and checks grading operations.

“We’ve achieved an estimated 25% to 35% gain in productivity
using Trimble GPS grade control systems.”

Gerhard Pilcher , president,
H.B. Rowe & Co., Mount Airy, N.C.

“The Volvo motor grader does most of the finish grading because it’s equipped with the Trimble ATS Construction Total Station in order to achieve very tight tolerances,” Pilcher said. “The ATS is almost a ‘must have’ on this project. It works great and ties in seamlessly with the onboard computer to give the grader operator the ability to move the material freely. There’s no need for any stakes or stringlines.”

Shaping the future

H.B. Rowe is no stranger to grade control technology. “We’ve been using Trimble systems since 1990, and we’re probably among the first in the area to adopt 3D GPS,” Pilcher said. “We’ve achieved an estimated 25% to 35% gain in productivity using Trimble GPS grade control systems. Plus, there are a lot of hidden cost savings such as reducing the need for surveyors and support machines."

H.B. Rowe & Co.’s corporate tagline is “Shaping Earth since 1946.” As grand as that claim may appear, it certainly applies to the shape of transportation in North Carolina. H.B. Rowe’s work on the I-system loop is helping to relieve the congestion in and around metropolitan Charlotte.