GPS makes quick work of runway paving

Twenty years of sun, heat, rain, cold, ice, snow and traffic left the runway at the Albert J. Ellis Airport in Jacksonville, NC, showing signs of oxidation and some slight cracking. It was time for rehabilitation of the 7,100-foot runway.

The problem facing the airport commission and the contractor was how to work on the only runway when two commercial airlines operate 12 flights in and out of the airport a day? There were only two alternatives:

1) Work at night over a long period of time, or

2) Close the runway and work non-stop until the work was completed.

Airport Director Jerry Vickers says the project involved milling off one inch of pavement of the 7,400-foot long (including blast pads), 150-foot-wide runway and then overlaying it with two inches of asphalt. To make matters a bit more complicated a 532-foot-long, 48-inch drainage pipe needed to be replaced under the runway.

Barnhill Contracting Company, based in Tarboro, NC, was the successful bidder and offered a solution that met the needs of both Vickers and the contract management team of Reynolds, Smith and Hills Inc., an engineering firm based in Jacksonville, FL. Barnhill would use pavers equipped with Topcon Millimeter GPS to complete the job in 60 hours.

“Our issue here was we had a drainage pipe spanning under a section of the runway that had been there quite a number of years and it needed to come out,” Vickers says. “We had to shut down for two and a half days to get the pipe taken care of. The pipe excavation and replacement provided a good opportunity to pave as much of the rest of the runway as we could instead of having to do that at night, in five- and six-hour increments.

“It’s much more efficient for the contractor to muster his resources and do this compressed two and a half day paving schedule,” he explains. The airport was closed Tuesday night through Friday morning because that time period had the fewest travelers.

Ninety five percent of the $4.1 million project was funded through the Federal Aviation Administration’s Airport Improvement Program, 2.5 percent by the North Carolina Department of Transportation’s Division of Aviation, and the remainder of the project was funded by passenger facility charges, which are the surcharges airports impose on tickets sold. “Over the 60-hour shutdown, we spent $3 million of the total funds. That’s the scope and scale of what we did over two and a half days,” Vickers says.

Tackling the project

Mark Collins of Barnhill Contracting Company was the senior project manager for the project and knew at the start that this was a big job, given the designated timeframe. The FAA required Barnhill to hit all the design grades within a half-inch. Because the milling operation was a variable and they could not guarantee the grade they would be working from, Collins and Thumper Swann, Barnhill vice president, believed the only way the project could be completed to specification within the allotted time was to use GPS on the pavers.

Why the Topcon Millimeter GPS? “We had been using GPS on our grading equipment. We knew enough about Millimeter GPS to know its reputation for accuracy and reliability. We knew from talking to others in the industry that you could put the model in and basically take off paving and it would hit what you told it to hit with millimeter accuracy,” Collins says.

Barnhill’s plan called for paving 25-foot-wide lanes using two pavers. To do this, crews used two sets of pavers, each equipped with the Topcon Millimeter GPS, which provides enhancement in the vertical-measuring precision of RTK (real-time kinematic) positioning systems.

In concert with the Millimeter GPS, Barnhill used Topcon PZL-1 lasers to create a Lazer Zone - a rotating (600 rpm) signal that fans out to a height of 33 feet, creating a “wall of laser light,” Collins says. With Lazer Zone, the resulting integrated system can generate vertical accuracy within a few millimeters, compared to centimeter-level vertical accuracy using conventional RTK GPS systems.