RDU Runway Challenges Earthmovers

By: Richard Stradling
Source: The Herald-Sun, Durham, N.C. (TNS)

To build an airport runway, you need a long strip of earth that is basically flat. Right now, the place where Raleigh-Durham International Airport plans to put its new main runway is anything but.

The land on the west side of the airfield is typical of the eastern Piedmont, undulating with dips and rises. To make it level, RDU and its contractors expect to bring in 5.2 million cubic yards of dirt and crushed rock, enough to fill a half million standard-size dump trucks.

Read today’s top news.

That process has begun. Travelers in RDU’s Terminal 2 can look out across the airfield and see huge Caterpillar off-road dump trucks with six-foot tires lumbering back and forth, bringing 50 tons of material at a time to low spots.

With a couple of exceptions, the site of the new runway is much lower than the existing one and needs to be raised so that they’re roughly level, said Trent Johnson, who is overseeing the work for Balfour Beatty, RDU’s general contractor.

“So we’re having to bring that entire platform up, over two miles long, as deep as 70 feet in some areas,” Johnson said, as he drove along the site recently.

RDU’s main runway, 5L/23R, was completed in 1986 and has shown its age for several years now. The airport has spent tens of millions of dollars replacing hundreds of slabs of crumbling concrete, something it will need to keep doing in coming years.

The new runway will parallel the existing one, exactly 537 feet to the northwest. When it opens in 2029, contractors will begin converting the old runway into a new taxiway, which could take another couple of years as they work while planes take off and land nearby.

Combined, the new runway and taxiway are expected to cost about $1.1 billion. Moving dirt and creating a solid foundation for the runway will account for about $200 million of that, says Michael Landguth, RDU’s president and CEO. Where all that dirt and rock come from

Early on in the planning, RDU and its engineers expected they would need to bring that dirt to the runway site from airport land off Pleasant Grove Church Road. That would entail cutting hundreds of acres of trees and then either trucking the material around Brier Creek Reservoir or building a conveyor system over the water and Aviation Parkway.

But the engineers now think they can get enough material from land adjacent to the runway site, Landguth said. They’ve begun by using earth and rock excavated from six new stormwater basins contractors began building this summer. Other work underway includes moving a city sewer line and Duke Energy power lines and extending stormwater pipes under the path of the new runway.

Landguth said it will likely take until the middle of 2027 before the earthen foundation for the runway is complete and paving can begin.

Building that platform is not as simple as moving rock and dirt, Landguth and Johnson say. Each layer of material must be compacted and then tested to ensure it meets Federal Aviation Administration specifications designed to avoid settling and help preserve the runway surface.

It starts with getting everything the right size, Johnson said.

“Two-thirds of the material that we have to borrow is actually rock,” he said. “So we have to blast to break that rock up, then run it through our screeners and crushers to get it down to the gradation that we need to meet the spec.”

Once the material is moved to where it’s needed, it is spread with graders, then compacted with what’s known as a sheep’s foot—rollers with knobs on them.

The work all takes place without interfering with planes on the existing runway, Johnson said. The only change to airport operations occurs when the contractors ask that flights be moved to RDU’s other runway for a short time every couple of weeks so they can fly a drone that measures their progress. New runway will be longer

The new runway will be 10,639 feet long, or 639 feet longer than the existing one. At that length, all cargo and passenger carriers now doing business at the airport will be able to operate their planes fully loaded.

RDU had initially hoped the new runway would be 11,500 feet, long enough to handle nonstop flights to Asia. The airport pared down its ambitions during the COVID-19 pandemic, in part to reduce cost and potentially speed up federal approval. The safety zone at the north end of the new runway, near Lumley Road, will be sized to allow an extension in the future.

Opening a new runway and taxiway will allow RDU to eventually add gates to Terminal 2. Both must be a minimum distance from passenger terminals, so shifting them farther west will provide room to expand the building.

Terminal 2 has 36 gates now, though two will disappear after the airport expands the main ticketing hall and baggage claim area. That work will begin this fall.

The airport hopes to someday expand the number of gates in the terminal by building wings at either end and two more from the middle of the existing concourses.