Because there are no parallel runways at DCA, they can't shut a runway down for the duration of the project. As a result, some of the runway that has been milled was left open to aircraft movement. Then planes are actually landing on a fine-milled surface.
Lagan Construction used two Vogele Super 1900-2 pavers with 25-foot screeds for paving.
Mark-Lang spent weeks removing aged asphalt from the main runway of Ronald Reagan Washington National Airport (DCA).
The runway was open to milling only after the last flight had landed, sometimes as late as 1:30 a.m.
The Level Pro system allowed operators to control both sides of the cold mill machine at the same time from one controller.
In a critical mill-and-fill application, working midnight to before dawn in excruciatingly tight time frames, two to four Wirtgen cold mills spent weeks removing aged asphalt from the main runway of Ronald Reagan Washington National Airport (DCA) in advance of paving.
With cohorts of workers and Wirtgen Group equipment waiting quietly in the middle of the night, the runway would be released only after the last flight had landed, sometimes as late as 1:30 a.m. Only then -- following runway closure by the tower – would the work zone blaze with light and throb to the sounds of engines starting, machines moving and voices shouting.
In late 2011, Mark-Lang was milling Runway 1-19, plus tie-backs into all adjoining taxiways, a total of nearly 300,000 square yards. The job began in mid-June and most of the paving operations had to be completed by November.
“This job is difficult because most airports have parallel runways, and you can shut one runway down and still have access to the others,” said Charles Boswell, secretary/treasurer. “But here, all three runways intersect each other. In order to do the intersections you have to shut down two runways, and one is smaller and can’t handle commercial aircraft.” As a result, much critical work had to take place after the airport closed.
The DCA airfield contains three runways. Runway 1/19, the main north-south runway, is 6,869 feet. In the 1980s, overruns were added to each end of this runway. The other two runways are Runway 15/33 at 5,204 feet and Runway 4/22 at 4,911 feet. When visited Mark-Lang was removing the intersection of runways 1/19 and 15/33.
“The intersection work requires a hard closure,” Boswell says. “We typically will have from 1 a.m. to 6 a.m. to do the work. It’s got to be open to air traffic by 6 a.m., so we really only have until 4:30 a.m. to do any construction. After that we have to be cleaning up the area and getting off the airfield.”
Every night is different, Boswell says. “This job is not as straight cut as a ‘shave-and-pave’ project,” he says. “We’re basically profile-milling, or fine-grading, the runways. Survey teams check elevations and determine what needs to be cut to place 3 inches of asphalt back on top. As a result we will remove anywhere from 1 inch to as much as 7 inches in some areas, but the majority is 3 to 4.5 inches.”
For this work, Mark-Lang was using a W 2200 with a 12.5-foot fine-texture drum, and a W 210 with a fine-texture drum. At times one to two additional W 2000s with fine-texture drums of Mark-Lang were put into action. Cutting tools were spaced at 516 inches. “This project actually requires the fine milling head,” Boswell says. “Because there are no parallel runways at DCA, they can’t shut a runway down for the duration of the project. As a result, some of the runway that has been milled was left open to aircraft movement. Then planes are actually landing on a fine-milled surface.”
Whether the planes are landing on a fine-textured surface, or on a freshly paved surface placed early that morning, the danger exists that small bits of RAP could be sucked into the intake of jet engines. As a result, Mark-Lang was required to meticulously clean operations all during milling.
“The cleaning operation is very important,” Boswell says. “Every night we spend about an hour and a half using multiple vacuum sweeper trucks to remove all traces of millings from the work areas.”
Asphalt paving by Lagan
Mark-Lang was milling subcontractor to Lagan Construction of Belfast. The $13.9-million project was undertaken by Lagan Virginia LLC on behalf of the Metropolitan Washington Airports Authority.
Lagan Construction is an international specialist in airport rehabilitation and improvement projects and has delivered more than 40 such contracts worldwide, including international contracts at Puerto Rico, Hong Kong, Bermuda, Guyana and the British Virgin Islands and numerous United Kingdom projects.
In addition to the complete resurfacing of the main runway, taxiways and intersections, Lagan replaced centerline and touch down zone lighting. The work also involved earthmoving, soil erosion control measures (the airport is constructed on landfill in the Potomac River), and the relocation of communication cables and access roads at the north end runway safety area. Approximately 60,627 tons of asphalt was milled out and replaced.
For this work Lagan was using two Super 1900-2 pavers with 25-foot screeds from Vgele, and two HW 90 static rollers from Hamm. So keen is Lagan on the performance of this Wirtgen Group equipment that the firm ships the equipment overseas from one airport job to another.
Mark-Lang in Tidewater states
Mark-Lang was founded in 1976, and now operates in the states of Maryland, Virginia, Delaware and Pennsylvania. The firm started out doing soil-cement and soil-lime stabilization. In 2005 the firm expanded into asphalt cold milling.
The firm owns four Wirtgen cold mills. Its new W 210 has both the camera option which gives the operator’s platform a view from conveyor into dump truck, and behind the machine when it’s put in reverse, and the new vacuum cutting system, which removes fines from the cutter drum housing and around the vicinity of the machine, prolonging equipment life and enhancing the operating environment.
“It also has parallel-to-ground technology, which is a huge plus,” Boswell says. “Basically it sets the whole machine down, level with the ground surface, using all four legs. You just hit the button, set the machine down and it cuts. It’s a huge time saver.”
When Mark-Lang first got into cold milling it already had a WR 2500 soil stabilizer/reclaimer from Wirtgen, Boswell says. “Their support system and local dealer Elliot & Frantz Inc., Jessup, MD, are outstanding,” he adds. “Parts availability and service are key; we are contractors, not mechanics, and if something goes wrong we need someone local who can handle it.”
Operating on the level
Wirtgen’s Level Pro system was making the critical adjustments in runway milling easier for Mark-Lang. “The Level Pro allows us to control both sides of the machine at the same time from one controller,” Boswell says. “The controllers talk to each other, too. If you change entries on one monitor it will show up on the other.
“Not only that: When we’re cutting shoulder edges we tend to run slope for that, and you can see your slope in the center screen, or your depth,” Boswell says. “You are able to monitor your depth while still seeing the slope, and it allows a lot of functionality for the guys running ground controls.”
But that was not an issue at DCA. “We are not running any slope at Reagan National Airport,” Boswell says. “Everything is laid out and marked on the ground in metric. Our machines are set up to mill in metric and follow their metric grades, which is a different ‘beast’ in itself, as we are used to working in tenths of inches, and then we are working in millimeters.” However, the Level Pro system permits easy switch from Imperial to metric measurements.