Alternate Landing Surface Keeps Air Traffic Moving at Northwest Arkansas Regional

Author: 
Robert Nordstrom
Published in: 
March-April
2012

When Northwest Arkansas Regional Airport (XNA) was built in 1998 to replace the commercial component at Fayetteville's Drake Field, no one expected its sole runway would need to be completely reconstructed 13 years later.




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Project: Alternate Landing Surface/Taxiway

Location: Northwest Arkansas Regional Airport

Approximate Cost: $41 million

Funding: $9.5 million ARRA; remaining costs split between AIP (95%) & state/airport (5%)

Design & Engineering: Kimley-Horn and Assoc.

Engineering Consulting & Inspection: McClelland Consulting Engineers

Electrical & Navaids Installation Design: Aviation Alliance

Site Preparation: Crossland Construction

Paving Contractor: APAC-Tennessee

Electrical Contractor: Hypower

MALSRs: Astronics DME Corp.

MALSR Installation: Carter Construction

Lighting & Signage: ADB Airfield Solutions

Paint Removal & Marking: Hydro Blasting

Erosion Control: JLA Construction

Quality Testing: GTS

Concrete Work: Backus Concrete

Fencing: Arkansas Fence Co.

Earthwork: Ground Zero Construction

Asphalt Paving: Hutchins

Surveying: Blew & Associates

Hauling: DownUnder Trucking

Key Benefits: Construction of alternate landing surface allows airport to remain open while primary runway is reconstructed; alternate surface will be used as a taxiway when primary runway work is complete.

Thanks to a severe case of alkali silica reaction (ASR), that's just what happened. And to date, no one knows exactly why.

ASR is a chemical reaction between alkalis typically found in cement powder and silica in fine aggregate (sand). Once initiated, the reaction acts much like cancer: A gel-like material surrounds the fine aggregate particles and begins to grow. As the gel grows, it expands the concrete and causes cracks and eventually concrete pop-outs. The crumbling debris can result in costly foreign object damage to aircraft engines.

McClelland Consulting Engineers, a subcontractor to Kimley-Horn and Associates, found ASR in all the concrete core samples it took during a pavement evaluation on XNA's Runway 16/34 in September 2011.  Crews inspected the pavement and its base to determine whether the base might be salvaged. Unfortunately, when several core samples were removed, the base was bonded to the concrete pavement.

"We're pretty sure we're looking at replacement of the pavement and possibly a portion of the base material," reports Larry Whitehorn, McClelland's senior inspector.

With reconstruction of the runway a foregone conclusion, the airport turned its attention to finding a way to maintain operations throughout the reconstruction process.

Airport management worked closely with FAA personnel, who concurred that XNA had a serious ASR problem on its hands. With major corporations such as Wal-Mart, Tyson Foods and J.B. Hunt depending on the airport, the FAA also agreed that closing the airport during its extensive runway reconstruction would have a significantly negative impact on commercial air traffic in the surrounding communities.

Airport director Kelly Johnson, who also serves as chair of the American Association of Airport Executives, found herself in a difficult spot. "If it hadn't been for the ASR problem, we'd be in great shape," reflects Johnson. "It's not something anyone anticipated, and it's truly unfortunate. We had to figure out a way to maintain an airport and justify the need to reconstruct a runway that's only 13 years old."

Funding a Two-Stage Fix

To resolve the problem, the airport decided to construct an alternate landing surface for carriers to use while it prepares for runway reconstruction later this year. Funding the immediate and long-term solutions was another issue.

"As with everyone else in the country," Johnson relates, "our challenge has been to find the necessary funds while dealing with continuing resolution after continuing resolution in Congress."

In 2009, XNA secured $9.5 million of stimulus funds from the American Recovery & Reinvestment Act (ARRA) and was able to jumpstart construction of its alternate landing a year earlier than expected.

"We were very happy to see the stimulus money," Johnson recalls. "I know some people don't agree that the stimulus program was the way the country should go, but in my estimation it certainly accelerated our project."

In 2010, she submitted testimony to the House Transportation and Infrastructure Committee that chronicled how the ARRA project helped avert significant economic harm to local businesses that depend on the airport maintaining operations. Johnson also quantified other benefits of the alternate landing surface project: about 100 new jobs and an $8 million economic boost to the community.

XNA construction project manager Barb Busiek enthusiastically agrees that stimulus funds were key to the project.

"The funds allowed us to do the first two or three phases of the project," says Busiek. "We kept a lot of people working when things were kind of scary. I think we put every truck driver within a 50-mile radius to work; they were lining up 10 to 20 deep out there on the jobsite.

"It worked out for everyone: People needed the work, and we needed the alternate landing surface. When people are working, they go out to eat, they buy gasoline to get back and forth to work. It creates a trickle-down effect."

First Things First

Kimley-Horn and Associates divided the design and engineering for the overall project into two parts: construction of the alternate landing surface (17/35) and subsequent demolition and reconstruction of Runway 16/34.

Construction of the 8,800-foot long, 150-foot-wide alternate landing surface began in early summer 2009 and ended in early January 2012. When demolition of 16/34 begins in 2012, air traffic will move to the alternate landing surface. Upon completion of 16/34, the alternate landing surface will serve as Taxiway A and a backup landing surface.

The new $41 million alternate landing surface was constructed on virgin ground. Approximately 1 million cubic yards of material was excavated and nearly 123,000 square yards of Portland cement concrete placed. A stormwater collection system was installed and existing electric and natural gas transmission lines were relocated. The airport's perimeter service road and security fencing were also relocated. As part of the design, the FAA required XNA to submit an aeronautical survey and airspace analysis to develop instrument approach procedures to the alternate landing surface.

Mark Manning, vice president of Kimley-Horn, notes that the design required the alternate surface to be separated from 16/34. "We had to make sure that the navaids on the two landing surfaces did not conflict with each other," recalls Manning, explaining that the new alternate landing surface was designated as 17/35 rather than 16/34 to help prevent pilots from lining up to land on the wrong surface. "We also had to make sure the frequencies on the glide slope antennas for the two runways were compatible," he adds.

Constructing the connector taxiways to 16/34 at each end of the alternate surface while maintaining traffic on 16/34 was a "significant challenge," recalls Manning. "We actually had traffic taxiing alongside the construction area in order to get to the displaced threshold," he relates. "It required a lot of coordination and communication."

Navaids & Lighting

Aviation Alliance designed the lighting and signage systems as well the installation of navaids for the new landing surface. "Our job was to design lighting and signage systems to meet FAA criteria for an alternate landing surface that would eventually be used primarily as a taxiway," relates CEO/president Shirley Roberts. "It was determined that the airlines required a Category I instrument landing system on each end of the alternate surface. We provided the lighting, signage and PAPI installation designs for the interim displacements of Runway 16/34 thresholds during the construction of the connector taxiways."

Astronics DME Corp., the FAA-approved supplier of Category I precision approach visual guidance lighting systems, monitored and directed the installation of medium-intensity approach lighting systems (MALSR) at each end of the alternate landing surface in runway approach zones along the extended runway centerline. The systems will pierce moderate to very limited visibility, enabling pilots to transition from instrument to visual during runway approach and provide lateral centering guidance.

Deborah LaPenta, project manager for Astronics DME, is proud that crews completed the project on time and within budget despite challenging heat and rain. "We had 43 days with temperatures over 100 degrees," recalls LaPenta. "There's not much shade to be had in the middle of an airfield. We adjusted our schedules so that we were working earlier in the morning and later at night."

Astronics DME has supplied more than 200 MALSR systems nationwide since its first contract in 1994.

Ready & Waiting

With the last piece of the navaids and MALSR systems installed, alternate runway surface 17/35 is ready for traffic. The plan is to make the switch to 17/35 shortly before demolition begins on 16/34.

"We've had the flight checks," reports Busiek. "We're working with Kimley-Horn to come up with a phasing plan. We're trying to figure out which way the wind blows to determine which end we'll have aircraft approach primarily."

The FAA has asked XNA to conduct an autopsy of the pavement when demolition of 16/34 begins. Several engineering firms have studied samples to try to determine what caused the ASR problem. Collectively, they have uncovered five or six potential explanations, but no one has determined a definitive cause.

"Most people think it's the fly ash used in the concrete mix," Busiek reports. "We have switched to Class F fly ash for this project, which is supposed to be less chemically reactive than Class C. We are also following FAA P-501 specs, which allow for a 28-day testing period up front to check for possible ASR reactions in the cement."

The first phase for reconstruction of 16/34 has been bid out, and the airport has received its first $10 million grant to begin design, engineering and drainage work. Although the projected cost for reconstruction has not been finalized, Johnson says the airport has a verbal commitment from the FAA for three $10 million grants.

"We're trying to time it so that we can start the demolition and drainage work in May, then get the second grant around October to begin the paving work," explains Johnson. "Ideally, the third grant would flow around the beginning of next year, so we can continue the paving portion with a single contractor. Chopping work up into pieces with different contractors increases costs and makes it difficult to manage."

Johnson speaks highly of the FAA's ongoing support: "A project like this - constructing a taxiway that will also be used as an alternate runway surface - is not commonly done. Our friends at the FAA have been true partners every step of the way."  

Subcategory: 
Runway/Ramp

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