In April, McCarran International Airport (LAS) in Las Vegas reopened its 14,500-foot primary runway, following a six-month closure. Runway 7L-25R, which handles about one-third of the airport's traffic, had been temporarily closed from October to April during each of the past two years to replace nearly 366,000 square yards of deteriorated asphalt concrete pavement. Now, aircraft operate on 19-inch-thick, full-strength Portland cement concrete pavement.
Dennis Anderson, assistant director of airside operations at LAS, explains the split-season strategy: "Runway 7L-25R is our longest runway. To take it down for a full year would have had a negative impact on our air carriers during the hot summer months, when larger aircraft need the longer runway for takeoff. The cooler winter temperatures are also better for concrete work."
In addition, local wind patterns often push traffic to north-south runways during the cooler months.
Project: Runway & Taxiway Reconstruction
Location: McCarran Int'l Airport (Las Vegas)
Timeline: Oct. 2014 - April 2015 (Phase 1); Oct. 2015 - April 2016 (Phase 2)
Cost: $64.7 million
Funding: Airport Improvement Program (75%); local match (25%)
Engineering & Design: Kimley-Horn & Assoc.
General Contractor: Las Vegas Paving Corp.
Concrete Contractor: TAB Contractors
Electrical Contractor: Royal Electric
Construction Inspection: Clark County Dept. of Aviation
Geotechnical Quality Control: Aztech Engineering
Preformed Pavement Seals: D.S. Brown
Airfield Lighting: ADB Airfield Solutions
Of Note: Project completed over 2 winter seasons on time, on budget & with a perfect safety record
The reopening of 7L-25R in April completed LAS' transition from asphalt to Portland cement concrete on all four of its runways. The FAA is pushing major airports to change to all concrete runways, informs Todd Cooklin, project manager for Clark County Department of Aviation. "Cleaning rubber residue off concrete is easier than cleaning it off asphalt," he explains. "And there can be some issues with asphalt pushing and moving when you get into the August heat."
Editor's Note: When it comes to runways and other airfield pavement, there are two major camps: concrete and asphalt. While some airports, engineers and contractors have distinct individual preferences, the FAA does not categorically advocate one material over the other.
The FAA's Office of Airport, Airport Safety and Standards directs the industry to Advisory Circular 150/5320-6E, "Airport Pavement Design Evaluation," for further guidance.
According to the FAA, with proper design, materials, construction and maintenance, any pavement type can provide the desired pavement service life. The selection of a pavement section requires the evaluation of multiple factors including cost and funding limitations, operational constraints, construction time-frame, cost and frequency of anticipated maintenance, environmental constraints, material availability, future airport expansion plans and anticipated changes in traffic.
New Pavements & More
The first phase of the airport's nearly $65 million project broke ground in October 2014 and was completed in April 2015. Demolition and reconstruction began on the east end of the runway, where most westbound aircraft touch down when landing, and extended over nearly two-thirds of the runway's length.
In addition to the east-end runway reconstruction, cross taxiways A-3, A-4 and A-5 between taxiways A and B were reconstructed with Portland cement concrete. Crews removed and replaced deteriorated pavement on Taxiway B between cross taxiways B-1 and C-1. The asphalt blast pad on the east end of the runway was also reconstructed.
Phase Two on the west end of the runway ran from October 2015 through April 2016 and included reconstruction of cross taxiways A-6, A-7 and A-8.
Between the two major construction phases (May to October 2015), workers replaced nearly 38,000 square yards of deteriorated asphalt on a segment of Taxiway C between cross Taxiways B-5 and B-7 with Portland cement concrete.
Complicating matters throughout the project, adjacent cross taxiways could not be closed simultaneously. This restriction prompted Kimley-Horn, design lead for the project, to create sub-phases to define areas where contractors could work. "It required a lot of coordination with the tower, Operations and Maintenance in order to set up appropriate barricades and make sure everyone knew which taxiways were open and closed so that aircraft could move efficiently to and from the gates," informs Kimley-Horn Project Manager Kory Andryscik.
A new subsurface drainage system was installed to replace an aboveground drainage system that did not meet FAA standards, with ditches and culvert crossings between Runway 7R-25L and Taxiway A. The new system, which includes catch basins and reinforced concrete pipe, drains to the east and empties into a detention basin on airport property.
"The old system consisted of open channels and swales that didn't meet current FAA standards, and a lot of the infields were not graded correctly," explains Andryscik. "We removed a lot of material from the infields on the west end of the project to fill the infields on the east end of the project, getting rid of those open channels and bringing the infields into compliance with FAA standards."
LAS also upgraded airfield lighting during the project. In addition to installing new elevated and in-pavement high-intensity runway edge lights, crews added infrastructure for future runway guard lights by installing circuit conductors and ferroresonant constant current regulators in the east airfield lighting vault.
Taxiways A-2, A-3, A-4, A-5, A-6, A-7 and A-8 received in-pavement bidirectional medium-intensity taxiway centerline lights, and the holding bay on the east side of Taxiway A-2 received omnidirectional medium-intensity edge lights.
New LED mandatory hold signs and guidance signs were installed, and new duct banks crossing beneath paved surfaces were encased with a minimum of 3 inches of 4,000 psi concrete.
The airport's new LED fixtures reduce the electrical load on its lighting vault, notes Andryscik.
Saving Time & Money
The airport significantly reduced its project expenses by reusing existing materials such as aggregate base when possible and by cold-milling approximately 137,000 cubic yards of asphalt. Fully 90% of the material was placed in the airfield infields to control dust and erosion; and asphalt millings were rolled and compacted to form an asphalt lift that abuts the new shoulder.
Throughout the project, general contractor Las Vegas Paving removed 44,000 cubic yards of Portland cement concrete, excavated 128,000 cubic yards of existing base material and then reprocessed the existing P-209 base. TAB Contractors followed, laying down approximately 193,000 cubic yards of Portland cement concrete. In total, crews laid 43,000 tons of P-401 asphalt to construct 4-inch-thick, 50-foot-wide shoulders on each side of the runway.
An onsite concrete batch plant saved money, time and environmental costs by limiting the distances trucks traveled to deliver materials. Bryan Pringle, project manager of Las Vegas Paving, estimates trucks hauled in up to 25,000 loads of concrete and asphalt.
To save time, LAS officials established a robust escort system for trucks hauling materials between the batch plant and construction site. Trucks lined up for inspection at a main gate adjacent to the batch plant, and then 15 to 20 escort vehicles operated by FAA-trained personnel led two to three trucks at a time onto the airfield and to the construction site.
"It was a very efficient system and really helped with meeting project deadlines," Pringle reflects. "We were able to move trucks in and out on a continuous basis. TAB was running anywhere between 15 to 20 dump trucks with PCC (Portland cement concrete), and we had 20 to 30 trucks hauling our materials in."
During peak construction, 50 to 75 people worked on the runway at the same time. In areas where aircraft traffic would have been impeded, contractors used nighttime and weekend shifts.
"The scheduling requirements were very tight," reflects Pringle, noting that contractors had to meet 24 separate milestone completion dates. About half of the 11 active taxiways involved went directly to the main terminal, he adds.
Airport officials, contractors and the design team all proudly note that the nearly $65 million project was completed on time and on budget.
Excellent communication among all the parties involved was key to the project's success, observes Jim Chrisley, deputy director of Aviation, Operations at LAS. "We had great teamwork," he elaborates. "They met every morning at 7:30 a.m.-contractor, Airfield Operations and Construction and Engineering. The Airport Operations coordinators coordinated airfield movements with the tower and tenants, then created diagrams so everyone understood what would be happening on any given day. We didn't hit roadblocks because everyone kept talking and communicating."
Pringle seconds that notion, adding, "As a contractor, we do these large projects all the time. But the team atmosphere on this project was wonderful. This was a special project."