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O’Hare Completes Widest, Higher-Strength Runway

Aerial view at 200 ft of the Chicago O'Hare International Airport
At 200 ft, the new 10C runway, which runs east-west, is Chicago O’Hare International Airport’s widest, and is capable of accommodating the largest and heaviest commercial aircraft. The runway’s completion marks a significant milestone in a larger project to modernize the site-constrained airport. Chicago Department of Aviation

With the completion of the first of a series of east-west runways, the O’Hare Modernization Program has reached a milestone in its effort to streamline air traffic, increase capacity, and accommodate larger aircraft.

November 26, 2013—First announced in 2001, the $8.7-billion O’Hare Modernization Program (OMP) was, from the beginning, a gargantuan undertaking, aimed at bringing one of the world’s busiest airports into the 21st century. (See “Chicago Mayor Proposes $6-Billion O’Hare Project,” Civil Engineering magazine, September 2001, page 13.)
Last month the project passed an important milestone when crews completed a new, $1.3-billion, 10,800 ft runway called 10C. It’s the first runway at O’Hare capable of handling such large, Class VI aircraft as the Airbus A-380 and the Boeing 747-8.

Runway 10-C is the latest in a series of runway projects to open at the airport in recent years. Runway 9L-27R began construction in 2005 and opened in November 2008, along with the north air traffic control tower. In September 2008 Runway 10-28 was lengthened to 13,000 feet. The third runway in the airport modernization, 10C, began construction in 2011 and opened October 17. At 200 ft wide, the new runway is the airport’s widest.

Now that 10C is open, the airport is seeing major changes in its airspace. Formerly, flight paths around the airport were essentially square shaped: departures would go to the corners and arrivals would follow diagonal alignments between the corners. Air traffic at the airport is now mostly flowing east-to-west, according to Nate Smith, a program manager for the global consulting firm AECOM, which is providing program management services for the project; Smith serves as the deputy program manager for the OMP. About 70 percent of the time, Smith says, aircraft will now arrive from the east and depart to the west; the remainder will come from the west and depart to the east.

According to the City of Chicago Department of Aviation, the new runway is expected to pump $4 billion into the local economy, as well as help the airport run more smoothly. According to statistics from the U.S. Department of Transportation, O’Hare’s percentage of on-time arrivals over the last two years was among the best in the country among major cities, but its on-time departure percentage was not as good. Ray Gooding, a construction manager at Parsons Brinckerhoff and the construction manager for the OMP, says, “Delays can be reduced by up to 50 percent with the opening of 10C, and it could allow for 90,000 more additional flights annually.”

Work on the project began in 2006, but before engineers could even get to work on the runway itself, they faced an even bigger challenge: moving a huge quantity of existing structures and infrastructure out of the way to clear a path for the runway.

At only 7,259 acres, and with little room to grow, the airport is severely space constrained. Smith likens the work to the handheld sliding puzzle in which nine squares contain the pieces of a picture that must be correctly arranged. The runway 10C project was just like the game, he says, “but we didn’t have the open square.”

For the first three and a half years, all workers did was carve out enough space to get the runway work started while maintaining operations. All told the airport acquired about 433 acres of land, demolished about 500 properties, and completed 19 “enabling” projects, which represented half of the $1.3 billion price tag. The enabling work entailed relocating a United Airlines cargo facility, which Smith notes was, at the time it was originally constructed, the largest single-roof cargo facility in the world. A major Fed-Ex facility, called the Metroplex, which handles around 18,000 packages an hour, also had to be relocated. Cargo satellite fueling facilities were moved.

Additionally, the airport’s largest detention basin, 1,492-acre Lake O’Hare, had to be reconfigured, growing smaller but deeper. “We actually used a series of grouting [operations] and a slurry cutoff wall in order to build the basin so that we wouldn’t cross-contaminate any of the water tables or put any of the glycol into the water tables,” Smith explains.

And that’s not all. Railroad lines had to be relocated, not once but twice, and a cemetery with 1,500 graves had to be moved as well.

Surprisingly, though, for all the reconfiguration going on, precious little earth was moved off the site. The 10C job required moving around 7.2 million cu yds of dirt, according to Frank Grimaldi, the assistant commissioner of design and construction for the city’s Department of Aviation. Of that, 98 percent was retained on the field. This eliminated the carbon emissions that would have resulted from transporting it away, and also allowed engineers to use the earth to place berms between runways and to construct runway protection zones. In building the new runway, demolished pavement was crushed to the right gradation and used on the shoulders of the runway and its associated taxiways instead of new aggregate.

Smith says that the most distinctive aspect of the project was the diversity of elements involved. “There was probably every aspect of civil engineering [in it]” he says. “We’ve probably run into every sort of design you can imagine.”

Runway engineers hewed closely to guidelines laid out by the Federal Aviation Administration (FAA). The runway’s lowest layer, or subbase, is composed of 12 in. of lime-stabilized earth for frost protection. This base layer, Gooding notes, also contributed to the project’s sustainability, as crews didn’t have to haul aggregate in from off site. Above this layer is 6 in. of asphalt treated permeable base, and above this a 6 in. asphalt base. Atop the asphalt is 18 to 19 in. of portland cement concrete (PCC), placed in segments using slipforms. In between the PCC segments are reinforced steel dowels, which were inserted about 9.5 in. down in the pavement section as it was being constructed.

According to Smith, the longitudinal dowels were inserted mechanically—placed with “chairs”—while the transverse bars were placed by drilling holes in the slab and epoxying the bar in place.

While noise levels around the airport have been an ongoing issue at O’Hare for years, airport spokesman Gregg Cunningham says the city’s Department of Aviation has 37 permanent noise monitors in communities around the airport that were established to record aircraft noise levels in the wake of the new runway. The department also insulated more than 3,000 homes for sound during the first phase of the OMP.

With the completion of 10C, the first phase of the OMP has concluded. Runway 10R-27L, along with a south air traffic control tower, are under construction now and scheduled to open in late 2015. Another new runway and an extension to an existing runway are in design. When complete, O’Hare will have six east-west runways and two more diagonal runways that cut across the airfield.



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