O'Hare International Airport
High-Flying Curtain Wall Taking Wing on Terminals
by Craig Barner

Curtain wall that represents a first-ever installation in the United States will form terminal facades at Chicago's O'Hare International Airport as part of a $319 million upgrade.

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Art Andros, director of development for the Chicago Department of Aviation, said that the curtain wall will have no mullions between the glazing. Glass will sit atop glass, and only the seams will form the horizontal and vertical lines.

Two-ft.-wide metal plates with rods that extend about 1 ft. from glazing joints will carry the curtain wall's gravity load, said Tom Chambers, principal architect with Chicago-based Murphy/Jahn, the project designer. Silicone in the glazing will keep the plates hidden.

Besides the seam lines, the only visible element will be vertical cables, which are attached to the glazing's inside face with brackets. The cables will provide bracing against winds.

The curtain wall will be attached to a column-supported canopy also being erected as part of the project. The metal canopy will cantilever over the two inner traffic lanes of the departures area.

Chicago-based Walsh Construction Co. is the general contractor.
Architect Helmut Jahn worked with structural engineer Werner Sobek of Germany on the design. "I am told that this is the first time they have done a cantilever with a canopy and curtain wall," Andros added.

Germany's Josef Gartner GmbH manufactured the 40-ft.-tall curtain wall with tinted glass. Testing was done, also in Germany, to ensure the system could withstand the elements.

A mockup was built, and one trial included subjecting the structure to 70-mph wind with water propelled from a jet engine. An independent agency observed the test procedures and recorded the results to ensure the system meets requirements.

Chambers said that despite the similarity, the curtain wall is different than the "net wall" that forms the lobby of the UBS Tower, a much-lauded office completed in 2001 at One N. Wacker Drive in Chicago. The difference is that the net wall, which is also a first-of-its-kind American installation, has visible cables horizontally, in addition to vertically, and a visible gasket in the glazing joints.

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Project Practicality

Functionality is driving the O'Hare work - formally known as the Facade and Circulation Enhancement, or Face, project - especially the need to create more check-in space.

With the exception of Terminal 3's expansion in the mid-1980s, the check-in and baggage claim facilities of terminals 2 and 3 are virtually unchanged since they were constructed 40 years ago, even though they now serve several times the number of passengers.

Under the project's first bid package, the existing curtain wall and vestibules were demolished on terminals 2 and 3, and the terminals will be expanded 20 ft. toward the roadway. This will increase the check-in lobby's width by more than a third and the clear area in front of the check-in by more than 50 percent.

The new space will be used for new circulation elements - glass elevators, glass escalators and stairs - and check counters more spacious than the existing ones.

"We wanted to keep it open to enhance passenger orientation so passengers can see where they're going, especially in regard to [the lower level] passenger tunnels," Chambers said. "Before, they had no visual connection between the tunnel level and check-in, and now you'll be able to see all the way up."

Thirty-five columns that are 23 ft. in front of the existing curtain wall and spaced 70 ft. apart are being erected. The metal canopy will be about 2,000 lin. ft. long, and it will cantilever 42 ft., 6 in.

Face's second bid package, which has not been awarded, covers the canopy erection for Terminal 1 and the interior renovations of terminals 2 and 3. The work will include the installation of new ceilings, signage, lighting, terrazzo tile and rental-car areas.

Unlike its neighbors, Terminal 1 will not be expanded.
Two tenant projects involving United and American airlines will occur while the second bid package is under way. "They are going to be doing a lot of little pieces - curb front, lobby technology and other things - to bring them up to date," Andros said.

A preliminary project element that is already complete involved the installation of new beams that support the roadway separating the upper and lower levels and the roadway itself. The change was needed to beef up these elements to handle the Face cranes.

"[The work] needed to be done anyway," Andros said. "It was up there for 30 to 40 years."

Face construction started in May 2003, and work is expected to run until March 2007. The project will act as a run-up to the airport's $14.8 billion expansion.

"O'Hare is the gateway to our city," Andros added. "Our customers have to come into a nice-looking terminal."

Dealing with Obstacles

The columns and canopies are being installed bit by bit to make sure the schedule is met.

Excavation teams encountered old tunnels and utility lines that were not in drawings, and some foundation types were changed, Andros said. Micropiles are holding the columns where there are obstructions, and caissons support the remaining columns.

"So instead of stopping and waiting for the micropiles to be done and continue like soldiers going down the terminals, we jumped ahead," he said. Activity on Terminal 2 was put off for awhile, and the teams moved to Terminal 3.

The caissons were set 55 ft. below grade on bedrock, and the eight to 12 micropiles for each column line were seated 10 ft. below the bedrock. The drilling was done on the grade-level road.

Alerting Passengers

Coordination was key so that the project impact on the 190,000 travelers who use O'Hare every day was kept to a minimum.

Most of the work takes place between 8 p.m. and 5 a.m., said John Cornell, senior project manager with Walsh Construction Co.

"We never know when we will have a full day's work," he added. "It could be raining in Tennessee, and that could delay flights here or have flights sent here."

Flexibility was needed because the daily go-ahead to set the steel varied depending on traffic.

Staging areas were located on Mannheim, Montrose and Bessie Coleman Drive to allow materials to be delivered quickly. Some columns were partly assembled in the yards.

The public awareness campaign included putting project information on the Internet, passing out fliers to taxicab and limousine drivers and posting road construction alerts on orange signs outside the airport as far as Cumberland Avenue on the Kennedy Expressway.

Useful Source

Find out more about the project at O'Hare International Airport by visiting www.flychicago.com/FACE on the Internet.