There is a lot of talk these days about domes. Domes in the desert, domes over stores, domes on the moon, at the bottom of the sea, a dome for Nome. All of these ultramodern environments are the creations or expectations of Geiger Berger Associates, a New York engineering firm, and all stem from the technology that was defined and refined with the construction of the Pontiac (Mich.) Silverdome, where Super Bowl XVI will be played on Jan. 24. That technology has been further advanced as Geiger Berger's list of air-supported, fabric-domed buildings has grown to include, among others, the Carrier Dome at Syracuse University, the Hubert H. Humphrey Metrodome in Minneapolis, the Thomas E. Leavey Activities Center at the University of Santa Clara, the Sun Dome at the University of South Florida, the Ice Arena at MIT, the Lindsay Park Aquatic Center in Calgary, the Stephen C. O'Connell Center at the University of Florida and the B.C. Place Amphitheater in Vancouver.
David Geiger, the president of the company, has long been driven in his work by the belief that "people don't want to play in well-lit caves," and thus he uses a Teflon-coated fabric that's translucent. Geiger has obtained four patents and has become recognized as the world's leading authority on fabric roofs. He sees stadiums and sports arenas as natural—and necessary—small steps on the way to the giant leap of doming cities.
Geiger and chairman of the board Horst Berger formed Geiger Berger Associates in 1969, after Geiger had been commissioned to design the U.S. Pavilion at the 1970 World's Fair in Osaka, Japan. "We won with an air structure because a world's exhibition is traditionally where new technology is introduced," Geiger says. "But it isn't always that technology that winds up being put into use later on in actual building; consider the one-of-a-kind Eiffel Tower."
The U.S. Pavilion turned out to be one smashing success, and it sent Geiger Berger on its way. Next came the UNI-Dome, an air-supported fabric roof enclosing 218,000 square feet at the University of Northern Iowa. And, after that, the Silverdome, the largest air-supported, fabric-domed stadium in the world.
The dome rises to a height of 205 feet above the playing field at its highest point, and is inflated by 29 large fans. Once inflated, only two or three fans are needed to supply normal operating air pressure of 3.5 pounds per square foot above atmospheric pressure and to interchange the air for ventilation.
A recent risk-analysis study sponsored by Owens-Corning, which along with the Chemical Fabrics Corporation is one of the top manufacturers of the Teflon-coated fiberglass panels used in the roofs, found fabric structures safer than conventional, rigid roofs because their lightweight materials aren't a major threat to crowds in the event of failure. For example, when 10 feet of snow smothered Minneapolis in less than a day last November and the snowmelt systems at the Metrodome hadn't been turned on, the weight of the snow ripped one of the 106 panels in the 9½-acre, 340-ton roof. And, just as it was supposed to do, the dome deflated. In a deflated state, the fabric hangs well above the seats and the field and is perfectly safe. ("There will never be another Kansas City or Hartford," Geiger says, in reference to rigid-structure roofs that have caved in.) It took four days to reinflate the Metrodome.
The Silverdome deflated a year after the roof was raised when a tornado blew out a piece of metal siding. "People eating in the Stadium Club restaurant watched the roof come down," Geiger says. "In fact, when the roof was in a deflated state, two football games were played. The roof was 100 feet off the floor instead of 205. The only major problem was what to do if the ball hit the roof."
Simple. A ruling was made that the down would be replayed in that event.
One of the most appealing aspects of air-supported fabric roofs is the moderate cost. The 80,400-seat Silverdome was built for $41.8 million, or about $529 per seat, and the $28 million Carrier Dome cost about $554 per seat. Compare that to the rigid-structure domes: The $121.6 million New Orleans Superdome cost $2,244 per seat, the $67 million Seattle Kingdome $1,432 per seat, and the $24.4 million Houston Astrodome $1,302 per seat.
"The only complaint I've heard about the Silverdome," Geiger says, laughing, "is that it's very noisy. The roof holds in sound. But in building any big stadiums, team officials always say, 'Don't make it too dead.' That's part of the 'home-court advantage.' "
After the Silverdome, where is all this technology leading? No rigid-structure domes have been built in the last seven years; all large domes put up in that time, except one of wood, have been Geiger Berger air-supported fabric domes. Geiger predicts that two to three new fabric-domed stadiums will be built in North America every year for at least the next 10 years. He also says he expects many existing stadiums to be covered with air-supported fabric domes. "A fabric dome roof can cover any shape," Geiger says. "It takes the weight off existing columns. And it can be done very cheaply." Geiger Berger already has had feelers about covering Giants Stadium, Milwaukee County Stadium and Candlestick Park.
And, down the road, will come bigger and better things: domes over entire cities. Geiger believes that this prospect is only 30 years away.
"We can make new materials in outer space—steel cables that are 1,000 times stronger and the size of a whisker," Geiger says. "We can make a glass covering that is one molecule thick but is as flexible as Saran Wrap. We'll be covering cities with materials people can barely see. H.G. Wells wrote in 1890 about a fabric dome covering London. Well, he really was quite prophetic, since the materials, design and engineering he described are virtually the same as those we are using today.
"A lot of engineers have dreamed dreams, but we have been able to make ours happen."