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Minneapolis’ Metrodome fabric roof may be the last of a dying breed.
By Mason Riddle
Are air-supported dome stadia dead? Has the characteristic “marshmallow-in-bondage” design had its day for multipurpose stadia? Many within the building industry, as well as professional sports teams and their fans, answer a decided “yes.” However, a few, such as David Campbell, principal and CEO of Geiger Engineers, say “not so fast.” Granted, Campbell works for the company that propelled the air-supported dome concept into the mainstream. But Campbell also sees a future for the design, one differing from the past.
The backstory
The air-supported dome “craze” was ignited when U.S. engineer David Geiger’s design for the U.S. Pavilion was built at Expo ’70 in Osaka Japan. This memorable structure spawned, among others, the 1975 Pontiac Silverdome, the 1980 Syracuse University Carrier Dome, the 1982 Hubert H Humphrey Metrodome, the 1983 Hoosier Dome, (now demolished), Vancouver’s 1983 BC Place Stadium and the 1988 Tokyo Dome, affectionately named “The Big Egg.”
What are the advantages? First, air-supported domes were—and still are—a cost-effective way of building a stadium, a fact that appealed three decades ago to cities that were counting their pennies. If a municipality or university determined it needed a roof, an air-supported dome was far cheaper than a fixed or retractable roof stadium and it could be constructed with relative expediency. The Metrodome cost $68 million, coming in $2 million under budget, a fantasy number when compared to current stadia. Air-supported domes also offer an unobstructed open interior space. Since there is no need for support columns, sports fans never miss a strikeout or interception. Additionally, an air-supported roof allows for the scheduling of multiple activities, from sports events to music concerts, civic gatherings to political events. A dome could then generate income year-round, in all weather.
“The economy of professional sports has changed since the early 1980s,” states Campbell, who worked as a design engineer on the Metrodome. “Much more capital is now spent on venues than 20 and 30 years ago, making the cost saving aspect of an air-supported dome far less relevant.” Geiger Engineers is currently reconstituting the BC Place Stadium with a retractable roof after decommissioning its air-supported dome following the 2010 Winter Olympics. “It is a huge decision to make. Retractable roof stadia are expensive and a “rare bird—maybe 25 in the entire world,” explains Campbell.
Issues?
So what are the issues? Foremost is that the professional sports culture—owners, teams, management, fans—has realized that multipurpose stadia serve no particular sport well, especially baseball. (Campbell notes the demise of many multipurpose stadia in the last decade, even those without an air-supported dome such as Busch Stadium in St. Louis.) Not only do baseball fans like to watch their team in rain or shine, but each field is uniquely sized. The dimensions of a baseball field vary stadium by stadium, and that adds to a team’s identity and the game’s drama. Irregular dimensions are not easily accommodated in the strict configuration of an air-supported dome. Football, because of its regulation size field, fares better. Moreover, most sports franchises realize that it is next to impossible for an air-supported dome to provide the amenities now expected by the public, such as sophisticated digital technology, restaurants and bars, private loges and so on. In the 21st century, attending a sports event is more than simply going to see a team play. It is being indoors and outdoors all at once.
A second issue is the public perception that air-supported domes can “collapse” and are thus dangerous. This is simply not true. An air-supported dome has never collapsed and, in fact, a dome cannot collapse on people. But it can deflate and that has happened —occasionally—due to climatic conditions such as snow and ice. Campbell emphasizes that air-supported dome stadia are active systems, not passive systems like open air or fixed roof facilities. Consequently, they rely on people to actively manage or monitor them 24/7, and people make mistakes. When active systems are well managed, and Campbell notes that this is now being done extremely well in most domes, a deflation incident is rare. The Tokyo Dome has never had a deflation.
With regard to energy use, an air-supported dome cannot attain the insulation values of hard-walled structures, thus increasing heating and cooling costs. Although fans must operate continually to keep the structure pressurized, a larger cost and use of energy is to initiate the snowmelt system. Someone must make the decision to activate the system before an impending snow or ice storm. If that storm never materializes, a substantial waste of energy and money is incurred.*
Does Campbell believe there is a future for air-supported dome stadia? “Yes, definitely, but not in the area of professional sports in North America,” he states. “Our teams want to distinguish themselves and they want to be outside, not under a dome.” However, he notes that Geiger Engineers has done preliminary designs for air-supported domes for universities and other clients, although none has been built. A university may have a need for a multipurpose facility that offers shelter. Campbell adds that air-supported domes may be desirable in a sports market in other countries, where capitalization options are not as great as in the U.S. But, states Campbell, “It all comes back to one initial question ‘Why do I want a roof?’”
As a Twin Cities resident (Minneapolis/St. Paul, Minn.), I have lived, at least metaphorically, in the shadow of the Metrodome. I attended the Dome’s public debut, the Minnesota Twins’ 1982 home opener. Last fall, the Twins departed for its new state-of-the-art Target Field on the other side of downtown Minneapolis, I don’t miss the Dome for baseball, but it is history.
Mason Riddle is a contributing editor for Fabric Architecture. Her piece on a Bard College canopy appeared in the May/June issue.
*“Turning on a snowmelt system is very costly,” states Campbell. “Although far more continuous in operation, illuminating the arena and powering the fans may be less expensive than turning on a snowmelt over the course of a year.”