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Long-spans amplify the collaborative relationship between architects and engineers

By Sara Hart

Play ball … anytime

The world’s first covered and air-conditioned superstadium was the Houston Astrodome (Wilson, Morris, Crain and Anderson, and Lloyd, Morgan & Jones; Walter P. Moore and Associates). It covers 150,000 square feet of playing surface and is covered by a skylit dome 642 feet in diameter. Not without the serious flaws that prototypes often have, it was nonetheless touted as the “eighth wonder of the world” when it opened in 1965, and became a huge tourist attraction. Since the city’s National League team, the Houston Astros, left the Astrodome in 1999, the stadium’s fate is uncertain.

Miller Park, Milwaukee, Wisconsin Architect: NBBJ Sports & Entertainment Structural engineer: Arup Date of completion: 2001 Roof span: 590 feet (retractable) Consultants: Mitsubishi Heavy Industries of America (roof fabricator) Photography: © Tim Griffith

Fast-forward 37 years and witness one example of how spanning a superstadium has evolved. Miller Park, the new home to the Milwaukee Brewers, opened in April 2001. Designed by Los Angeles–based NBBJ Sports & Entertainment, it’s topped with one of the most advanced and elegant roofs in the U.S. Furthermore, it’s the only fan-shaped, retractable roof of this scale in the world. Design principal Dan Meis calls the concept “drop-dead simple.” Its panels pivot from a point directly above home plate following a radial line, which, unlike other linear stadium roofs, reflects the the layout of a baseball field and the motion of the game. “We were originally concerned about moving the panels on a radius,” explains Meis, having feared that a fan-shaped design would be more expensive than the typical linear roof. “When we submitted a model for our design [to the client], we instructed the model maker to make the roof actually open with the push of a button, figuring that if it worked in model, we’d figure out a way to make it work in reality,” says Meis.

A retractable roof solves what might be called the Astrodome problem. When the roof glazing at the Astrodome produced too much glare for catching fly balls in the outfield, it was painted white. Of course, without proper daylight, the natural grass promptly died. Although this serious problem was solved by the immediate invention of AstroTurf, it did reflect the drawbacks of playing field sports inside. Miller Park does not have this problem. When the weather is cold and rainy, spectators are protected from the elements; the rest of the time, the games are played outdoors on natural turf, as they should be.