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Speaker 1: Welcome to Brainstuff from dot com where smart happens. Hi.

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Speaker 1: I'm Marshall Brain with today's question, how do the retractable

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Speaker 1: roofs on stadium's work? Ballparks are just as trendy as

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Speaker 1: clothes and hairstyles. In the nineteen sixties and the nineteen seventies,

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Speaker 1: many cities built donut shape multi purpose stadiums. It was

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Speaker 1: also the era of the domed stadium. We were in

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Speaker 1: awe at the immensity of the Astrodome in Houston and

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Speaker 1: the Kingdome in Seattle. Today, a new trend in stadiums

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Speaker 1: has led to the demolition of the Kingdome and the

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Speaker 1: likely demise of the Astrodome. The latest trend in sports

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Speaker 1: stadiums is the retractable roof stadium. These new convertible stadiums

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Speaker 1: allow athletic fields to be covered during inclement weather, but

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Speaker 1: can be open to allow the sun to shine in

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Speaker 1: on fair weather days. This new type of stadium has

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Speaker 1: all been killed off the idea of artificial turf stadiums,

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Speaker 1: which cause a greater number of injuries than natural turf.

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Speaker 1: Retractable roofs are an idea whose time has come, But

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Speaker 1: just how do they work? It? Turns out there's no

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Speaker 1: single answer to that question, because no two retractable roof

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Speaker 1: stadiums are exactly alike. Let's look at a few of

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Speaker 1: these convertible stadiums and see what's going on. First, there's

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Speaker 1: the sky Dome in Toronto. It's the home of the

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Speaker 1: Blue Jays of Major League Baseball, and it was opened

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Speaker 1: in nine nine to begin the era of retractable roof stadiums.

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Speaker 1: While other stadiums had previously been built with removable tops,

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Speaker 1: for example Montreal's Olympics Stadium, the sky Dome was the

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Speaker 1: first to have a fully retractable roof. The roof consists

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Speaker 1: of four steel panels, and it moves along rails at

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Speaker 1: a rate of seventy one ft or twenty one meters

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Speaker 1: per minute, takes about twenty minutes to open or close.

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Speaker 1: When closing the roof, seventy two motors are used to

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Speaker 1: move the two panels backward and forward over a fixed

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Speaker 1: panel like a telescope, and a fourth panel rotates a

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Speaker 1: hundred eighty degrees to completely close the roof. Then there's

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Speaker 1: the Bank One Ballpark in Phoenix. It's home of the

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Speaker 1: Diamondbacks of Major League Baseball. Bank One ballpark or the

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Speaker 1: Bob opened in in the searing heat of the Arizona Desert,

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Speaker 1: it was almost a necessity to have a ballpark that

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Speaker 1: could be opened during moderate days and closed and air

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Speaker 1: conditioned on hot summer days. Bank One's roof uses a

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Speaker 1: system similar to a drawbridge. A pair of two hundred

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Speaker 1: horsepower motors drive the roof panels to open and close

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Speaker 1: in just four minutes, using four miles of cable strung

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Speaker 1: through a complicated police system. They're Safeco Field in Seattle.

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Speaker 1: In baseball's mariners said goodbye to the key Dome and

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Speaker 1: moved to Safeco. Safecoas roof is divided into three independent

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Speaker 1: panels made of a thin gypsum and glass fiberboard. A

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Speaker 1: waterproof skin covers the panels. The three panels are staggered

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Speaker 1: so that the roof can slide completely away from the

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Speaker 1: field of play. The panels roll on motorized steel wheels

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Speaker 1: that move over steel rails. The wheels are powered by

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Speaker 1: ninety six ten horsepower d C motors. Power is provided

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Speaker 1: by long cables that are reeled in and out as

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Speaker 1: the roof slides open and shut. Opening and closing the

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Speaker 1: roof is done at a rate of thirty ft or

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Speaker 1: nine point one meters per minute and takes ten to

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Speaker 1: fifteen minutes. There's Minute Made Park in Houston, opened in

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Speaker 1: two thousand is Enron Field, and then after the Enron scandal,

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Speaker 1: it was temporarily known as the Astroids Field before Minute

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Speaker 1: Made bought the naming rights. Minute Made Park is the

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Speaker 1: home of Baseball's Astros. The newest of the retractable roof stadiums,

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Speaker 1: it consists of three panels with staggered heights that slide

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Speaker 1: completely off the top of the playing field. Even the

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Speaker 1: glass walls on one side of the stadium retract to

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Speaker 1: allow baseballs to be hit completely out of the stadium.

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Speaker 1: Sixty electric motors with seven point five horsepower drive a

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Speaker 1: hundred and forty thirty six inch steel wheels that slide

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Speaker 1: over tracks on the east and west sides of the stadium.

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Speaker 1: Opening and closing takes between twelve and twenty minutes. And

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Speaker 1: then there's Reliance Stadium in Houston. Reliant, opened in two

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Speaker 1: thousand three, is the home of the Texans, the National

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Speaker 1: Football League expansion team. Reliance nine fifty six by three

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Speaker 1: hundred eighty five foot roof divides into two panels that

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Speaker 1: open in the middle of the stadium over the fifty

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Speaker 1: yard line. The panels are made out of a transparent

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Speaker 1: teflon coated fiberglass. Five tri chord trusses support each panel

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Speaker 1: and span between super trusses. The panels will slide over

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Speaker 1: rails built on top of the super trusses at a

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Speaker 1: rate of about thirty five ft per minute. Retractable roofs

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Speaker 1: are really marvels of modern architecture. They're designed to move

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Speaker 1: panels that weigh millions of pounds in just a few minutes.

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Speaker 1: By doing so, they give fans a new experience at

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Speaker 1: baseball and at football games. Given their popularity, it's likely

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Speaker 1: we'll see many more of these convertible stadiums built in

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Speaker 1: the next decade, until they're replaced by the next stadium trend.

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