WEBVTT - How do retractable roofs in convertible stadiums work?

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<v Speaker 1>Welcome to Brainstuff from dot com where smart happens. Hi.

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

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<v Speaker 1>roofs on stadium's work? Ballparks are just as trendy as

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<v Speaker 1>clothes and hairstyles. In the nineteen sixties and the nineteen seventies,

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<v Speaker 1>many cities built donut shape multi purpose stadiums. It was

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<v Speaker 1>also the era of the domed stadium. We were in

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<v Speaker 1>awe at the immensity of the Astrodome in Houston and

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<v Speaker 1>the Kingdome in Seattle. Today, a new trend in stadiums

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<v Speaker 1>has led to the demolition of the Kingdome and the

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<v Speaker 1>likely demise of the Astrodome. The latest trend in sports

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<v Speaker 1>stadiums is the retractable roof stadium. These new convertible stadiums

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<v Speaker 1>allow athletic fields to be covered during inclement weather, but

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<v Speaker 1>can be open to allow the sun to shine in

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<v Speaker 1>on fair weather days. This new type of stadium has

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<v Speaker 1>all been killed off the idea of artificial turf stadiums,

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<v Speaker 1>which cause a greater number of injuries than natural turf.

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<v Speaker 1>Retractable roofs are an idea whose time has come, But

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<v Speaker 1>just how do they work? It? Turns out there's no

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<v Speaker 1>single answer to that question, because no two retractable roof

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<v Speaker 1>stadiums are exactly alike. Let's look at a few of

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

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<v Speaker 1>the sky Dome in Toronto. It's the home of the

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<v Speaker 1>Blue Jays of Major League Baseball, and it was opened

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<v Speaker 1>in nine nine to begin the era of retractable roof stadiums.

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<v Speaker 1>While other stadiums had previously been built with removable tops,

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<v Speaker 1>for example Montreal's Olympics Stadium, the sky Dome was the

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<v Speaker 1>first to have a fully retractable roof. The roof consists

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<v Speaker 1>of four steel panels, and it moves along rails at

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<v Speaker 1>a rate of seventy one ft or twenty one meters

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<v Speaker 1>per minute, takes about twenty minutes to open or close.

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<v Speaker 1>When closing the roof, seventy two motors are used to

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<v Speaker 1>move the two panels backward and forward over a fixed

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<v Speaker 1>panel like a telescope, and a fourth panel rotates a

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<v Speaker 1>hundred eighty degrees to completely close the roof. Then there's

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<v Speaker 1>the Bank One Ballpark in Phoenix. It's home of the

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<v Speaker 1>Diamondbacks of Major League Baseball. Bank One ballpark or the

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<v Speaker 1>Bob opened in in the searing heat of the Arizona Desert,

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<v Speaker 1>it was almost a necessity to have a ballpark that

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<v Speaker 1>could be opened during moderate days and closed and air

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<v Speaker 1>conditioned on hot summer days. Bank One's roof uses a

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<v Speaker 1>system similar to a drawbridge. A pair of two hundred

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<v Speaker 1>horsepower motors drive the roof panels to open and close

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<v Speaker 1>in just four minutes, using four miles of cable strung

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<v Speaker 1>through a complicated police system. They're Safeco Field in Seattle.

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<v Speaker 1>In baseball's mariners said goodbye to the key Dome and

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<v Speaker 1>moved to Safeco. Safecoas roof is divided into three independent

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<v Speaker 1>panels made of a thin gypsum and glass fiberboard. A

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<v Speaker 1>waterproof skin covers the panels. The three panels are staggered

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<v Speaker 1>so that the roof can slide completely away from the

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<v Speaker 1>field of play. The panels roll on motorized steel wheels

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<v Speaker 1>that move over steel rails. The wheels are powered by

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<v Speaker 1>ninety six ten horsepower d C motors. Power is provided

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<v Speaker 1>by long cables that are reeled in and out as

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<v Speaker 1>the roof slides open and shut. Opening and closing the

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<v Speaker 1>roof is done at a rate of thirty ft or

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<v Speaker 1>nine point one meters per minute and takes ten to

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<v Speaker 1>fifteen minutes. There's Minute Made Park in Houston, opened in

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<v Speaker 1>two thousand is Enron Field, and then after the Enron scandal,

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<v Speaker 1>it was temporarily known as the Astroids Field before Minute

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<v Speaker 1>Made bought the naming rights. Minute Made Park is the

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

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<v Speaker 1>it consists of three panels with staggered heights that slide

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<v Speaker 1>completely off the top of the playing field. Even the

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<v Speaker 1>glass walls on one side of the stadium retract to

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<v Speaker 1>allow baseballs to be hit completely out of the stadium.

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<v Speaker 1>Sixty electric motors with seven point five horsepower drive a

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<v Speaker 1>hundred and forty thirty six inch steel wheels that slide

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<v Speaker 1>over tracks on the east and west sides of the stadium.

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<v Speaker 1>Opening and closing takes between twelve and twenty minutes. And

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<v Speaker 1>then there's Reliance Stadium in Houston. Reliant, opened in two

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<v Speaker 1>thousand three, is the home of the Texans, the National

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<v Speaker 1>Football League expansion team. Reliance nine fifty six by three

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<v Speaker 1>hundred eighty five foot roof divides into two panels that

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<v Speaker 1>open in the middle of the stadium over the fifty

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<v Speaker 1>yard line. The panels are made out of a transparent

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<v Speaker 1>teflon coated fiberglass. Five tri chord trusses support each panel

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<v Speaker 1>and span between super trusses. The panels will slide over

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<v Speaker 1>rails built on top of the super trusses at a

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<v Speaker 1>rate of about thirty five ft per minute. Retractable roofs

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<v Speaker 1>are really marvels of modern architecture. They're designed to move

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<v Speaker 1>panels that weigh millions of pounds in just a few minutes.

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<v Speaker 1>By doing so, they give fans a new experience at

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

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<v Speaker 1>we'll see many more of these convertible stadiums built in

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<v Speaker 1>the next decade, until they're replaced by the next stadium trend.

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<v Speaker 1>Be sure to check out our new video podcast, Stuff

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