|
| |
roof Metrodome
Features
The roof
Action during a Vikings game, from a location similar to 2004 ALDS photo. Note
the retractable seats in the lower-right portion of this photo.
Action during a Vikings game, from a location similar to 2004 ALDS photo. Note
the retractable seats in the lower-right portion of this photo.
The teflon fabric dome is air-inflated and requires 250,000 ft³/min (120 m³/s)
of air to keep it inflated. Three times in the stadium's history, heavy snows
have caused a small puncture in the roof and caused it to deflate. Varying air
pressure due to a severe storm once contributed to a dramatic deflation during a
regular season baseball game. The stadium construction is notable in that the
$68 million price tag was on budget, and the facility was completed on time, a
rare feat in the world of stadium construction. The Metrodome roof, consisting
of 20 acres of double-layered Teflon-coated fiberglass fabric, is the largest
application of Teflon on Earth.
The Metrodome's roof is made of two layers of Teflon fabric, and is supported by
positive air pressure. To maintain the differential air pressure, spectators
usually enter and leave the seating and concourse areas through revolving doors,
since the use of regular doors is accompanied by a strong breeze. The
double-walled construction allows warmed air to circulate beneath the top of the
dome, melting accumulated snow. However, on November 19, 1981, a rapid
accumulation of over a foot of snow caused the roof to collapse, requiring it to
be reinflated.
Because it is unusually low to the playing field (172 feet/52.4 m), the
air-inflated dome is occasionally touched by baseballs, altering play. Any ball
which strikes the Dome roof remains in play; if it lands in foul territory it
becomes a foul ball, if it lands in fair territory it becomes a fair ball. Any
ball which becomes caught in the roof over fair ground (which has only happened
twice in its history - Dave Kingman for the Oakland Athletics in 1984 and Corey
Koskie in 2004) - is a ground rule double. More common is for a ball to strike
an overhead speaker, which are even closer to the playing surface; such balls
are also alive and in-play (although starting with the 2005 MLB season, the
ground rules for balls hitting the speakers have been changed as David Ortiz of
the Boston Red Sox discovered when a deep fly ball that would have been a
homerun excepting speaker interference bounced off a speaker and landed in fair
territory. Ortiz was awarded a single and the Twins went on to win the game).
The low roof has never been a concern for events other than baseball.
| |
|
