Ever felt a bridge move while on it?
The Manhattan Bridge in New York City. A nickel steel suspension bridge built in 1901 that has 7 lanes of traffic and 4 subway tracks. Spans between Manhattan and Brooklyn. An estimated 150,000 vehicles cross it daily.
SUBWAY TRAFFIC TAKES ITS TOLL: As applied on the Manhattan Bridge, deflection theory allowed for economies of material, cost and time. However, the theory did not take into account the problem of the subway trains on the outer parts of the lower deck. Over the years, heavy subway traffic caused considerable twisting of the deck. Maximum torsion occurs when subway trains start to cross opposite sides of the bridge at the same time. At that moment, one side of the roadway dips four feet to the north side, while the other side of the roadway dips four feet to the south side, creating a total roadway deflection of up to eight feet.
Watch it.
Manhattan bridge piers
July 23, 2009
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