Science Fair Project Encyclopedia
Lift bridge
A lift bridge or vertical lift bridge is a type of movable bridge in which a span rises vertically while remaining horizontal.
The vertical lift offers several benefits over other movable bridges such as the bascule and swing span bridge. Generally speaking they cost less to build. The counterweights in a vertical lift are only required to be equal to the weight of the deck, whereas bascule bridge counterweights must weigh several times more than the span being lifted. As a result, heavier materials can be used in the deck.
The biggest disadvantage to the lift bridge is the height restriction that results from the deck being above the passageway.
The most famous such bridge is the Aerial Lift Bridge in Duluth, Minnesota.
10-26-2009 08:16:03
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The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details