Focus Friday - Vertical-Lift Bridges
Friday, Aug 12 2011 by kjfitz
A vertical-lift bridge or lift bridge is a type of movable bridge in which a span rises vertically while remaining parallel with the deck. 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 for longer moveable spans. 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 as much as the span being lifted. As a result, heavier materials can be used in the deck, and so this type of bridge is especially suited for heavy railroad use.