A vertical-lift bridge or just 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 bridges. Generally speaking, they cost less to build for longer moveable spans.[1] 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. The biggest disadvantage to the vertical-lift bridge (in comparison with many other designs) is the height restriction for vessels passing under it, due to the deck remaining suspended above the passageway.