 An animation showing how a vertical-lift bridge operates with vehicular and shipping traffic | |
| Ancestor | Truss bridge |
|---|---|
| Related | Bascule bridge, swing bridge, folding bridge, retractable bridge |
| Descendant | Submersible bridge, table bridge |
| Carries | Automobile, pedestrians, truck, light rail, heavy rail |
| Span range | Short |
| Material | Steel |
| Movable | Yes |
| Design effort | medium |
| Falsework required | Depends upon degree of prefabrication |
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.
Most vertical-lift bridges use towers, each equipped with counterweights. An example of this kind was built at La Salle in Illinois, United States in 1929 (and demolished in 2001).[2]
Another design uses balance beams to lift the deck, with pivoting bascules located on the top of the lift towers.[3]
![Hawthorne Bridge (in Portland, Oregon, U.S.), built in 1910, the oldest vertical-lift bridge in the United States[4]](/en/File:Hawthorne_Bridge_(Portland,_Oregon)_from_southwest,_2012.jpg)
