Retractable bridge
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| Retractable bridge | |
|---|---|
| Image:Uppsala Ultunabron02 2005-06-16.jpg | |
| Ultuabron in Uppsala (retracted) | |
| Ancestor | Plate girder bridge |
| Related | Lift bridge, submersible bridge, folding bridge |
| Descendant | None |
| Carries | Automobile, pedestrians |
| Span range | Short |
| Material | Steel |
| Movable | Yes |
| Design effort | Medium |
| Falsework required | No |
A recent example can be found at Queen Alexandra Dock in Cardiff, Wales, where the bridge is jacked upwards before being rolled on wheels. Helix Bridge [1] at Paddington Basin, London is a more unusual example of the type, consisting of a glass shell supported in a helical steel frame, which rotates as it retracts.
Many retractable bridges are also floating bridges, such as the Hood Canal Bridge, where a retractable span can be withdrawn between two lines of pontoons in the shape of a "U". A similar arrangement exists on the Evergreen Point Floating Bridge and Lacey V. Murrow Memorial Bridge.
Historical examples of designs for retractable bridges include those by Leonardo da Vinci [2], and Agostino Ramelli. [3]
[edit] See also
- Movable bridge for a list of other movable bridge types
- Guthrie rolling bridge
