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A tilt bridge is a type of moveable bridge which rotates about fixed endpoints rather than lifting or bending, as with a drawbridge. For this rotation to serve a useful purpose, namely facilitating boat traffic underneath, its deck must follow a curved shape. For this reason, the concept is generally impractical if the bridge is intended to serve vehicular traffic.
The tilting Gateshead Millennium Bridge spanning the River Tyne between Gateshead on the south bank and Newcastle upon Tyne on the north is a pedestrian bridge with two large hydraulic rams at each side that tilt the structure back allowing small watercraft to pass under.
The pedestrian and cycle pathway is an almost-horizontal curve, suspended above the river from a just-beyond-the-vertical parabolic arch. To raise the bridge, this whole assembly rotates as a single, rigid structure. As the arch tilts lower, the pathway rises, each counterbalancing the other so that a minimum of energy is needed. The resultant appearance in motion leads to it sometimes being called the "eyelid bridge", since its shape is akin to the blinking of an eye if seen from along the river.
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