A tilt bridge is a type of moveable bridge

Moveable bridge

A moveable bridge is a bridge that moves to allow passage for boats or barges. An advantage of making bridges movable include lower price, due to the absence of high piers and long approaches. The principal disadvantage is that the traffic on the bridge must be halted when it is opened for passages...

 which rotates about fixed endpoints rather than lifting or bending, as with a drawbridge

Drawbridge

A drawbridge is a type of movable bridge typically associated with the entrance of a castle surrounded by a moat. The term is often used to describe all different types of movable bridges, like bascule bridges and lift bridges.-Castle drawbridges:...

. 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

Gateshead Millennium Bridge

The Gateshead Millennium Bridge is a pedestrian and cyclist tilt bridge spanning the River Tyne in England between Gateshead's Quays arts quarter on the south bank, and the Quayside of Newcastle upon Tyne on the north bank. The award-winning structure was conceived and designed by architects...

 spanning the River Tyne between Gateshead

Gateshead

Gateshead is a town in Tyne and Wear, England and is the main settlement in the Metropolitan Borough of Gateshead. Historically a part of County Durham, it lies on the southern bank of the River Tyne opposite Newcastle upon Tyne and together they form the urban core of Tyneside...

 on the south bank and Newcastle upon Tyne

Newcastle upon Tyne

Newcastle upon Tyne is a city and metropolitan borough of Tyne and Wear, in North East England. Historically a part of Northumberland, it is situated on the north bank of the River 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.