A lift bridge is a type of movable bridge that raises its roadway to allow boats and ships to pass underneath. This design is particularly useful in areas where waterways are busy, and fixed bridges would obstruct maritime traffic. The lifting mechanism typically involves counterweights and cables, enabling the bridge to elevate quickly and efficiently. Lift bridges can be found in various locations around the world, often spanning rivers or canals. They are essential for maintaining both road and waterway traffic flow. Notable examples include the Chicago River bridges in Chicago and the Tower Bridge in London, which showcase the engineering behind this unique structure.