A transporter bridge is a type of movable bridge that carries a gondola across a river. The bridge usually consists of a framework of steel girders spanning the river or waterway to be crossed, but instead of a roadway or railway lines built on a deck spanning the gap, a platform or "gondola" is suspended by steel cables from a moveable trolley running across the top of the span on a track. The trolley moves across the span taking with it the gondola, onto which are loaded the passengers and vehicles. The transporter bridge is a rare type of bridge, with fewer than two dozen built all over the world. Only eight operate today.

The iconic Middlesbrough Transporter Bridge across River Tees. Photo credit