Bridge four-lane highway on the upper level and a pair of railway tracks at the lower level. Tower Bridge in London is different example of a double-decked bridge, with the central section consisting of a low level bascule span and a high level footbridge. A viaduct is made up of multiple bridges connected into one longer structure. The longest and some of the highest bridges are viaducts, such as the Lake Pontchartrain Causeway and Millau Viaduct. A three-way bridge has three separate spans which meet near the center of the bridge. The bridge appears as a "T" or "Y" when viewed
Albert Bridge, London light and thus to reduce the risks of ships colliding with the fragile structure during the day. At night, a network of 4,000 low-voltage tungsten-halogen bulbs illuminated the bridge. In 1993 the innovative use of long-life low-energy lighting was commended by Mary Archer, at the time Chairwoman of the National Energy Foundation. Except for Tower Bridge, built in 1894, Albert Bridge is the only Thames road bridge in central London never to have been replaced. Intended as a temporary measure to be removed in 1978, the concrete central piers remain in place, and although in 1974 its lifespan was estimated