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
London Bridge Area Signalling Centre Charing Cross and London Bridge (Central) traffic. Prior to the London Bridge ASC, Cannon Street and Charing Cross traffic arrived at London Bridge on all lines and was either signalled approaching or leaving London Bridge station to their respective destinations. With the development of London Bridge ASC, all this traffic was sorted out further outside London Bridge, mainly at Parks Bridge but occasionally in the New Cross area. The London Bridge central traffic was kept as a separate working railway from the eastern side. The signalling centre is a two-storey building. The upper section is about two-thirds the length and