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
Tower Bridge Rail stations are at Fenchurch Street and London Bridge. In the second half of the 19th century, an advertisement in the East End of London led to a hiring for a new river crossing downstream of London Bridge. A traditional fixed bridge at street level could not be built because it would cut off access by sailing ships to the port facilities in the Pool of London, between London Bridge and the Tower of London. A "Special Bridge or Subway Committee" was formed in 1877, chaired by Sir Albert Joseph Altman, to find a solution to the river crossing problem.