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 William IV and Queen Adelaide attended a banquet in a pavilion erected on the bridge. In 1896 the bridge was the busiest point in London, and one of its most congested; 8,000 pedestrians and 900 vehicles crossed every hour. It was widened by , using granite corbels. Subsequent surveys showed that the bridge was sinking an inch (about 2.5 cm) every eight years, and by 1924 the east side had sunk some three to four inches (about 9 cm) lower than the west side. The bridge would have to be removed and replaced. In 1967, the Common Council of the