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
Bridge tower Bridge tower A bridge tower () was a type of fortified tower built on a bridge. They were typically built in the period up to early modern times as part of a city or town wall or castle. There is usually a tower at both ends of the bridge. During the 19th century, a number of bridge towers were built in the Gothic Revival style – Tower Bridge in London is perhaps the best known example; however, many original medieval towers survive across Europe. These towers were built in pre-medieval and medieval times to guard access to the bridge and