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
Grand Tower Pipeline Bridge Grand Tower Pipeline Bridge The Grand Tower Pipeline Bridge is a suspension bridge carrying a natural gas pipeline across the Mississippi River between Wittenberg, Missouri and Grand Tower, Illinois. Although construction of a natural gas pipeline under the Mississippi River would have been cheaper, this option would have created great difficulty in handling any leaks and maintenance, so it was decided to construct a bridge to carry the gas pipeline. The bridge was the first pipeline suspension bridge to cross the Mississippi River. It was constructed for the Texas-Illinois Natural Gas Pipeline company for an estimated $3,800,000 in 1953. It