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 cost of £4 million (£ in ), was met entirely by the Bridge House Estates charity. The current bridge was built in the same location as Rennie's bridge, with the previous bridge remaining in use while the first two girders were constructed upstream and downstream. Traffic was then transferred onto the two new girders, and the previous bridge demolished to allow the final two central girders to be added. In 1984, the British warship HMS "Jupiter" collided with London Bridge, causing significant damage to both the ship and the bridge. On Remembrance Day 2004, several bridges in London were furnished