Name: Tower Bridge (view items)
Industry type: Transportation
Country: Great Britain
Start year: 1884
End year: 0
Notes: Tower Bridge is an iconic London landmark crossing the River Thames. A competition was held in the early 1880s to determine the best design for a new Thames crossing, and it was not until 1884 that a design submitted by Horace Jones was approved.
Jones' engineer, Sir John Wolfe Barry devised the idea of a bascule bridge 800 feet (244 m) in length with two towers each 213 feet (65 m) high, built on piers. The central span of 200 feet (61 m) between the towers was split into two equal bascules or leaves, which could be raised to an angle of 83 degrees to allow river traffic to pass. The bascules, weighing over 1,000 tons each, were counterbalanced to minimize the force required and allow raising in five minutes.
The two side-spans are suspension bridges, each 270 feet (82 m) long, with the suspension rods anchored both at the abutments and through rods contained within the bridge's upper walkways. The pedestrian walkways are 143 feet (44 m) above the river at high tide.
Construction started in 1886 and took eight years with five major contractors to complete. The bridge was opened to traffic in 1894