Day 83/365 of Steel – Tower Bridge

The funny thing about this trip through the history of steel in construction, design & art is jumping from futuristic supertrees in Singapore to a 130 year old icon of London. Technology and brilliant engineering has allowed steel to remain as relevant as it was almost 150 years ago, when the I-beam was invented.

Ship Passing Under The Tower Bridge
Fig 1: Ship Passing Under The Tower Bridge

Official opening of the Tower Bridge in London on 30 June 1894.
Tower Bridge is a combined bascule and suspension bridge in London, built between 1886 and 1894, designed by Horace Jones and engineered by John Wolfe Barry with the help of Henry Marc Brunel. It crosses the River Thames close to the Tower of London The bridge was opened by Edward, Prince of Wales and Alexandra, Princess of Wales in on 30 June 1894.

Tower Bridge London in 1956
Fig 2: Tower Bridge London in 1956
© RuthAS

The bridge is 240 m in length and consists of two 65 m bridge towers connected at the upper level by two horizontal walkways, and a central pair of bascules that can open to allow shipping. Originally hydraulically powered, the operating mechanism was converted to an electro-hydraulic system in 1972.

Tower Bridge At Night
Fig 3: Tower Bridge At Night
source: flickr

Construction started in 1886 and took eight years. Two piers, containing over 70,000 tons of concrete, were sunk into the riverbed to support the construction. More than 11,000 tons of steel were used in the framework for the towers and walkways, which were then clad in Cornish granite and Portland stone to protect the underlying steelwork. The central span of 61 m between the towers is split into two equal bascules, or leaves, which can be raised to an angle of 86 degrees to allow river traffic to pass. The bascules, weighing over 1,000 tons each, are counterbalanced to minimize the force required and allow raising in five minutes. The two side spans are suspension bridges, each 82 m long, with the suspension rods anchored both at the abutments and through rods contained within the bridge’s upper walkways. 

Tower Bridge - Aerial View
Fig 4: Tower Bridge – Aerial View
© Bob Collowan

About the Author:

Bruno Dursin – Managing Director at Believe in Steel. Bruno has more than 30 years of experience in promoting steel & steel solutions. His clients benefit from his extensive network within the building industry.

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