Tower Bridge

Category: Bridges

Tower Bridge is a bascule bridge in London, England over the River Thames. It is close to the Tower of London, which gives it its name. It has become an iconic symbol of London and is sometimes mistakenly called London Bridge, which is actually the next bridge upstream.

The bridge is owned and maintained by Bridge House Estates, a charitable trust overseen by the Corporation of London.

In the second half of the nineteenth century, increased commercial development in the East End of London led to a requirement for a new river crossing downstream of London Bridge. A traditional fixed bridge could not be built because it would cut off access to the port facilities situated at that time in the Pool of London, between London Bridge and the Tower of London. A tunnel beneath the Thames, the Tower Subway, was opened in 1870, but it could only accommodate pedestrian traffic.

A Special Bridge or Subway Committee was formed in 1876 to find a solution to the river crossing problem. It opened the design of the crossing to public competition. Over 50 designs were submitted, including one from civil engineer Sir Joseph Bazalgette. The evaluation of the designs was surrounded by controversy, and it was not until 1884 that a design submitted by Horace Jones, the City Architect, was approved.

Jones’ design was for 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 is split into two equal bascules or leaves, which can be raised to an angle of 83 degrees to allow river traffic to pass. Although each bascule weighs over 1,000 tons, they are counterbalanced to minimise the force required and allow raising in one minute. The original hydraulic raising mechanism was powered by pressurised water stored in six accumulators. Water was pumped into the accumulators by steam engines.

Today the original hydraulic machinery still opens the bridge, however it has been converted to use oil instead of water and electric motors have taken the place of the steam engines and accumulators. The old mechanism is open to the public.


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