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London Tower Bridge & The Shard | by Arch_Sam
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London Tower Bridge & The Shard

Tower Bridge (built 1886–1894) is a combined bascule and suspension bridge in London, England which crosses the River Thames. It is close to the Tower of London, from which it takes its name, and has become an iconic symbol of London.

 

The bridge consists of two bridge towers tied together at the upper level by two horizontal walkways, designed to withstand the horizontal forces exerted by the suspended sections of the bridge on the landward sides of the towers. The vertical components of the forces in the suspended sections and the vertical reactions of the two walkways are carried by the two robust towers. The bascule pivots and operating machinery are housed in the base of each tower. The bridge's present colour scheme dates from 1977, when it was painted red, white and blue for Queen Elizabeth II's Silver Jubilee. Originally it was painted a mid greenish-blue colour.

 

The nearest London Underground tube stations are Tower Hill on the Circle and District lines, London Bridge and Bermondsey, and the nearest Docklands Light Railway station is Tower Gateway.

 

In the second half of the 19th 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 by tall-masted ships to the port facilities in the Pool of London, between London Bridge and the Tower of London.

 

A Special Bridge or Subway Committee was formed in 1877, chaired by Sir Albert Joseph Altman, 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 Sir Horace Jones, the City Architect (who was also one of the judges), was approved.

 

Jones' engineer, Sir John Wolfe Barry, devised the idea of a bascule bridge with two bridge towers built on piers. The central span was split into two equal bascules or leaves, which could be raised to allow river traffic to pass. The two side-spans were suspension bridges, with the suspension rods anchored both at the abutments and through rods contained within the bridge's upper walkways.

 

The bridge was officially opened on 30 June 1894 by The Prince of Wales (the future King Edward VII), and his wife, The Princess of Wales (Alexandra of Denmark).

 

The bridge connected Iron Gate, on the north bank of the river, with Horselydown Lane, on the south – now known as Tower Bridge Approach and Tower Bridge Road, respectively. Until the bridge was opened, the Tower Subway – 400 m to the west – was the shortest way to cross the river from Tower Hill to Tooley Street in Southwark. Opened in 1870, Tower Subway was among the world's earliest underground ("tube") railway, but it closed after just three months and was re-opened as a pedestrian foot tunnel. Once Tower Bridge was open, the majority of foot traffic transferred to using the bridge, there being no toll to pay to use it. Having lost most of its income, the tunnel was closed in 1898.

 

Tower Bridge is one of five London bridges now owned and maintained by the Bridge House Estates, a charitable trust overseen by the City of London Corporation. It is the only one of the Trust's bridges not to connect the City of London directly to the Southwark bank, the northern landfall being in Tower Hamlets.

 

Construction started in 1887 and took eight years with five major contractors – Sir John Jackson (foundations), Baron Armstrong (hydraulics), William Webster, Sir H.H. Bartlett, and Sir William Arrol & Co.– and employed 432 construction workers. E W Crutwell was the resident engineer for the construction.

 

Two massive piers, containing over 70,000 tons of concrete, were sunk into the riverbed to support the construction. Over 11,000 tons of steel provided the framework for the towers and walkways. This was then clad in Cornish granite and Portland stone, both to protect the underlying steelwork and to give the bridge a pleasing appearance.

 

Jones died in 1887 and George D. Stevenson took over the project. Stevenson replaced Jones's original brick façade with the more ornate Victorian Gothic style, which makes the bridge a distinctive landmark, and was intended to harmonise the bridge with the nearby Tower of London. The total cost of construction was £1,184,000 (equivalent to £118 million in 2015).

 

The bridge is 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 86 degrees to allow river traffic to pass. The bascules, weighing over 1,000 tons each, are counterbalanced to minimise 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.

 

Tower Bridge is still a busy and vital crossing of the Thames: it is crossed by over 40,000 people (motorists, cyclists and pedestrians) every day. The bridge is on the London Inner Ring Road, and is on the eastern boundary of the London congestion charge zone. (Drivers do not incur a charge by crossing the bridge.)

 

To maintain the integrity of the structure, the City of London Corporation has imposed a 20 miles per hour (32 km/h) speed restriction, and an 18 tonne weight limit on vehicles using the bridge. A camera system measures the speed of traffic crossing the bridge, utilising a number plate recognition system to send fixed penalty charges to speeding drivers.

 

A second system monitors other vehicle parameters. Induction loops and piezoelectric sensors are used to measure the weight, the height of the chassis above ground level, and the number of axles of each vehicle.

 

The bascules are raised around 1000 times a year. River traffic is now much reduced, but it still takes priority over road traffic. Today, 24 hours' notice is required before opening the bridge, and opening times are published in advance on the bridge's website. There is no charge for vessels.

 

A computer system was installed in 2000 to control the raising and lowering of the bascules remotely. It proved unreliable, resulting in the bridge being stuck in the open or closed positions on several occasions during 2005 until its sensors were replaced.

 

The bridge featured in publicity for the 2012 Summer Olympics being held in London. In June 2012 a set of Olympic rings was suspended from the bridge to mark one month to go until the start of the games. The rings cost £259,817 to make, measured 25 by 11.5 metres (82 by 38 ft) and weighed 13 tonnes (14 short tons).

 

On 9 June 2012 an AgustaWestland AW-139 (G-OLYM) flew three times through Tower Bridge while being filmed from a second helicopter for a segment of the opening ceremony entitled Happy and Glorious.

 

Professional footballer David Beckham piloted a dramatically illuminated Bladerunner BR RIB35X sportsboat, carrying the female footballer Jade Bailey and the Olympic Torch at the bow, under the raised bascules of the bridge during the ceremony. As they transited the crossing, fireworks exploded from the bridge.

 

On 8 July 2012, the west walkway was transformed into a 200 foot long Live Music Sculpture by the British composer Samuel Bordoli. 30 classical musicians were arranged along the length of the bridge 42 metres above the Thames behind the Olympic rings. The sound travelled backwards and forwards along the walkway, echoing the structure of bridge.

 

Following the Olympics, the rings were removed from Tower Bridge and replaced by the emblem of the Paralympic Games for the 2012 Summer Paralympics.

 

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Uploaded on April 15, 2015