Tower Bridge
Tower Bridge is a combined bascule and suspension bridge in London, England over the River Thames. The bridge consists of two towers which are tied together at the upper level by means of two horisontal walkways which are designed to withstand the horisontal forces exerted by the suspended sections of the bridge to the left and the right. The vertical component of the forces in the suspended sections and the vertical reactions of the two walkways are carried by the two robust towers. It is close to the Tower of London, which gives it its name. It has become an iconic symbol of London. Tower Bridge is one of several London bridges owned and maintained by the City Bridge Trust, a charitable trust overseen by the City of London Corporation.
Tower Bridge is sometimes mistakenly referred to as London Bridge, which is actually the next bridge upstream. A popular urban legend is that, in 1968 Robert McCulloch, the purchaser of the old London Bridge which was later shipped to Lake Havasu City, Arizona, believed mistakenly that he was buying Tower Bridge, but this was denied by McCulloch himself and has been debunked by Ivan Luckin, the seller of the bridge. Its present colour dates from 1977 when it was painted red, white and blue for the Queen's Silver Jubilee. Previous to this, it was painted a chocolate brown colour.
Tower Bridge Today
Road traffic
Tower Bridge is still a busy and vital crossing of the Thames: it is crossed by over 40,000 people (motorists and pedestrians) every day.[20] The bridge is on the London Inner Ring Road, and (as of 2007) is on the eastern boundary of the London congestion charge zone. (Drivers do not incur a charge by crossing the bridge.)
In order to maintain the integrity of the historic structure, the City of London Corporation have imposed a 20 miles per hour (32 km/h) speed restriction, and an 18 ton weight limit on vehicles using the bridge. A sophisticated 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 piezo-electric detectors are used to measure the weight, the height of the chassis above ground level, and the number of axles for each vehicle.
River traffic
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.
A computer system was installed in 2000 to control the raising and lowering of the bascules remotely. Unfortunately it proved less reliable than desired, resulting in the bridge being stuck in the open or closed positions on several occasions during 2005, until its sensors were replaced.[20]
Tower Bridge Exhibition
The high-level walkways between the towers gained an unpleasant reputation as a haunt for prostitutes and pickpockets and were closed in 1910. In 1982 they were reopened as part of the Tower Bridge Exhibition, an exhibition now housed in the bridge's twin towers, the high-level walkways and the Victorian engine rooms. The walkways boast stunning views of the River Thames and many famous London sites, serving as viewing galleries for over 380,000 tourists who visit each year. The exhibition also uses films, photos and interactives to explain why and how Tower Bridge was built. Visitors can access the original steam engines that once powered the bridge bascules, housed in a building close to the south end of the bridge.
A Behind the Scenes tour can be booked in advance, during which it is possible to see the bridge's command centre, from where the raising of the bascules is controlled for a vessel to pass through, and go down into the bascule chambers too.
2008-2012 facelift
In April 2008 it was announced that the bridge will undergo a 'facelift' costing £4m, and taking four years to complete. The work entails stripping-off the existing paint and repainting in blue and white. Each section will be enshrouded in scaffolding to prevent the old paint falling into the Thames causing pollution. Starting in summer 2008, contractors will work on a quarter of the bridge at a time to minimise disruption, but some road closures are inevitable. The bridge will remain open until winter 2010, but is then expected to be closed for several months. It is hoped that the completed work will last 25 years.
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London Bridge: A Visual History
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