Coordinates : 51°30′20″N 0°04′32″W / 51.50556°N 0.07556°W / 51.50556; -0.07556 For the bridge in Sacramento, California, see Tower Bridge (California) . For the station in Co. Cork, Ireland, see Tower Bridge railway station .
Tower Bridge Road
MAINTAINED BY Bridge House Estates
HERITAGE STATUS Grade I listed structure
PRECEDED BY London Bridge
FOLLOWED BY Queen Elizabeth II Bridge
DESIGN Bascule bridge / Suspension Bridge
TOTAL LENGTH 801 ft (244 m)
HEIGHT 213 ft (65 m)
LONGEST SPAN 270 ft (82.3 m)
CLEARANCE BELOW 28 ft (8.6 m) (closed) 139 ft (42.5 m) (open) (mean high water spring tide)
OPENED 30 June 1894; 123 years ago (1894-06-30)
TOWER BRIDGE is a combined bascule and suspension bridge in London
built between 1886 and 1894. The bridge crosses the
The bridge consists of two bridge towers tied together at the upper level by two horizontal walkways, designed to withstand the horizontal tension 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. Before its restoration in the 2010s, the bridge's colour scheme dated from 1977, when it was painted red, white and blue for Queen Elizabeth II 's Silver Jubilee . Its colours were subsequently restored to blue and white.
The bridge deck is freely accessible to both vehicles and
pedestrians, whereas the bridge's twin towers, high-level walkways and
Victorian engine rooms form part of the
* 1 History
* 2 Design
* 2.1 Bridge structure * 2.2 Hydraulic system * 2.3 Signalling and control
* 3 Traffic
* 3.1 Road * 3.2 River
* 8 See also
* 8.1 Historic places adjacent to
* 9 References * 10 External links
Elevation, with dimensions
In the second half of the 19th century, an advertisement in the East
Barry designed 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.
Construction started in 1886 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 as they were only accessible by stairs they were seldom used by regular pedestrians, and were closed in 1910.
SECOND WORLD WAR
During the Second World War and as a precaution against the existing engines being damaged by enemy action, a third engine was installed in 1942: a 150 hp horizontal cross-compound engine, built by Vickers Armstrong Ltd. at their Elswick works in Newcastle upon Tyne. It was fitted with a flywheel having a 9-foot (2.7 m) diameter and weighing 9 tons, and was governed to a speed of 30 rpm. The engine became redundant when the rest of the system was modernised in 1974, and was donated to the Forncett Industrial Steam Museum by the Corporation of the City of London.
In 1974, the original operating mechanism was largely replaced by a
new electro-hydraulic drive system, designed by BHA Cromwell House,
with the original final pinions driven by modern hydraulic motors and
gearing. In 1982, the
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.
In April 2008 it was announced that the bridge would undergo a 'facelift' costing £4 million, and taking four years to complete. The work entailed stripping off the existing paint down to bare metal and repainting in blue and white. Each section was enshrouded in scaffolding and plastic sheeting to prevent the old paint falling into the Thames and causing pollution. Starting in mid-2008, contractors worked on a quarter of the bridge at a time to minimise disruption, but some road closures were inevitable. It is intended that the completed work will stand for 25 years.
The renovation of the walkway interior was completed in mid-2009. Within the walkways a versatile new lighting system has been installed, designed by Eleni Shiarlis, for when the walkways are in use for exhibitions or functions. The new system provides for both feature and atmospheric lighting, the latter using bespoke RGB LED luminaires , designed to be concealed within the bridge superstructure and fixed without the need for drilling (these requirements as a result of the bridge's Grade I status).
The renovation of the four suspension chains was completed in March 2010 using a state-of-the-art coating system requiring up to six different layers of 'paint'.
LONDON 2012 OLYMPICS AND PARALYMPICS
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 8 July 2012, the west walkway was transformed into a 200-foot-long (61 m) Live Music Sculpture by the British composer Samuel Bordoli. 30 classical musicians were arranged along the length of the bridge 138 feet (42 m) above the Thames behind the Olympic rings. The sound travelled backwards and forwards along the walkway, echoing the structure of bridge.
* Undertaking major maintenance to the bridge lifting systems * Replacing the decking and resurfacing the walkways and road * Replacing the expansion joints along the bridge to provide a smoother surface * Waterproofing the arches made from brick on the approaches to the bridge
During this time the bridge was still open to water borne traffic as required by Act of Parliament. The bridge was open to pedestrians for all but three weekends, where a free ferry service was in operation.
The bridge is 800 feet (240 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.
The main bridge deck carries two lanes of road traffic between two low-level pedestrian walkways across both suspension spans and the opening bascule section of the bridge, with the walkways separated from the roadway by fences. The roadway passes through each of the two towers, whereas the low-level walkways pass around the outside of the towers.
One of the chimneys on the bridge, which are often confused as lamp posts, connects up to an old fireplace in a guardroom of the Tower of London. It is long-disused.
One of the original steam engines
The original raising mechanism was powered by pressurised water
stored in several hydraulic accumulators . The system was designed
and installed by
Hamilton Owen Rendel while working for Sir W. G.
Armstrong Mitchell & Company of
Newcastle upon Tyne
The entire hydraulic system along with the gas lighting system was installed by William Sugg by night, two red lights in the same position. Foggy weather required repeated blasts from the ship's steam whistle . If a black ball was suspended from the middle of each walkway (or a red light at night) this indicated that the bridge could not be opened. These signals were repeated about 1,000 yards (910 m) downstream, at Cherry Garden Pier , where boats needing to pass through the bridge had to hoist their signals/lights and sound their horn, as appropriate, to alert the Bridge Master.
Some of the control mechanism for the signalling equipment has been preserved and may be seen working in the bridge's museum.
To maintain the integrity of the structure, the City of London Corporation has imposed a 20-mile-per-hour (32 km/h) speed restriction, and an 18 tonnes (20 short tons) weight limit on vehicles using the bridge. A camera system measures the speed of traffic crossing the bridge, using 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 to open the bridge.
When needing to be raised for the passage of a vessel the bascules are only raised to an angle sufficient for the vessel to safely pass under the bridge, except in the case of a vessel with the Monarch on board in which case they are raised fully no matter the size of the vessel.
TOWER BRIDGE EXHIBITION
Interior of high-level walkway (used as an exhibition space)
The exhibition charges an admission fee. Entrance is from the west
side of the bridge deck to the northern tower, from where visitors
ascend to level 4 by lift before crossing the high-level walkways to
the southern tower. In the towers and walkways is an exhibition on the
history of the bridge. The walkways also provide views over the city,
the Tower of
Although the bridge is an undoubted landmark, professional
commentators in the early 20th century were critical of its
aesthetics. "It represents the vice of tawdriness and pretentiousness,
and of falsification of the actual facts of the structure", wrote
Henry Heathcote Statham , while
Frank Brangwyn stated that "A more
absurd structure than the
Architectural historian Dan Cruickshank selected the bridge as one of his four choices for the 2002 BBC television documentary series Britain\'s Best Buildings .
A partial replica of
In December 1952, the bridge opened while a number 78 double-decker bus was crossing from the south bank. At that time, the gateman would ring a warning bell and close the gates when the bridge was clear before the watchman ordered the raising of the bridge. The process failed while a relief watchman was on duty. The bus was near the edge of the south bascule when it started to rise; driver Albert Gunter made a split-second decision to accelerate, clearing a 3-foot (0.91 m) gap to drop 6 feet (1.8 m) onto the north bascule, which had not yet started to rise. There were no serious injuries. Gunter was given £ 10 (equivalent to £260 in 2015 ) by the City Corporation to honour his act of bravery.
Hawker Hunter Tower Bridge incident occurred on 5 April 1968 when
Royal Air Force
In the summer of 1973, a single-engined
Beagle Pup was twice flown
under the pedestrian walkway of
In May 1997, the motorcade of United States President Bill Clinton
was divided by the opening of the bridge. The Thames sailing barge
Gladys, on her way to a gathering at
St Katharine Docks , arrived on
schedule and the bridge was opened for her. Returning from a
Thames-side lunch at Le Pont de la Tour restaurant with UK Prime
Tony Blair , President Clinton was less punctual and arrived
just as the bridge was rising. The bridge opening split the motorcade
in two, much to the consternation of security staff. A spokesman for
On 19 August 1999, Jef Smith, a Freeman of the City of
Before dawn on 31 October 2003, David Crick, a Fathers 4 Justice
campaigner, climbed a 100-foot (30 m) tower crane near
On 11 May 2009, six people were trapped and injured after a lift fell 10 feet (3 m) inside the north tower.
* * * * * * * * * * * *
HISTORIC PLACES ADJACENT TO TOWER BRIDGE
Comparison of the side elevations of the
* ^ A B "
* ^ Statham, H.H., "Bridge Engineering", Wiley, 1916. * ^ Brangwyn, F., and Sparrow, W. S. , "A Book of Bridges", John Lane, 1920. * ^ Cruickshank, Dan. "Choosing Britain\'s Best Buildings". BBC History. Retrieved 3 June 2008. * ^ Jason Cochran, Pauline Frommer (2007). Pauline Frommer\'s London. Frommer's. p. 184. ISBN 978-0-470-05228-0 . Retrieved 9 July 2011. * ^ "How London Bridge was sold to the States (From This Is Local London)". Thisislocallondon.co.uk. Retrieved 13 June 2012. * ^ Silk, Michael; Manley, Andrew (3 June 2014). "From Tower Bridge to Sydney Harbour, welcome to China’s city of clones". The Guardian. Retrieved 14 July 2015. * ^ "Tower Bridge, London, UK". BBC. Retrieved 11 November 2008. * ^ "The Jumping Bus". Time . 12 January 1953. Archived from the original on 22 December 2008. * ^ Car Journals. "Mind The Gap When Jumping Over Tower Bridge". Car Journals. Retrieved 20 June 2014. * ^ p.157, Shaw, Michael 'No.1 Squadron', Ian Allan 1986 * ^ " Hawker Hunter History". (scroll down half-way). Thunder & Lightnings. 29 February 2004. Retrieved 8 April 2008. * ^ "Gives Suici