Clifton Suspension Bridge
2008/9 Schools Wikipedia Selection. Related subjects: Architecture; Engineering
| Clifton Suspension Bridge | |
|---|---|
 Clifton suspension bridge taken from a slip road off Brunel Way. |
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| Carries | Cars, pedestrians and cycles |
| Crosses | River Avon |
| Locale | Bristol |
| Maintained by | Clifton Suspension Bridge Trust |
| Design | Suspension |
| Longest span | 702 ft (214 m) |
| Total length | 1,352 ft (414 m) |
| Width | 31 ft (9.5m) |
| Clearance below | 245 ft (75 m) above high water level |
| Opening date | 1864 |
| Toll | 50 pence |
| Coordinates | |
The Clifton Suspension Bridge is a suspension bridge, spanning the Avon Gorge and linking Clifton in Bristol to Leigh Woods in North Somerset, England. Designed by Isambard Kingdom Brunel, it is a distinctive landmark that is used as a symbol of Bristol. It is a grade I listed building.
History
The idea of building a bridge across the Avon Gorge originated in 1753, with a bequest in the will of Bristolian merchant William Vick, who left £1,000 invested with instructions that when the interest had accumulated to £10,000, it should be used for the purpose of building a stone bridge between Clifton Down (which was in Gloucestershire, outside the City of Bristol, until the 1830s) and Leigh Woods (then in Somerset).
By 1829, Vick's bequest had reached £8,000, but it was estimated that a stone bridge would cost over ten times that amount. An Act of Parliament was passed to allow a wrought-iron suspension bridge to be built instead, and tolls levied to recoup the cost. A competition was held to find a design for the bridge; the judge, Thomas Telford, rejected all designs, and tried to insist on a design of his own, a suspension bridge supported on tall Gothic towers. Telford claimed that no suspension bridge could exceed the 600 feet (183 m) span of his own Menai Suspension Bridge. A second competition, held with new judges, was won by Brunel's design on 16 March 1831, for a suspension bridge with fashionably Egyptian-influenced towers.
An attempt to build Brunel's design in 1831 was stopped by the Bristol Riots, which severely dented commercial confidence in Bristol. Work was not started again until 1836, and thereafter the capital from Vick's bequest and subsequent investment proved woefully inadequate. By 1843, the towers had been built in unfinished stone, but funds were exhausted. In 1851, the ironwork was sold and used to build the Brunel-designed Royal Albert Bridge on the railway between Plymouth and Saltash.
Brunel died in 1859, without seeing the completion of the bridge. Brunel's colleagues in the Institution of Civil Engineers felt that completion of the Bridge would be a fitting memorial, and started to raise new funds. In 1860, Brunel's Hungerford suspension bridge, over the Thames in London, was demolished to make way for a new railway bridge to Charing Cross railway station, and its chains were purchased for use at Clifton. A slightly revised design was made by William Henry Barlow and Sir John Hawkshaw; it has a wider, higher and sturdier deck than Brunel intended, triple chains instead of double, and the towers were left as rough stone rather than being finished in Egyptian style. Work on the bridge was restarted in 1862, and was complete by 1864.
The bridge is now managed by a trust set up by Act of Parliament in 1952. Tolls are levied on vehicles but no longer on cyclists or pedestrians.
Coordinates:
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| Shown within Bristol and the UK |
In 2003 the weight of crowds travelling to and from the Ashton Court festival and Bristol International Balloon Fiesta put such great strain on the bridge that it was decided to close the bridge to all traffic, including pedestrians, during the whole of the Ashton Court Festival and part of the Balloon Fiesta in 2004. This arrangement has continued since.
On 26 November 2003, the last ever Concorde flight (Concorde 216) flew over the bridge before landing at Filton Airfield. It was a symbolic moment which commemorated Bristol's feats in engineering.
In April 2006 the bridge was the centrepiece of the Brunel 200 weekend, celebrating the 200th anniversary of the birth of Isambard Kingdom Brunel. At the climax of the celebration a large firework display was launched from the bridge. The celebrations also saw the switch on of an LED-based array to illuminate the bridge.
Engineering
The towers from which the bridge is suspended are not completely identical in construction, although they are generally similar in size, Clifton has cut outs in the sides and the Leigh tower has more pointed arches. Brunel proposed that sphinxes be built on the top of the two towers, which were then fashionable, but they were never built.
The tower on the Leigh Woods side of the gorge is 85 ft (26 m) high but stands on a red sandstone clad abutment 110 ft (33 m) high. In 2002 it was discovered that this was not a solid structure but contained 12 vaulted chambers, up to 35 ft (11 m) high, linked by shafts and tunnels.
Roller mounted "saddles" are used at the top of each tower to absorb the force created by the movement of the chains when loads pass over the bridge. The total movement is about 1mm but if this mechanism were not in place the forces would damage the structure of the towers.
The bridge has a set of three independent wrought iron chains on each side, which are made of eyebars, in numerous parallel rows, connected by bolts, from which the hangers reach down to the bridge. The chains are anchored in tunnels in the rocks 60 ft (17 m) below ground level at the side of the gorge. The deck or floor of the roadway is suspended from the chains by 162 wrought iron rods (81 on each side) which range from 65 ft (20 m) in length at the ends to 3 ft (0.9 m) in the centre. The deck was originally laid with wooden planking which was later covered with asphalt.
The weight of the Bridge, including chains, rods, girders and timber deck is approximately 1,500 tons.
Dimensions
- Span: 702 ft (214 m)
- Height of towers: 86 ft (26 m) above deck
- Clearance: 245 ft (75 m) above high water level
- Traffic: Four million vehicles per year
Suicides and accidents
Two men were killed during the construction of the bridge.
The Clifton Suspension Bridge is well known as a suicide bridge. Between 1974 and 1993, 127 people fell to their deaths from the bridge. In 1998 barriers were installed on the bridge to prevent people jumping. In the 4 years after installation this reduced the suicide rate from 8 deaths per year to 4. The bridge is fitted with plaques that advertise the number of The Samaritans.
In 1885, a 22-year-old woman named Sarah Ann Henley survived a fall from the bridge when her billowing skirts acted as a parachute, and subsequently lived into her eighties.
Although flying under the bridge has been outlawed since 1911, in 1957 an RAF Vampire jet flew at high subsonic speed under the deck, before crashing in the Gorge, killing the pilot.
Popular culture
The bridge is a distinctive landmark that is used as a symbol of Bristol and appears on a variety of postcards and promotional material. It is used as a symbol on several Bristol web sites such as Visit Bristol.
The bridge has featured in numerous scenes of the BBC1 hospital drama Casualty, which is filmed on location in Bristol. It was featured in the first episode, broadcast on 6 September 1986, when Charlie Fairhead (played by Derek Thompson) drove his yellow Volkswagen Beetle across the bridge on his journey to work.
Construction of the bridge was featured in the Channel 4 television series The Worst Jobs in History, as part of an episode entitled The Worst Industrial Jobs in History, first broadcast on 7 May 2006. Presenter Tony Robinson climbs the chains over one of the towers during the sequence, tied off to a safety line, to demonstrate what the workers building the span endured. He particularly struggles with the swirling winds and states that during construction the wind blew the platform for the lines seventy feet in the air at one point, yet all the workers survived.