CLIFTON SUSPENSION BRIDGE

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.^[1]

Contents

History

Engineering

Dimensions

Suicides and accidents

In the arts

References

External links

History

The idea of building a bridge across the Avon Gorge originated in 1754, 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 the 1820s, Vick's bequest was nearing £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. In 1829, a competition was held to find a design for the bridge; the judge, Thomas Telford, rejected all designs, and tried to insist on a hugely expensive design of his own. A second competition, held with new judges, was won by Brunel's design, 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.


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.^[2]
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.^[3]
The celebrations also saw the switch on of an LED-based array to illuminate the bridge.^[4]

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. ^[5]
The tower on the Leigh Woods side of the gorge is 26 metres high but stands on a red sandstone clad abutment 33 metres (110 ft) 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.^[6]
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.^[7] The chains are anchored in tunnels in the rocks 17 metres (60 ft) 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 65ft (20 m) in length at the ends to 3ft (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.⁸

Dimensions

★ 'Span:' 702 ft (214 m)

★ 'Height of towers:' 86 ft (26 m)

★ '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.^[8]
The Clifton Suspension Bridge is well known as a suicide bridge. Between 1974 and 1993, 127 people fell to their deaths from the bridge.^[9]
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.^[10]
The bridge is fitted with plaques that advertise the number of The Samaritans.
In 1885, a 22 year old woman called Sarah Ann Henley survived a fall from the bridge when her billowing skirts acted as a parachute, and subsequently lived into her eighties.⁸

In the arts

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.^[11]

References

1. Clifton Suspension Bridge
2. Suspension bridge shut for events
3. Brunel 200 Fireworks
4. LEDs help to light Clifton Suspension Bridge
5. Clifton Suspension Bridge
6. The Hidden Bridge
7. CliftonSB
8. Suspension Bridge Frequently Asked Questions
9. Suicide from the Clifton Suspension Bridge in England
10. Effect of barriers on the Clifton suspension bridge
11. Visit Bristol

External links

★ Official website

★ 'Brunel 200 Weekend' provided by BBC Bristol

★ Photographs

★ Panorama showing the suspension bridge

★

★ Time-lapse video, shows the bridge as the tide falls and night time arrives