Clifton Suspension Bridge, Bristol, England, UK
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 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. 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. On 4 April 2009 the bridge was being shut overnight due to a crack in one of the support hangers.Engineering
Although generally similar in size, the bridge towers are not completely identical in construction, the Clifton having side cut-outs, the Leigh more pointed arches. Brunel''s original plan proposed they be topped with then-fashionable sphinxes, but the ornaments were never constructed. The 85 ft (26 m) tall Leigh Woods tower stands atop a 110 ft (33 m) red sandstone clad abutment. 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 employed at the top of each tower to allow movement of the chains when loads pass over the bridge. Though their total travel is only minute, their ability to absorb forces created by chain deflection prevents damage to both tower and chain. The bridge has three independent wrought iron chains per side, from which the bridge deck is suspended by eighty-one matching vertical wrought iron rods ranging from 65 ft (20 m) at the ends to 3 ft (0.9 m) in the centre. Composed of numerous parallel rows of eyebars connected by bolts, the chains are anchored in tunnels in the rocks 60 ft (17 m) below ground level at the side of the gorge. The deck was originally laid with wooden planking, later covered with asphalt. The weight of the bridge, including chains, rods, girders and 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