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 span of his own Menai Bridge.
1831 A second competition, held with new judges, was won by the design of Isambard Kingdom Brunel on 16 March, 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.
1836 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 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.
Towers: Although similar in size, the bridge towers are by no means identical in design. Leigh (south) tower has chamfered corners. The Clifton tower has square corners, and has openings in the sides. The arches above the road have different shapes on the two towers. Brunel’s original plan proposed the towers be topped with fashionable sphinxes, but the ornaments were never constructed.
Abutments: The 85 ft tall Leigh Woods tower stands atop a 110 ft 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 high, linked by shafts and tunnels. It is now possible to visit two of these chambers on guided ‘Hard Hat Tours’.
Saddles: Roller mounted “saddles” at the top of each tower allow movement of the chains when loads pass over the bridge. Though their total travel is miniscule, their ability to absorb forces created by chain deflection prevents damage to both tower and chain.
Chains, Hangers, and Deck: 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 at the ends to 3 ft in the centre. Composed of numerous parallel rows of eyebars connected by bolts, the chains are anchored in tunnels in the rocks 60 ft below ground level at the sides of the gorge. The deck was originally laid with wooden planking, later covered with asphalt, which has been renewed in 2009.
The weight of the bridge, including chains, rods, girders and deck is approximately 1,500 tons.
The Clifton Suspension Bridge, in The Life of Isambard Kingdom Brunel, Civil Engineer