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Conwy Suspension Bridge
River Conwy, Conwy, Wales, UK
Conwy Suspension Bridge
associated engineer
Thomas Telford
date  1822 - 1826
UK era  Georgian  |  category  Bridge  |  reference  SH785776
ICE reference number  HEW 107
photo  courtesy PHEW, ICE
Conwy Suspension Bridge is the most successful of Thomas Telford’s six ‘Gothic’ bridge designs, and it is one of the earliest surviving suspension bridges. Now closed to vehicular traffic, the Grade I listed structure is flanked to the north by the modern A547 road bridge (1958) and to the south by Robert Stephenson’s iron box girder railway bridge (1848). All cross the River Conwy near its mouth on the North Sea coast of north Wales.
In 1821, as part of the improvements to the road between Chester and Holyhead, £41,000 of public money was allocated for a bridge across the River Conwy. The engineer for road and bridge was Thomas Telford (1757-1834), with William Alexander Provis (1792-1870) as resident engineer.
Work on the bridge began in 1822. Its design is similar to Telford’s contemporaneous Menai Bridge (constructed 1819-26), though its castellated towers deliberately echo the turrets of medieval Conwy Castle (built 1283-87). The bridge’s western end is situated at the foot of the promontory occupied by the castle, giving it the appearance of an extended drawbridge.
The bridge’s wrought iron suspension chains are supported on two pairs of towers 3.75m in diameter and 12.2m high, constructed in solid ashlar limestone. Each pair is linked by castellated walls incorporating 3m wide arches over the carriageway.
The main span is 99.7m between the tower chain supports. The two tiers of chains are each made up of four 2.75m long links joined by deeper plates with alternating joints. Vertical rods suspended at 1.5m intervals from the joining plates carry the deck. The balustrade is of diamond lattice ironwork. The original deck probably consisted of two layers of longitudinal timber planks carried on a light iron framework braced with bars on its underside.
During construction, a small part of Conwy Castle was demolished so that the bridge’s suspension chains could be anchored into the rock on the west side of the river. The east side has a block plinth for anchorage. The bridge was completed in 1826 at a cost of £51,000.
Conwy Suspension Bridge was originally a toll bridge, replacing the ferry that plied between Conwy and Anglesey. The former bridge keeper’s lodge and tollhouse (SH785775) is at the eastern end of the bridge.
The bridge has undergone regular strengthening and refurbishment. In 1896, its timber deck was replaced by a 2.5m wide roadway of iron plates. In 1903, the suspension capacity was strengthened by the addition of wire cables above the chains, making five layers in each of the two tiers. In 1904, a 1.8m wide corbelled footway was added on the north side of the deck.
The structure was Grade I listed in September 1950. Until the new road bridge opened in 1958, the narrow deck of Telford’s bridge carried the A55 but since then has been used by pedestrians only. It was saved from demolition following worldwide pressure and became the responsibility of the National Trust in 1965-66.
In August 1981, the bridge’s tollhouse was Grade II* listed and was later been restored. Since 1991, the A55 has used an immersed tube tunnel under the river and the road bridge now carries the A547.
The suspension bridge receives ongoing maintenance and was closed for repainting in 2007.
Resident engineer: William Alexander Provis
Contractor (masonry): John Wilson
Ironwork: William Hazledine
Research: ECPK
reference sources   CEH WalesBDCE1

Conwy Suspension Bridge