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Llandinam Bridge
River Severn, Llandinam, Powys, Wales, UK
Llandinam Bridge
associated engineer
Thomas Penson jnr
date  1846
UK era  Victorian  |  category  Bridge  |  reference  SO024886
ICE reference number  HEW 850
photo  © Crown copyright: Royal Commission on the Ancient and Historical Monuments of Wales | © Hawlfraint y Goron: Comisiwn Brenhinol Henebion Cymru
Llandinam Bridge over the River Severn was the first cast iron bridge to be constructed in Montgomeryshire (now in Powys). Its design follows Thomas Telford’s philosophy and may include some of his castings. Now Grade II* listed, it carries a single lane minor road and is in use for vehicles of up to 3 tonnes.
Montgomeryshire county surveyor Thomas Penson junior (1790-1859) designed Llandinam Bridge, in accordance with the principles used by Thomas Telford (1757-1834) for his bridges at Craigellachie (completed 1814) and Tewkesbury (1826). It replaced an earlier bridge, said to be out of repair in 1707.
It crosses the River Severn in a single span of 27.4m between Llandinam and Trefeglwys. The arch rises 2.7m and consists of three curved cast iron ribs, 685mm deep and 63mm wide, each made from five segments of X lattice panels. Rectangular diaphragms brace the ribs at the bolted segment joints.
The spandrels are of a more-open X pattern in 100mm cruciform raking members, generally similar to those of Mythe Bridge at Tewkesbury in Gloucestershire. Ribs and spandrels are stiffened and tied laterally by cruciform and circular cross-members.
The almost flat deck falls slightly to the west. It is 3.2m wide and made of cast iron plates with a macadam roadway on top. Plain horizontal girders run along each side topped by railings 1.1m high. At the east end of the bridge, the downstream side of the girder is cast with the inscription "Thomas Penson County Surveyor" and the upstream side with "Hawarden Iron Works". The west ends of both girders bear the date 1846.
The bridge's ashlar masonry abutments slope at 30 degrees from the points of connection with the arch at their bases to the roadway support above. They were constructed by Edward Jones of nearby Gellidywyll. The foundations and approaches were built by David Davies (1818-90), a local industrial entrepreneur and future Member of Parliament for Cardigan (Ceredigion). A statue of Davies stands at the east end of the bridge.
The iron superstructure was cast at Hawarden Ironworks in Flintshire (now in Deeside), which had acquired some of the castings and moulds from the Telford bridges manufactured by William Hazledine (1763-1840) at the Plas Kynaston Iron Foundry in Cefn Mawr. It is possible that some of Telford’s original designs and components were re-used here.
In 1906, Montgomeryshire County Council restricted vehicles crossing the bridge to 3 tonnes gross weight, a limit that remains in force to this day.
In plan, the bridge runs perpendicular to the A470 through Llandinam village and is also subject to a 40mph (64kph) speed restriction. In February 1994, it was Grade II* listed and around 2002 it was repainted.
Foundations and approaches: David Davies, Llandinam
Masonry abutments: Edward Jones, Gellidywyll
Superstructure: Hawarden Ironworks
Research: ECPK
reference sources   CEH Wales

Llandinam Bridge