special feature
What difference?
At the dawn of the Railway Age, timber
was in widespread use for the construction of railway infrastructure. Explore the story of timber rail structures in Wales, source of materials
vital to the Industrial Revolution.
This essay was funded by
the ICE R&D Panel
Institution of Civil Engineers
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Timber Railway Viaducts in Wales
introduction |  use of timber |  Brunel in South Wales |  Rhys William Jones
South Wales Railway |  Vale of Neath Railway |  Cambrian Coast Railway
other timber railway structures |  sources + reading list
Timber viaducts : Cambrian Coast Railway
The modern Welsh network known as the Cambrian Coast Railway incorporates a number of early lines that included trestle viaducts for major waterway crossings. The coast route originated as part of a single-track system that ran from Aberystwyth to Pwilheli, with branch lines. This system opened in 1867.
The Cambrian lines had two notable timber viaducts in Gwynedd, north west Wales. Both were constructed under the supervision of a succession of the railway company's chief engineers — Benjamin Piercy (1827-88), Henry Conybeare (1823-84) and George Owen (c.1827-1901). Such structures were once common all around Wales, and a typical feature of its coastal railways. Most have long been replaced.
Pont Briwet
The railway viaduct known as Pont Briwet was constructed in 1865-67. It carried the Cambrian Coast Railway and a single-lane toll road on 22 equal spans of 5.8m across the River Dwyryd, near Penrhyndeudraeth, Gwynedd. In 1932, the viaduct was substantially rebuilt, but ultimately it proved unable to bear modern traffic loadings. In February 2012, Pont Briwet was approved for demolition by Snowdonia National Park, and was replaced with a new road and rail crossing in 2014-15.
Barmouth Viaduct
By contrast, Barmouth Viaduct, also completed in 1867, survives and remains in use. Ongoing maintenance and replacement of timbers affected by borer has kept it operational. It carries a single track of the Cambrian Coast Railway and at 699m long is one of the longest extant timber viaducts in the UK.
Timber rather than iron was chosen for its construction because it could be brought to site by sea, directly from the Baltic, and was in this case around a quarter the cost of an iron structure. It was also thought — incorrectly — that the wide sandy estuary of the Afon Mawddach was borer free. The viaduct is composed of 113 timber spans, two spans on cast iron piers and an iron drawbridge over the navigation channel, since replaced in steel and no longer operational.
next >
introduction |  use of timber |  Brunel in South Wales |  Rhys William Jones
South Wales Railway |  Vale of Neath Railway |  Cambrian Coast Railway
other timber railway structures |  sources + reading list

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Pont Briwet, site of
Detail of the construction of Pont Briwet from the south. The viaduct was replaced completely in 2014-15.
Photo: © Crown copyright: Royal Commission on the Ancient and Historical Monuments of Wales | © Hawlfraint y Goron: Comisiwn Brenhinol Henebion Cymru
Barmough Viaduct
Barmouth Viaduct in Gwynedd, Wales — one of the longest extant timber viaducts in the UK.
Photo: © Crown copyright: Royal Commission on the Ancient and Historical Monuments of Wales | © Hawlfraint y Goron: Comisiwn Brenhinol Henebion Cymru