This is described as the longest estuarial bridge in Wales, and it's certainly the longest timber bridge in Britain, being a total of 731m long. It has carried the Cambrian coast railway across the mouth of the Mawddach Estuary, between Barmouth and Fairbourne, since 1867. There are 113 timber spans, comprising braced wooden trestles, and five metal truss spans at the northern end.
Originally, an opening span was included of so-called "cock-and-draw" construction, which reportedly took some 37 minutes for two men to open. This was replaced by Cleveland Bridge in 1900 with the present arrangement. The timber trestles have been entirely replaced at least once in their history, and were most recently refurbished by Network Rail the early 1980s.
The metal spans are an interesting arrangement. There are two bowstring trusses, which at first glance appear identical. However, one is a simply-supported span, and the other is a swing bridge supported from its centre on a pivot pier. Closer examination reveals that the swing span has vertical members above its pier which are not present on the other span, as you would expect, and I expect the detailed build-up of steel sections is also different.
The bridge has clearly not opened for some time (there's a photo of it open here). The opening mechanisms are in a state of considerable disrepair, and the rails across the bridge are now continuous across the span joints.
Only a single rail track passes over the bridge. The bulkhead rails are supported from longitudinal baulk timbers, which are held at the correct spacing by a series of metal struts and ties. Metal cleats hold the timbers in position on the main timber decking. On the metal spans, short lengths of longitudinal timber sit within "bath-tubs" in the metal bridge deck.
A toll was levied on the footway since the early twentieth century, but this has recently been abolished.
At the south end, the footway slopes steeply up to the nearby highway, and Barmouth residents have established a campaign for a better footway connection.
Meanwhile, the local council, which essentially "rents" the walkway from Network Rail for £30,000 per year, is under severe pressure to reduce costs and is considering closing the footpath. It's hard to argue that it should be more of a priority than many other hard-pressed council services, but unsurprisingly there is a great deal of opposition to closure, including an online petition with over 40,000 signatures.
I think this is a lovely bridge, of great engineering, historic and social value, and it would be a shame to see it closed or not maintained. It's not far from the site of Pont Briwet, another timber viaduct which, despite its Listed status, was recently demolished and replaced with a new concrete bridge. It would be a terrible shame for Barmouth Bridge to ever follow suit.
- Google maps / Bing maps
- British Listed Buildings
- Transport Heritage
- Engineering Timelines
- Timber railway viaducts in Wales
- Description of viaducts across the estuaries on the line of the Cambrian Railway (Conybeare, Proc. ICE, 1870-71) (and Discussion)
- British Railway Bridges and Viaducts (Smith, 1994)
- Civil Engineering Heritage: Wales and West Central England (Cragg, 1997)
- The Bridges of Wales (Breese, 2001)
- An Encyclopaedia of Britain's Bridges (McFetrich, 2010)