Barmouth Viaduct

A stunning view of the imposing timber-built bridge, ahead of a £25m upgrade to secure the future of the structure.

AS the only major timber-built bridge still in regular use, Barmouth Viaduct has a unique place on the rail network.

Opened in 1867, the Grade 2-listed structure is more than 800 metres long and carries the Cambrian Coast Line between Machynlleth and Pwllheli across the estuary of the River Mawddach.

Used by rail traffic, cyclists and pedestrians, the viaduct originally incorporated a drawbridge at its northern end to allow the passage of tall ships. This was replaced after only 30 years by a steel swing bridge that was last opened in 1987 and which is no longer in use.

Designed by civil engineers Benjamin Piercy and Henry Conybeare, a timber construction was chosen because it was deemed much cheaper to import wood by sea rather than to use iron. However, cast iron piers were used to support 113 wooden trestles, with construction severely hindered by strong tidal currents.

In August 1899, the viaduct encountered its first significant threat when underwater inspections of the piers revealed extensive corrosion. All ironwork was replaced over a period of three years, during which a speed restriction was imposed of just 2mph.

In 1946, the bridge endured a near miss when a naval mine swept past one of its piers but did not detonate as it was washed ashore by stormy weather.

Less than 40 years later, a new prospect of destruction emerged when in 1980 British Rail discovered that 69 of the supporting pillars were under attack from marine woodworm.

With BR estimating that it would cost around £ 2.5 million to repair, locomotive-hauled trains were banned as an interim measure while the viaduct‘s future was discussed.

This was eventually resolved when the government applied for a grant from the European Economic Community, after

Gwynedd County Council opposed the viaduct’s closure owing to the tourist revenue that rail traffic brought to the area.

Locomotive-hauled traffic was able to return briefly before being banned once again until 2005, when major repairs meant that the weight restriction could be relaxed.

The viaduct’s 150th anniversary was then celebrated in October 2017 with a firework display and several charter trains.

And its long-term future now looks to have been secured, following the announcement from Network Rail in May that some £ 25m is to be spent on replacing a large number of the bridge’s timber and metal elements. Track will also be replaced along its entire length.

The work is due to be completed in stages over the next three years, with the first of three short closures planned for this autumn. Preparatory work began in June.

For a full feature on Barmouth Viaduct, see

RAIL 911.