At over 150-years old, Barmouth Viaduct in Gwynedd is the only major timber-built bridge still in use by Network Rail.
The 820m long viaduct is in poor condition. Many of the timber elements of the viaduct have decayed significantly over time and a large proportion of the metallic elements have corroded.
Replacing these timber elements alone on a like-for-like basis to preserve its appearance will take two years to complete.
Then during 2022, metal structures will be replaced along with and the track. Tenders for this element of work have been invited.
Network Rail has adapted the plans to make sure work can be delivered safely in line with Government guidance.