Cefn Viaduct

Discover Cefn Viaduct

The viaduct is the third largest in Wales and is now a Grade II listed building. It was designed by Alexander Sutherland in conjunction with Henry Conybeare and partly built by Thomas Savin and John Ward. In early 1866, the project faced disaster when Savin and Ward suffered serious financial and legal difficulties. It was eventually completed with the assistance of Alexander Sutherland. He produced an alternative route into Merthyr, curving the viaduct, so that the railway line avoided property owned by ironmaster Robert Thompson Crawshay. It cost £25,000 to build (equivalent to £2.1 million in 2016).

It consists of 15 arches, each one 39 feet 6 inches wide, and is 770 ft. long with a maximum height of 115 ft. It was planned to be constructed entirely of limestone like the nearby Pontsarn Viaduct but a trade union strike by stonemasons in February 1866 caused the company to buy 800,000 bricks and use bricklayers to complete the 15 arches. It was completed on 29 October 1866, three years after the main line which linked it with Brecon. The last trains travelled over the viaduct in the mid 1960s and it subsequently fell into disrepair. It was refurbished by Merthyr Tydfil County Borough Council with assistance from a grant from the National Lottery. It has now become part of the Taff Trail, route 8 of the National Cycleway

Cefn Coed Viaduct from the Alan George CollectionCefn Coed Station from Alan George CollectionCefn Coed Viaduct


Our latest video helps to capture the essence of the majestic Cefn Coed and Pontsarn Viaducts. Both can be found on the Taff Trail NCN Route 8.  See what else is on offer in the splendour of Southern Wales.



  • Cefn Viaduct
  • Cefn Viaduct
  • Cefn Viaduct
  • Cefn Viaduct
  • Cefn Viaduct
  • Cefn Viaduct

What’s happening in Merthyr Tydfil

Latest News

Merthyr’s Blue Pool features on Visit Wales

Proud to present our very own hidden cascade…. The Blue Pool - Pwll Glas at Cwm Glais

Adjacent to the Taff Trail below the Pontsarn Viaduct close to Morlais Castle is the Taf Fechan Gorge. The Gorge has trails on both sides of the river forming part …

Official Visitor Guide 2022

Visitors Guide - it's ready!

We’ve got everything from world class adventures to breath-taking landscapes waiting to be discovered.  

Pick it up locally or download from this website.

Interactive map pinpoints all Merthyr’s visitor attractions

Visitors to Merthyr Tydfil who want to become more familiar with the county borough will be able to pinpoint exactly where they need to go through a new interactive website map.

The Visit Merthyr Location Finder put together by County Borough Council…

© Merthyr Tydfil County Borough Council 2022