The Cefn-coed Viaduct is the third-largest viaduct in Wales. This huge, curved structure once carried the Brecon and Merthyr Tydfil Junction Railway and is now part of the Taff Trail, which is Route 8 of the National Cycle Network that runs between Cardiff and Brecon. It offers walkers and cyclists a superb view of the Taf Fawr as it cascades over the many weirs in the valley.
|County||Merthyr Tyfdil County Borough|
|Engineer||Alexander Sutherland & Henry Conybeare|
Free street parking
Merthyr Tydfil – 2 miles
What is the best way to enjoy Cefn-coed Viaduct?
You can start from either end of the viaduct. This guide will start from its southern entrance. Head up the path onto the viaduct.
Carefully look over the edge to appreciate the sheer scale of this structure and its magnificent curve.
You will also get a magnificent view of the Taf Fawr valley with the crashing sounds of water cascading over the river’s weirs.
Continue over the viaduct and take in the views. Once you are ready to move on, exit the viaduct and follow the path past the apartments until you reach Station Road where you will see the Station Hotel, another relic of the railway that continued up to Brecon on the right.
Turn left on Maes-Y-Garreg then take your first left onto Job’s Lane. This will lead you down under the viaduct.
This is a fine spot to inspect the stone piers and yellow brick arches.
Continue along Job’s Lane and turn right at the end onto Pontycapel Road. This is where you will get one of the best views of the viaduct at ground level.
Follow Pontycapel Road and cross the road bridge over the Taf Fawr. The sheer scale of the viaduct becomes apparent now that you are viewing it from the lowest point of the valley. Follow the road round until you come to a fork, take the left path.
Follow the road up under the bridge that carries the A470. Look back and you will see a path that follows the southwest abutment, take this route. The path will take you back under the viaduct and up to where you started this walk.
How long does it take to see Cefn-coed Viaduct?
It will take you roughly 30 mins to cross the viaduct then walk back to your starting position through the valley as detailed above.
Is Cefn-coed Viaduct suitable for a picnic?
The only decent spot for a picnic would be further down the Taf Fawr on its banks; however, the roaring sound of the weirs might not be relaxing for everyone. It’s probably best to bring sandwiches and a flask of tea rather than a full-on spread.
How do I get to Cefn-coed Viaduct?
The viaduct is part of the Taff Trail, which is Route 8 on the National Cycle Network. It runs from Merthyr Tydfil town centre so you can easily reach the viaduct by foot or bike if you are travelling in via train or bus. The viaduct is 1.5 miles from the centre.
If you are travelling by car, you can park on the streets north of the viaduct in Cefn-coed-y-cymmer; however, we would recommend you park in the northern Cyfarthfa Retail Car Park by B&Q. There is a path around the back of the store that will take you down to the Taff Trail and then it’s a short walk to the viaduct. Please note the car park may have terms and conditions so park there at your own risk.
History of Cefn-coed Viaduct
1865 – During the construction of the viaduct, a carpenter was killed after falling into the Taff Fawr. He had slipped on the scaffolding. A newspaper article prompted a safety review noting the lack of precautions taken during the winter months. .
1866 – Several hundred masons go on strike over grievances in March following the employment of five turncoats who were not connected with the mason’s society or union. The five men left, and work resumed four days later . The viaduct was completed in September after 200 additional men were hired .
1881 – Several telegraph poles are blown down by a ferocious storm. This removed several large stones that form part of the wall running along the viaduct leaving multiple gaps several yards in length .
1927 – The viaduct was repaired and pointed throughout .
1951 – The viaduct is first designated as a listed structure .
1961 – Passenger services between Merthyr and Ponsticill are withdrawn, freight traffic continues to run on the line.
1966 – Freight traffic is withdrawn and the line closes .
Architecture and dimensions
Cefn-coed Viaduct is 770 ft (235 m) long and 120 ft (36.6 m) high. It is a rusticated-limestone structure of fifteen arches, set on a curve . The tall, slender piers and parapets are constructed with coursed irregular sized rock-faced limestone blocks. The semi-circular arches are of brick  measuring 39.75 ft (12.1 m) long .
- (1865) ‘The Late Accident at Cefn’, Cambria Daily Leader, 5 December, p. 2.
- (1866) ‘The Strike’, Cardiff Times, 23 March, p. 7.
- (1866) ‘Cefn Viaduct’, Cardiff and Merthyr Guardian, Glamorgan, Monmouth, and Brecon Gazette, 17 August, p. 3.
- (1881) ‘The Storm’, Wrexham Advertiser, 15 October, p. 5.
- (1927) ‘Cefn Coed Viaduct Beauty of a Structural Triumph Renewed’, Western Mail, 5 January, p. 9.
- Cadw (2020) Full Report for Listed Buildings. Available at: https://cadwpublic-api.azurewebsites.net/reports/listedbuilding/FullReport?lang=en&id=11377 (Accessed: 4 January 2022).
- Barrie, D. S. M. (1980) The Brecon and Merthyr Railway. Trowbridge: The Oakwood Press.
- Coflein (2020) Cefn-coed-y-cymmer Viaduct;cefn Viaduct, Merthyr Tydfil. Available at: https://coflein.gov.uk/en/site/34786 (Accessed 9 January 2021).
- Cragg, R. (1997) Civil Engineering Heritage Wales and West Central England. London: Thomas Telford Publishing.