The Cwm Prysor viaduct, a marvel of Victorian engineering, continues to stand majestically even 122 years after its construction. Situated along the A4212 in Eryri (Snowdonia), this impressive structure often goes unnoticed in the sparsely populated area of the national park. While other railway crossings in North Wales attract attention, the Cwm Prysor Viaduct has quietly slipped into obscurity. However, with its nine graceful arches, it remains a sought-after destination for many walkers. Despite being close to the main road between Capel Celyn and Trawsfynydd, accessing the viaduct can be challenging. Those who undertake the journey are treated to stunning views of the valley and the Arenig and Rhinog mountains.
For a quick visit, many opt to park at a forestry layby near Llyn Tryweryn and embark on the half-mile walk to the viaduct. Longer treks are possible on the former route of the Bala and Ffestiniog Railway, with a grassed permissive path extending 5.5 miles down to Trawsfynydd. This trail offers encounters with picturesque hillside cuttings, quaint stone bridges, and abundant birdlife. Visitors are advised to wear appropriate footwear as some sections can be quite boggy. Spanning 450ft across the valley, the viaduct stands prominently, with the Afon Prysor river flowing beneath its central span, varying in intensity with the seasons from a trickle to a raging torrent.
Constructed for the Blaenau Ffestiniog slate quarries, the viaduct spanned 22 miles to connect isolated communities with no road access until the 1960s. Despite its historical significance, dwindling usage led to the closure of the railway line in 1961. The viaduct, also known as the Blaen-y-Cwm Viaduct, received grade II listing in 2004, serving as a poignant reminder of the lost community of Capel Celyn, submerged under the Llyn Celyn reservoir. Discussions about the viaduct’s railway heritage continue, with hopes for a revival of the route to attract tourists to appreciate the natural beauty of Wales.
Though the prospect of restoring the railway and reviving train services over the viaduct appears daunting due to financial constraints, a heritage group established in 2019 aims to resurrect a section of the line between Blaenau Ffestiniog and Trawsfynydd Lake Halt for heritage tourism purposes. The project, projected to cost £18 million, envisions restoring 6.5 miles of the track and constructing four new stations alongside refurbishing existing ones. As volunteers clear overgrown sections of the line post-Covid restrictions, the Cwm Prysor Viaduct and its surroundings remain peacefully isolated, blending harmoniously with the landscape’s grandeur.
The viaduct, once a prominent feature, now gracefully merges into the backdrop against the majestic mountains that envelop it. Its stoic presence and historical significance serve as a testament to Victorian engineering and the community that once thrived in its shadow. As discussions about its revival continue, the future of the Cwm Prysor Viaduct remains intertwined with the rich tapestry of Welsh history and the natural beauty of Snowdonia.