Nant Prysor Viaduct

Waterfall on the Afon Prysor with the viaduct in the distance


29 September 2012

Blaen-y-cwm, Cwm Prysor

SH 77602 38806; 52.93264°N, 3.82247°W


The nine-arch viaduct crossing the Afon Prysor was built as part of the Bala and Festiniog Railway, which opened in 1882. This 25½-mile standard-gauge line was constructed by the Great Western Railway primarily to transport slate from Blaenau Ffestiniog. Rail level on the viaduct stands at 32 m (105 ft) above the bed of the river, which flows through the central arch. Remedial work on the bridge was undertaken in 1953, when new concrete parapet walls were built. The railway, however, closed only a few years later: to passengers in 1960, and to freight in 1961. A section of the line was flooded when Llyn Celyn reservoir was created and the transport link it had provided was replaced by the A4212 Bala to Trawsfynydd road, which opened in 1964.

Nant Prysor Viaduct (Treasure Maps);
Bala and Festiniog Railway (Wikipedia);
Arenig Fawr

Nine arches spanning 285 m across the Afon Prysor valley

The parapet walls were rebuilt in concrete in 1953

Looking down

The Afon Prysor valley to the north from the viaduct

Looking westwards


The bridge was built as part of the Bala and Festiniog Railway allowing slate to be transported from Blaenau Ffestiniog on to Birmingham

Stone piers and brick arches

The viaduct suffered a collapse in 1881 but was rebuilt in time for the opening of the railway line in 1882

Nant Prysor Viaduct, looking towards Arenig Fawr (top left)

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