Railway Viaduct over Nant Clydach (partly in Abercynon Community)

Location

On a minor road between Glyncoch and Abercynon, immediately S of Cwm Farm.

History

The Taff Vale Railway was the first major locomotive railway in Wales. It was incorporated in 1836, built 1837-40 and opened in 1840-1 from Merthyr Tydfil to Cardiff, primarily to serve the ironworks of Merthyr Tydfil. The chief engineer was Isambard Kingdom Brunel. The railway was built to the standard gauge, rather than Brunel's preferred broad gauge, because it was primarily intended as a mineral railway, although extant original bridges are wide enough to have accommodated a broad-gauge track. The viaduct, with its wide elliptical span across the river and narrower outer arches, is a similar concept to the skewed viaduct across the River Rhondda in the centre of Pontypridd. The railway was widened to a double track 1845-61, which required the widening of the viaduct in 1861-2.

Exterior

A 3-bay viaduct built in 2 phases, of which the wider section on the W side is 1837-41, the narrower section on the E side of 1861-2. Both phases are of coursed rock-faced stone. In the centre is a wide elliptical arch across the river springing from projecting impost bands (the inner sides of the piers now strengthened with concrete). The narrower round-headed outer arches span unclassified roads. The parapet comprises replaced steel railings on original hammer-dressed coping stones. Abutting stone retaining walls are built against the outer arch abutments, except the SE side which is an earthen bank.

Reason for designation

Listed as an integral component of the original Taff Vale Railway, and as a well-preserved early railway viaduct from the office of C19 Britain's foremost railway engineer.