Only the north-west abutment, the first pier and the lower part of the middle pier remain of the quarry tramway viaduct which was built be the Welsh Slate Company to provide access to a new tipping site on the south-east bank of the Afon Barlwyd. The three piers were built in two sections, the lower part in non-slate local rock and the upper section originally as fan-shaped timbers supporting the horizontal timber deck. Later the piers were extended upwards in sawn slate to replace the timber supports. At first the viaduct had five spans, but the abutments were extended to replace the outer spans, and the centre span over the London & North Western Railway was replaced in steel. Latterly there was no gap between the first pier and the western abutment, which was built up in slate.

A new slate mill was eventually built on the Glan y Don (or Penybont) tip, but this and most of the viaduct was swept away by "landscaping" in the 1980s.
W J Crompton, RCAHMW, 12 January 2012.