Twelve years ago today, two plaques in Welsh and English were unveiled on Quakers Yard Viaduct to commemorate the 200th anniversary of Isambard Kingdom Brunel’s birth.
The Quakers Yard Viaduct was constructed as part of Brunel’s single-track Taff Vale Railway that connected Merthyr Tydfil to the docks at Cardiff. It carried the railway over the River Taff just south of Treharris.
The Taff Vale Railway was the first in Wales to be powered only by locomotives and the railway company that constructed it appointed Isambard Kingdom Brunel as engineer for the line and its structures. Its original track was standard gauge (4ft 8.5in or 1.435m). The northern section, from Abercynon to Merthyr Tydfil, opened on 12 April 1841, and the first rail traffic crossed Quakers Yard Viaduct on 21 April 1841.
The viaduct is slightly curved in plan and set at a skew angle to the river. Overall, it is 32.3m high, with six arches of 15.2m span each. The masonry is pennant sandstone, which has tooled detailing on all visible faces.
Brunel was concerned about the potential for damage the foundations of the river piers. To minimise this, the piers are octagonal in plan, aligned with their sides parallel to the river’s axis. This was an innovative idea, removing sharp corners that could obstruct river flow and possibly lead to cavitation. Substantial pediments cap the piers and the rounded arches have deep chamfers, echoing the angled pier faces.
The railway’s gradient between the Quakers Yard Viaduct and nearby Abercynon was too steep (up to 1 in 19) for the locomotives of the 1840s, so trains were cable-hauled by a stationary steam winding engine, which was located at the southern end of the viaduct.
In 1861-62, the structure was widened as part of the project to make the Taff Vale Railway double track throughout. Engineer John Hawkshaw (1811-91) designed the new work, which is of plainer masonry, with unchamfered arches and rectangular piers, and located immediately adjacent to the original against its outer curve, on the downstream (north) side.
In 1864, the cable-worked incline south of the viaduct was reconstructed at a shallower gradient (1 in 40). In addition, trains of the 1860s had more pulling power and did not require the winding engine.
In April 1988, the structure was Grade II* listed.
