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Robertstown Tramway Bridge
River Cynon, Aberdare, Rhondda Cynon Taf, Wales, UK
Robertstown Tramway Bridge
associated engineer
George Overton
date  1811
era  Georgian  |  category  Bridge  |  reference  SN997037
ICE reference number  HEW 371
photo  courtesy PHEW, ICE
The cast iron bridge across the River Cynon between Trecynon and Robertstown is one of the oldest surviving ‘railway’ bridges in the world. It was built by the Aberdare Canal & Navigation Company to carry the Llwydcoed Tramroad that ran from Hirwaun to the canal head at Cwmbach, south east of Aberdare. Little remains of the tramway’s structure, though its route has survived as a footpath.
Tramroads were precursors to the early railways — horses rather than steam locomotives pulled loaded wagons along railed tracks. The Llwydcoed Tramroad, engineered by George Overton (1774-1827), connected the Aberdare Canal with the Hirwaun Ironworks and the Hirwaun to Abernant Tramroad, enabling goods transportation in the Cynon Valley.
The bridge at Robertstown is most likely also the work of Overton, though there is so far no definitive proof. It spans 10.7m between stone abutments on the river banks and its soffit is some 3.7m above the river bed. Four trussed cast iron lattice beams support the level deck, and spring from continuous cast iron brackets built into the abutments. Each arched truss is only 76mm thick, and rises from a depth of more than 1.5m at the abutments to just 305mm at midspan.
The bridge abutments are about 4m wide and more than 3.7m high from pediment to coping. They were constructed with obvious skill, of dressed stone bedded in mortar, with large stones for the quoins and returns and alternating courses of large, small and thin stones elsewhere.
The deck is 11.2m long and 3m wide, and consists of 17 parallel cast iron plates. There are 15 plates of 710mm and two end plates of 254mm. Transverse ridges on the deck provided grip for horses' hooves.
The cast iron railings on each side are fixed to posts attached to the trusses independently of the deck. The central stanchion is inscribed "Abernant 1811".
No rails or fixing shoes from the tramway remain on the bridge, though imprints of the fixings show that it carried a 1.27m (4ft 2in) gauge single track.
The tramway closed in 1900, and the bridge is now used as a pedestrian footbridge between Trecynon and Robertstown. It has been modified with steps constructed at the north abutment to accommodate the adjacent A4059 trunk road.
The route of the Llwydcoed Tramroad, between Hirwaun and Cwmbach, is now a footpath. On the 3km section east of the bridge is an embankment and the remnants of stone sleeper blocks in their original positions.
In the 1980s, the bridge was restored and the railings replaced, with the date-stamped original stanchion was reinstated. In 1991, it became Grade II listed.
Robertstown Tramway Bridge was made a scheduled ancient monument (number Gm347) in 2008, and was given a blue plaque as part of the Rhondda Cynon Taf heritage trail. On 22nd March 2010, an information panel was unveiled near the bridge, sponsored jointly by ICE Wales Cymru and Rhondda Cynon Taf County Borough Council.
Research: ECPK
reference sources   CEH W&WCEH Wales

Robertstown Tramway Bridge