All three of these impressive viaducts were of steel spans supported on brick piers. Due to duplication of rail routes, following the 1922 GWR Grouping, the extension to the Brecon & Merthyr Railway was taken out of use on 4th August 1926 and the latter two viaducts had been demolished by 1937. Walnut Tree viaduct survived in use until December 1967 and was demolished in 1969. The other main works on the former Barry Railway's Cadoxton-Tehafod railway were the Pontypridd (or Graig) tunnel at Treforest and a viaduct over the River Ely long and high. plus the St. Fagans viaduct mentioned above. A British Rail Gazetteer says the tunnel, between Wenvoe and Drope Junction, is just over long, at . More simply, the closed tunnel on the former Barry–Pontypridd route is long, the 9th longest Great Western tunnel. It is brick-lined apart from a short section at the south end. It has an air shaft near the centre of its length, almost as wide as the tunnel. Its original air shaft chimney of circular red brick with Staffordshire blue corbelling, was removed following closure and a breeze-block structure built to the rear of a concrete-aproned area of a retail outlet and which at ground level, occupies an airway of only a quarter of the circular air shaft area below ground. As at 2020, a large bore concrete water main maintained by Welsh Water is run at tunnel ground level and against the east side of the bore. Since falling out of use following 1963, the tunnel, has suffered much flooding. The Barry Docks and Barry Railway Company were founded to break the effective monopoly that the Taff Vale Railway and the Cardiff Docks had established over export of coal from the South Wales Coalfield. Work on the railway began in 1885, and within four years included an line from Trehafod to the Barry Docks, with several branch lines. In July 1885 "The Engineer" reported that the heavy work at Wenvoe Tunnel was being pressed forward, and it was expected that there would soon be 3,000 men at work on the project. The earth was removed from the tunnel using skips that held and ran on three roads, mostly pulled by ponies. The skips were run out to the tip, where they could be lifted by hand when off the road. Several pressurized oil lights were used to allow night work.