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Talerddig Cutting
Talerddig, Powys, Wales, UK
Talerddig Cutting
associated engineer
Robert Piercy
Benjamin Piercy
date  1859 - 1861, railway opened 3rd January 1863
UK era  Victorian  |  category  Walls/Abutments/Cuttings  |  reference  SH929000
ICE reference number  HEW 1829
photo  © John Lucas and licensed for reuse under this Creative Commons Licence
The village of Talerddig lies halfway along the Newtown & Machynlleth Railway in Powys, where its single track passes through a long cutting high above sea level. The cutting was the world’s deepest when completed and remains one of the deepest on British railways. Stone excavated during its construction was used to build many of the masonry structures along the railway line.
The enabling Act for the Newtown & Machynlleth Railway was passed in 1856, and the first train travelled the line on 1st May 1862, though its official opening ceremony was held on 3rd January 1863. The railway company’s engineers were brothers Robert Piercy (1825-94) and Benjamin Piercy (1827-88), and the contractors were David Davies (1818-90) of Llandinam and Thomas Savin (1826-89).
The route between Newtown and Machynlleth leaves the River Severn valley at Caersws, climbs north west over the hills and descends into the River Dyfi valley at Cemmaes Road. The line reaches its summit midway, at Talerddig, where the original idea was to tunnel through the rock. The plan was changed to making a deep rock cutting to provide stone for building other structures on the line. This also had the advantage of making rail maintenance easier.
Talerddig Cutting was constructed in 1859-61 by gunpowder blasting. The rock strata appear as arching bands of shales and mudstones, a geological feature now known as the Talerddig Grits. The layers dip steeply south westwards, and when completed the cutting had a near vertical face on the west side and a slightly flatter slope on the east side. The west face of the cutting is deeper than the east side owing to the sloping topography of the ground.
During construction, a wagon ran across the gap on rails fixed to the sheer sides of the cutting. The biggest challenge of the works was water ingress from underground springs bringing moisture from the surrounding boggy ground and the excavation flooded repeatedly.
The cutting follows a curved alignment 366m long and is a maximum of 37m deep. The railway’s standard gauge (4ft 8.5in or 1.435m) single track is 211.2m above sea level at the summit. It is reached by a climb of 83.2m from Caersws and a descent of 196.6m to Machynlleth, involving a gradient of up to 1 in 52.
The hill slopes proved hard work for steam locomotives ascending the line and wearing on the brakes for those descending. A siding was constructed at Llanbrynmair, north west of Talerddig, to catch runaway downhill trains and act as a refuge siding or shunting area for uphill trains. However, the only passing loop for trains on the line between Newtown and Machynlleth is at Talerddig Station (SN930994).
Talerddig Cutting was one of the most important achievements of Davies’ career. Looking into the cutting after its completion, he is reported to have said: "I often feared this was going to be the rock of my destruction, but with hard work and Heaven's blessings it has proved to be the rock of my salvation".
In July 1864, the Newtown & Machynlleth Railway Company was absorbed into the Cambrian Railways network. The Cambrian in turn was amalgamated with the Great Western Railway, with effect from 1st January 1923.
Rail accidents in 1893 and 1921, fortunately non-fatal, as well as landslides, led to safety concerns and Talerddig Cutting's original near vertical side slopes have been trimmed back.
At the south end of the cutting, on the west side, is a small concrete retaining wall with two buttresses (visible on the right hand side of the photo). A minor road, carried on a modern concrete beam bridge (bridge No.195) with brick abutments, crosses the railway at the north end of the cutting.
In 1968, Talerddig Station became disused and the building is now private property. The line at the station remains twin track for passing trains.
Contractors: David Davies of Llandinam, and Thomas Savin
Research: ECPK
"The Story of the Cambrian: A Biography of a Railway" by C.P. Gasquoine, Woodall, Minshall, Thomas & Co. Ltd, 1922
reference sources   CEH Wales

Talerddig Cutting