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Three Arch Viaduct of former Merthyr, Tredegar and Abergavenny Railway

A Grade II Listed Building in Llanelly, Monmouthshire

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Latitude: 51.8059 / 51°48'21"N

Longitude: -3.1247 / 3°7'28"W

OS Eastings: 322552

OS Northings: 212516

OS Grid: SO225125

Mapcode National: GBR F1.XFJM

Mapcode Global: VH6CP.SVGZ

Entry Name: Three Arch Viaduct of former Merthyr, Tredegar and Abergavenny Railway

Listing Date: 27 July 2000

Last Amended: 27 July 2000

Grade: II

Source: Cadw

Source ID: 23817

Building Class: Transport

Location: Located some 0.5km SW of Clydach village, over steep gorge off SE side of Darrenfelen-Clydach by-road.

County: Monmouthshire

Community: Llanelly (Llanelli)

Community: Llanelly

Locality: Clydach

Traditional County: Brecknockshire

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Built 1862 and widened 1877, forming part of the Merthyr, Tredegar and Abergavenny Railway. The Engineer was John Gardner (1821-1894), who has engineered the Staines and Wokingham Railway, and also the Nantwich and Market Drayton Railway, as well as having doubled the line between Abergavenny and Brynmawr. The company was set up in 1859, consisting largely of ironmasters including Crawshay Bailey of Nantyglo, Thomas Brown of Ebbw Vale and James Hill of Blaenavon. A local director was John Jayne of Pant-y-beiliau. First sod cut at Abergavenny on 18th June 1860 by Mrs Crawshay Bailey. By August 1860, 8 bridges were under construction, as well as the tunnels at Gellifelen. By 1861, the company was overdrawn, due to the high engineering costs. The London and North Western Railway took a 1000 year lease of the company, confirmed by Act in August 1862, by which time the line was operating from Abergavenny to Brynmawr. Brynmawr-Nantybwch section finished by March 1864. The rest of the line to the west was completed by 1879. In 1877 the line was doubled.


Three arch viaduct over steep and narrow river gorge. Side abutments spring from steep sides of ravine. Rock-faced limestone construction, stone voussoirs to round arches. Rock-faced stringcourse, with rock-faced copings to low parapet.

Reasons for Listing

Listed as a major survival of later C19 railway engineering, the railway being important to the iron and coal industry of the eastern valleys of Wales. The viaduct is a prominent survival of the important industrial landscape of the Clydach Gorge.

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