History

Constructed as part of the development of the South Wales Railway (SWR) from 1844 by the Great Western Railway (GWR). The Chief Engineer of the GWR Isambard Kingdom Brunel was appointed as engineer for the SWR. No direct evidence exists that shows that Brunel was directly responsible for the engineering of the line but is probable that he had direct influence on the laying out of the line and the design of the structures along it.

Initially the SWR was connected to the Cheltenham branch of the GWR across the Severn estuary, to Chepstow and then Newport, Cardiff, Bridgend, Neath and Swansea, eventually to Carmarthen, Fishguard and Pembroke. The route was laid out to follow the largely level coastal plain, avoiding the difficult contours of the South Wales Valleys but still requiring substantial engineering works along the line, notably at Neath (the Neath Abbey Viaduct across the River Clydach) and Landore (where a timber viaduct was constructed). Brunel would have been responsible for designing or supervising these works.

Work on the construction of the SWR began in 1846 with the line from Chepstow to Swansea opening in 1850. With the construction of the Wye Bridge in 1852 the South Wales Railway was connected to the rest of the railway network via Gloucester. The Severn Tunnel was constructed in 1886 taking the line on the more direct route from Severn Tunnel Junction to Bristol. To further improve journey times the line from Newport to Cardiff was quadrupled in 1941, removing many of the original line structures. The line west of Cardiff has not been quadrupled.

The Mill Bridge underbridge carries the railway over the Afon Cynffig and is a substantial well preserved bridge dating to the original phase of construction of the SWR. It is comparable in design with the River Black Underbridge 500m to the west which also carries the railway over a loop of the Afon Cynffig. At its base it incorporates the tailrace for Llanmihangel Mill (ref. 14176) parallel to the river in a masonry channel.

Exterior

Railway bridge, single span masonry underbridge with projecting wingwalls. Constructed from coursed and squared rock faced sandstone with rusticated voussoirs. Parapet with later metal railings. Plain sloping wingwalls.

Reasons for Listing

Included for its special architectural interest as a well preserved example of a mid C19 railway bridge, one of the original structures of the South Wales Railway.

It is also of special historic interest for being associated with the renowned Victorian engineer IK Brunel, forming part of a remarkably complete body of work by him and a significant contribution to the engineering heritage of the UK. It forms part of the growth of the railway network in the age of ‘Railway Mania’ in the mid C19, a period when long distance travel was revolutionised and South Wales became linked much closer to England, leading in part to the industrial and urban boom of Victorian South Wales.

Group value with Llanmihangel Mill.

External Links

• Cadwr Listing

External links are from the relevant listing authority and, where applicable, Wikidata. Wikidata IDs may be related buildings as well as this specific building. If you want to add or update a link, you will need to do so by editing the Wikidata entry.

Recommended Books

• 
  The Victorian House Manual (2nd Edition): How They Were Built, Improvements & Refurbishment, Solutions to All Common Defects - Includes Relevant ... ... Properties (Haynes Manual) (Haynes Manuals)
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  Harrow on the Hill: A photographic portrayal of listed buildings and structures (Historic Buildings Picture Guides)
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  Department for Communities Listed Historic Buildings of Northern Ireland: Information Guide for the 2nd Survey of Historic Buildings
• 
  Derbyshire (Pevsner Architectural Guides) (Pevsner Architectural Guides: Buildings of England)
• 
  Development and Design of Heritage Sensitive Sites: Strategies for Listed Buildings and Conservation Areas
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  Building Small Projects (New Best of Fine Woodworking)