Bridge in Caerphilly, South Wales
Crumlin Viaduct was a railway viaduct located above the village of Crumlin, in Caerphilly county borough, South Wales. Originally built to carry the Taff Vale Extension of the Newport, Abergavenny and Hereford Railway (NA&HR) across the Ebbw River.
Hailed as "one of the most significant examples of technological achievement during the Industrial Revolution",[1][2] in its 109 years of service until being dismantled in 1967, it remained: the least expensive bridge for its size ever constructed; the highest railway viaduct in the United Kingdom;[1] the third highest railway viaduct in the world, after the railway viaduct at Spoleto, Italy, and the Portage Timber Viaduct in Portage, New York state in the United States.[1]
Background
During the Industrial Revolution, and the mass-extraction of coal from South Wales, there was a resultant growth in construction of railways into the South Wales Coalfield. The Taff Vale Railway so monopolised the trade of shipping coal to Cardiff Docks, that mine owners were desperate for competitor railway companies to both improve speeds of shipping, provide access to new markets, and hence reduce shipping rates.
The London and North Western Railway had developed a route for the industrialised West Midlands and Northwest England, by controlling the Llanfihangel Railway and the Grosmont Railway's as feeder lines into the Hereford Railway, and hence onwards via the joint GWR/LNWR controlled Shrewsbury and Hereford Railway. This allowed shipment of goods from Pontypool and the Ebbw Valley to Hereford. However, access to the productive Rhymney Valley and Rhondda Valley coalfields was at best restricted, through having to route trains south to Cardiff along the TVR, then along the South Wales Railway to Newport via the GWR, before being able to access LNWR controlled track.
The UK Parliament hence approved an Act of Parliament on 3 August 1846, the construction of the Taff Vale Extension, which would connect Coedygric North Junction at Pontypool with the TVR/GWR at Quakers Yard, and hence allow direct and LNWR controlled access. The LNWR approved the required capitol expenditure, and merged the existing three railways and the extension project in the new Newport, Abergavenny and Hereford Railway.
Construction
The route for the Taff Vale Extension required the construction of two significant vaiducts across two major river valleys: one across the Ebbw River; and one across the Rhymney River, the Hengoed Viaduct.
The Ebbw Valley posed two significant challenges through its geography:[3]
- Its height, created both a structural problem and a wind problem, as the valley funnelled and hence increased wind speed
- It is actually two valleys, the Ebbw and the smaller Kendon
Chief Engineer Charles Liddell concluded that stone would be a poor choice for construction of a suitable bridge, as additional stone would need to be shipped to the valley, and the height of the resulting structure would result in an unstable and high-maintenance bridge. Further, the solidity of a stone structure would create additional compressed wind flow around the rail tracks, resulting in a possible safety hazard for passengers and train crew. Overall, the required over-engineered result would also have been very expensive. His recommendation therefore to the board was for an cast iron structure.[3]
Two tender responses were received by August 1852, with Liddell's recommendation for a design by Scottish civil engineer Thomas W. Kennard, using an amended design on the Warren Truss. Contracts were signed in December 1852, with a stipulated completion date of October 1st 1857. After further experimentation of his design system at his fathers Blaenavon Ironworks, the iron structures were cast at the Falkirk Ironworks and shipped to Newport Docks.[1]
Kennard commenced construction in October 1853, by building the Crumlin Viaduct Works on the east bank. Here castings from Falkirk were brought together with wrought iron from Blaenavon, and all fitting and fabrication work took place. After shortening the spur from the Monmouthshire and Brecon Canal, and with the natural land between the two valley's acting as the ninth pier, the first girder was hoisted into place on 3 December 1854.[1] The completed structure linking Pontypool Clarence Street railway station in the north to the Bryn Tunnel (398 yards (364 m)) in the south by the end of May 1857.[3]
Testing commenced that same month, in front of the Board of Trade Inspector, Colonel Wynne. Six locomotives loaded with pig iron or lead weighing a total of 380 tonnes (370 long tons; 420 short tons) were placed in charge of locomotive driver "Mad Jack" of Pontypool, who before making his first crossing had visited every public house in Crumlin. After a series of tests, during which a deflection of less than 1.5 inches (38 mm) was measured, the bridge was approved for use in the same month.[1]
Operations
Lady Isabella Fitzmaurice opened the viaduct on Whit Monday, 1 June 1857, with the first train crossing bridge and entering the Bryn Tunnel in June 1854,[3] but could not proceed further as Kennard's construction team had not yet finished the Hengoed Viaduct, which he had won the contract to design and act as civil engineer on. The final Crumlin viaduct, at 200 feet (61 m) high and 1,650 feet (500 m) across its two spans and ten trusses in length (1,066 feet (325 m) and 584 feet (178 m)), remained the highest railway viaduct in Great Britain throughout its working life. Nearby were the Crumlin railway stations, both at high (viaduct) and valley levels.
The location proved as Liddell predicted to be susceptible to high winds and resultant swaying, resulting in continual and high cost maintenance. The NA&HR route, due to a combination of its height and steepness, proved to be one of the most expensive railway lines in all of the UK to operate. It was therefore no surprise post-World War 2 nationalisation, that British Railways reduced the entire extension line to single track post 1947.
Closure and demolition
As a result of the Beeching Axe, the last scheduled passenger train ran over the bridge on Saturday 13 June 1964, the 21:10 from Pontypool to Treherbert.[1]
Preservation of the historic viaduct was discussed, and the structure was scheduled as being of architectural and historical interest by the Ministry of Housing and Local Government.[1] But while the stone Hengoed Viaduct survived, a structural survey of the cast iron Crumlin Viaduct showed its poor state, and resultant need for high investment to secure its future, let alone ongoing maintenance costs. The decision was therefore made to dismantle it, as by now housing was extending into the lower valley area.[3]
In the period between closure of the NA&HR and dismantling operations beginning, scenes for the Universal Pictures film Arabesque which starred Sophia Loren and Gregory Peck were shot both on and around the bridge. Demolition of the Viaduct was carried out by Bird's of Swansea from June 1966, taking nine months with the help of a Bailey bridge.[1]
The iron parts of the bridge had been completed dismantled by the end of 1967, and now only the stone and cast concrete abutments remain visible on the valley sides.[1][3]
