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Sankey Viaduct (L&MR)
Sankey Brook, west of Newton-le-Willows, Merseyside, UK
Sankey Viaduct (L&MR)
associated engineer
George Stephenson
date  June 1827 - July 1833, opened 15th September 1830
UK era  Georgian  |  category  Railway Viaduct  |  reference  SJ568947
ICE reference number  HEW 94
photo  watercolour by Henry Pyall (public domain) via Wikimedia Commons
The architecture of Sankey Viaduct ó the first major viaduct of the railway era ó is reminiscent of earlier canal aqueduct designs. It is one of the most notable structures on the Liverpool & Manchester Railway, the world's earliest inter-city line. The masonry viaduct is Grade I listed and still carries national rail traffic on recently electrified tracks.
The enabling Act for the Liverpool & Manchester Railway (L&MR) was passed in 1826, with George Stephenson (1781-1848) as its principal engineer. The 50km route approved included crossing the Sankey valley west of Newton-le-Willows, 22.5km from Liverpool, near the present Earlestown Station.
The shallow valley held two watercourses ó the Sankey Brook and an adjacent river navigation. The Sankey Brook Navigation, later known as the St Helens Canal or Sankey Canal, was engineered by Henry Berry (1719-1812) to link the St Helens coalfield with the River Mersey. It opened in 1757, and by being a discrete manmade waterway, could be regarded as the first English canal since Roman times. (Manchesterís Bridgewater Canal is generally cited as Britainís earliest arterial canal.)
Stephenson had to take his double-track railway over the valley without obstructing shipping and at gradients suitable for the locomotive steam engines of the day. However, the Sankey Brook Navigation Company objected to the construction of the railway and insisted any structure must have 18.3m clearance above the water to allow fully rigged Mersey Flats to pass underneath. Mersey Flats were canal boats with sails, typically 21-22m long and 4.3-4.8m wide, capable of carrying up to 80 tonnes.
Stephensonís solution was to construct an embankment over the west side of the valley, about 823m long, and to cross the brook and canal with a viaduct, with a much smaller embankment to the east. He designed a nine arch viaduct with architectural detailing, aided by his chief draughtsman Thomas Longridge Gooch (1808-82). Its form evokes the substantial design of canal aqueducts.
In June 1827, work began on the embankment for the western approach. Its construction used more than 100,000 tonnes of clay, marl and moss compacted with brushwood. The clay was excavated from the edges of the valley. The finished embankment was later planted with trees to provide natural camouflage.
Early in 1828, William Allcard (1809-61) was appointed resident engineer for the middle section of the railway, including Sankey Viaduct and Kenyon Cutting. Work commenced on piling for the viaduct in spring 1828.
The viaduct stands between 18.3m and 21.3m above Sankey Brook. It has nine semicircular arches of 15.2m span, 7.6m rise, and is of red brick with yellow sandstone facings. The arches are supported on eight rectangular piers and abutments at either end of the structure. The abutments' curved wing walls retain the ends of the embankments.
Owing to the soft ground conditions, the bases of the piers are splayed and rest on sandstone foundation slabs quarried locally and from Olive Mount Cutting. Each slab is founded on some 200 driven timber piles, between 6.1m and 9.1m long.
Projecting pilasters forming rectangular cutwaters extend up the face of the piers to form part of the parapet walls. The width between parapets is 7.6m.
The piers were completed in summer 1829, and work began on the superstructure. By February 1830, the parapet walls had been completed. The viaduct was opened officially on 15th September 1830, as part of the Liverpool & Manchester Railway. However, passengers had been transported across the viaduct on excursion trains earlier in the year.
Construction costs for the viaduct, known locally as Nine Arches Viaduct for obvious reasons, are reported variously as £45,208 and £46,000. Finishing touches were not completed until July 1833, when copings were added to the parapet walls.
The retaining walls of the west embankment were later strengthened by the addition of stay bolts, extending right through it, with bolt fixings on the retaining wall faces. Rather unsightly repairs have been made in concrete to the vertical pilasters and some of the masonry.
In 1931, Sankey Canal was abandoned north of the viaduct. In 1963, the last navigable section closed and the waterway was infilled in stages. The canal beneath the viaduct was infilled in 2002.
In February 1966, Sankey Viaduct was awarded Grade I listed status for its "international significance being the earliest major railway viaduct in the world".
In early 2015, Network Rail carried out work on the viaduct to install overhead line equipment for the electrification of the railway main line.
Consultant: Jesse Hartley
Resident engineer: William Allcard
Assistant resident engineer: Mr Fife
Contractor (embankment): Mr Greenshields
Research: ECPK
"Obituary. William Allcard, 1809-1861", in Minutes of ICE Proceedings, Vol.21, pp.550-551, London, January 1862
"An Accurate Description of the Liverpool and Manchester Railway, and the Branch Railways to St. Helen's, Warrington, Wigan, and Bolton" by James Scott Walker, 3rd edition, J.F. Cannell, Liverpool, 1832
reference sources   CEH NorthBDCE1

Sankey Viaduct (L&MR)