St Anne's Tunnel West Portal (MLN111648)

Summary

A tunnel portal in the Neo-Norman style, with a round arch, set in the hillside under Birchwood Road, erected c.1836-40.

Reasons for Designation

St Anne's Tunnel West Portal, built c.1836-1840 for the Great Western Railway, to the designs of Isambard Kingdom Brunel, is designated at Grade II* for the following principal reasons:
* Architectural interest: its Gothic-Revival design illustrates Brunel's vision of engineering a line according to picturesque principles;
* Date: it is a remarkably intact structure from the pioneering first phase of railway development in England;
* Historic interest: it is constructed to a design by Isambard Kingdom Brunel who is widely regarded as one of the most important engineers and architects of the C19;
* Group value: it forms part of a sequence of Tudor-Gothic structures between Bristol and Bath, designed by Brunel in response to the scenic route along the Avon valley.

History

Great Western Railway

The Great Western Railway was authorised by an Act of Parliament in 1835 to construct a line from London to Bristol. At 118 miles this was slightly longer than the other major trunk railway of its time, the London and Birmingham (112 miles) and considerably longer than other pioneering lines. Construction of the line began in 1836, using a variety of contractors and some direct labour. The first section to be completed, from London to Maidenhead Riverside (Taplow), opened in 1838, and thereafter openings followed in eight phases culminating in the completion of the whole route in 1841. Work at the Bristol end of the line had started in 1835, and the section from Bristol to Bath had opened in August 1840.

The engineering of the railway was entrusted in 1833 to Isambard Kingdom Brunel (1806-59), who was already known for his engineering projects in Bristol. More than any other railway engineer of his time he took sole responsibility for every aspect of the engineering design, from surveying the line to the detailing of buildings and structures. He sought to achieve as level a route as possible and, working from first principles, he persuaded the Directors of the GWR to adopt a broad gauge of 7ft 0¼ in rather then the standard (4ft 8½in) gauge in use on other lines. A two track broad gauge line was 30ft wide, and this determined the span of the overbridges and other structures. Except for larger bridges such as Maidenhead Bridge, the majority of Brunel’s masonry bridges did not need to be as innovative as his works in timber and iron, and his structures followed the typical architectural idioms of his time, but they were all beautifully detailed and built and together they formed integral parts of a consistently-designed pioneering railway.

Although he left no written statement concerning his design concept for the line, it can be inferred from its design and from the way it was described when opened that part of his vision was a line engineered according to picturesque principles. This influenced his selection of the route and the design of structures along it. For reasons of cost, but also because it helped blend the railway to the landscape, he used local materials for bridges and other structures, ranging from stock brick at the London end of the line, to red brick, Bath stone east of Bath and Pennant stone west of Bath. This intentional variety was remarked on by contemporaries, for instance in J.C. Bourne, 'The History and Description of the Great Western Railway' (1846). On the line from Bristol to Bath, where the track runs along the Avon valley, Brunel chose to use Tudor four-centred arches for both the over- and underbridges, and castellation for tunnel portals and viaducts. This makes it the most distinctive part of the whole route from London to Bristol, and it is also the section on which the structures have generally survived in their original form because this part of the route was not quadrupled and the Pennant stone used for most structures has lasted well.

St Anne's Tunnel

St Anne’s Tunnel was one twelve constructed by Brunel between Chippenham and Bristol. It was built c. 1836-40 and is 141m long. The original contract drawings for the West Portal survive. Other surviving contract drawings for bridges and other structures on the Bath-Bristol section of the line carry the signature of I.K. Brunel, reflecting his involvement with every aspect of the project. The Resident Engineer was G.E. Frere (1807-87), assisted by G.T. Clark (1809-98) and Michael Lane (1802-68), but their individual contributions have not been identified.

The Portal was illustrated in Bourne with the top left (north) corner of the face missing following a landslide during construction (though Bourne in his text mistakes it for the East Portal). Brunel left it like this, but at some time during the C20 the damage was rebuilt to the original design.

Details

MATERIALS: Pennant stone throughout. Squared and coursed to tunnel portal, side tower faces, soffit and irregular supporting buttress. Ashlar to all dressings, voussoirs, copings, crenulations, machicolations and quoins.

DESCRIPTION: asymmetric composition. Round arch with a span of 30ft (9m) composed of plain double voussoirs, a set back and chamfer, terminating at the foot in large chamfer stops. Plain spandrels beneath double-step corbelled, false machicolations with pointed gothic arches supporting embattled parapet with profiled copings falling to the track. A square, battered tower to the north (Down) with crenellations matching parapet. To the south (Up) side, the portal face abuts the rockface, and attached free-form rubble buttresses prop the tumble-home bedrock.

Legacy

The contents of this record have been generated from a legacy data system.

Legacy System number:

378820

Legacy System:

LBS

Sources

Books and journals
Brindle, S, Cruickshank, D, Brunel: The Man Who Built the World, (2005)
Bourne, J C, The History and Description of the Great Western Railway, (1846)
Cross-Rudkin, P, Chrimes, M, EDS, Biographical Dictionary of Civil Engineers Volume 2: 1830–1890, (2008)
MacDermot, E T, A History of the Great Western Railway, (1927, revised ed. 1964)
Pugsley, A, The Works of Isambard Kingdom Brunel, (1976)
Vaughan, A, A Pictorial Record of Great Western Architecture, (1977)
Maggs, C, The GWR Bristol to Bath Line , (2001)

Other
Network Rail , National Records Centre Roll Number 13108 ,
Alan Baxter & Associates, The History and Significance of the Great Western Main Line , 2012,
Kinchin-Smith, R, Crossrail Technical Assessment of Historic Railway Bridges , 2005,

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