Fox's Wood Tunnel West Portal (MLN111622)

Summary

Tunnel portal in a castellated style, with a semicircular stilted arch flanked by towers, set into a rocky hillside close to the banks of the River Avon. Erected c. 1836-40. The portal is largely unaltered.

Reasons for Designation

Fox's Wood Tunnel West Portal in Bristol is designated at Grade II* for the following principal reasons:
* Early date: the portal dates from the Pioneering phase of railway design, prior to 1840;
* Architectural interest: its castellated, Gothic design by Isambard Kingdom Brunel is of clear architectural interest, as is its response to the rugged, picturesque steep-sided river valley in which it stands;
* Historic interest: as a design of circa 1836-40 by Brunel, whose hand-coloured drawings for the structure survive;
* Intactness: the portal is remarkably unaltered and survives well;
* Group value: as part of the most architecturally interesting and imaginative sequence of railway tunnels in the country.

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 (the 'B' section), 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.

Surviving contract drawings for bridges and other structures on this 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.

Fox's Wood Tunnel

Fox's Wood Tunnel is one of twelve constructed by Brunel between Chippenham and Bristol. Constructed c. 1836-40, it is 984 m long and only partially lined. A design sketch by Brunel for the West Portal survives in his sketchbooks (University of Bristol & the Brunel Institute). It is also depicted in Bourne’s 'History' as ‘Long Tunnel, Fox's Wood (from the West)’. The East Portal was not originally faced at all, but an engineering brick arch was later fitted.

Details

MATERIALS: squared and coursed Pennant stone with dressings of Pennant ashlar for the voussoirs and capping stones.

DESCRIPTION: asymmetric composition. Semi-circular arch with stilted voussoirs and a stepped section including chamfer, flanked by towers of differing height and plan. North (Up side) tower circular but rising from spurred square base, the upper part of the tower stepped out to form a parapet with crenellations, finished with moulded capping stones. Attached to the tower, a curved retaining wall which steps down. The parapet of the north tower continues without crenellations over the central arch. C20 century railings. South (Down side) tower rectangular in plan and slightly taller, but otherwise similarly treated. It abuts to the south a cliff of rock outcrops reinforced with massive buttresses.

The Portal is at the eastern end of a short stretch of line running on a shelf between a steep hillside and the River Avon, which was diverted by Brunel.

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)

Other
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,
Brunel, I, K , Sketchbooks, Brunel Institute and the University of Bristol,

End of official list entry

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