Summary
Accommodation overbridge in the Tudor-Gothic style with a four-centred arch and gently humpbacked profile, erected over a cutting c.1839-40.
Reasons for Designation
Clay Lane Bridge (MLN111226), Saltford, is designated at Grade II for the following principal reasons:
* Date: it is an early example of a GWR railway structure dating from the pioneering phase in national railway development;
* Architectural interest: it is characteristically well designed, by the hand of Brunel, with a chamfered four-centred arch and stepped buttresses in a Tudor-Gothic style and local stone, effectively deployed;
* Historic interest: it is constructed to a design by Isambard Kingdom Brunel who is widely perceived as one of the most important transport engineers and architects of the C19;
* Group value: it forms a group with other architecturally similar overbridges on this particular section of the line between Paddington and Bristol.
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.
Clay Lane Bridge
The accommodation bridge at Clay Lane is one of a series of near identical Tudor Gothic overbridges erected on this section of the line in time for its opening in August 1840. These bridges share common details with a number of similar underbridges.
Existing 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.
Details
MATERIALS: pennant stone, squared and coursed on the faces and soffit, with Bath stone ashlar voussoirs, string course, buttress and parapet copings. Some patching in red and purple GWR engineering brick.
DESCRIPTION: depressed, four-centred arch with 30ft (9m) span and stepped and chamfered voussoirs terminating at the footings in chamfer stops. Some engineering brick patching of the voussoirs on both faces. Arch flanked by buttresses, each with two off-sets with arris profile. The lower stage of both buttresses on the west (high mileage) elevation and one on the east (low mileage) elevation have been refaced in engineering brick. To either side the elevations spreads out as straight wing walls. Moulded string course with arris incorporates the line of the upper buttress off-set and runs the full width of the elevation until abutting the plain bands of projecting end piers. Parapets have coping flush to the inside face and chamfered to an arris on the outer face, and a substantial step with quarter-round profile at the base of the inside face against the roadway. Low raked retaining walls of course and squared Pennant stone extend from the wing walls along the base of the cutting sides in both directions for various distances.
