Summary
This is a triple, semi-elliptical arch, humpback road overbridge, erected across a low cutting c. 1839-40.
Reasons for Designation
The Bridge near Swindon Road, constructed c.1839-40, is designated at Grade II for the following principal reasons:
* Date: an early example of a railway structure dating from the pioneering phase in national railway development on this significant line;
* Design and materials: an elegant design of three semi-elliptical arches built of Swindon Portland stone; the western face remains largely intact, with its half-round string course, and demonstrates Brunel's effective use of local materials;
* Historic association: 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.
History
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.
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).
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.
This bridge was built c. 1839-40 on the Challow - Wootton Bassett section of the route, which opened in December 1840. This stretch of the line was never quadrupled and so the bridge has not been extended. In the later C19 or the C20 the east (low mileage) elevation was refaced in engineering brick, possibly in more than one phase, and tie rods were inserted.
Details
MATERIALS: grey Swindon Portland stone, squared and coursed, apart from the arch rings and the east (low mileage) face from the springing point upwards, which has been refaced in GWR contrasting red and purple engineering brick.
DESCRIPTION: sweeping humpback profile, the faces continuing unbroken as gently curving wing walls. Central arch with standard 30ft (9m) span; side arches lower and with c. 17ft (5m) spans. A later tie rod in each spandrel, with rectangular plate. The west (high mileage) face retains its roll moulded string course, but as part of the refacing the east (low mileage) face has been given a plain brick version. The parapets have stepped inner faces and end in terminating piers, expressed on the outer faces. Stone coping (surviving on both sides), with a slight fall to the outer face.
