A small bridge or culvert over the By Brook north of the village of Ashley, designed by Brunel and made of Bath stone c.1840. With coursed rubble walls/parapets above each arch, which may be later alterations.
Reasons for Designation
By Brook Bridge, Box, 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;
* Rarity: a highly-individual example of a culvert or underbridge that survives well from the earliest phase of the Great Western Railway;
* Design: an architectural treatment on structures of this type is unusual and, in this case, the rusticated voussoirs on the south side add to the special interest;
* 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.
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 that the other major trunk railway of its time, the London and Birmingham (112 miles) and considerably longer that 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 railways 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 than the standard (4ft 8½ in) 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 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 Blue Lias stone west of Bath. This intentional variety was marked 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.
By Brook Underbridge
By (or Box) Brook Underbridge was built c.1840 under Contract 15B on the Chippenham to Bath section of the route, which opened on 30 June 1841. A contract drawing for ‘Cutting Mill Culvert’ survives which may be for By Brook Underbridge. Cuttings Mill stood in this location but was demolished to construct the railway line. The elevations on the drawing are generally similar to the those of the bridge, but differ in detail. For example, the drawing shows projecting wing walls and does not show the bridge’s narrowly-coursed walls-cum-parapets above the arches. This may be a later addition: Brunel rarely combined ashlar and unfinished stone in the design of structures on the GWR. In the late C19 or early C20 the south (Down) elevation was extensively refaced in purple engineering brick.
MATERIALS: Bath stone ashlar with narrowly coursed rubble Bath stone walls/parapets above each arch, and patching in purple engineering brick.
DESCRIPTION: a semi-circular arch springing from water level. The lower part of each elevation is built in Bath stone ashlar, with the abutments / wing walls projecting only very slightly, and raked in towards, the springing point of the arch. Above the coping/string course there is a high wall-cum-parapet of squared and narrowly-coursed Bath stone rubble with iron railings on top.
The arch of the south (Down) side has giant rusticated voussoirs and emphatic keystone, filling the face to the abutments and the plain coping above. Almost all of this has been refaced, carefully, in engineering brick. Only the keystone and the outer parts of some keystones are still Bath stone. The north (Up) side face, by contrast, is plain ashlar, with smaller keystone and narrower coping. The soffits is mainly Bath stone, but with minor brick patching at the south (Down) end.