Building record 1234600000 - MAIDENHEAD RAILWAY BRIDGE

Maidenhead Bridge included on Tentative List of UK World Heritage Sites in 1999 (B2-3).
Grade I. Summary of Building: Viaduct across the River Thames built in two phases, 1837-9 and 1890-3. Approximately 700ft (214m) long and c.55ft (16.75m) wide, the 1837-9 section being 30ft wide with 1890-3 extensions either side. Symmetrical composition comprising approach abutments and four semi-circular flood arches on each bank flanking the two wide semi-elliptical arches across the river with a pier on a mid-stream island. The elevations are articulated by classical dressings in the shape of Doric pilasters and a bold cornice. The two elevations are identical.
Reasons for Designation: Maidenhead Railway Bridge is designated at Grade I for the following principal reasons:
- Structural interest: a highly innovative structure that made pioneering use of calculus to push the techniques of arch design far beyond their previous limits; the two principal spans are believed still to be the longest and flattest brick arches ever built;
- Historic interest: one of Isambard Kingdom Brunel’s most celebrated bridge designs, and one of the most important features of the early, ‘pioneering’ phase of the GWML;
- Group value: a celebrated feature of the Thames Landscape which forms part of an outstanding group with the Grade I-listed Maidenhead [road] Bridge of 1777 as well as with the smaller (Grade II) footbridge to Guards’ Club Island and the various listed houses on both sides of the river;
- Alteration: although Brunel’s original bridge is now largely encased in later extensions, these – by the leading railway engineer Sir John Fowler – exactly replicate the design and construction of the original.
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.
By the 1870s the growth of traffic, especially at the London end of the route, necessitated the widening of the line from two to four tracks. This was carried out in two stages, from London to Taplow in 1875- 84 and from Taplow to Didcot in 1890-93. By the time of these widenings the broad gauge was being phased out (the final conversion to standard gauge took place in 1892), and the design of the extended or new structures took this into account. However the designs were exceptionally sympathetic to Brunel’s original designs, in form and detail; also in the choice of materials, although engineering brick, seldom or never used by Brunel, began to make an appearance in 1890s. The engineers chiefly responsible for the widened lines, whose names appear on the surviving archive drawings, were William George Owen (1810-85), Lancaster Owen (1843-1911) and Edmund Olander (1834-1900).
Maidenhead Railway Bridge is a viaduct carrying the Great Western Main Line across the River Thames east of Maidenhead. It was built in brick in 1837-9 to the designs of I.K. Brunel for two broad gauge tracks. The resident engineer was John Hammond. From the outset, the viaduct was recognised as one of Brunel's tour-de-forces. It was illustrated in J.C. Bourne's 'The History and Description of the Great Western Railway' (1846) and by J.M.W. Turner in his celebration of technological progress, 'Rain, Steam and Speed' (1844).
Many doubted that the two principal arches, with an unprecedented span of 128ft (c.39m) across a rise of only 25ft 3in (7.4m), would ever stand unsupported. The doubts appeared justified when the contractor removed the centring before the mortar had set and the eastern arch settled by 5in. Brunel was certain of the cause, ordered the centring to be put back and repaired the arch ring. He was vindicated the following year when flood water washed away the centring; the arches remain true to this day, despite supporting dozens of trains every day that weigh several hundred tons and travel at 100mph.
Brunel was drawn to his daring solution by the design constraints he faced, primarily: his overwhelming desire for a level gradient on the railway; the requirement not to impede river navigation; and the local geology. As with other large bridges on the route, he reduced the forces acting through the structure by using a system of internal longitudinal walls and voids to lighten the superstructure above the arches. This reduced the mass of the bridge and its foundations, saving material, time and cost. Dozens of surviving design, contract and construction drawings illustrate these features.
In 1890-3 the bridge was widened for four tracks with inordinate care and sympathy by Sir John Fowler acting as consultant to the GWR's Lancaster Owen. Extensions were attached to both sides with elevations that exactly replicated the originals, and probably reused original fabric. The extensions were closely piled to prevent differential settlement. There have been no significant alterations since. The western half of the bridge was listed in 1950 and the eastern half in 1985, at Grade II+.
Details: MATERIALS: fine red brick with Bramley Fall gritstone dressings, and thick York stone slabs for the deck. The two phases are tied together internally with iron tie rods.
DESCRIPTION: south (Down) elevation: symmetrical, from east to west: plain terminal projecting pier, plain walling, then three flood arches with 28ft (8.5m) semi-circular spans, and then a projecting pier framed by paired Doric pilasters and pierced by a 25ft (6.5m) semi-circular flood arch; next the western river arch with a semi-elliptical span of 128ft (c.39m) across a rise of only 25ft 3in (7.4m), then the central pier on Guards' Club Island, projecting and articulated by corner pilasters, then the eastern river arch, with again a semi-elliptical span of 128ft (c.39m) across a rise of 25ft 3in (7.4m); on the eastern bank a projecting pier framed by paired Doric pilasters and pierced by a 25ft (6.5m) semi-circular flood arch, then three flood arches with 28ft (8.5m) semi-circular spans, then plain walling and finally the plain projecting east pier. Across the whole length of the elevation is a parapet with gritstone coping above a bold gritstone cornice with roll moulding and a plain frieze.
North (up) elevation identical.
Soffits: with gritstone imposts bands (which continue as the bases of the pier pilasters). In the soffits the boundary between the 1837-9 bridge and the 1890-3 extensions is defined by a chamfered edge, the 1890s parts being a few inches higher than the original arches (perhaps to allow for settlement that never occurred).
Because of the mature vegetation on both banks, the Bridge is not visible in the wider landscape except when viewed from the River Thames, its banks and the Grade I listed eighteenth century Maidenhead [road] Bridge to the north (carrying the A4). In these views the railway bridge is very prominent, and together with the Maidenhead Bridge, it forms a celebrated river scene.
Selected Sources:
Bourne, J, C, The History and Description of the Great Western Railway , 1846
Bradley, S., Pevsner, N., and Tyack, G., Buildings of England: Berkshire, 2010
Brindle, S, Brunel – The Man who Built the World , 2005
Cross-Rudkin, P and Chrimes, M, EDS, Biographical Dictionary of Civil Engineers Vol 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
Alan Baxter & Associates, The History and Significance of the Great Western Main Line , 2012, Alan Baxter & Associates
Kinchin-Smith, R, Crossrail Technical Assessment of Historic Railway Bridges , 2005, RPS Planning and Environment
Network Rail , National Records Centre, various historic drawings (B4).