Windmill Bridge: single-span cast iron bridge and aqueduct, 86m north of 230 Tentelow Lane.
Reasons for Designation
Iron was used as one of the components of bridge construction for at least a thousand years before it was first used as the principal construction material in the Iron Bridge erected by Abraham Darby in 1779 over the Severn at Coalbrookdale. Despite its use of iron, however, the Iron Bridge simply copied existing construction techniques suited to timber, and therefore did not make maximum use of the new material's potential. The engineer Thomas Telford subsequently recognised that the lighter cast iron frames allowed the use of flatter angles and less substantial foundations, whilst still enabling single spans and avoiding the central piers which hindered navigation and caused instability by attracting water-scouring. The development of the single span cast iron bridge thus represented a turning point in British bridge design and engineering. All examples which retain significant original fabric are of national importance and will merit statutory protection.
Despite some later alterations and repairs, Windmill Bridge is an extremely impressive example of a combined bridge and aqueduct, which survives remarkably well. It is a rare surviving example of a bridge design by Isambard Kingdom Brunel, one of the greatest engineers of the 19th century. There are thought to be only about 10 surviving iron bridges attributable to Brunel, the earliest of which was built in 1838 across the Paddington Arm of the Grand Union Canal. Windmill Bridge however presented a different challenge and is a considerable feat of engineering, combining as it does a crossing of road, railway and canal to such great effect.
This record was the subject of a minor enhancement on 30 March 2015. This record has been generated from an "old county number" (OCN) scheduling record. These are monuments that were not reviewed under the Monuments Protection Programme and are some of our oldest designation records.
The monument includes a 19th century single-span cast iron bridge and aqueduct forming a single structure where road, canal and rail routes intersect at different angles. It is situated on low-lying ground west of the River Brent near Osterley Park in Ealing.
The structure includes a cast-iron trough or aqueduct carrying the Grand Union Canal over the Great Western Railway, above which is a cast iron bridge carrying the public road Windmill Lane over the canal, one occupying the space vertically over the other. The piers and retaining walls are of brick, and there is a pair of strainer arches over the railway, helping to abut the canal bank at its weakest point east of the combined crossing. Cast into the side plate girders of the upper bridge are the iron founders name and address: ‘MATTw T SHAW 64 CANNON STREET CITY’.
The Grand Junction Canal was built between 1793 and 1808 between Brentford and Braunston (Oxfordshire). It was later amalgamated into the Grand Union Canal linking London to Birmingham. A bridge already carried Windmill Lane over the canal but from 1855 the Great Western railway constructed a branch off its main line at Southall to Brentford and the intersection had to be re-designed, presenting a considerable challenge of engineering. Windmill Bridge, or Three Bridges as it is also known (though there are only two bridges), opened in 1859. It was designed by Isambard Kingdom Brunel and built by E R Murray and J L Tredwell. A cutting was made for the railway, the canal was suspended in a trough or aqueduct overhead and the structure incorporated a new road bridge. The bridge is named after a windmill that originally stood on the site, which is featured in a painting by Joseph Turner.