Maidenhead Railway Bridge

Maidenhead Railway Bridge
Maidenhead Railway Bridge
Carries	Great Western Railway
Crosses	River Thames
Locale	Maidenhead
Heritage status	Grade I listed
Characteristics
Design	Arch
Material	Brick
Height	32 feet 2 inches (9.80 m)
Longest span	Each span 128 feet (39 m)
Number of spans	2
History
Designer	Isambard Kingdom Brunel
Opened	1 July 1839 (1839-07-01)

Maidenhead Railway Bridge (aka Maidenhead Viaduct, The Sounding Arch) is a railway bridge carrying the main line of the Great Western Railway over the River Thames between Maidenhead, Berkshire and Taplow, Buckinghamshire, England. It crosses the Thames on the reach between Bray Lock and Boulter's Lock at the downstream end of Guards Club Island.

Maidenhead Railway Bridge features in Rain, Steam and Speed – The Great Western Railway, painted by Turner in 1844 and now in the National Gallery, London

The bridge was designed by the Great Western's engineer, Isambard Kingdom Brunel, and it was completed in 1838, but not brought into use until 1 July 1839. Brunel's first plan envisaged a triple-arch viaduct, but he then developed the design that is still used today. It was inspired by experiments made by his father, Marc Brunel in 1832 which Isambard had at the time financed. The railway is carried across the river on two elliptical brick arches, which at the time of building were the widest and flattest in the world. Each span is 128 feet (39 m), with a rise of only 24 feet (7 m). The flatness of the arches was necessary to avoid putting a "hump" in the bridge, which would have gone against Brunel's obsession with flat, gentle gradients (1 in 1,320 on this stretch). The Thames towpath passes under the right-hand arch (facing upstream), which is also known as the Sounding Arch, because of its spectacular echo.

It has been claimed that the board of the Great Western Railway did not believe that the arches would stay up under the weight of the trains and ordered Brunel to leave the wooden formwork used to construct the arches in place. However, Brunel simply lowered the formwork slightly so that it had no structural effect, but appeared to be in place. Later, when the formwork was washed away in floods, but the bridge remained, the strength of the arches was accepted.