Railway Bridge

Railway bridge, 1836-8, with later additions of 1878 and 1914, designed by Isambard Kingdom Brunel.

The bridge carries Middlegreen Road over the Great Western Railway. The original structure of 1836-8 is built of London stock brick, 18 feet wide, with a 30-foot-span semi-elliptical arch in brick, supported on limestone imposts with dressed gritstone copings. The arch accommodated two broad-gauge tracks, later converted to accommodate two mixed broad-gauge and standard-gauge tracks from 1861 until the abolition of broad gauge in 1892. The original arch retains its parapets, approach, copings, and south-western terminal pilasters.

In 1878, during the Southall-Slough quadrupling of the line, a matching 25-foot-span arched extension was added to the north of the original arch, constructed in the same London stock brick with white hydraulic mortar. Raking buttresses were introduced on each side of the pier between the two arched spans. These retain fabric from the original north abutment of Brunel's bridge and thus reflect the angle of the surviving Brunel abutment to the south. The 1878 arched span also features semi-elliptical arches on limestone imposts and dressed gritstone copings, matching the original work.

In 1914, a 20-foot-span level-beam steel girder span was added to the north for the single-line Langley-Dolphin (Slough) loop, with steeply-angled wing walls replacing Brunel's original gently-splayed abutment style. The south-eastern parapet was subsequently rebuilt in blue brick.

The bridge was erected as part of Brunel's contracts 4L and 5L between spring 1836 and May 1838, when the Paddington-Maidenhead section of the Great Western Railway opened. Approximately two-thirds of Brunel's original bridge survives, retaining considerable historic significance for its early Brunel fabric.