Mills Hill Bridge, Chadderton

Railway bridge over Rochdale canal cc-by-sa/2.0 - © Michael Smith - geograph.org.uk/p/6814873

Section of part of Chalk Farm railway bridge, which was of similar construction to Mills Hill bridge

in Chadderton, near Oldham

Also known as Bridge 69B, and locally as Th' Iron Dongle. The name Mills Hill Bridge is assigned to it in 'Britain's Historic Railway Buildings' by Gordon Biddle.

The attractive and historically important skewed iron bridge carried the railway from Rochdale to Manchester over the Rochdale Canal, adjacent to Lock 61 (Scowcroft). A girder bridge was added immediately alongside in the late 19thC to provide quadruple tracks. In the 1970s the line reverted to double tracks and the original bridge was taken out of use and had its deck removed.

Grade II listed (No. 1356431). Historic England listing here. This gives the construction date as 1863. However, the line was built over the Rochdale canal in 1839, and the design is consistent that of several similar bridges built by George and Robert Stephenson in the late 1830s (see below).

The bridge is of the iron bowstring (tied arch) type with a suspended deck, a form pioneered by George Leather. Each side of the bridge comprises a pair of girders, spaced several feet apart. These are joined to each other by transverse X-braces, bolted to the vertical ribs of the girders. Each of these cast iron girders includes a 'Tudor' arch as its main member, and the 'string' of this 'bow' is a group of four tensioned rods. Each of these tensioned wrought iron rods comprises several bars joined by cast iron spools with tapered cotters. Decorative castings are attached to the top and bottom of the girders.

The transverse X-braces have a vertical central hole through which a wrought iron rod passes. From these rods are suspended fish-bellied cross beams which supported the deck. See Chalk Farm Bridge drawing.

Details of construction of a somewhat similar bridge can be seen in drawings of Robert Stephenson's 1838 bridge which carried the London & Birmingham Railway over Regent's Canal near Chalk Farm.

At some point the deck supports were augmented by the insertion of additional cross beams between the original cast iron beams. These additional beams are of riveted wrought iron or steel construction. The ends of these horizontal beams turn upwards between the pairs of girders, and terminate in riveted crossheads which sit on top of the girders to take the weight.

Numerous photos, showing details, here.

Geograph entry here. The photo is reproduced above. This was taken in 2021 and shows that the decorative castings below the girder to be missing from the right hand side, presumably removed for repair.

Note: The older Todmorden - Gauxholme No. 2 Viaduct is of similar construction, but has been much altered.

See Also

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