Mills Hill Bridge, Chadderton
in Chadderton, near Oldham
Also known locally as Th'iron Dongle.
The attractive 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 quadriple tracks. In the 1970s the line reverted to double tracks and the original bridge was taken out of use and had its deck removed.[1]
The original bridge is of the 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. Each of these girders has a cast iron 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.
Below the arch, and cast integral with it, is a series of vertical ribs connected to a longitudinal member. Judging by its slenderness, this horizontal member was not intended to be a significant extra string to the bow. The vertical ribs are continued above the arch and joined in pairs by Gothic arches, which in turn join a horizontal member (not quite horizontal, being slightly inclined from each end to the crown). The bottom of each vertical rib ends with a small lug with a hole. The purpose of these holes is not obvious. However, it is probable that they were there to accommodate decorative cast iron 'skirts' to hide the tie bars. This assumption is supported by the contemporary lithograph and, more convincingly, by drawings of Robert Stephenson's 1838 bridge which carried the London & Birmingham Railway over Regent's Canal near Chalk Farm[2]. Gauxholme viaduct had similar decorative castings at the bottom and top of the girders.
Geograph entry here
Numerous photos, showing details, here.
Note: The older Todmorden - Gauxholme No. 2 Viaduct is of similar construction, but has been much altered.
See Also
Sources of Information
- ↑ 'Britain's Historic Railway Buildings' by Gordon Biddle, Oxford University Press, 2003
- ↑ [1] 'Railway practice: A Collection of Working Plans and Practical Details of Construction in the Public Works of the Most Celebrated Engineers Comprising Tunnels and Tunnel Fronts, Turnpike Road Bridges...' by S. C. Brees, 1838