Railway Structures
Cast Iron Underbridges
Many cast iron underbridges were entirely rebuilt after 1891,
but some were strengthened, usually by the addition of plate girders in wrought
iron or steel. However, cast iron components were often retained as a
decorative feature.
Luton Arch, Chatham has attractive cast iron arches, but the horizontal plate girders added later take most of the load.
This cast iron arch bridge was built in 1852 to carry the branch line to Brighton Lower goods yard (now closed) over New England Road. The cast ironwork is lettered Regent Foundry Brighton. It can be seen how three steel plate girders were added between the four cast iron arches.
Another interesting cast iron bridge in Brighton carries the station forecourt over Trafalgar Street. Cast iron brackets, many of which have been damaged by passing vehicles, support cast iron beams. Plate girders were used when the forecourt was extended eastwards, and the contrasting methods of construction can be seen. Unfortunately, plate girders never have the elegance of cast iron.
Joiner Street bridge, at London Bridge station, is of exceptional interest, comprising truss girders largely in cast iron. The main members are six parallel Warren trusses. The upper member and the triangles are in cast iron. The lower members are wrought iron. This is because the upper edge of a horizontal beam is in compression, but the lower edge is in tension. The bridge was constructed in 1850 and collapsed very soon after. However, it was rebuilt to the same design and stands to this day. Joiner Street has been closed to traffic and the bridge now spans an entrance to the station. |
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This page was created 8 January 2010
