Bridges presentation
tramroad bridge below the confluence of the Taff and Taff Fechan, built in January-June 1793 by
Watkin George, Chief Engineer of the Cyfarthfa Ironworks, to carry an edge railway and water
channel. An iron trough-like girder is carried in an A-frame truss of cast iron spanning 47ft (14.2m),
held together by mortise-and-tenon and dovetail joints. The next extant iron railway bridge seems to
be another recently discovered at Aberdare (1811), followed by Gaunless. The oldest still in service
is Hall's Station Bridge, a Howe truss designed in 1846 by Richard Osborne, a London-born
Irishman who worked as engineer for the Philadelphia & Reading Railroad, although its current use
is vehicular and not rail. The first major iron truss with pin connections was built in the USA in
1859, and the earliest iron cantilever in Germany in 1867, over the Main at Hassfurt.
Figure 11 Bollman Bridge (c 1869), Savage,
Maryland (USA)
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