Bridges presentation
floorless chambers filled with compressed air.
The first major bridge of steel in France was the Viaur Viaduct (1902), a three-hinged steel arch of
721ft (220m) flanked by 311ft (95m) cantilevers. The crowning achievement of the material during
the 19th century, however, was the mighty Forth Railway Bridge in Scotland (1890). Its design was
motivated by the Tay Bridge disaster. About 54,000 tons of Siemens-Martin open-hearth steel were
required for the 1710ft (521m) cantilever spans whose main compression struts of rolled steel plate
were riveted into 12ft (4m) diameter tubes. Another authority on the effects of wind on structures
was Gustav Eiffel, who conducted similar experiments in France prior to designing another of the
world's great arch bridges, the 541ft (165m) Garabit Viaduct (1885) in the windy valleys of the
Massif Central, though he held to wrought iron, not being convinced of the efficacy of the new
material.
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