Bridges presentation
ribs of cast iron made of nine 14ft (4m) segments
flanged at the ends and bolted. The triangular bracing
in the spandrels is reminiscent of Telford's iron bridges
in Shropshire (UK), and the tubes resemble the eliptical
arches of the Pont du Carrousel, built over the Seine in
Paris in 1834. Library of Congress
The first successful all-iron bridge in the world was designed by Thomas Farnolls Pritchard, an
architect who suggested using the material as early as 1773. Built by two ironmasters, Abraham
Darby and John Wilkinson, to demonstrate the versatility of cast iron, the bridge spans 100ft (30m)
over the River Severn at Coalbrookdale (UK), on five semi-circular ribs of cast iron. The Iron
Bridge was followed by a succession of cast-iron arches built throughout Europe. Few cast-iron arch
bridges were built in the USA as the iron truss, derived from wooden forms, was preferred. One iron
arch, however, merits mention, as it is the oldest iron bridge in America
annaabi.ee 
