Bridges presentation
the wilderness. Dating from 1853, it was a series of inclined cast-iron columns resting on stone
pedestals connected at the top by cast-iron arches, the whole system braced by wrought-iron ties.
Examples surviving today in North America include the Kinzua Viaduct (1900) on the former Erie
Railroad in Pennsylvania (Figure 15), and the Lethbridge Viaduct (1909) on the Canadian Pacific in
Alberta, composed of alternating 67ft (20m) trestles and 100ft (30m) girders, at 5327ft (1624m)
long the longest and heaviest in the world. The Tunkhannock Viaduct (1915), 240ft high (73m) by
2375ft long (724m), is the largest reinforced concrete-arch bridge in the world.
Suspension bridges
Although suspension bridges had been known in China as early as 206 BC, the first chain
suspension bridge did not appear in Europe until 1741, when the 70ft (21m) span Winch Bridge was
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