I like Wired’s “This Day in Tech” feature. Today’s feature is this day in bridge history: March 4, 1890, the opening of the Forth Bridge across the Firth of Forth, north of Edinburgh in Scotland.
Three 330-foot towers went up, each atop four separate foundations. The towers cantilevered out toward one another, not quite touching. Machinery hoisted two 350-foot truss spans into place to be supported by the ends of the cantilever arms. Result: two clear spans of 1,710 feet each and a total length of 5,350 feet, not counting the approaches.
The muscular design, with its massive cross-bracing and 58,000 tons of steel, was hailed as a triumph of Victorian engineering on its completion in 1890.
The length of the total span, and the wind patterns in the Firth, make it important to have a really strong bridge, which had not been possible before this effort.