Bridges presentation
favoured by European engineers, who had the mathematical knowledge to analyse the indeterminate
stresses introduced by such systems. A case in point is the Town lattice truss invented by Ithiel
Town, an American, in 1820, which is a rare instance of reverse techno- logical transfer. The form
originated in the USA, but was widely adopted in Europe, especially in iron railway bridges. The
lattice fell into disfavour in the USA, where a preference existed for statically determinate bridges of
heavy timber, whose forces were easier to calculate.
A more complex form of the beam is the truss, a rigid self- supporting system of triangles
transferring both dead and live loads to the abutments or piers. A more complex form of the girder is
the cantilever, where trussed and anchored ends of the girder support a central span. They were
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