Bridges presentation
distinct types: stiffened-slab arches and three-hinged arches with an integrated road slab. The 295ft
(90m) Salginatobel Bridge (1930) near Schiers (Switzerland) is the most spectacular and classic
example of this type in the world.
The world's longest concrete and masonry arch bridge is the Rockville Bridge (1902), which carries
four tracks of the former Pennsylvania Railroad over the Susquehanna River (USA) on 48 arches,
70ft (21m) each, for a total length of 3820ft (1164m). It was part of a massive twenty-year
improvement programme under the direction of William H Brown, chief engineer. The largest all-
reinforced concrete bridge, however, is the Tunkhannock Viaduct (1915) built by the Delaware,
Lackawanna & Western Railroad in north-eastern Pennsylvania (USA), composed of ten semi-
circular double-arch spans of 180ft (55m) with the spandrels filled with eleven smaller arches. Like
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