VIADUCT
viaduct
(noun) bridge consisting of a series of arches supported by piers used to carry a road (or railroad) over a valley
Source: WordNet® 3.1
Noun
viaduct (plural viaducts)
(transport) A bridge with several spans that carries road or rail traffic over a valley or other obstacles.
Source: Wiktionary
Vi`a*duct, n. Etym: [L. via a way + -duct, as in aqueduct: cf. F.
viaduc. See Via, and Aqueduct.]
Definition: A structure of considerable magnitude, usually with arches or
supported on trestles, for carrying a road, as a railroad, high above
the ground or water; a bridge; especially, one for crossing a valley
or a gorge. Cf. Trestlework.
Source: Webster’s Unabridged Dictionary 1913 Edition