viaduct

n. long bridge built over columned arches which carries a road or a railroad across a valley or a river

A viaduct is a bridge composed of several small spans. The term viaduct is derived from the Latin via for road and duco to lead something. However, the Ancient Romans did not use that term per se; it is a modern derivation from an analogy with aqueduct. Like the Roman aqueducts, many early viaducts comprised a series of arches of roughly equal length. Viaducts may span land or water.
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Noun
1. bridge consisting of a series of arches supported by piers used to carry a road (or railroad) over a valley
(hypernym) bridge, span

n. viaduct, archway, railway arch, overpass

(n.)
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.