Viaduct
a term applied to extended constructions of arches or other way, artificial works to support a roadway, and thus distinguished from aqueducts, which are similar constructions to support waterways. This term became familiar during the 19th century, in consequence of the great number of vast structures so designated which were erected in various parts of the civilized world for the purpose of carrying railways or roadways over valleys and districts of low levels, or above surface roads, and the general name of viaduct is now recognized as applicable to all for which artificial constructions constructions of timber, iron, bricks, or are established; and accordingly among the principal railway works are to be enumerated viaducts of all these materials.