EMBANKMENT. In engineering, generally, a mound or bank of earth, stone, or other material, usually narrow in com parison with its length, artificially raised above the prevailing level of the ground. Embankments may form parts of works or structures of varied character but usually serve for one or other of two main classes of purpose. On the one hand, they are used to preserve the level of railways (q.v.), roads, canals, and cause ways in cases where a valley or piece of low lying ground has to be crossed. In such circumstances they are commonly of earth suitably consolidated and drained. Embankments are also con structed for carrying railways and roads over marsh land or land liable to flooding, and, in some cases, over the shallow beds of lakes and seas : e.g., the railway across the Great Salt Lake in Utah and that joining the mainland with the Florida Keys (q.v.). When formed on marsh land it is often necessary to make special provision to prevent or minimize sinking. A problem which fre quently has to be considered by the railway engineer and the roadmaker is the relative economy of constructing an embank ment or, its usual alternative, a viaduct.
On the other hand embankments are employed, in varied forms and 'circumstances, to stop or limit the flow of water, for in stance: (a) For confining a river, canal, or other water course within fixed limits (see CANALS AND CANALIZED RIVERS ; RIVER ENGINEERING; AQUEDUCTS). (b) In fen or marsh lands to pre vent flooding or to form the sides of drainage channels or ditches raised above the general level of the land. In the Fens (q.v.) they are known as "banks" and the men employed in constructing and maintaining them as "bankers." (c) On the sea coast or in estuaries for the purpose of coast protection (q.v.) and land reclamation, in some cases combined with a wall. Such embank ments are sometimes referred to as sea-walls irrespective of their form. (d) For retaining water in a reservoir (q.v.) or for raising the water level of a lake when they are more usually described as "earth-dams" (see DAMS).
Puddled clay, curtain walls of concrete, and steel sheet piling are frequently utilized in the construction of embankments when it is necessary to secure watertightness, and in most uses of em bankments to limit or stop the flow of water some form of protec tion of the face of the work against erosion is required such as covering it with stone, slag, or concrete.
The word embankment has come to be used in particular in stances for the mass of material, faced and supported by a stone or concrete wall, placed along the banks of a river where it passes through a city, whether to guard against floods or to gain addi tional space. Such is the Thames Embankment in London, which carries a broad roadway. In this sense an embankment is dis tinguished from a quay, though the structural form may be sim ilar, the latter word being confined to places where ships are loaded and unloaded, thus differing from the French quai which is used both of embankments and quays, e.g., the Quais along the Seine at Paris. In Holland (q.v.) the term dike is applied to any embankment designed to limit the flow of water. (N. G. G.)