(1) Placing points along a straight line or in a common vertical plane. (2) Locating points with respect to a straight line or to a set of straight lines. The term should be used, in surveying, only for operations associated with straight lines. It is also called lineal surveying when the distance is appreciable. (3) The ground plan showing the horizontal direction and components of the centre line of a highway or railroad. (4) The horizontal position of a railroad track, as described by tangents and curves. Alinement is distinguished from profile, which shows the vertical element. Alinement is also spelled alignment.