Highway surveys involve measuring and computing horizontal and vertical angles, elevations, and horizontal distances. The results of these surveys are used to prepare detailed plan and profile base maps of proposed roadways. In addition, the elevations determined in the survey serve as the basis for calculation of construction cut and fill quantities, and in determining roadway banking. This section presents a review of basic terminology, concepts, and standard procedures used in highway surveys. The review begins with some basic definitions.

Highway curves can be either circular arcs or spirals. A simple curve is a circular are connecting two straight lines (tangents). A compound curve consists of two or more circular arcs of different radii tangent to each other with their centers on the same side of the common tangent. Compound curves where two circular ares having centers on the same side are connected by a short tangent are called broken-back curves. A reverse curve is two circular arcs tangent to each other but with their centers on opposite sides of the common tangent. A curve whose radius decreases uniformly from infinity to that of the curve it meets is called a spiral curve. Spiral curves with the proper superelevation (banking) provide safe and smooth riding qualities. Circular and spiral curves are used for curves in the horizontal plane. Tangents in the vertical plane are joined by parabolic curves (also referred to simply as vertical curves).