the process of directly or indirectly measuring vertical distances to determine the elevation of points or their differences in elevation

buildings, roads, canals and other vertical and horizontal structures can be designed and laid out to best conform to the configuration of the ground.

is a curved surface which is at any point perpendicular to the direction of gravity or the plumb line. It is best represented by the surface of a large body of still water. However, a level surface is not a plane and does not have a regular form because of the deviation of the plumb bob.

is a curve line in a level surface all points of which are normal to the direction of gravity and equidistant from the center of the earth.

is plane that is tangent to a level surface at a particular point. It is also perpendicular to the plumb line at the same point.

is a straight line in a horizontal plane which is tangent to a level line at one point. This is perpendicular to the direction of gravity at the point of tangency.

is a line parallel to the direction of gravity. It is exemplified by the direction taken by a string supporting a suspended plumb bob passing through a point.

is an imaginary surface of the sea which is midway between high and low tides. It is taken as reference surface to which most ground elevations are referred.

is any convenient level surface coinciding or parallel with mean sea level to which elevations of a particular area are referred.

is the vertical distance above or below the mean sea level or any other selected datum. It is either positive or negative, depending if the point is above or below the mean sea level.

is the vertical distance between the two-level surfaces in which the points lie.

The process of determining the difference in elevation between two points or more points some distance apart.

is a fixed point of reference whose elevation is either known or assumed. They may be permanent or temporary.

is a reading taken on a rod held on point of known or assumed elevation

is a reading taken on a rod held on a point whose elevation is to be determined.

is an intervening point between two bench marks upon which point foresight and backsight rod readings are taken to enable a leveling operation to continue.

is the elevation of a line of sight of an instrument above or below a selected datum.

This method of leveling is used to determine the differences in elevation between points at designated short measured intervals along an established line to provide data from which a vertical section of the ground can be plotted.

is a curve line which graphically portrays the intersection a vertical plane with the surface of the earth.

It depicts ground elevations of selected critical points along a surveyed line and the horizontal distance between these points.

is a numerical designation given in terms of horizontal distance any point along a profile line away from the starting point.

are also known as ground rod readings, taken along the centerline of the proposed project to provide an accurate representation of the ground surface.

These are observed at regular intervals and at points where sudden changes in elevation occur.

are points which are established along the profile route at uniformly measured distances. These points are usually made in multiples of 100, 50, 30, 20 or 10 meters.

are other intermediate points established along a profile level route which is not designated as a full station.

These points are taken at breaks in the ground surface slope and at critical points such as the intended location of culverts, bridges and other structures.

is the process of drawing the vertical scale for profile much larger than the horizontal scale in order to accentuate the differences in elevation.

is a special heavy grade paper used for plotting profile.