Line Definitions for Land Surveyors
line—A set of ordered points representing a feature that has minimal or no area such as a stream, centerline, or political boundary line. See also link.
line, agonic—The line through all points on the earth’s surface at which the magnetic declination is zero; that is. the locus of all points at which magnetic north and true north coincide. This line is a particular case of an isogonic line. The position of this line exhibits variations in time. See also line, isogonic.
line, base [USPLS]—A line extending east and west along the astronomic parallel passing through the initial point. along which standard township, section, and quarter-section corners are established. As may be inferred from its designation, the base line is the line from which is initiated the survey of the meridional township boundaries and section lines. Auxiliary governing lines, known as standard parallels or correction lines, are established along astronomic parallels usually at intervals of 24 miles north or south of the base line. In sonic of the early surveys, the base line was referred to as the “basis parallel.”
line, boundary—A line along which two areas meet. In specific cases, the word “boundary” is sometimes omitted, as in “state line.” sometimes the word “line” is omitted, as in “international boundary,” “county boundary,” etc. The term “boundary line” is usually applied to boundaries between political territories, as in “state boundary line.” between two states. A boundary line between privately owned parcels of land is termed a property line by preference, or if a line of the United States public land surveys, is given the particular designation of that survey system, as section line, township line, etc.
line, bulkhead—See bulkhead line.
line, center—Applied to a street, right-of-way, or any other strip of land of uniform width; defines the line midway between the side lines of said snip.
line, contour—An imaginary line connecting the points on a land surface that have the same elevation; also, the line representing this on a map or chart.
line, correction—See parallel, standard [USPLS]
line, cutoff —A survey line run between two or more stations on a traverse for the purpose of producing a closed traverse of that part of the survey.
line, double-rodded—A line of leveling wherein two sets of turning points are used to give independent sets of measurements between bench marks.
line, envelope—A form of line used to delimit the seaward boundary of the marginal sea, and the one incorporated in the Convention on the Territorial Sea and the Contiguous Zone adopted at Geneva in 1958. Defined as a line every point of which is at a distance from the nearest point of the baseline equal to the breadth of the marginal sea. Geometrically, it is the locus of the center of a circle of fixed radius the circumference of which is always in contact with the baseline. The name is derived from the fact that it forms a continuous series of intersecting arcs which are farthest seaward of all the possible arts that can be drawn from the baseline with the same radius, thus enveloping all arts that fall short of the seaward arcs.
line, flowage—A contour or line around a reservoir, pond, lake or along a stream. corresponding to some definite water level (maximum, mean, low, spillway, crest, etc.). Generally used in connection with the acquisition of rights to flood lands for storage purposes.
line, geodesic—A line of shortest distance between any two points on a mathematically defined surface. The geodesic between two points on a plane is the segment of the straight line joining the points. lime geodesic between two points on a sphere is the shorter arc of the great circle joining the points. The geodesic between two points on an ellipsoid is, in general, not a second-degree curve.
line, geodetic–The shortest distance line on the surface of the ellipsoid between any two points thereon.
line, grade—The slope in the longitudinal direction of the roadbed, usually expressed in percent which is the number of units of change in elevation per 100 units horizontal distance. Also has a general use to mean the “highway profile.”
line, harbor—See harbor line.
line, high water—See high water line.
line, isogonic—A line joining points on time Earth’s surface having magnetic declination as of a given date. See also line, agonic.
line, low water—See low utter line.
line, lower low water—See lower low water line.
line, meander—A term used in the public-land surveys to denote a metes-and-bounds traverse approximately along the mean high water line of a permanent natural body of water. By following the sinuosities of the bank or shoreline, the meander line provides data for computing the area of land remaining after the water area has been segregated. A meander line differs from other metes-and-bounds surveys in that it does not ordinarily determine or fix boundaries.
line, non-riparian meander—A qualified condition brought about through judicial opinion holding that gross error was committed in the recording of the field notes relating to the meander of a bank or shore line, finding that the line as wonted did not follow the actual bank or shore as it existed at the date of survey, but that instead a large area was omitted (situated between the true bank or shore and the location of the meander line as recorded). Ordinarily in this condition the opinion annuls the usual doctrine that the bank or shore line here should be construed as the boundary of the survey. and contrarily gives that status to the meander line as recorded.
line, normal-section—That line, on an ellipsoid, which is the intersection of the ellipsoid with a plane perpendicular to it at a given point. A normal-section line is in general elliptical. It is not, in general, a geodesic.
line, offset—A supplementary line close to and roughly parallel with a main line, to which it is referred by measured offsets. Where the line for which data are desired is in such position that it is difficult to measure over it, the required data are obtained by running an offset line in a convenient location and measuring offsets from it to salient points on the other line.
line, pierhead—See bulkhead line.
line, plumb—1line of force in the geo-potential field. The continuous stave to which the direction of gravity is everywhere tangential. 2 A cord with a plumb bob at one end for determining the direction of gravity.
line, property—The division between two parcels of land, or between a parcel of land and the street.
line, radial—A radius line of a circular curve to a designated point in the curve; if the line is extended beyond the convex side of the curve, it is a prolongation of the radial line.
line, random—A trial line, directed as closely as possible toward a fixed terminal point which is invisible from the initial point. The error of closure (amount by which the second station is missed) permits the computation of a correction to the initial azimuth of the random line; it also permits the computation of offsets from the random line to establish points on the line between the survey stations.
line, range [USPLS] boundary of a township surveyed in a north-south direction. See also line, township [USPLS].
line, rhumb—A line on the surface of the earth making the same angle with all meridians; a loxodrome or loxodromic curve spiraling toward the poles in a constant true direction. Parallels and meridians, which also maintain constant true directions, may be considered special cases of the rhumb line. A rhumb line is a straight line on a Mercator projection. Also referred to as “equi-angular spiral.” “loxodrome,” “loxodromic curve.” or “Mercator track.”
line, setback—1 A line outside the right-of-way, established by public authority, on the highway side of which the erection of buildings or other permanent improvement is controlled. 2 A line established by law, deed restrictions, or custom, fixing the minimum distance of the exterior face of the building, walls, and any other construction from a street or highway right-of-way. See also setback.
line, side—Applied to a strip of land such as a street or a right-of-way, it defines measurement, by the use of a transit or other device. It is not necessarily an actual line of final survey but may be an accessory line.
line, township [USPLS]—An exterior boundary of a township extending in an east-west direction. See also line, range [USPLS].
line, transit—Any line of a traverse which is projected, either with or without measurement, by the use of a transit or other device. It is not necessarily an actual line of final survey, but may be an accessory line. Also called “traverse line.”
line, traverse–See traverse, transit.
line, true [USPLS]—The term true line is used to indicate the direct forward bearing from one monument to the next, as distinguished from random line.
line evidence—Evidence of a survey line such as blazes, called-for monuments, flagging, fences, or rock walls.
line-in-polygon—An operation involving the overlay of lines in one la and polygons in another layer. Lines that are contained within polygons are selected, creating another layer in which the lines possess the same attributes as the polygons in which they were contained.
line map—See map, planimetric.
line of collimation—See collimation, line of
line of constant scale—See principal plane [PHOTOGRAMMETRY].
line of position—See circle of position.
line of sight—The straight line between two points. This line is in the direction of a great circle, but does not follow the curvature of the earth. See also collimation, line of
line symbology—The use of different line styles to distinguish different kinds of linear features on a map.
line tree [USPLS]—A tree intersected by a surveyed line, reported in the field notes of the survey, and marked with two hacks or notches cut on each of the sides facing the line.
Source: NSPS “Definitions of Surveying and Related Terms“, used with permission.
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