FS Surveying flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Peg test

A field procedure that checks a level's line of sight for parallelism to the bubble tube by comparing elevation differences taken with the instrument set up at unequal distances from two points.

Basis of bearing

The single line in a survey or plat whose direction is held fixed and from which all other directions are referenced, always stated explicitly on the drawing.

Right of entry

Permission from a property owner allowing survey crews to enter private land; without it, entry can be treated as trespass and create liability for the surveyor.

Utility locate request

A notice to the regional one-call center, generally required by law several working days before excavation, so buried utilities can be marked for crew and public safety.

Curvature and refraction

The combined correction of about 0.0675 K squared meters, with K in kilometers, applied in leveling because level surfaces and refracted lines of sight depart from horizontal.

Prism constant

An offset added to an EDM-measured distance to compensate for the difference between the electrical phase center of the instrument and the effective center of the prism assembly.

Face left and face right

Two telescope positions separated by 180 degrees, used to cancel collimation, trunnion-axis, and vertical-index errors when turning angles with a total station.

Angular closure

The difference between the measured sum of a closed polygon's interior angles and the theoretical sum of n minus two times 180 degrees used to detect angular misclosure.

Senior rights

The doctrine that an earlier conveyance prevails over a later one covering the same land, so the junior deed conveys only what the senior deed left.

Meander line

A traverse run along a water boundary to compute upland area; it is evidence of the water's position at survey time and not itself a boundary line.

Accretion and reliction

Gradual, imperceptible additions of land caused by water action, which belong to the riparian owner; a sudden change, avulsion, does not move the boundary.

Quarter-quarter section

A Public Land Survey System subdivision nominally 40 acres, formed by halving a section twice and bounded by monumented corners or, absent monuments, by proportionate measurement.

Photo scale

The ratio of lens focal length to flying height above ground, so a 6-inch lens flown 6,000 feet above ground produces a scale of 1:12,000.

Relief displacement

The radial shift of an elevated object's image on a vertical photograph, equal to r times h over H, and zero at the principal point directly below the lens.

Ground sample distance

The ground spacing between adjacent pixel centers in a digital image; smaller values indicate finer spatial resolution and allow detection of smaller features.

Digital surface model

A raster elevation model that includes the tops of vegetation, buildings, and other above-ground features, in contrast with a bare-earth terrain model.

Geoid undulation

The separation between the geoid and the reference ellipsoid at a location; ellipsoidal height equals orthometric height plus this value, symbolized capital N.

Combined factor

The product of grid scale factor and elevation factor, used to convert between ground distances and grid distances on a state plane or other projection.

UTM central meridian

The line of true origin at the center of each 6-degree UTM zone, where the grid scale factor is exactly 0.9996 and grid north equals true north.

Deflection of the vertical

The angle between the local plumb line and the normal to the reference ellipsoid; it separates astronomic from geodetic azimuths and affects zenith angles.

Bowditch rule

A traverse adjustment distributing latitude and departure misclosures in proportion to course length, also called the compass rule, suited to random errors in angles and distances.

Relative precision of closure

The linear error of closure divided by total traverse length, expressed as 1 to N; a larger N indicates a more precise traverse.

Degree of curve

Under the arc definition, the central angle subtended by a 100-foot arc; the radius equals 5,729.58 feet divided by the degree of curve.

Area by coordinates

A computation in which twice the enclosed area equals the sum of cross products of successive coordinate pairs minus the reverse sum, the shoelace formula.

Contour interval

The constant vertical distance between adjacent contour lines on a topographic map, selected from map scale, terrain relief, and the intended use.

Representative fraction

A map scale expressed as a dimensionless ratio such as 1:24,000, meaning one unit on the map equals 24,000 of the same units on the ground.

Plat curve data

Values tabulated along each curved boundary, including radius, arc length, chord bearing and distance, and central angle, so the parcel can be retraced.

Cut and fill

The vertical difference between design and existing ground elevation at a point; positive values indicate cut and negative values indicate fill.

Batter boards

Horizontal boards set outside an excavation at a known elevation and offset, from which stringlines locate building corners and grades are measured.

Slope stake

A stake placed where the design side slope intersects original ground, marked with cut or fill to guide excavation of a roadway or embankment.

Standard of care

The degree of skill and care ordinarily exercised by reputable surveyors under similar circumstances; a failure to meet it is the basis for a negligence claim.

Statute of repose

A law barring design and construction claims after a fixed period following substantial completion, regardless of when the injury is discovered.