NV Land Surveyor flashcards

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

Azimuth from bearing

Convert a bearing to azimuth by quadrant: NE = bearing; SE = 180 − bearing; SW = 180 + bearing; NW = 360 − bearing. Azimuths are always clockwise from north.

Back bearing

The reverse direction of a line, differing by 180 degrees. If a bearing is N 40 E, the back bearing is S 40 W. Used to check angular closure in traverses.

Interior angle sum

For a closed polygon with n sides, the sum of interior angles equals (n − 2) × 180 degrees. Use this to compute angular misclosure and distribute error among the observed angles.

Zenith angle

A vertical angle measured downward from the zenith (directly overhead) to the line of sight, ranging 0 to 180 degrees. Zenith angle plus altitude angle equals 90 degrees.

Magnetic declination

The angle between true north and magnetic north at a location, varying with time and place. East declination means magnetic north lies east of true north, so true azimuth = magnetic azimuth + declination.

Accuracy versus precision

Accuracy is closeness to the true value; precision is repeatability among repeated measurements. A precise set of observations can still be inaccurate if a systematic error is present.

Height of instrument

HI equals the benchmark elevation plus the backsight reading. Point elevations are then found by subtracting foresight readings from the HI.

Map scale ratio

A scale of 1:24,000 means one unit on the map represents 24,000 of the same units on the ground. One inch equals 2,000 feet at that scale.

Horizontal curve tangent

Tangent length T = R tan(Δ/2), where R is the radius and Δ is the central deflection angle. Used to locate the PC and PT from the PI.

Degree of curve arc

For arc definition, D = 5729.58 / R in feet. The arc definition is standard for highway curves; the chord definition is used for railroad curves.

Vertical curve K value

K equals curve length divided by algebraic grade change A in percent. Curve length L = K × A. K also gives the stationing distance per one percent grade change.

Average end area volume

Volume equals (A1 + A2) / 2 × L, where A1 and A2 are cross-section areas at the ends and L is the distance between them. Assumes linear area change.

Prismoidal volume

V = L(A1 + 4Am + A2) / 6, where Am is the mid-section area. More accurate than average end area when cross sections change nonlinearly.

Shoelace area formula

Twice the area equals the sum of Xi × Yi+1 minus Xi+1 × Yi around the closed traverse. Coordinates must be in consistent units and ordered around the boundary.

Slope to horizontal distance

Horizontal distance equals slope distance times the sine of the zenith angle. Vertical distance equals slope distance times the cosine of the zenith angle.

Latitude and departure

Latitude (northing) equals distance times cosine of azimuth; departure (easting) equals distance times sine of azimuth. Sums of latitudes and departures close in a closed traverse.

DEM versus DSM

A DEM represents bare-earth elevations with surface features removed. A DSM includes buildings, vegetation, and other above-ground objects, as from LiDAR or photogrammetry.

Level loop check

Sum of backsights minus sum of foresights equals the last elevation minus the first elevation. Any difference is misclosure to be compared with allowable closure.

Compass rule

Bowditch adjustment distributes latitude and departure misclosure in proportion to course length. Correction equals misclosure times course length divided by traverse perimeter, with opposite sign.

Transit rule

Traverse adjustment that distributes misclosure in proportion to the magnitude of each latitude or departure rather than course length. Used when distances are more reliable than angles.

Relative precision

Linear misclosure divided by traverse perimeter, expressed as a ratio such as 1:10,000. Smaller ratios indicate a better traverse.

Inverse computation

Distance between points equals the square root of ΔN² plus ΔE². Azimuth is arctangent of ΔE over ΔN, adjusted to the proper quadrant.

Angular misclosure

The difference between the sum of observed angles and the theoretical sum. For interior angles, theoretical sum is (n − 2) × 180 degrees; distribute the error among angles.

Stadia distance

Horizontal distance equals the stadia interval times the stadia factor, times cosine squared of the vertical angle, plus the instrument constant. Modern EDM total stations replace stadia.

Three-point resection

A method to locate an unknown station by observing angles to three known points. The unknown position is solved from the geometry of the triangle formed.

Standard of care

The degree of care and skill a reasonably prudent surveyor would exercise under similar circumstances. It is the benchmark for negligence in professional practice.

Seal and signature

A licensed surveyor applies the seal and signature only to work personally prepared or directly supervised. Sealing work outside one's competence is an ethics violation.

Conflict of interest

A financial or personal interest that could bias professional judgment. It must be disclosed and avoided; accepting undisclosed compensation from multiple parties is prohibited.

Monument preservation

Existing monuments must not be disturbed or removed without legal authority. Found monuments are evidence and should be recorded and shown on plats and field notes.

Boundary retracement

Following the footsteps of the original surveyor, giving priority to original monuments, then distances, then areas. Senior rights and intent of the original survey govern.

ALTA/NSPS survey

A survey meeting current ALTA/NSPS minimum standards, typically for title insurance and lending. Scope is set by the table of optional items agreed with the client.

State minimum standards

State board rules governing plat content, monumentation, and accuracy of surveys. Compliance is required for record plats and is enforced through licensure.