LSIT Geodesy and Control Surveys 5

Question 1

The scale factor at the central meridian of a Transverse Mercator projection used in State Plane is typically:

Accepted Answer

Less than 1.0000

Answer

To minimize overall distortion, SPCS Transverse Mercator zones use a scale factor slightly less than 1 (e.g., 0.9999) at the central meridian.

Question 2

Which of the following best defines the term 'geoid undulation' (N)?

Accepted Answer

The vertical distance between the geoid and the reference ellipsoid

Answer

Geoid undulation N is the signed vertical distance from the ellipsoid surface to the geoid surface at any point.

Question 3

In differential spirit leveling, 'rod readings' are taken as backsights and foresights. The elevation of a turning point is calculated as:

Accepted Answer

HI − foresight

Answer

Elevation of the next point = Height of Instrument (HI) − foresight rod reading, where HI = previous elevation + backsight.

Question 4

When computing a geodetic azimuth from an astronomic azimuth, the correction applied is called:

Accepted Answer

Laplace correction

Answer

The Laplace correction accounts for deflection of the vertical and converts an astronomic azimuth to a geodetic azimuth.

Question 5

A GPS observation yields an ellipsoidal height h = 312.45 m. The GEOID12B undulation N at that point is −28.37 m. What is the NAVD 88 orthometric height?

Accepted Answer

340.82 m

Answer

Using H = h − N: H = 312.45 − (−28.37) = 340.82 m, because N is negative (geoid below ellipsoid).

(LSIT) Land Surveyor in Training Practice Test

(LSIT) Land Surveyor in Training Practice Test

LSIT Geodesy and Control Surveys 5