LSIT Surveying Principles and Practices 2 — Questions and Answers
Question 1: In a closed traverse, the angular closure error is distributed by the Compass Rule. What does this rule assume?
- All angles are equally reliable
- Errors are proportional to the length of each course (Correct answer)
- Errors are proportional to the latitude and departure of each course
- The traverse starts and ends at the same point
Correct answer: Errors are proportional to the length of each course
The Compass Rule (Bowditch Rule) distributes closure error in proportion to each course's length relative to the total traverse length.
Question 2: What is the purpose of a backsight when using an automatic level?
- To set the horizontal circle to zero
- To establish a known elevation on the rod and compute the Height of Instrument (Correct answer)
- To check that the bubble is centered before reading
- To measure horizontal distance to a benchmark
Correct answer: To establish a known elevation on the rod and compute the Height of Instrument
A backsight is taken on a benchmark or turning point of known elevation to compute the Height of Instrument (HI = elevation + rod reading).
Question 3: Which map projection preserves true directions from a central point, making it useful for navigation charts?
- Mercator
- Lambert Conformal Conic
- Gnomonic (Correct answer)
- Albers Equal-Area Conic
Correct answer: Gnomonic
The Gnomonic projection is the only projection on which all great circles appear as straight lines, making directions from the center true.
Question 4: A surveyor measures a slope distance of 250.00 ft at a vertical angle of +3°30'. What is the approximate horizontal distance?
- 249.31 ft (Correct answer)
- 248.66 ft
- 250.00 ft
- 247.11 ft
Correct answer: 249.31 ft
Horizontal distance = slope distance × cos(vertical angle) = 250.00 × cos(3°30') ≈ 249.31 ft.
Question 5: In the State Plane Coordinate System (SPCS), which projection is used for states or zones with a greater east-west extent?
- Transverse Mercator
- Lambert Conformal Conic (Correct answer)
- Polyconic
- Stereographic
Correct answer: Lambert Conformal Conic
Lambert Conformal Conic is used for zones elongated east-west, while Transverse Mercator is used for zones elongated north-south.
Question 6: When referencing a property corner, what information should a witness corner contain?
- Only the bearing and distance to the true corner
- The deed book and page number
- Bearing, distance, and description of the true corner location (Correct answer)
- Only the PLSS township and range
Correct answer: Bearing, distance, and description of the true corner location
A witness corner (reference monument) must record bearing, distance, and a complete description so the true corner can be relocated.
Question 7: What is 'parallax' in the context of surveying instruments, and how is it corrected?
- The apparent shift of the crosshair relative to the image when the eye moves; corrected by focusing the eyepiece then the objective lens (Correct answer)
- The angular error caused by the telescope not being level; corrected by double-centering
- The refraction of light through the lens; corrected with temperature tables
- The shift of the horizontal circle; corrected by calibrating the index error
Correct answer: The apparent shift of the crosshair relative to the image when the eye moves; corrected by focusing the eyepiece then the objective lens
Parallax is the apparent movement of the crosshair relative to the target when the observer's eye shifts; it is eliminated by focusing the eyepiece first, then sharpening the image with the objective focus.
LSIT Surveying Principles and Practices 2
In a closed traverse, the angular closure error is distributed by the Compass Rule.
What does this rule assume?