LSIT Surveying Fundamentals 5 — Questions and Answers
Question 1: The 'area by coordinates' method (Coordinate or Shoelace formula) computes area by using:
- Latitudes and departures of each course summed with DMDs
- The cross product of X and Y coordinates of traverse vertices (Correct answer)
- Breaking the traverse into triangles from the origin
- Summing each course's midpoint ordinate multiplied by its length
Correct answer: The cross product of X and Y coordinates of traverse vertices
The coordinate (Shoelace) formula computes area as half the absolute value of the sum of (X_i × Y_{i+1} − X_{i+1} × Y_i) for all consecutive vertices.
Question 2: What does the term 'geoid' represent in geodesy?
- The mathematical ellipsoid approximating Earth's shape
- The equipotential surface of Earth's gravity field approximating mean sea level (Correct answer)
- The topographic surface of the Earth
- The reference frame for GPS measurements
Correct answer: The equipotential surface of Earth's gravity field approximating mean sea level
The geoid is the irregular equipotential surface of Earth's gravity field that approximates mean sea level and defines orthometric (physical) heights.
Question 3: A surveyor sets up an instrument at point A and measures an angle to point B as 42°15'30". After rotating 180° and measuring the same angle in face-right, the reading is 222°15'00". What is the best value for the angle?
- 42°15'15" (Correct answer)
- 42°15'30"
- 42°15'00"
- 42°14'45"
Correct answer: 42°15'15"
The mean angle is found by averaging: face-left = 42°15'30" and face-right = 222°15'00" − 180° = 42°15'00"; average = 42°15'15".
Question 4: Which of the following best describes the 'three-wire leveling' technique?
- Using three level vials to ensure instrument is truly level
- Reading the top, middle, and bottom stadia wires on the rod to check accuracy and compute distances (Correct answer)
- Leveling with three separate instruments to reduce error
- Running three parallel level loops and averaging the results
Correct answer: Reading the top, middle, and bottom stadia wires on the rod to check accuracy and compute distances
Three-wire leveling reads all three horizontal crosshairs (top, middle, bottom stadia wires) on the leveling rod; the middle wire gives the elevation reading and the outer wires provide a check.
Question 5: In stadia surveying, if the stadia interval factor (K) is 100 and the rod intercept (s) is 1.25 ft, what is the horizontal distance (assuming a horizontal sight)?
- 100.25 ft
- 125.00 ft (Correct answer)
- 12.50 ft
- 1250.00 ft
Correct answer: 125.00 ft
Stadia horizontal distance (level sight) = K × s = 100 × 1.25 = 125.00 ft (plus instrument constant C, usually negligible for modern instruments).
Question 6: What is the main purpose of the 'Transit Rule' in adjusting traverse misclosure?
- Distribute error proportionally to each course length
- Distribute error proportionally to the absolute values of latitudes and departures of each course (Correct answer)
- Assign all closure error to the longest course
- Apply equal correction to all latitudes and departures
Correct answer: Distribute error proportionally to the absolute values of latitudes and departures of each course
The Transit Rule distributes closure error in latitude proportionally to the absolute latitude of each course, and similarly for departures, rather than by course length as in the Compass Rule.
Question 7: In a legal description using the Public Land Survey System (PLSS), a 'section' nominally contains how many acres?
- 40 acres
- 160 acres
- 320 acres
- 640 acres (Correct answer)
Correct answer: 640 acres
A standard PLSS section is nominally 1 mile × 1 mile = 640 acres, though boundary sections may vary due to convergence of meridians and survey errors.
LSIT Surveying Fundamentals 5
The 'area by coordinates' method (Coordinate or Shoelace formula) computes area by using: