LSIT Surveying Fundamentals 3 — Questions and Answers
Question 1: What is the primary purpose of a benchmark (BM) in surveying?
- A point of known horizontal position
- A point of known elevation used as a reference (Correct answer)
- A control point for GPS surveys only
- A marker indicating property corners
Correct answer: A point of known elevation used as a reference
A benchmark is a permanent point with a known elevation that serves as a vertical datum reference for leveling surveys.
Question 2: In differential leveling, a 'backsight' reading is taken to:
- Determine the elevation of the next point forward
- Establish the height of instrument (HI) from a known elevation (Correct answer)
- Close the level loop back to the starting BM
- Check the rod reading against a turning point
Correct answer: Establish the height of instrument (HI) from a known elevation
A backsight is read on a point of known elevation to compute the height of instrument (HI = known elevation + BS reading).
Question 3: Which of the following best describes 'closure error' in a traverse?
- The angle sum minus 180°
- The difference between computed and starting coordinates after the loop is closed (Correct answer)
- The maximum allowable precision for a survey
- The error in a single horizontal angle measurement
Correct answer: The difference between computed and starting coordinates after the loop is closed
Closure error is the linear distance between the computed end position and the starting position when a closed traverse is calculated.
Question 4: The term 'latitudes and departures' in traverse calculations refers to:
- Geographic coordinates of latitude and longitude
- North-south and east-west components of a traverse course (Correct answer)
- Horizontal and vertical distance components
- Bearing and distance of each leg
Correct answer: North-south and east-west components of a traverse course
Latitude is the north-south component and departure is the east-west component of each traverse course, used to compute coordinate changes.
Question 5: A surveyor measures a slope distance of 250.00 ft at a vertical angle of +5°. What is the approximate horizontal distance?
- 249.05 ft
- 248.98 ft (Correct answer)
- 250.95 ft
- 245.11 ft
Correct answer: 248.98 ft
Horizontal distance = slope distance × cos(vertical angle) = 250.00 × cos(5°) ≈ 250.00 × 0.99619 ≈ 248.98 ft.
Question 6: Which map projection minimizes distortion for small-scale state surveys in the US and is the basis of the State Plane Coordinate System?
- Mercator and Lambert Conformal Conic (Correct answer)
- Universal Transverse Mercator (UTM) only
- Albers Equal Area and Orthographic
- Gnomonic and Stereographic
Correct answer: Mercator and Lambert Conformal Conic
The State Plane Coordinate System uses either Transverse Mercator (for narrow N-S zones) or Lambert Conformal Conic (for wide E-W zones) projections.
Question 7: What is the purpose of 'Bowditch (Compass) Rule' adjustment in traverse calculations?
- Distribute angular error proportionally to each angle
- Distribute linear closure error proportionally to the length of each course (Correct answer)
- Convert bearings to azimuths before adjustment
- Correct for curvature and refraction in long traverses
Correct answer: Distribute linear closure error proportionally to the length of each course
The Compass (Bowditch) Rule distributes the closure error in latitudes and departures proportionally to the length of each course relative to the total traverse length.
LSIT Surveying Fundamentals 3
What is the primary purpose of a benchmark (BM) in surveying?