SMQT Fundamentals of Surveying 3 — Questions and Answers
Question 1: What is the relationship between a 'foresight' and a 'backsight' in differential leveling?
- Both are readings on unknown points
- The backsight is on a known elevation; the foresight establishes a new elevation (Correct answer)
- The foresight is on a known elevation; the backsight establishes a new elevation
- Both readings are taken simultaneously
Correct answer: The backsight is on a known elevation; the foresight establishes a new elevation
In leveling, the backsight is taken on a point of known elevation to set the height of instrument, and the foresight is taken on an unknown point to determine its elevation.
Question 2: A total station instrument combines which two primary measurement capabilities?
- GPS and magnetometer
- Electronic distance measurement (EDM) and electronic angle measurement (Correct answer)
- Spirit leveling and gravity measurement
- Remote sensing and photogrammetry
Correct answer: Electronic distance measurement (EDM) and electronic angle measurement
A total station integrates an EDM for distance and an electronic theodolite for horizontal and vertical angles into one instrument.
Question 3: What does the term 'azimuth' describe in surveying?
- The vertical angle from the horizon to a celestial body
- A horizontal angle measured clockwise from north (0°) through 360° (Correct answer)
- The difference in elevation between two points
- The bearing of a line measured from the south pole
Correct answer: A horizontal angle measured clockwise from north (0°) through 360°
An azimuth is a horizontal direction measured clockwise from a reference meridian (usually north) ranging from 0° to 360°.
Question 4: Which error source is classified as a 'systematic' error in surveying?
- Reading the rod incorrectly due to inattention
- An instrument that consistently reads 0.01 ft too short due to miscalibration (Correct answer)
- Randomly misidentifying a target
- Transcription mistakes in the field book
Correct answer: An instrument that consistently reads 0.01 ft too short due to miscalibration
Systematic errors follow a consistent pattern (always too long, always too short) and can often be corrected with calibration or mathematical adjustment.
Question 5: What is meant by 'parallax' in instrument sighting?
- The curvature of the Earth affecting long-distance measurements
- An apparent shift of the cross-hairs relative to the target when the observer's eye moves (Correct answer)
- The vertical angle error caused by instrument tilt
- The horizontal error introduced by magnetic declination
Correct answer: An apparent shift of the cross-hairs relative to the target when the observer's eye moves
Parallax occurs when the cross-hair image and target image are not focused at the same plane, causing apparent movement and reading errors as the eye shifts.
Question 6: In a bearing system, what does 'S 45° W' mean?
- 45° measured clockwise from south toward west (Correct answer)
- 45° measured counterclockwise from south toward west
- 45° measured clockwise from north
- The line points due southwest at exactly 225° azimuth
Correct answer: 45° measured clockwise from south toward west
Bearings are read as an angle from either north or south toward either east or west; S 45° W means starting from south and rotating 45° toward west.
Question 7: What is the purpose of 'balancing a traverse' using the Compass Rule (Bowditch)?
- To verify that all interior angles sum to the correct total
- To distribute closure error proportionally to the length of each traverse course (Correct answer)
- To adjust elevations using the least-squares method
- To recalculate all angles using GPS coordinates
Correct answer: To distribute closure error proportionally to the length of each traverse course
The Compass Rule distributes the linear closure error among traverse legs in proportion to each leg's length, assuming errors accumulate uniformly with distance.
SMQT Fundamentals of Surveying 3
What is the relationship between a 'foresight' and a 'backsight' in differential leveling?