FUNDAMENTAL SURVEYING Measurement and Data Collection 1 — Questions and Answers
Question 1: Which type of leveling is most accurate for establishing precise vertical control?
- Trigonometric leveling
- Barometric leveling
- Differential leveling (Correct answer)
- Reciprocal leveling
Correct answer: Differential leveling
Differential leveling uses a level instrument and rod to directly measure height differences and is the most accurate field method.
Question 2: A backsight reading of 8.25 ft is taken on a BM with elevation 100.00 ft. What is the Height of Instrument (HI)?
- 108.25 ft (Correct answer)
- 91.75 ft
- 100.00 ft
- 116.50 ft
Correct answer: 108.25 ft
HI = elevation of BM + backsight reading = 100.00 + 8.25 = 108.25 ft.
Question 3: What is the allowable misclosure for a first-order leveling loop of 100 km?
- ± 4 mm √K (Correct answer)
- ± 8 mm √K
- ± 12 mm √K
- ± 24 mm √K
Correct answer: ± 4 mm √K
FGCS first-order Class I leveling requires misclosure ≤ 4 mm √K, where K is distance in kilometers.
Question 4: In EDM measurements, which atmospheric variable has the greatest effect on the speed of light?
- Humidity
- Temperature (Correct answer)
- Pressure
- Wind speed
Correct answer: Temperature
Temperature has the greatest effect on atmospheric refraction and the speed of electromagnetic waves in air.
Question 5: What is the purpose of a two-peg test in leveling?
- To test the level tube sensitivity
- To determine and correct collimation error (Correct answer)
- To calibrate the rod graduation
- To check for instrument settlement
Correct answer: To determine and correct collimation error
The two-peg test determines the collimation error (line of sight not horizontal) and allows the surveyor to correct it.
Question 6: What is the formula for the elevation of a point using a foresight reading?
- Elevation = HI + FS
- Elevation = HI − FS (Correct answer)
- Elevation = BM + FS
- Elevation = BM − FS
Correct answer: Elevation = HI − FS
The elevation of the foresight point = HI − FS (Height of Instrument minus foresight rod reading).
FUNDAMENTAL SURVEYING Measurement and Data Collection 1
Which type of leveling is most accurate for establishing precise vertical control?