SMQT Introduction to Surveying 5 — Questions and Answers
Question 1: A 'total station' combines which two instruments into one device?
- Level and compass
- Electronic distance meter (EDM) and theodolite (Correct answer)
- GPS receiver and data collector
- Planimeter and transit
Correct answer: Electronic distance meter (EDM) and theodolite
A total station integrates an electronic distance meter for measuring distances and a theodolite for measuring angles into a single instrument.
Question 2: What is 'resection' in surveying?
- Setting a new point by intersecting lines from known points
- Determining your instrument's position by observing angles to known control points (Correct answer)
- Re-measuring a line to check for errors
- Rotating the instrument 180° to eliminate systematic errors
Correct answer: Determining your instrument's position by observing angles to known control points
Resection is the process of determining the position of an unknown point (the instrument station) by measuring angles or distances to at least two known points.
Question 3: In surveying, what does the abbreviation 'NGS' stand for?
- National Geodetic Survey (Correct answer)
- National Geographic System
- Network of Ground Stations
- North Grid Standard
Correct answer: National Geodetic Survey
The National Geodetic Survey is the federal agency that defines and manages the National Spatial Reference System, including horizontal and vertical datums.
Question 4: What is the primary difference between NAD83 and NAD27 horizontal datums?
- NAD83 uses feet while NAD27 uses meters
- NAD83 is geocentric and based on the GRS80 ellipsoid, while NAD27 uses the Clarke 1866 ellipsoid (Correct answer)
- NAD27 incorporates GPS data while NAD83 is purely ground-based
- NAD83 applies only to Alaska while NAD27 applies to the contiguous US
Correct answer: NAD83 is geocentric and based on the GRS80 ellipsoid, while NAD27 uses the Clarke 1866 ellipsoid
NAD83 is a geocentric datum based on the GRS80 ellipsoid and was defined using satellite data, while NAD27 is based on the Clarke 1866 ellipsoid with its origin at Meades Ranch, Kansas.
Question 5: Which surveying term describes the height of the instrument's line of sight above the datum?
- Rod reading
- Height of instrument (HI) (Correct answer)
- Foresight elevation
- Backsight correction
Correct answer: Height of instrument (HI)
The height of instrument (HI) is the elevation of the telescope's line of sight, computed by adding the backsight rod reading to the known benchmark elevation.
Question 6: What type of survey is performed to map underwater features such as river channels and harbor depths?
- Geodetic survey
- Hydrographic survey
- Bathymetric survey
- Both B and C, as these terms are interchangeable (Correct answer)
Correct answer: Both B and C, as these terms are interchangeable
Hydrographic and bathymetric surveys are synonymous terms for surveys that measure and map underwater depths and bottom features.
Question 7: In which situation would a surveyor use 'stadia' measurements?
- When measuring angles with a digital theodolite
- When estimating distances quickly using cross-hair readings on a rod (Correct answer)
- When determining magnetic declination in the field
- When calculating the area of an irregular polygon
Correct answer: When estimating distances quickly using cross-hair readings on a rod
Stadia is a rapid distance measurement method using the interval between upper and lower stadia hairs in a telescope reading on a graduated rod, with distance = rod interval × 100.
SMQT Introduction to Surveying 5
A 'total station' combines which two instruments into one device?