Fundamentals of Surveying Exam (FS) Field Data Acquisition and Reduction Syllabus

Field Data Acquisition and Reduction syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Field Data Acquisition and Reduction in Fundamentals of Surveying Exam (FS), not a summary of it.

1. 1

   Distance Measurement

   3 topics

   • Taping and Chaining
     • Standardization and tension corrections
     • Temperature, sag, and slope corrections
   • Electronic Distance Measurement (EDM)
     • EDM principles and instrument constants
     • Atmospheric (ppm) and prism corrections
   • Slope and Horizontal Distance Reduction
     • Reduction of slope distance to horizontal
     • Reduction to grid and ellipsoid distances
2. 2

   Angle and Direction Measurement

   3 topics

   • Total Station and Theodolite Operation
     • Setup, leveling, and centering over a point
     • Direct and reverse (face left/face right) observations
   • Angles, Bearings, and Azimuths
     • Interior, deflection, and angles to the right
     • Conversion between bearings and azimuths
   • Instrument Errors and Adjustments
     • Collimation, trunnion, and vertical index errors
     • Pointing and reading errors
3. 3

   Leveling and Vertical Measurement

   3 topics

   • Differential Leveling
     • Backsight, foresight, and height of instrument
     • Benchmarks and turning points
   • Trigonometric Leveling
     • Vertical angle and slope distance elevation differences
     • Reciprocal observations to cancel curvature and refraction
   • Leveling Errors and Loop Closure
     • Collimation and Earth curvature effects
     • Loop misclosure and order of accuracy standards
4. 4

   Traverse Computation and Adjustment

   4 topics

   • Traverse Types and Field Procedures
     • Open, closed-loop, and connecting traverses
   • Latitudes, Departures, and Closure
     • Computing latitudes and departures
     • Linear misclosure and precision (relative accuracy)
   • Traverse Adjustment Methods
     • Compass (Bowditch) rule
     • Least squares adjustment concepts
   • Area Computation from Traverse Data
     • Coordinate (cross-multiplication) method
     • Double meridian distance (DMD) method

Field Data Acquisition and Reduction flashcards for Fundamentals of Surveying Exam (FS)

18 of 50 cards from the Field Data Acquisition and Reduction deck — real questions with worked answers.

1. In taping, what is the standard correction formula for a tape that is not its nominal length (incorrect tape length)?

   $$C_l = \left(\frac{L_a - L_n}{L_n}\right) L$$ where $L_a$ is the actual tape length, $L_n$ the nominal length, and $L$ the measured distance. Add the correction when measuring a distance with a tape that is too long; subtract when laying out.

2. State the temperature correction formula used in taping.

   $$C_t = \alpha (T - T_0) L$$ where $\alpha$ is the coefficient of thermal expansion of steel ($\approx 6.45 \times 10^{-6}\ \text{/}^{\circ}\text{F}$ or $11.6 \times 10^{-6}\ \text{/}^{\circ}\text{C}$), $T$ the field temperature, $T_0$ the standardization temperature, and $L$ the length.

3. What is the sag correction in taping and its formula?

   Sag correction accounts for the tape hanging in a catenary between supports, which shortens the horizontal distance. $$C_s = -\frac{w^{2} L_s^{3}}{24 P^{2}}$$ where $w$ is weight per unit length, $L_s$ the unsupported span, and $P$ the applied tension. It is always subtractive.

4. Give the tension (pull) correction formula for taping.

   $$C_p = \frac{(P - P_0) L}{A E}$$ where $P$ is the applied tension, $P_0$ the standardization tension, $A$ the cross-sectional area, $E$ Young's modulus ($\approx 29{,}000{,}000\ \text{psi}$ for steel), and $L$ the length.

5. How is a measured slope distance corrected to horizontal distance using the elevation difference between the two ends?

   $$C_h = -\frac{h^{2}}{2L}$$ (slope correction), so $H = L - \frac{h^{2}}{2L}$ approximately, where $L$ is the slope distance and $h$ the vertical difference. Exactly, $H = \sqrt{L^{2} - h^{2}}$.

6. What is the principle of operation of an Electronic Distance Measurement (EDM) instrument?

   An EDM transmits a modulated electromagnetic (infrared or microwave/laser) wave to a reflector and measures the phase shift (or time of flight) of the returned signal to compute distance from $D = \frac{c \cdot t}{2}$, where $c$ is the speed of light and $t$ the round-trip travel time.

7. What are the two main classes of systematic error that affect EDM accuracy, and how is total EDM accuracy typically stated?

   A constant (instrument/prism) error independent of distance, and a proportional (scale/ppm) error that grows with distance. Accuracy is stated as $\pm(a\ \text{mm} + b\ \text{ppm})$, e.g. $\pm(3\ \text{mm} + 3\ \text{ppm})$.

8. What atmospheric conditions must be recorded for high-precision EDM measurements, and why?

   Temperature, atmospheric pressure, and sometimes humidity. They change the refractive index of air, altering the effective wave velocity, and are used to apply a ppm (parts-per-million) atmospheric correction to the measured distance.

9. Define 'reflector (prism) constant' in EDM work.

   A systematic offset (often $-30\ \text{mm}$ or $0\ \text{mm}$) caused by the difference between the prism's optical center and its physical mounting point. It must be entered into the instrument so the correct distance is computed; mismatched constants produce a fixed error in every measurement.

10. For a measured slope distance $S$ and a vertical (zenith) angle $z$ from a total station, give the horizontal distance and vertical distance formulas.

    Horizontal: $H = S \sin z$; Vertical: $V = S \cos z$. If instead a vertical angle $\alpha$ above horizontal is used: $H = S \cos \alpha$ and $V = S \sin \alpha$.

11. What is the principal advantage of a total station over a separate theodolite and EDM?

    A total station integrates an electronic theodolite, an EDM, and an onboard microprocessor/data collector, so it measures horizontal angle, vertical angle, and slope distance simultaneously and computes/records coordinates, horizontal distance, and elevation differences automatically.

12. Distinguish between a 'bearing' and an 'azimuth.'

    A bearing is an angle measured from north OR south, toward east or west, ranging $0^{\circ}$ to $90^{\circ}$ (e.g. $N\,45^{\circ}E$). An azimuth is a clockwise angle measured from a single reference meridian (usually north), ranging $0^{\circ}$ to $360^{\circ}$.

13. Convert the bearing $S\,30^{\circ}\,W$ to an azimuth from north.

    Southwest quadrant: $\text{Azimuth} = 180^{\circ} + 30^{\circ} = 210^{\circ}$.

14. Give the rule for converting an azimuth in each quadrant to a quadrant bearing.

    NE ($0^{\circ}$–$90^{\circ}$): $N\,\alpha\,E$. SE ($90^{\circ}$–$180^{\circ}$): $S\,(180^{\circ}-\alpha)\,E$. SW ($180^{\circ}$–$270^{\circ}$): $S\,(\alpha-180^{\circ})\,W$. NW ($270^{\circ}$–$360^{\circ}$): $N\,(360^{\circ}-\alpha)\,W$.

15. How do you compute the azimuth of the next line in a traverse given the back azimuth and the interior deflection/angle?

    Forward azimuth of next line $=$ back azimuth of previous line $+$ measured clockwise angle. The back azimuth $=$ forward azimuth $\pm 180^{\circ}$. If the result exceeds $360^{\circ}$, subtract $360^{\circ}$.

16. Define 'deflection angle' and state its sign convention.

    A deflection angle is the angle between a survey line and the prolongation of the preceding line. It is measured right (R, clockwise) or left (L, counterclockwise) and ranges $0^{\circ}$ to $180^{\circ}$. It must always be labeled R or L.

17. What is the difference between a direct (face left) and reversed (face right) instrument reading, and why take both?

    Face left and face right are observations made with the telescope on opposite sides of the vertical axis (plunged). Averaging the two (double centering) cancels instrumental errors such as collimation error, horizontal-axis (trunnion) tilt, and vertical-circle index error.

18. What is collimation error in a theodolite/level, and how is it eliminated in angle measurement?

    Collimation error is the non-perpendicularity of the line of sight to the horizontal axis (instrument's line of sight not aligned with the optical axis). It is eliminated by averaging direct and reversed (face-left/face-right) pointings to the same target.

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