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194/3336–9FE Reference Handbook 10.4 · Civil · Surveying · Leveling
1. Height of Instrument2. Differential Leveling Closure3. Azimuth and Bearing4. Latitude and Departure5. Traverse Closure and Precision6. Slope Distance to Horizontal7. Tape Temperature Correction8. Area by Coordinates (Shoelace)9. Stadia Distance10. Photo Scale11. Curvature and Refraction12. Trigonometric Elevation Difference13. Double-Meridian-Distance Area14. Circular Curve: Tangent and Length15. Missing Course of a Traverse16. Compass (Bowditch) Rule17. Vertical Curve Elevation18. Prismoidal Earthwork Volume19. Circular Curve External and Middle Ordinate20. Magnetic Declination21. Three-Wire Leveling22. Percent Grade and Slope Distance23. Latitudes, Departures, and Closure

Handbook formula

Three-Wire Leveling

Read upper, middle, lower hairs. The average of three reduces error; U+L should be 2M as a check. Distance ≈ 100 s (stadia constant 100) if needed.

Upper, middle, lower rod readings
Stadia interval

Step-by-step solved example

U=1.842, M=1.555, L=1.268 m. Mean and check?

ULM
Upper, middle, lower hairs on the rod; stadia interval s.

  1. 1. Mean

    (1.842+1.555+1.268)/3=1.555 m.

  2. 2. Check

    (U+L)/2=1.555 = M, good. s=0.574 m, D≈57.4 m.

Answer: mean = 1.555 m (checks); D ≈ 57 m

10 practice questions

0/10 correct

1.If M is not the average of U and L

2.Stadia constant is typically

3.Three-wire is more precise than single because

4.s=0.250 m, k=100: D≈

5.Curvature and refraction still apply to

6.HI = elev + BS_mean

7.A turning point is

8.Misclosure allowable often scales with

9.Upper hair reading is

10.U=2.00, L=1.40: M should be