LSIT Measurement Technology 3

Question 1

A total station's EDM measures a slope distance of 452.38 ft at a vertical angle of +6°24'. What is the horizontal distance?

Accepted Answer

449.64 ft

Answer

Horizontal distance = slope distance × cos(vertical angle) = 452.38 × cos(6°24') ≈ 449.64 ft.

Question 2

Which type of level is most affected by atmospheric refraction and Earth's curvature over long sights?

Accepted Answer

Trigonometric leveling

Answer

Trigonometric leveling uses vertical angles over long distances, making it most susceptible to refraction and curvature errors.

Question 3

A surveyor uses a prism constant of –30 mm. If the EDM reads 125.340 m to the prism, what is the corrected distance?

Accepted Answer

125.310 m

Answer

Corrected distance = measured distance + prism constant = 125.340 + (–0.030) = 125.310 m.

Question 4

What does 'index error' refer to in theodolite/total station usage?

Accepted Answer

The deviation of the vertical circle index from 0° when the bubble is centered

Answer

Index error is the amount by which the vertical circle reads something other than 0° (or 90°) when the instrument is leveled.

Question 5

Which GNSS error source is mitigated by using a dual-frequency receiver?

Accepted Answer

Ionospheric delay

Answer

Dual-frequency receivers can model and remove ionospheric delay because it is frequency-dependent.

(LSIT) Land Surveyor in Training Practice Test