In levelling, error due to earth’s curvature is to be corrected using:

Question

Question

This question was previously asked in

OSSC JE (Civil) 2015 (Special Drive) Official Paper

Answer 1

Concept:

Error due to earth curvature:

\(Earth\, curvature\, error(C_c)={D^2\over 2R}=0.07849D^2\)

Where R = Radius of earth curvature

D = Distance in km

Curvature correction = \(-{D^2\over 2R}=-0.07849D^2\)

Additional information:

Refraction correction (C_R) = \({D^2\over 14R}=0.01121D^2\)

Combined correction (C) = \(-{6D^2\over 14R}=-0.06728D^2\)