Civil Engineering - Surveying - Discussion
Discussion Forum : Surveying - Section 2 (Q.No. 20)
20.
Two hill tops A and B 20 km apart are intervened by a third top C. If the top most contour of the three hill tops are of the same value, state whether the line of sight AB
Discussion:
22 comments Page 3 of 3.
Tark Raj Bhatt said:
3 years ago
It's simple.
Due to the curvature of the earth, centre point is raised than the other two so the line of sight AB is below point C.
Due to the curvature of the earth, centre point is raised than the other two so the line of sight AB is below point C.
(9)
Sumit Purbey said:
3 years ago
According to me, here reciprocal levelling is considered as two hilltops is intervened by the third hilltop. so for large obstruction like this reciprocal levelling is done and this levelling completely eliminates the curvature effect and line of collimation error but refraction is partly left. Due to partly left refraction, it makes the object look higher than what it is actually sine we apply + correction for this. So by this 3rd hill top appear to be raised so LOS passes below hill c.
(2)
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