Explain Fly Levelling with neat sketch. State situation under which fly levelling is needed.

Explain Fly Levelling with neat sketch. State situation under which fly levelling is needed.
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1 Answer

Answer :

Ans: When DifferentialLevelling is done in order to connect a bench mark to the starting point of the alignment of any project, it is called as fly levelling. Fly levelling is also done to connect the B.M at any intermediate point of the alignment for checking accuracy of work.

In such levelling only the back sight and foresight are taken at every setup of level and no distance are measured along the direction of levelling. The level should be set up just midway between B.S and F.S.

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Situations :i) fly levelling is used in setting Temporary Bench mark.

 ii)if distance is more between two points.

 iii)if there obstacles between the two points.  

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