In a leveling survey work, the first staff reading taken to a staff station after shifting the instrument and the last staff reading taken to a staff station before the instrument is shifted are, respectively:

In a leveling survey work, the first staff reading taken to a staff station after shifting the instrument and the last staff reading taken to a staff station before the instrument is shifted are, respectively:

Right Answer is:

Backsight and foresight

SOLUTION

Back Sight (BS) or back sight reading: It is a first staff reading taken by the leveling instrument at a point of known elevation. For example, after adjusting the level the first reading should be taken on a point of known elevation to determine the height of the instrument. Thus reading on a benchmark or on change point (CP) is BS reading.

Fore Sight (FS) readings: The last staff reading taken before shifting the level (instrument) to another position is FS reading. The reading from the first instrument station is FS reading. This reading gives the RL (elevation) at the point (change point, i.e. CP). It is the staff reading taken on a point whose RL is to be determined. This sight is considered as negative and deduced from the height of the instrument to determine the RL of the point.

Intermediation Sight (IS) readings: They are the readings taken after the BS reading before the change of the position of the instrument. These are the points whose RL is determined by the method already mentioned above in FS.

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