Correct Answer - Option 1 : Profile leveling
Types of levelling:
Profile leveling
- Profile leveling is a method of surveying that has been carried out along the central line of a track of land on which a linear engineering work is to be constructed/ laid.
- The operations involved in determining the elevation of the ground surface at small spatial intervals along a line is called profile leveling.
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The route along which a profile is run may be a single straight line, as in the case of a short sidewalk; a broken line, as in the case of a transmission line or sewer; or a series of straight lines connected by curves, as in case of a railroad, highway or canal.
Fly levelling
Fly leveling is conducted when the benchmark is very far from the workstation. In such a case, a temporary benchmark is located at the work station which is located based on the original benchmark. Even it is not highly precise it is used for determining approximate level.
Differential levelling:
It is the method of levelling to determine the elevation of points located at some distance apart or to determine the elevation difference between two points or to establish benchmarks. The method is used in order to find the difference in elevations between two points: (i) if they are far apart, (ii) the difference in elevation between two points is too great and (iii) if there are obstacles intervening.
Reciprocal levelling:
When it is not possible to locate the levelling instrument in between the intervisible points, reciprocal levelling is performed. This case appears in case of ponds or rivers etc. In case of reciprocal levelling, instrument is set nearer to 1st station and sighted towards 2nd station.
