levelling may be classified as under :
The operation of spirit levelling which is employed to determine the elevations of a number of points some distance apart to establish Bench Marks in the area is called differential levelling. It is done regardless of the horizontal positions of the points with respect to each other. It is also sometimes known as taking fly levels or simply fly levelling.
2. Check levelling.
The operation of running level line to check the accuracy of the bench marks previously fixed is called check levelling. The stability of the existing bench marks can only be ascertained if the difference in line of the sections between three bench marks agree with the observed differences obtained by check levelling.
3. Profile levelling.
The operation of levelling carried out to determine the elevations of the points at known distances apart and also other known features at a given straight line is called profile levelling. If we plot the elevations of different points as ordinates and the horizontal distances between the points as abscissa, then the line joining the ends of the ordinates, gives the profile of the surface of the earth. Profile levelling is also called Longitudinal !culling.
4. Cross-sectioning levelling
- Differential levelling
- Cross-sectioning levelling
- Check levelling
- Reciprocal levelling
- Profile levelling
- Precision levelling
The operation of spirit levelling which is employed to determine the elevations of a number of points some distance apart to establish Bench Marks in the area is called differential levelling. It is done regardless of the horizontal positions of the points with respect to each other. It is also sometimes known as taking fly levels or simply fly levelling.
2. Check levelling.
The operation of running level line to check the accuracy of the bench marks previously fixed is called check levelling. The stability of the existing bench marks can only be ascertained if the difference in line of the sections between three bench marks agree with the observed differences obtained by check levelling.
3. Profile levelling.
The operation of levelling carried out to determine the elevations of the points at known distances apart and also other known features at a given straight line is called profile levelling. If we plot the elevations of different points as ordinates and the horizontal distances between the points as abscissa, then the line joining the ends of the ordinates, gives the profile of the surface of the earth. Profile levelling is also called Longitudinal !culling.
4. Cross-sectioning levelling
The operation of levelling which is carried out to provide levels on either side of the main line at right angles, in order to determine the vertical section of the earth surface on the ground, is called cross sectioning.
S. Reciprocal levelling.
The operation of levelling in which difference in elevations between the points is accurately determined by two sets of reciprocal observations. it called reciprocal levelling. Reciprocal levelling is employed when it is not possible to set up the level between two points due to an intervening structures such as large water bodies.
6. Precision levelling.
The operation of levelling in which further refinement of field technique, is made by using precise staves and levels, and special precautions are taken Turing observation, to eliminate all errors, is known as precision (evening. G.T.S. bench marks are established by carrying out precision levelling -
S. Reciprocal levelling.
The operation of levelling in which difference in elevations between the points is accurately determined by two sets of reciprocal observations. it called reciprocal levelling. Reciprocal levelling is employed when it is not possible to set up the level between two points due to an intervening structures such as large water bodies.
6. Precision levelling.
The operation of levelling in which further refinement of field technique, is made by using precise staves and levels, and special precautions are taken Turing observation, to eliminate all errors, is known as precision (evening. G.T.S. bench marks are established by carrying out precision levelling -
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