FUNDAMENTALS OF SURVEYING : Classification of surveying

Classification based on purpose of survey:

1.      Control surveying:

 To establish horizontal & vertical position of control points using geodetic surveying  For India, control surveying is done by “Survey of India”.

2.      Topographical Surveys:

To prepare a plan or map of a region which consists of natural features such as rivers, streams,
hills, lakes, forests etc. and also manmade features like roadways, canals, town & villages, etc.

3.      Cadastral Surveys: (Revenue Engineer)

Cadastral surveys are done to fix property boundaries, calculation of land area, or for transfer of land from one owner to another.

This is also done to fix boundaries of municipalities, state & federal jurisdictions.

4.      Engineering Surveys:

These are done for engineering works such as structures, roads and reservoirs etc.

5.      Hydrographic Survey or Marine Survey:

Deals with water bodies for purpose ofnavigation, water supply, harbor works, determination of water depth, etc.

6.      Mine Survey:

This is done to explore mineral wealth.

7.      Astronomical Surveys:

These surveys are done to determine latitude, longitude & Azimuth of a point to get absolute location on earth.

8.      Geological survey:

These surveys are done to find out different strata present in the earth crust. This is done by geologist.

Classification based on instrument used:

1.    Chain Survey:

> Only linear measurements are taken.

> No angular measurements are taken.

> This surveying is adopted when high precision (accuracy) is not required.

2.    Compass Survey:

> This is more precise than chain survey.

> In this survey horizontal angles are measured with the help of compass and linear distances are measured using chain or tape.

> Compass is not a precise instrument since it can have declinations, dip, etc.

3.    Leveling:

> Leveling is done to measure vertical angles with respect to assumed datum. > This is more precise than compass survey.

4.    Plane Table Survey:

> This is the graphical method of survey in which taking field observations and plotting proceed simultaneously.

> Alidade is used to direct object while chain or tape is used for linear measurement. > It is less accurate.

> Useful in the field where magnetic influence is there and when other instruments like compass cannot be used.

5.    Theodolite Survey:

> Most precise instrument designed to measure horizontal as well as vertical angles.

> Has a wide applicability in surveying like laying offhorizontal angles, locating points on line, prolonging survey lines, establishing grades, determining difference in elevation setting out curves, etc.

> Useful in traverse survey & triangulation.

6.    Tacheometric Survey:

> Horizontal & vertical distances are obtained by optical means.

> Under favorable conditions error will not exceed 1/1000.

> This is suitable for inaccessible regions or for topographical regions.

7.    Photogrammetric Survey:

> This survey is done by taking photographs of land to be surveyed.

> Used when area is vast & inaccessible.

8. EDM Surveys:

> Based on triangulation.

> All the sides oftriangle are measured with EDM instrument.