Classification and Principle of Surveying

 Classification of Surveying 

A)      On The basis of Curvature off Earth concerned:

1)      Plane Surveying

2)      Geodetic Surveying

S.N	Plane Surveying	Geodetic Surveying
1.	The earth surface is considered as a plain surface.	The earth surface is considered as a curved surface.
2.	The line formed by any two points are considered as a straight line as the same angles are plain angles.	The line formed by joining any two points are considered as arch-as the same angles are spherical angles.
3.	Plane Surveying Effect of the curvature of the earth's surface is ignored.	Geodetic Surveying Effect of the curvature of the earth's surface is included.
4.	Length up to 12KM is treated as plane surveying.	Length more than 12KM is treated as plane surveying.
5.	Plane Surveying Suitable for small area surveying.	Geodetic Surveying Suitable for large area surveying.
6.	Plane Survey accuracy is low.	Geodetic Survey accuracy is high.
7.	Involves smaller areas less than about 260 km².	Involves larger areas more than about 260 km².
8.	Economical and easy survey method.	The special instrument needed and long survey method.
9.	Knowledge of plane trigonometry is required.	Knowledge of spherical trigonometry is required.
10.	Used in general civil engineering survey project work.	They are used for the precise location of a widely distant area.
11.	Plane surveying uses normal instruments like a chain, measuring tape, theodolite, etc.	Geodetic surveying uses more precise instruments and modern technology like GPS.technology like GPS.
12.	Done locally by the individual organization.	Done by the concerned state or government department.

 B) On The basis of nature of field:

1) Land Survey: The Survey that is done in land including all man made and natural feature is called land survey. e.g, topographical survey, boundary survey, cadastral Survey etc.

2) Marine or Hydrographic Survey: The survey that is related to water bodies is called marine survey. e.g, depth of oceans, ocean navigation for shapes or boat etc.

3) Astronomical Survey: It is carried out to determine the locations. i.e, latitude of different places on the earth surface and the direction of any live on the earth surface by observation of heavenly bodies such as stars and sun.

C) On The basis of purpose of Surveying:

1) Engineering Survey: The surveying which is done in order to plan, design and layout different types of engineering works such as roads, railways, hydropower etc.

2) Military Survey: The survey that occures by the team of military personnel in order to provide facility of protection and defense for enemies is called military survey.

3) Mine Survey: The survey that is done to explore the minerals beneath the surface of earth like coal, gold, iron etc.

4) Geological Survey: It is used to determine location and extent different minerals and rock types that may impact on the geological stability of the earth. e.g, earthquake study, Dams or bridges, life and span, the impact from disasters. on earth's today's study.

5) Archeological Survey: The survey that is carried out to prepare maps of ancient cultures and civilizations. e.g, antiquities, Kingdoms town, villages, etc.

D) On the basis of instruments used:

1) Chain Survey: The survey that is carried out using chain or tape by talking linear measurements.

2) Compass Surveying: It is the survey in which magnetic compass is used to measure magnetic bearing with respect to north direction. in this tape is used to linear measurements.

3) Plane Table Survey: The Graphical Method of Surveying in which plane table and telescopic Alidade is used to survey the features. also, tape is used to linear measurements.

4) Theodolite Survey: The survey that is done by using Theodolite instrument.

 5) Tacheometric Survey: Survey done by Tacheometer.

6) Levelling: Survey that is done to measure relative height of any point using level machine.

7) TS Survey: Done by using TS.

8) GPS Survey: Done by using GPS receiver instruments.

E) On the Basis of Method:

1) Ground Survey: The survey that carried out by staying on the ground or field,

2) Aerial Survey: The survey that is carried out by taking photograph through platform like Airplanes, Drones, etc.

3) Satellite Survey: The survey that is done by using satellite images or using control points with reference to satellite is called satellite survey. e.g. GPS survey, Remote Sensing etc.

# Principles of Surveying:

The main principles of surveying are; 

1) Working from whole to part.

2) Location of point should be determined by using at least two points.

3) Consistency in work.

4) Independent Check.

5) Economy of Accuracy.

1) Working from whole to part:

✓ It is the main principle of Surveying whether plane or geodetic surveying. initially the control points are established and the control points inside the area coverage is again established. then the detailing of area is adopted

The main reason to work from whole to part is to prevent accumulation of errors and to localize errors.

2) Location of point should be determined by using at least two points:

 According to this principle, two other known points are used to determine the location on the field.

Suppose P and Q is two known points on the ground. The distance between these two points is measured with PQ accuracy and drawn on a sheet of paper with the appropriate scale. The location of the other third point R is determined as follows;  

a. PR and QR distances are known.

Two arcs PR and QR are drawn from the scale from which PQ is drawn. At crossing of these two arc is R points. This principle is useful in chain surveying.

b. Locations P and Q are known.

RS perpendicular to the PQ line from point R is drawn. Length is measured PS and SR. Point R is then plotted using set squares. This principle is useful for defining information.

c. Distance QR and angle PQR are known. With which point R can be plotted. This principle is useful in traversing.

d. Angles RPQ and RQP are known.

The line is drawn at point P at Angle RPQ and at point Q at angle RQP. The point R obtained by crossing of these two lines. This principle is useful for triangulation.

e. Angle RQP and length PR are known.

Point Q ahead, the angle RQP at which the line is drawn. A point is obtained by taking an arc with a radius equal to PR from the point P. This principle is useful in traversing.

3) Consistency of Work:

✔ Another important principle of surveying is the consistency of work.

 ✔ It must be noted that keeping consistency in the method, instrument, reading and noting observations, etc helps to gain the desired level of accuracy.

4) Independent Check:

✔ According to this principle, every measurement that is taken in the field must be re-checked by adopting a suitable method of independent field tests and observations so that any mistake if present is not passed without notice.

5) Economy of Accuracy/ Accuracy Required:

✓ According to this principle of surveying; the proper method and instrument must be used for the survey work on the basis of the degree of accuracy required.