Introduction to Surveying
It is the art of determining the relative positions of different object on the surface of the earth by measuring the horizontal distance between them and by preparing a map to any suitable scale. Thus, in this process, the measurements are taken only in the horizontal plane.
Leveling is the art of determining the relative vertical distance of different points on the surface of earth. Hence, in leveling, the measurements are taken only in the vertical plane.
Types of Surveying [Classification]:
Primary Classification or Primary Division :
Plane surveying and
Plane Surveying :
The shape of the earth is spherical. Thus the surface is obviously curved. But in plane surveying the curvature of earth is not taken into account. This is because plane surveying is carried out over a small area, so the surface of the earth is considered as a plane. The degree of accuracy required in this type of surveying is completely low. Plane surveying is done on an area of less than 250km^2.
Geodetic surveying :
In geodetic surveying the curvature of the earth is taken into consideration. It is extended over a large area greater than 250km2. The line joining any two points considered as a curved line. Very refined methods and instruments are used in this type of surveying. IN this method very high precision or accuracy is required.
Survey can be classified on different bases.
1. Based on instrument:
Plane Table survey
2. Based on methods:
3. Based on Objects:
4. Based on nature of field
A. Land Survey
B. Marine survey
C. Astronomical survey
Again Land Survey is classified into following Classes:
1. Topographical Survey
To determine natural features of a country such as valleys, rivers and artificial features such as road, railways, etc.
2. Cadastral Survey:
To determine boundaries of field, estate
3. City survey:
To locate premises, streets, water supply and drainage systems
4. Engineering survey:
To collect detailed data for the design for of projects involving roads, railways, etc Engineering surveys are sub divided into:
1. Reconnaissance Survey
2. Preliminary Survey
3. Location Survey