DEFINE SURVEYING ,PURPOSE AND PRINCIPLE OF SURVEYING 

DEFINE SURVEYING ,PURPOSE AND PRINCIPLE OF :  Basic Concept of surveying is to collect data about points on the surface of the earth, prepare plans and maps, calculate areas and volumes, and transfer points from plans to the ground.Surveying is essential in all Civil Engineering activities, including the construction of buildings, bridges, roads & railways, pipe lines, dams, ports and harbours etc., Engineering projects cannot commence without survey data, i.e., planning, and execution of Engineering projects.

SURVEYING

Surveying is the art of determining the relative positions of points on, above or beneath the surface of the earth, by taking linear and angular measurements. Generally, surveying is considered as a process of determining positions of points on horizontal plane.

Purpose of Surveying

The main purpose of surveying is to prepare a plan or map with the help of field measurements. Surveying may be done for the following purposes.
1. To prepare a map of a country or state showing the detailed location of cities, towns, villages, major roads, boundaries of areas etc.
2. To prepare a topographical map which shows the hills, valleys, rivers, forests etc. of a country.
3. To prepare a cadastral map showing the boundaries of fields houses and other properties.
4. To prepare a engineering detailed plans and sections of various engineering works such as Roads, Railways, Bridges, Dams, Irrigation Canals etc.
5. To prepare a Military map showing the road and railway communications with different parts of country.
6. To prepare a contour map to determine the capacity of reservoir and to find the economical route for roads and railways etc.
7. To prepare an archaeological map.

Fundamental Principles of Surveying

The fundamental principles based on the various methods of plane surveying are
1. To work form whole to the part, and
2. A new station can be located by at least two measurements (Linear or Angular) from fixed Reference points.

1. To Work from Whole to the Part: The main principle of surveying is working from whole to the part. To satisfy this rule, sufficient number of primary control points are established with higher precision in and around the area to be surveyed. For establishing these points more precise instruments are used. Minor control points are then established by less precise methods and the details can be located using these minon control points by running traverses. The main purpose of this principle is to control the accumulation of errors and to localies the errors within the frame work of control points. Other wise if followed a reverse procedure i.e., working from part to whole the errors would expand to greater magnitudes and a stage will come these errors will become uncontrollable.
2.  A new station can be located by at least two measurements (Linear or Angular) from fixed Reference points : According to the second principle, the new stations should always be fixed by at least two measurements (Linear or Angular) from fixed reference points. Linear measurement refer to horizontal distance measured by chain or tape. Angular measurement refer to the magnetic bearing or horizontal angle taken by a prismatic compass or theodolite,