Principle of Chain Surveying, Surveying and Levelling | Surveying and Levelling Notes- Agricultural Engg - Agricultural Engineering PDF Download

1. PRINCIPLE OF CHAIN SURVEYING
The principle of chain surveying is triangulation. This means that the area to be surveyed is divided into a number of small triangles which should be well conditioned. In chain surveying the sides of the triangles which should be well conditioned. In chain surveying the sides of the triangles are measured directly on the field by chain or tape, and no angular measurements are taken. Here, the tie lines and check lines control the accuracy of work.
It should be noted that plotting triangles requires no angular measurements to be made, if the three sides are known. 
Chain surveying is recommended when:

1. The ground surface is more or less level
2. A small area is to be surveyed
3. A small-scale map is to be prepared and
4. The formation of well-conditioned triangles is easy

Chain surveying is unsuitable when:

1. The area is crowded with many details
2. The area consists of too many undulations
3. The area is very large and
4. The formation of well-conditioned triangles becomes difficult due to obstacles

A. Large-Scale and Small-Scale Maps
When 1 cm of a map represents a small distance, it is said to be a large-scale map.
For example,

When 1 cm of the map represents a large distance, it is called a small-scale map.
For example,

A map having an RF of less than 1/500 is considered to be large-scale. A map of RF more than 1/500 is said to be small-scale.