##### Types of Chain Surveying in Survey and Representative Factor

**Chain surveying** is that surveying in which only linear measurements are made in the field.

### Types of Chain Surveying

1.**Plane Surveying **During Surveying when two points of observation are at very less distance, that is the effect of curvature not taken into consideration, this is termed as Plane Surveying. Mostly preferred when the Surveying area is less than or equal to 195.5 sq. km.

2.**Geodetic Surveying** Generally the surface of earth is Oblate i.e. round in shape, which is termed as Curvature of Earth. During Surveying when two points of observation are at very far distance, that is, the effect of curvature taken into consideration, this is known as Geodetic Surveying. Mostly preferred when the Surveying area is more than 195.5 sq. km.

### Plumb Bob Line

Plumb Bob Line is an imaginary line passing longitudinally through its centre.

P.B.L. is **parallel **in case of Plane Surveying.

P.B.L. always **intersect** at the center of earth in case of Geodetic Surveying.

### Classification of Surveying

- Land Survey
- Hydrographic Survey
- Cadestal Survey
- Astronomical Survey
- Topographic Survey

### Scale

Ratio of Map distance to Ground distance. Scale is the amount by which reducing the quantity w.r.t. the original quantity.

For instance, if we plot a distance of 2m on a map with a distance of 2cm, then we write it as 2cm/2m; this fraction is known as representative factor.

Representative factor (RF) = 2cm/2m = 2cm/200cm = 1/100

Therefore, RF = 1:100 (in above case)

**Note**: The more is the RF,the more will be the scale.

### Chains and its various types

click the following link of **linear measurements** to know in detail about chain and its various types:

Linear Measurements

### Principle of chain surveying

**Triangulation**: Divide the area which is to be surveyed into a network of triangles remaining connected. This is because the triangle is the only simple figure that can be plotted from the lengths of its sides measured in the field.

### Principle of field surveying

- Working from whole to part
- Locate a point by measurement from two points of references.

https://www.youtube.com/watch?v=1_pvRGQBwEg&list=PLXzfaUM1u1NLpGc8EsTgc7T_FkCrzduFz&index=3