# Reduced Bearing (RB) / Quadrantal Bearing (QB) | Surveying

## In Quadrantal bearing (QB) / Reduced bearing (RB) - Bearings are measured either clockwise/anti-clockwise from north/south whichever is close to the line.

Bearing system is of two types - Whole circle bearing and reduced bearing. First let us understand what is meant by bearing and meridians.

### Bearing and Meridians

• Bearing of line : ​Direction with respect to a given meridian

• Meridian is a fixed reference line

### Types of meridian and bearing

True Meridian - Line through true north and south poles, and this remains constant throughout. To find out this line, we need astronomical observations.

• Bearing with respect to true meridian is known as true bearing

Magnetic Meridian - Direction indicated by freely suspended magnetic needle, and this magnetic N-S line changes with location and time as they are affected by earth’s magnetism.

• Bearing with respect to magnetic meridian is known as  magnetic bearing.

Arbitrary Meridian - Well defined reference object like a tower whose position is not going to change, directions are measured with respect to it and they are known as arbitrary bearings

### Reduced Bearing (RB) / Quadrantal Bearing (QB)

Bearings are measured either clockwise/anti-clockwise from north/south whichever is close to the line.

• Angles vary from 0 degrees to 90 degrees

• It is measured from either clockwise/anti-clockwise from north/south (If the line is closer to south and going towards west, it is read as Sβ°W)

• Four quadrants are possible namely NE, SE, SW and NW

• Surveyor's compass used RB system

In the figure below, the line lies closer to south line (and towards west) - in the third quadrant.

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