Whole Circle Bearing (WCB) and Quadrantal Bearing (QB) are two different types of bearing measurements utilised in surveying. To select between these two types of bearing measurement a civil engineer must know the difference between them. The main difference between Whole Circle Bearing (WCB) and Quadrantal Bearing (QB) are described below.
| Whole Circle Bearing (WCB) | Quadrantal Bearing (QB) |
| The horizontal angle created by a line with the magnetic north in the direction clockwise is known as the whole circle bearing of the line. | The horizontal angle created by a line with the magnetic south or north (whichever is near from the survey line) in the westward or eastward direction is the Quadrantal Bearing or Reduced Bearing of the line. |
| In the Whole Circle Bearing (WCB), only the magnetic north line is considered as reference meridians. | In the Quadrantal Bearing (QB) or Reduced Bearing, both south and north are considered as reference meridians. |
| The clockwise angle taken from the reference line. | The clockwise and anticlockwise both angles are taken from the reference line. |
| In WCB (Whole Circle Bearing), the bearing’s value changes from 0° to 360°. | In QB (Quadrantal Bearing), the bearing’s value changes from 0° to 90°. |
| For Example – 30°, 45°,120°,190°,300° etc. | For Example – N45°E, N60°W,S75°E,S65°W etc. |
What is Whole Circle Bearing (WCB) ?
The horizontal angle created by a line with the magnetic north in the direction clockwise is known as the whole circle bearing of the line. This system is also called azimuthal system. North direction is the reference meridian in the whole circle bearing system.
Whole Circle Bearing Formula
In WCB (Whole Circle Bearing), the bearing’s value changes from 0° to 360°. Just measure the angle between the north meridian line to the survey line in clockwise direction to find WCB (Whole Circle Bearing).
If a survey line stays in the 1st quadrant, its WCB (Whole Circle Bearing) changes from 0° to 90°. Similarly, in the 2nd quadrant, WCB (Whole Circle Bearing) changes from 90° to 180°. In the 3rd quadrant, WCB (Whole Circle Bearing) changes from 180° to 270°. In the 4th quadrant, WCB (Whole Circle Bearing) changes from 270° to 360°.
Whole Circle Bearing Example
To study a whole circle bearing an example, please carefully see the following images.
In the above images, the vertical line N is the north line. In image 1, the line X at an angle of 45° with north line N in the clockwise direction. So, WCB (Whole Circle Bearing) of line X is 45°.
In image 2, the line Y is making a 225° angle with the north line N in the clockwise direction. Therefore, WCB (Whole Circle Bearing) of line Y is 225°.
What is Quadrantal Bearing or Reduced Bearing?
The horizontal angle created by a line with the magnetic south or north (whichever is near from the survey line) in the westward or eastward direction is the Quadrantal Bearing or Reduced Bearing of the line.
In the QB (Quadrantal Bearing) or Reduced Bearing, both south and north are considered as reference meridians.
In above image, the line A at an angle of 45° with north line N in the clockwise direction, QB (Quadrantal Bearing) of line A is N45°E.
In above image, the line B at an angle of 45° with north line N in the anticlockwise direction, QB (Quadrantal Bearing) of line B is N45°W.
In above image, the line C at an angle of 45° with south line S in the clockwise direction, QB (Quadrantal Bearing) of line C is S45°W.
In above image, the line D at an angle of 45° with south line S in the anticlockwise direction, QB (Quadrantal Bearing) of line D is S45°E.
Conclusion
In surveying, bearing is very necessary to get direction of the survey line. The WCB (whole circle bearing), QB (Quadrantal Bearing) or Reduced Bearing are general notation system of bearings. In this article, we covered whole circle bearing (WCB), Quadrantal Bearing (QB) and difference between them. We hope that this article will be help to you.
Refference :
- “Surveying” by Punmia B C
Very useful blog of compass surveying. Thanks.