What is WCB & RB in surveying?/ Comparing whole circle bearing with reduced bearing.

  WCB 👉  Whole circle bearing:

In WCB, the bearings are measured from the north of the reference meridian.

These bearings lie between 0° to 360° in the clockwise direction. In prismatic compass surveying, we use whole circle bearings. WCB is also referred to as the Azimuthal bearing system.

In the WCB system,

North 👉  0°

East   👉  90°

South 👉  180°

West  👉 270°

Some Eg:

In WCB, line AB is measured at 52° from the north as shown below.

Similarly, line BC  is measured at 285° from the north as shown in the below drawing.

To understand A to Z of surveying, click here.

RB 👉  Reduced bearing:

In RB, the bearings are measured from the north or south, either in clockwise or anticlockwise directions. The reading is taken depending on the quadrantal positioning of the line.

 In this system, the bearing is referred to by 4 possible quadrants i.e. NE, NW, SE, & SW. Therefore this system is also called quadrantal bearing.

The angles in the RB system lie between 0° to 90°. 

In the surveyor's compass, we use the RB system. 

Some Eg:

1. Line AB lies in the NW quadrant i.e. 4th quadrant. This line is nearer to the north line & away from the south line. So, the angle is measured in an anti-clockwise direction from the north line. 

To understand the position of line AB, the measured angle is denoted as N34°W 

2. The line AB lies in the NE quadrant i.e. 1st quadrant. This line is nearer to the north line & away from the south line. So, the angle is measured in a clockwise direction from the north line. 

To understand the position of line AB, the measured angle is denoted as N55°15'E 

3.  The line AB lies in the SE quadrant i.e. 2nd quadrant. This line is nearer to the south line & away from the north line. So, the angle is measured in an anti-clockwise direction from the south line. 

To understand the position of line AB, the measured angle is denoted as S67°45'E 

 4. The line AB lies in the SW quadrant i.e. 3rd quadrant. This line is nearer to the south line & away from the north line. So, the angle is measured in a clockwise direction from the south line. 

To understand the position of line AB, the measured angle is denoted as NS42°W

 

From the above eg., you can observe that the angles in the 1st & 4th quadrants are measured with reference to the north & angles in the 2nd &3rd quadrants are measured from the south.

I hope you understood the concept.

To understand A to Z of surveying, click here.

Thank you for going through this article ❤. Have a good day 😄.

Share: