To calculate the minimum value of ruling radius of horizontal curves in plains, the design speed is given by A. 8 kmph B. 12kmph C. 16kmph D. 20 kmph

The correct answer is: D. 20 kmph

The minimum value of ruling radius of horizontal curves in plains is calculated using the following formula:

$R = \frac{v^2}{127}$

where:

• $R$ is the ruling radius in meters
• $v$ is the design speed in kilometers per hour

Therefore, for a design speed of 20 kmph, the minimum value of ruling radius is:

$R = \frac{20^2}{127} = 34.64$ meters

The other options are incorrect because they are not the minimum value of ruling radius for a design speed of 20 kmph.