Question

While aligning a road along a hill with a ruling gradient of 4.5%, a horizontal curve of radius 150 m is encountered. The compensated gradient in percentage is________

• A. 4

Answer 1

The correct option is A 4
As per IRC, grade compensation is not required for gradients flatter than 4.00%. Hence, after applying the grade compensation correction, gradients need not be made flatter than 4.00%.

Grade compensation required for the given curve
$=min(\frac{30+R}{R},\frac{75}{R})$

$=min(\frac{30+150}{150},\frac{75}{150})$

$=min(1.2,0.5)$

$=0.5$

Compensated gradient = 4.5 - 0.5 = 4%

Hence, the compensated gradient is 4.00%