GATE 2020 CE (CE1) – Question 31
A hill road has 4.5% gradient and a horizontal curve of radius 100 m. The gradient must be eased for combined horizontal and vertical curvature. As per IRC, find compensated gradient (%), to one decimal place.
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Correct answer: 4 to 4
Explanation
IRC grade compensation is the smaller of $(30+R)/R=1.3\%$ and $75/R=0.75\%$. Subtraction gives 3.75%, but compensation need not reduce grade below 4%. Thus the compensated gradient is **4.0%**.