Question

What is the steepest gradient permissible on a 2° curve for a BG line having a ruling gradient of 1 in 250?

• A. 1 in 342
• B. 1 in 313
• C. 1 in 248
• D. 1 in 288

Answer 1

The correct option is B 1 in 313

Grade compensation of BG line
= 0.04% per degree of curve

$\therefore$ Grad compensation of 2° curve
$=2\times 0.04=0.08\%$

Ruling gradient = 1 in 250
$=\frac{1}{250}\times 100=0.4$

$\therefore$ Maximum allowable gradient
$=0.4-0.08$
$=0.32\%$
$=\frac{1}{312.5}\simeq \frac{1}{313}$