Which of the following is the value of maximum grade compensation for a horizontal curve of radius 150 m?
- A0.50%Correct
- B0.80%
- C1.10%
- D1.40%
Solution
Concept
Grade Compensation on Horizontal Curves
Formula
Grade Compensation (max) = 75 / R (%)
Step-by-step solution
1. Use the formula: Max Grade Compensation (%) = 75 / R. 2. Substitute R = 150 m into the formula: 75 / 150 = 0.50%.
Explanation
The maximum grade compensation on a horizontal curve is limited to 75/R according to IRC standards. For a curve radius of 150 m, calculating 75 divided by 150 gives 0.50%, which matches option A.
Shortcut
Remember the maximum limit formula as 75/R. Since 75 is exactly half of 150, the result is immediately 0.5%.
Common mistake
Students often calculate the grade compensation using the formula (30 + R) / R without checking the maximum allowable limit of 75 / R.
Correct answer: A) 0.50%