Which of the following statement(s) is/are correct regarding flexible pavement design methods? (i) McLeod method is based on empirical approach (ii) Burmister method is based on elastic two-layer theory (iii) Group Index method is a theoretical approach based on elasticity (iv) California Bearing Ratio method is purely theoretical
- AOnly (ii)
- B(i) and (ii)Correct
- C(ii) and (iii)
- D(i) and (iv)
Solution
Concept
Classification of flexible pavement design methods
Formula
NONE
Step-by-step solution
1. McLeod method is empirical/semi-empirical based on plate load tests; statement (i) is correct. 2. Burmister method uses layered elastic theory; statement (ii) is correct. 3. Group Index is an empirical formula based on soil index properties, not elasticity theory; statement (iii) is incorrect. 4. CBR method is empirical based on penetration testing, not purely theoretical; statement (iv) is incorrect. 5. Therefore, statements (i) and (ii) are correct. Answer: B
Explanation
Flexible pavement design methods are classified as empirical, semi-empirical, and theoretical. The McLeod method uses plate bearing test data and is semi-empirical/empirical. The Burmister method is based on elastic two-layer system theory. Group Index and CBR methods are empirical, not theoretical. Therefore, statements (i) and (ii) are correct.
Why the other options are wrong
A) Incorrect because statement (i) is also correct. C) Incorrect because Group Index method is empirical, not theoretical. D) Incorrect because CBR method is empirical, not purely theoretical.
Shortcut
Burmister = Layered Elastic Theory; CBR & Group Index = Empirical.
Common mistake
Assuming CBR or Group Index methods are theoretical when they are classic empirical approaches.
Correct answer: B) (i) and (ii)