# Highway Engineering Questions and Answers – Flexible Pavement Design Method – 1

This set of Highway Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Flexible Pavement Design Method – 1”.

1. How many types of methods are there to design a flexible pavement?
a) One
b) Two
c) Three
d) Four

Explanation: There are three types of methods to design a flexible pavement they are empirical, semi empirical and theoretical method.

2. Empirical method is dependent on the strength of _____________
a) Soil
b) Sub base
c) Base
d) Surface

Explanation: The strength of the soil sub grade is used to design the flexible pavement, because the sub base and base are more stronger than the sub grade, so design depends on sub grade only.

3. The stress strain approach is used in _____________
a) Empirical method
b) Semi empirical method
c) Theoretical
d) CBR method

Explanation: The design of pavement using stress strain approach is used in semi empirical method, which depends both on theory and graph.

4. CBR is a _____________
a) Measure of soil strength
b) Flexible pavement design method
c) Rigid pavement design method
d) Measure of soil characteristics

Explanation: CBR is a method of designing flexible pavement by using the soil characteristics.

5. The design charts are prepared based on _____________
a) Climate
b) Past experience
c) Location
d) Traffic

Explanation: The design charts are prepared based on the past experience hence they are not reliable, as it changes according to location.
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6. For which material the semi empirical method is useful?
a) Elastic
b) Plastic
c) Rigid
d) Semi rigid

Explanation: If the material is elastic, then it will obey hookes law, so after that limit it is not so useful.

7. The CBR method was developed by _____________
a) California division of highway
b) IRC
c) MORTH
d) NHAI

Explanation: In 1925, the California division of the highway designed the CBR method for the design of flexible pavement.

8. The soaking period in CBR sample is _____________
a) 2 days
b) 3 days
c) 4 days
d) 5 days

Explanation: The soaking period usually specified is four days which may not be sufficient for some highways.

9. What is the total thickness of the pavement?
a) Constant
c) Changes with sub base
d) Changes with base

Explanation: The total thickness of the pavement remains constant as it does not depend on the number of layers.

10. As per MORTH the specified compaction of density is _____________
a) 95%
b) 96%
c) 100%
d) 99%

Explanation: MORTH recommends a field density of 97% for heavy compaction, in some cases it recommended even 99 or 100% of lab density.

11. The top 500mm of soil sub grade should be compacted at _____________
a) OMC
b) MDD
c) Dry density
d) Saturated density

Explanation: The top 500mm layer in the soil sub grade should be compacted at OMC, to obtain M.D.D, only at M.D.D the soil gets its maximum strength.

12. For how much amount of rainfall soaking of specimen is not required?
a) 100 mm
b) 200 mm
c) 300 mm
d) 500 mm

Explanation: For a rainy area which is having an amount of rainfall more than 500 mm, then soaking of specimen is not required.

13. What is the maximum aggregate size in CBR method?
a) 20 mm
b) 30 mm
c) 40 mm
d) 50 mm

Explanation: The maximum size of aggregate should be 20 mm in the design of flexible pavement if it is more than 20 mm then above layers are not valid.

14. The critical stress is considered in _____________
a) Surface
b) Sub base layer
d) Both sub grade and surface

Explanation: Both horizontal stress and vertical stress are considered for flexible pavement and measured at these two layers.

15. The design factor not considered in CBR is _____________
a) Weather
b) Traffic
c) VDF
d) Growth rate

Explanation: The weather factor is not considered in CBR method as it keeps changing frequently, growth rate keeps increasing, VDF is a constant so climate doesn’t actually affect the CBR.

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