Question

The ratio of contact pressure to the tyre pressure is known as ........

• A. rigidity factor
• B. flexibility factor
• C. load factor
• D. sub-grade modulus

Hint:

Rigidity factor helps in evaluating the effective pressure transmitted to the pavement surface and is important in pavement design.

Answer 1

The Correct Option is A

Step 1: Understand the definition
The ratio of the actual contact pressure under a tyre to the tyre pressure is called the rigidity factor.
Step 2: Formula representation
\[ \text{Rigidity Factor} = \frac{\text{Contact Pressure}}{\text{Tyre Pressure}} \]
Step 3: Interpretation
- A rigidity factor less than 1 indicates a flexible tyre and surface interaction.
- A value greater than 1 may indicate concentration of load due to tyre structure or surface stiffness.
Step 4: Eliminate other options
- Flexibility factor relates to deformation characteristics, not pressure ratio.
- Load factor is used in structural and load analysis, unrelated here.
- Sub-grade modulus (k-value) is a measure of sub-grade support, not a pressure ratio.
Step 5: Final Answer
Hence, the correct term for the given ratio is rigidity factor.