Standard carriageway widths as per common IRC practice According to typical Indian Road Congress (IRC) guidelines, which of the following carriageway widths are correct?

Introduction / Context:
Carriageway width determines lane capacity, safety margins, and comfort. IRC standards provide typical widths by facility type and roadside elements (e.g., presence of raised kerbs).

Given Data / Assumptions:

• Standard two-way and multi-lane categories.
• Urban kerbed sections tend to be slightly wider than rural without kerbs.

Concept / Approach:
Common IRC values include 3.75 m for single-lane, 7.0 m for two-lane without raised kerbs, 7.5 m for two-lane with raised kerbs, and 10.5 m for three-lane facilities. These provide adequate clearance and shy distances.

Step-by-Step Solution:

Verification / Alternative check:
Design manuals and typical cross-sections align with these nominal dimensions, subject to context-specific adjustments.

Why Other Options Are Wrong:
Since A–D are each correct, “All the above” is the correct consolidated choice.

Common Pitfalls:
Confusing carriageway width with roadway width (which adds shoulders and medians).

Final Answer:
All the above