Shoulder crossfall and camber: which of the following statements are correct for highway crossfall design?

Introduction / Context:
Crossfall (transverse slope) ensures rapid drainage, preventing water film formation that causes skidding, potholes, and structural damage. Shoulders, being unpaved or of different surface texture, require slightly steeper slopes to shed water efficiently.

Given Data / Assumptions:

• Paved carriageway with camber in tangent sections; superelevation on curves.
• Shoulders provided on both sides; material may be earthen or granular.
• Objective is quick runoff without erosion or driver discomfort.

Concept / Approach:

Because shoulders are rougher and permeable, they are sloped a little more than the paved surface to preclude ponding at the edge joint. On superelevated curves, maintaining the same slope on shoulders as the pavement avoids an abrupt lip at the edge and ensures continuity of drainage. Earthen roads need relatively high crossfall to counter lower surface permeability and to protect the formation from water ingress.

Step-by-Step Reasoning:

Verification / Alternative check:

Design guides routinely show shoulders 0.5% to 1.0% steeper than carriageway on tangents, and equal crossfall on curves with superelevation. Earthen roads carry 3%–6% (or more) crossfall depending on climate.

Why Other Options Are Wrong:

• Each statement independently reflects accepted practice; therefore “All the above” is correct.

Common Pitfalls:

• Leaving flat shoulders that trap runoff at the pavement edge.
• Creating a step between superelevated pavement and shoulder, which is hazardous.

Final Answer:

All the above.