Definition – differential gradient on a super-elevated road The difference between the grade after providing full superelevation and the original (initial) centre-line grade is termed:

Introduction / Context:
When a road is super-elevated on a curve, the pavement cross-fall rotates about a chosen pivot. This rotation alters the effective grade along the edges relative to the original longitudinal gradient; the difference created is important for drainage and profile control.

Given Data / Assumptions:

• Full super-elevation is provided.
• Comparison is with the initial longitudinal grade.

Concept / Approach:
The additional slope component introduced along the edges due to pavement rotation is known as the differential gradient. It is the algebraic difference between the new edge grades and the original centre-line grade.

Step-by-Step Solution:
Identify initial profile grade.Apply super-elevation by rotating the cross-section.Compute change in longitudinal slope along edges → differential gradient.

Verification / Alternative check:
Drainage checks and vertical profile drawings show the altered edge grades; the difference is labelled as differential gradient.

Why Other Options Are Wrong:
Ruling gradient is the maximum desirable longitudinal grade; rising gradient is a positive grade description; compensated gradient refers to reduction in grade on curves to offset extra resistance, not the cross-fall effect.

Common Pitfalls:
Confusing grade compensation with differential gradient; forgetting to check edge water flow after rotation.

Final Answer:
differential gradient