Constructing super-elevation: What is the most commonly adopted method of providing super-elevation on roads during construction?

Introduction / Context:
During field construction, the pavement cross-section must be transitioned from camber on the tangent to super-elevation on the curve. The choice of pivot line affects drainage, construction simplicity, and earthwork balance.

Given Data / Assumptions:

• Standard two-lane road with normal crown on straights.
• Transition length adequate for comfort and drainage.
• Objective: simple construction and balanced adjustments on both sides.

Concept / Approach:

Pivoting about the crown (centre line) is widely adopted because it symmetrically modifies both edges—raising the outer and lowering the inner—thereby limiting excessive lowering or raising of either edge alone. It also preserves drainage during transitions and reduces abrupt level differences at shoulders.

Step-by-Step Reasoning:

Verification / Alternative check:

Highway construction guidance frequently specifies centre-line pivoting as the default. Alternatives (pivot about inner/outer edge) are used in special constraints (e.g., urban drainage or property tie-ins) but are not the general practice.

Why Other Options Are Wrong:

• Outer-edge or inner-edge only pivoting can produce large level changes at one edge, complicating drainage and construction.
• “No pivoting” is not practical; crossfall must be physically formed.
• Alternating pivoting is not a recognized method.

Common Pitfalls:

• Forgetting to coordinate super-elevation runoff with shoulder shaping and side drains.

Final Answer:

Pivot about crown (centre line), raising outer edge and lowering inner edge.