Detailed survey for road alignment: Which of the following statements about the detailed survey along a selected trace are correct?

Introduction / Context:
After reconnaissance and preliminary location, a detailed survey refines the alignment and supplies data for earthwork, drainage, and structure design. The survey strip must be wide enough to capture side-slope needs, realignment at curves, and drainage corridors.

Given Data / Assumptions:

• Selected trace available on ground.
• Open, non-urban corridor where typical widths apply.
• Standard practices for level intervals and contouring are used.

Concept / Approach:

On straights, a narrower strip is adequate; at sharp curves, extra width is required for setting out, visibility triangles, and potential widening. Longitudinal leveling at short intervals supports profile design. A moderate contour interval balances detail and workload in rolling or hilly terrain.

Step-by-Step Reasoning:

Verification / Alternative check:

These values are commonly cited in route survey procedures for highways; project-specific constraints may adjust them, but the statements are broadly correct.

Why Other Options Are Wrong:

• Each individual statement is correct, so “All the above” is the comprehensive choice.

Common Pitfalls:

• Using too narrow a strip at curves, leading to late discovery of land/earthwork constraints.
• Excessively large contour intervals that miss drainage breaks and saddles.

Final Answer:

All the above.