Roadside safety appurtenances: which of the following statements about safety fences and guard stones on embankments and curves is correct under typical Indian practice?

Introduction / Context:
Roadside safety features reduce run-off-road crash severity, especially on elevated embankments and horizontal curves. The selection between guard stones, safety fences (guardrails), and barriers depends on embankment height, curve radius, and available recovery area. Recognizing threshold values helps designers pick the minimum treatment to protect errant vehicles.

Given Data / Assumptions:

• Embankment heights: < 1.6 m, 1.6–3 m, 3–6 m, > 6 m.
• Curves with radius less than 750 m are sharper and riskier.
• Spacing of guard stones around 2.5 m is a traditional provision.

Concept / Approach:
Where drop-offs are significant, containment is preferred over delineation. At moderate heights (1.6–3 m), guard stones provide physical and visual guidance. For higher embankments and sharper curves, safety fences (e.g., W-beam guardrails) are recommended, particularly on the outside of curves where the risk of departure is greatest. At very high embankments (> 6 m), bilateral protection may be justified where both sides present hazards.

Step-by-Step Solution:
Match embankment height bands with customary treatments. Associate sharper curves (R < 750 m) with installing safety fences on the outside edge. Recognize that very high embankments require stronger or bilateral containment. Conclude all listed prescriptions are consistent; choose “All the above”.

Verification / Alternative check:
These thresholds align with common Indian practice for two-lane rural highways and hill roads, where visibility constraints and slope hazards warrant progressive protection measures based on risk.

Why Other Options Are Wrong:

• Picking any single provision ignores other equally valid criteria that also apply.
• “None of these” is incorrect since each statement reflects accepted practice.

Common Pitfalls:

• Using delineators alone on high embankments where containment is needed.
• Forgetting that the outside of a curve is the departure side requiring priority protection.

Final Answer:
All the above.