Road shoulders – typical design width On standard highways, the width of each shoulder provided alongside the carriageway is generally kept at which value?

Introduction / Context:
Shoulders provide lateral support to the pavement, space for emergency stops, and added safety clearance. Their width is a key dimension in cross-sectional design of highways.

Given Data / Assumptions:

• Standard two-lane or multi-lane rural highway practice.
• One shoulder on each side of the carriageway.
• Conventional design without severe space constraints (e.g., not in steep hill cuttings).

Concept / Approach:
Typical guidelines recommend about 2.5 m (250 cm) shoulder width in rural areas to accommodate breakdowns and recovery of errant vehicles, improve drainage margins, and protect pavement edges from shear.

Step-by-Step Solution:

Verification / Alternative check:
Many cross-section drawings show 7.0 m carriageway plus 2.5 m shoulders each side for a 12.0 m roadway, confirming the order of magnitude.

Why Other Options Are Wrong:
100–200 cm are too narrow for safe emergency stops and reduce edge protection; larger than 2.5 m may be used but 2.5 m is the common baseline.

Common Pitfalls:
Confusing paved shoulder width (which may be smaller) with full shoulder width; reducing shoulder width in constrained sites without compensating safety measures.

Final Answer:
250 cm