On highways constructed in hilly regions, what is the usual overall height specified for parapet walls provided along the roadway edge?

Introduction / Context:
Parapet walls (or kerb–parapet combinations) on hill roads provide edge delineation and a modest physical barrier to reduce the severity of low-speed edge departures. Their height is standardized to ensure visibility and functional containment without obstructing sight lines from cars and light trucks.

Given Data / Assumptions:

• Facility: highway in hilly terrain.
• Parapet wall provided at road edge or on the valley side of cut-and-fill sections.

Concept / Approach:
Common exam and field references cite a usual parapet height close to 0.70–0.75 m for hilly roads, balancing visibility and containment. This provides a recognizable edge while not intruding significantly into driver sight envelopes on narrow, curvy alignments.

Step-by-Step Solution:
Select the standard height range around 0.7–0.75 m for hill highways.Choose the closest listed discrete value: 70 cm.

Verification / Alternative check:
Some agencies may adopt 0.75 m; however, 0.70 m is a widely quoted standard figure in exam-oriented materials and is within the typical range.

Why Other Options Are Wrong:

• 50–60 cm: too low for reliable delineation and containment.
• 80–100 cm: may obstruct sight in tight curves; not the usual baseline.

Common Pitfalls:

• Confusing parapet height with thickness/width of the wall.
• Ignoring additional railing or crash barrier requirements on high-risk edges.

Final Answer:
70 cm