Mountainous terrain – definition of roadway width 8.8 m for two-lane NH/SH For two-lane National or State Highways in mountainous terrain, a roadway width of 8.8 m is specified. Does this dimension include parapet and side drains?

Introduction / Context:
In hills, roadway width is the sum of carriageway plus shoulders (or marginal strips) measured between the roadway edges. Separate protective/boundary features such as parapets and side drains may lie outside the roadway width and are accounted for in formation width, not roadway width.

Given Data / Assumptions:

• Two-lane NH/SH in mountainous terrain.
• Roadway width = 8.8 m.
• Parapet and side drain are provided as protective and drainage elements at the edges.

Concept / Approach:
Standard definitions distinguish roadway width (carriageway + shoulders) from formation width (roadway + side drains + parapets/berms where applicable). Therefore, a stated roadway width does not include parapets and side drains unless expressly mentioned.

Step-by-Step Solution:

Verification / Alternative check:
Typical hill road cross-sections show the drain cut into the hill side and a parapet/guard wall on the valley side outside the roadway edge line.

Why Other Options Are Wrong:
Including parapet and/or drain within the roadway width contradicts standard definitions; options A and B only partly exclude, which is inconsistent.

Common Pitfalls:
Confusing roadway and formation widths; failing to provide additional space for drains leading to inadequate hydraulic capacity.

Final Answer:
Excludes the width of both parapet and side drain