Hill roads – definition of formation width In hill road cross-sections, the formation width is defined as the distance between which two elements?

Introduction / Context:
Formation width on hill roads differs from plain terrain because the cross-section typically contains a cut (hill) side drain and a parapet or guard wall on the valley side. Accurate definition is important for design and quantity estimation.

Given Data / Assumptions:

• Standard hill road cross-section with a lined side drain on hill side.
• Parapet/guard wall provided on valley side for safety.

Concept / Approach:
Formation width encompasses the usable formation including the carriageway and shoulders, bounded laterally by hydraulic and safety appurtenances. Hence it is measured from the inner limit (nearest to the carriageway) of the hill-side drain to the outer limit of the valley-side parapet.

Step-by-Step Solution:
Identify bounding elements on hill and valley sides.Take the inner edge of the drain (adjacent to shoulder) on hill side.Take the outer edge of the parapet wall on valley side.Distance between these equals formation width.

Verification / Alternative check:
Standard drawings of hill roads show this measurement convention to include functional space and safety margin.

Why Other Options Are Wrong:
They use inconsistent inner/outer references and may exclude necessary safety or drainage elements.

Common Pitfalls:
Measuring to the outer edge of the drain (on the far side) or to the inner edge of the parapet, underestimating formation width.

Final Answer:
Inner end of side drain to outer end of parapet wall