Difficulty: Easy
Correct Answer: 5%
Explanation:
Introduction / Context:
Gradient selection in hilly terrain balances vehicle power limits, safety, and earthwork costs. The ruling gradient is the preferred maximum used for most of the route, with limiting and exceptional gradients reserved for constrained sections.
Given Data / Assumptions:
Concept / Approach:
Ruling gradients for hilly/mountainous roads are steeper than for plains, but still need to be comfortable for heavy vehicles. Values around 5% are commonly adopted as ruling, with limiting 6% and exceptional up to 7% for short stretches where topography dictates.
Step-by-Step Solution:
Identify context: hilly terrain, moderate elevation.Adopt ruling gradient ≈ 5% (1 in 20).Use limiting/exceptional gradients only where necessary to control earthwork and land impacts.
Verification / Alternative check:
Vehicle gradeability, especially for loaded trucks and buses, suggests that maintaining gradients near 5% promotes safe speeds and manageable power demands while avoiding excessive hairpins and long detours.
Why Other Options Are Wrong:
Common Pitfalls:
Final Answer:
5%
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