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GATE 2021 CE (CE1) – Question 25

Transportation Infrastructure · Geometric design of roadways: cross-section, sight distance, alignments · 1 mark · Multiple choice

A highway designed for 80 km/h has horizontal curve radius 250 m. Assuming design lateral friction develops fully, the required superelevation is

  1. 0.02
  2. 0.05
  3. 0.07
  4. 0.09

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Correct answer: (B) 0.05

Explanation

Use $e+f=V^2/(127R)$ and the design lateral friction coefficient $f=0.15$. Thus $e=80^2/(127\times250)-0.15=0.05157$, approximately **0.05 (B)**. The assumption of fully mobilised friction matters; the separate no-friction design expression is not used here.