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GATE 2016 CE (CE1) – Question 63

Transportation Infrastructure · Geometric design of roadways: cross-section, sight distance, alignments · 2 marks · Multiple choice

A two-lane one-way road of radius 50 m predominantly carries lorries with wheelbase 5 m, at 60–80 km/h. The mechanical and psychological widening at 60 km/h are designated wm,60 and wp,60; at 80 km/h they are wm,80 and wp,80. Their correct values, in this order, are ______.

  1. 0.89 m, 0.50 m, 1.19 m, 0.50 m
  2. 0.50 m, 0.89 m, 0.50 m, 1.19 m
  3. 0.50 m, 1.19 m, 0.50 m, 0.89 m
  4. 1.19 m, 0.50 m, 0.89 m, 0.50 m

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Show answer and explanation

Correct answer: (B) 0.50 m, 0.89 m, 0.50 m, 1.19 m

Explanation

Mechanical widening is nl²/(2R)=2·5²/(2·50)=0.50m. Psychological widening is V/(9.5sqrtR), which is0.893m at60km/h and1.191m at80km/h. Total widths are therefore about1.39m and1.69m. This pair matches **B**.