The GATE Grind

GATE 2018 CE (CE1) – Question 44

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

At a priority intersection, a single-lane one-way road at 20 km/h crosses an undivided two-lane two-way road at 50 km/h. Perception–reaction time is 2.5 s, longitudinal friction coefficient 0.38 and g = 9.81 m/s². Minimum clear-sight-triangle sides along the two-lane and single-lane roads, respectively, are ______.

  1. 50 m and 20 m
  2. 61 m and 18 m
  3. 111 m and 15 m
  4. 122 m and 36 m

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Correct answer: (C) 111 m and 15 m

Explanation

The usual stopping-sight-distance formula is $vt+v^2/(2gf)$. For 50 km/h it gives 60.60 m, and for 20 km/h 18.03 m, close to B (61 m,18 m). The final official key instead specifies C (111 m,15 m). That grading is preserved, and the discrepancy with the printed data is explicitly recorded.