GATE 2025 CE (CE2) – Question 64
On a two-lane highway, a horizontal curve of radius 300 m is provided. The design speed is 80 km/h.
If the longest wheelbase of vehicle expected on this highway is 7 m, then the extra widening required (in m) is ______ (round off to two decimal places).
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Correct answer: 0.64 to 0.66
Explanation
The extra widening is the sum of the mechanical and the psychological widening. For $n = 2$ lanes, the mechanical widening is $W_m = \frac{nl^2}{2R} = \frac{2 \times 7^2}{2 \times 300} = 0.163$ m. The psychological widening is $W_{ps} = \frac{V}{9.5\sqrt{R}} = \frac{80}{9.5\sqrt{300}} = 0.486$ m. The total is $0.163 + 0.486 = 0.65$ m.