Calculate the extra widening required on a two-lane road having a horizontal curve of radius 100 m if the longest wheel base of vehicle expected on the road is 6.0 m. Design speed is 95 kmph.
- A1.30 m
- B1.33 m
- C1.36 mCorrect
- D1.39 m
Solution
Concept
Mechanical and psychological widening
Formula
Wm = nl²/2R; Wps = V/(9.5√R)
Step-by-step solution
1. Wm = 2 × 6²/(2 × 100) = 0.36 m. 2. Wps = 95/(9.5 × 10) = 1.0 m. 3. Total = 1.36 m.
Explanation
Both components are added.
Why the other options are wrong
Other values come from slips.
Shortcut
Wm + Wps.
Correct answer: C) 1.36 m