The Mechanical Widening of the Curve is Given by

By BYJU'S Exam Prep

Updated on: September 25th, 2023

The mechanical widening of the curve is given by-

  1. Wm=nl²/2R
  2. Wm=nl/2R
  3. Wm=nR²/2l
  4. None of the above

Answer: A. Wm=nl²/2R

The mechanical widening of the curve is given by Wm=nl²/2R.


Extrawidening is the extra width of road provided on the horizontal curve

Extrawidening is provided to-

  • Avoid the offtracking of the vehicle 
  • To account lateral skidding
  • To confront the psychological tendency of the driver
  • To increase the visibility at curves

Types of Extra Widening-

  1. Mechanical Widening: The Mechanical Widening of the Curve is given by Wm=nl²/2R
  2. Psycological Widening: WP=V/9.5 √R

Total Extra Widening 

We=Wm + WP

We=nl²/2R + V/9.5 √R


We – Total Extra Widening

Wm– Mechanical Extra Widening

WP – Psychological Extra Widening

n – Number of lanes

l – Length of wheel base

R – Radius of the curve

V – Speed in Kmph

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