Question

A vertical parabolic curve has a sight distance of 130m. The curve has a tangent graded of +2.8% and -1.6%. if the height of the driver's eye from the pavement is 1.08m and the height if the object is 0.50m. a) Compute the max speed of the car that can pass thru this curve. b) Compute the length of the vertical curve in meters for every 1% change in grade. c) Compute the equivalent radius of the vertical curve.

Answer 1

(i)

For finding max speed:

$V=s/t$

as t=12 because of 10%

$V=130/12 =10.8m/s^2$

(ii)

Change

$2.8\%-1.6\%=1.2\%$

$So, 130\times1.2=156 m$

(iii)

radius will be

object height+height of driver’s eye

$1.08+0.50 =1.58 m$