Question

Given the sight distance as 120 m, the height of the driver's eye as 1.5 m, the height of the obstacle as 15 cm and the grade difference of the intersecting gradients as 0.09, the required length of the summit parabola curve is

• A. 249.36

Answer 1

The correct option is A 249.36
Let, length of the summit curve is greater than sight distance.



Length of summit parabola curve,

$L_{sc}=\frac{N{S}^2}{{(\sqrt{2H}+\sqrt{2h})}^2}$

$=\frac{0.09\times {\left(120\right)}^2}{{(\sqrt{2\times 1.50}+\sqrt{2\times 0.15})}^2}$

$=249.36m>\text{sight distance}$

Hence our assumption is correct.

So, Length of the summit curve is 249.36 m.