K value and Vertical curve radius value.

[Mahmoud-elsayed145]

Hello, 

What is the relationship between K value and Vertical curve radius?

At profile labels, it gives me Radius = k * 100. Where did this equation come from and what is “Vertical curve radius” cuz it is parabola?

[MMcCall402]

It's been my understanding that the K value is a relationship between the length of the curve (any type of curve) and the grade change from the beginning to the end of the curve.  To change a K value one needs to make a curve longer or shorter.

[Mahmoud-elsayed145]

Ok I know that but I still don’t get it, why that radius which shows in labels, equals k *100??

[wfberry]

Perhaps if you had supplied a dwg with this problem someone could possibly figure it out.  Normally the value of "k" is the length of the parabolic curve divided by the algebraic difference of the two profile tangents grades.

Bill