vertical curve
vertical curve
(OP)
I am trying find out lentgh of a sag vetical curve.
Design speed, V = 50 mph
sight Distance, S = 425 ft (AASHTO Green Book)
Algebraic difference of Grades, A = 2.2%
There are two formulas one for S<L and other for S>L
Which one should I use? Also, is K value needed here? if yes, how do I find out?
Any help is greatly apprciated.
Design speed, V = 50 mph
sight Distance, S = 425 ft (AASHTO Green Book)
Algebraic difference of Grades, A = 2.2%
There are two formulas one for S<L and other for S>L
Which one should I use? Also, is K value needed here? if yes, how do I find out?
Any help is greatly apprciated.





RE: vertical curve
For a 50 mph design speed, the rate of vertical curvature (K) should have a minimum design value of 96.
L = K x A, L = 96 x 2.2 = 211.2. I would round up to 220' for the length of curve.
RE: vertical curve
RE: vertical curve
Is this homework?
RE: vertical curve
I have used S>L equation like you suggested for Sag vertical curve and got 1005 ft for S value. So you mean this should be the sight distance not 425 ft?
I am reviewing paving plans for a City in Arizona, I wish it was my homework :)
RE: vertical curve
RE: vertical curve
Thanks again.
RE: vertical curve
The L value you got (210.5) is based on the S<L equation not S>L. Based on S>L (equation 3-52 on page 277), I got -7 ft for L which clearly not close to L obtained from K*A!!!
What do you think?