Civil: Profile Slope Too Flat (in Vertical Curves)!

[Arizona]

A government reviewer has rejected our roadway widening design stating that the profile slope is too flat .... at the low and high points of vertical curves .... and demands we "fix" it. :cry:

When asked if he wants us to remove the vert curve and simply have a vertical angle point, he did not like that idea.

 

In this state, they use plain concrete vertical curb, no gutter, except when a profile slope is less than 1/2 a percent, then they use monolithic poured curb and gutter.

Theory is that pavers can not pave smooth enough for it to drain at less than half a percent profile slope. Concrete gutter can be formed very straight and smoothly, and gives the paver a straight edge to pave to.

 

So we asked him if he wants curb and gutter in the areas where the profile slope is less than half a percent, ya know, like, for 50 feet. He didn't like that either.

 

So, once we got done laughing about what this reviewer is demanding, which we're really not sure exactly what he really wants, we just sat here scratching our heads wondering what to do.

This is a roadway widening. We have very little flexibility in the profile of an existing road.

What's a guy to do!?!

OK, rant over...

[SLW210]

Since you do not seem to be using 3ds Max, I moved your thread to the Civil 3D & LDD Forum.

[BIGAL]

We go below 0.5% grade because we have to the road is already built and we are reconstructing, if you have a real big vc yes you will get instantaneous grades below 0.5% for a long distance, so shorten the vertical curve, one of the forgiving rules we can use is a change of grade if its less than say 0.4% you dont need a vertical curve unless you have high speed creeping in. Sometimes we will just change grade at say every 10m matching the existing road which has already a random vertical curve profile that you will spends hours trying to match, or just a series of shorter vc's to approx the existing road.

[Arizona]

Since you do not seem to be using 3ds Max, I moved your thread to the Civil 3D & LDD Forum.

OK, thanks.

[Arizona]

We go below 0.5% grade because we have to the road is already built and we are reconstructing, if you have a real big vc yes you will get instantaneous grades below 0.5% for a long distance, so shorten the vertical curve, one of the forgiving rules we can use is a change of grade if its less than say 0.4% you dont need a vertical curve unless you have high speed creeping in. Sometimes we will just change grade at say every 10m matching the existing road which has already a random vertical curve profile that you will spends hours trying to match, or just a series of shorter vc's to approx the existing road.

These are relatively short vertical curves. 250 feet is a long one, most are between 50 and 150 feet long.

The flat areas of them are typically about 50 feet long, with inlets at the low points. We depress the inlet grates 2 inches lower than the profile grade, providing good, positive drainage. If the curb height is 6 inches, the inlet hood will be 8 inches tall.

My point is, flat spots occur in vertical curves, at the high point or the low point. It's normal. Happens in Every curve. It's just the way it is. This reviewer does not understand that. He doesn't seem to grasp the whole concept of a vertical curve. He needs to turn over this review to an actual highway engineer!

Edited March 31, 2016 by Arizona

[MillerMG]

Bring on a new engineer. That should solve this issue. lol

[BIGAL]

I have to double check this "Length over which grade is less than a specified slope" l = (2*S*L) /(g2-g1) eg I used 50m VC, 0.5 minimum (s) g2=-2 g1=1 l=16.666m