spirals in vertical curves?

[Maverick91]

Is it possible to have spiral transitions in conjunction with circular vertical curves? I'm using C3D'07 but upgrading to '09.

[sinc]

In theory. But I haven't tried it... We've never used circular vertical curves, only the parabolic. Have you run into some problem in C3D 2007 that makes it impossible?

Just out of curiosity, what are you using the circular vertical curves for?

[Maverick91]

In theory. But I haven't tried it... We've never used circular vertical curves, only the parabolic. Have you run into some problem in C3D 2007 that makes it impossible?

Just out of curiosity, what are you using the circular vertical curves for?
In '07 I don't see an option for spirals in the vertical profiles.

We do mostly train-type work.

[sinc]

Oh, I've never seen a spiral in a vertical curve. I've only ever seen them in the horizontal. But then, we don't do railway work.

I don't think C3D can do spirals in the vertical....?

Why would use use a spiral + circular vertical curve instead of a parabolic vertical curve? It doesn't seem like there would be a significant difference... Is there?

[Maverick91]

Oh, I've never seen a spiral in a vertical curve. I've only ever seen them in the horizontal. But then, we don't do railway work.

I don't think C3D can do spirals in the vertical....?

Why would use use a spiral + circular vertical curve instead of a parabolic vertical curve? It doesn't seem like there would be a significant difference... Is there?
Different clients require different things, and different counties have different requirements.

Presumably, you'd use spirals in vertical curves for about the same reason you would in horizontal curves: a smooth transition from a tangent to a circular section.

[sinc]

Yeah, but a parabolic vertical curve does the same thing...