Circular vertical curves

[ivanov]

Can I draw true circular curves in profile ( for ex., with 3 points) or they are approximated by simmetrical parabola? Can I set C3D for draw circular vertical curve? Help me please. Thank you.

Alexander Ivanov

Data-Center

[Jeff_M]

Welcome to the forum! The following workflow when looking for an answer to a question will be helpful for future questions.

Inputting the word circular into the search box at the upper right gave this as the first link:

http://forums.autodesk.com/t5/AutoCAD-Civil-3D/Vertical-Circular-Curve-on-Profile/m-p/3696406#M18907...

and should answer your question.

If you don't find a satisfactory answer from a search, then please feel free to ask. I'm not saying it's wrong to just ask, but often times you will get a faster answer by searching first.

[sboon]

First of all - welcome to the board.

You cannot draw circular vertical curves by selecting three points, but you can draw tangents and PVI's with circular vertical curves added automatically, or you can just draw the lines and add the circular vertical curves later.

Open the curve settings dialog from the Profile Layout toolbar and switch the curve type before you start building the profile.

[ivanov]

Thank you, Steve... Bad news...

[peterfunkautodesk]

You can add a vertical circular curve by picking three points.

1. Set the curve type to Circular in the Curve Settings...

2. Use the Fixed Vertical Curve (Three Points) command to add the curve.

It may not look like an arc in the default profile view because of vertical exaggeration, but if you set that to 1 you will see your vertical curve.

Regards,

Peter Funk

Autodesk, Inc.

[sboon]

Peter is correct.  When I started looking at this last night I was using a drawing with two profile views for my experiments.  Unfortunately I didn't notice that one of them had vertical exaggeration while the other didn't.

[ivanov]

Hi, Peter! Thank you. But I think it isn't "true" circular - see type of curve in Panorama window. I am using this method because C3D haven't any more. I can't convert AutoCAD arcs too... Best regards, Alexander Ivanov Data Center

[peterfunkautodesk]

You are correct, my mistake.

How about this for a workflow (assuming that you know your arcs)

1. Set the profile grids to have equal scales

2. Draw the arc using AutoCAD 3p arcs

3. Draw the tangents between the arcs using line and use the tangent osnap.

4. Fillet the tangents to find the VPI points

5. Draw the profile tangents between the VPI points

6. Add the vertical curves using the "Free Circular Curve (PVI Based) option. Use the "Pass through" option and just pick a point "Near" to AutoCAD Arc (so that you don't need to know the radius value)

This requires a few extra steps, but it will produce the profile that meets your design requirements.

Cheers,

Peter Funk

Autodesk, Inc.