by TerryS » Tue Nov 30, 2010 6:38 pm
Matt,
Is this for vertical curves or horizontal? (Vertical Roadway curves are parabolic and are implemented in Carlson profiles).
If one does need horizontal elements, I believe one can achieve them with native Autocad. I have never had the need myself, but it appears that:
One way is to use an ELLIPSE command, then trim the ellipse as needed.
A bit of google searching implies the SPLINE command can create parabolic entities as long as one gets the correct settings. (Acad Help indicates using Control Vertices for the MEHTOD and DEGREE of 2 should create parabolic entities.)