Civil 3D 2015 – Convert Free Curve

A few people on my training courses have asked me what this option is used for, so here’s a quick explanation.

When designing a vertical alignment using fix, float and free elements you can place a vertical curve or vertical parabola between fixed elements using a pass through point:

However, a problem occurs if you save the drawing and open it in an earlier version of Civil 3D (i.e 2014 or before) such that the vertical curves would have disappeared!

The solution is to select the Convert Free Curve (Through Point) option, from the Profile Layout Toolbar.  N.B. all ‘pass through’ types curves will be converted to ‘constrained by length’ types  in one go, you don’t have to pick them individually.

Here’s the dwg opened in 2014 after the conversion.