[Closed] Smooth single axis of shape

Hi,

I’d like to have more control when I smooth a shapes. In my case: there’s a road, curving through the landscape. The road consists of a shape with every vertex as a bezier corner. I’ve fitted these beziers by hand to the underlying CAD-drawing. The road is also going up and down. There’s no CAD-section available, so I’d like to have smooth transitions in the Z-axis. I do not want to create this by hand. But when I make the vertices smooth, I lose the hand-positioned beziers obviously.
Is there a way to smooth vertices in a single axis and leave the other axes alone? The vertex would still be a bezier-corner but the position of the handle is calculated for a single axis.

Klaas