So I assume you made the Road by shrinkwraping a curve to the terrain and the let the road follow the curve. One way would be this: Where you create a second terrain that also follows the curve and on the edge shrinkwraps to the main terrain.
Thank you for your help. I'm looking for the easy way...I'm doing things the wrong way, I'm going to read the tutorials" How to build a road on terrain" so wait and see...