Make road have a smooth transition from one elevation to anther elevation ,at same time keep road cross-section up-right without tilt . TerrainAxe give you several methods to control how to smooth your road. Before you use this tools ,you need to select a part of border of your road.Maybe you also need to set several elevation for key verts and select them.
This tool has a Graphic UI,you can import road data to control curve,ajust curve shape to the road appearence you desired ,then export curve information to road.If you need more effcient methods ,you can use below SmoothRoad tools.
Base on the elevations of ends of road to make linear transition with the distance from start vertices.
Base on the elevations of start and end vertices of road to make bezier curve transition with the distance from start vertices.
Select a length of road by select border,and set the elevation of key vertices and select,then press a key to smooth the road.
Eliminate noise of road and make which have a smooth appearence.This is a very fast smooth method,you just need to select a part of road then press a key.