@ IceBreakr: For smooth roads there is a formal way... http://www.bundysoft.com/wiki/doku.p...als:l3dt:roads

For sat grids lower than 4 meters and many tiny slopes I used PS (illustrator might do the job too)... basically, I have exported that EMF vector with scale 1:1 matching the size of height map and then I've applied that as an overlay with some gaussian blur to get the terrain smooth enough for the road network... after some test you may get outstanding results... and this unorthodox method works for making those sort of trenches besides roads if you change border colors in your exported road layer... cheerio!