What I'm trying to do is draw some 3d roads and building massing models in sketchup over top of google earth terrain. I can get the terrain in by over and over again adding terrain sections to my sketchup file (wish we could select a bigger area, I'm trying to cover quite a few square km).

What I can't seem to figure out is how to draw a polygon over top of the roads. I was hoping I could just draw a line down the middle that followed the terrain, then do something to make that line a polygon with width and a bit of depth.

Any tips on this?