Hi there.
@Ruboy: check your pm
This work on psychedelic pictures was made at Autocad 2007. That colourful appeal is due to layers, which are not texturized yet.
It will be better ingame with proper material, but so far I judge it was important to show since 3deditor has come to GP4, many software has come to work with track making...
To do that land coverage:
1. I exported all DLrails and DRrails as 3ds to an autocad file.
2. With those inserted at global values, I have a base of reference to create all new land outside their boundaries...
3. Then at autocad I use 3dmesh and 3dface tools to create faces.
4. After all this land finished I'll send to a friend of mine who'll map all new objects with proper tgas.
Hope it's better to understand now.
Cheers