Hi Siggy.
Those road source textures are pretty sharp if you use the slider to display 7cm/pixel.
And yes, you could draw roadlines as photoreal and make the rest transparent. I think that would preserve the autogen.. but I don't know if the see-through parts would then be the default landclass, or if vectors and polys and new landclass would show underneath.
My sad advice is to give up on customised road textures, unless your scenery is pretty small. It's just one of those things that fell through the cracks in FSX.
I think the use of a terrain.cfg was a good idea, as was the new vector scenery. But the wasn't any input as to the need for local folder texturing, or customised texturing of polys and lines.
Maybe someone else has an idea that doesn't involve the terrain.cfg... and honestly, I haven't tried FS2004 VTP2 lines to see if they work with named textures. If that works, then that's the way to go.
EDITED___
It looks as if VTP2 ( from FS9 ) allows a full named texture set of winter;hardwinter;spring;summer;fall;night
BUT, the night texture doesn't seem to show,and showing the day texture wrecks the effect.
Dick