I watched tutorials, read articles from this site and started working on my map but some things still confuse me. The important thing is that I need to work with sloped terrain (crossing, streets, bus stops will be there) so I have to understand elevation correctly.
So my understanding is that we first use subgrades for base terrain modification. And the elevation of subgrades is relative to initial height (without DEM to 0m). Now, should this subgrade be in width of road (+/- some meters) or should I shape the terrain of that area? In that regard, I understand that OMSI-like terrain editing isn't yet implemented so should I just wait for that option or I should play around with subgrades?
When that is done, then I can start placing splines there. So I use curbstones and set them to -0.15 and that will modify terrain further for road. Now, for asphalt I can use either lane splines or polygons and they need to be on -0.15 too.
Finally, when it comes to AI (and reference lines too), I noticed that I cannot use just -0.15 for elevation properties. So my question is do AI paths follow terrain or polygons/splines?