This includes kerbs, pavements, bridges, railway etc. … just all the close track surrounding that needs to be modeled with quite accurate (but not as much as roads of course).
Actual modeling is quite easy because there is no need to fiddle with seamless texturing as with creating roads and intersections especially.
Still there is a lot of work on it mainly because many new textures need to be created from scratch – I try to match all surfaces to real ones such as pavements:

Now I am attaching some screenshots so you can see the actual progress in this area:

Model vs reality:

Quick in-game test: