Ok this is a dumb guess of mine, but, is not that the trc is just a file exported with max, that says that the material called XYZ is the only route cars can follow?
Let me explain it better; all your roads use the same exact material called XYZ, now you export a file with max that tells to the game the coordinates of all the objects(vertex) that use it, and create a kind of virtual mesh/grid/spline where the cars can go, then everything else is just randomized(the turn left/right)... is this too utopic?
With so much drama in the V-S-T, it's kinda hard being Bigg B-O-double-S-ninetythree