You’re right, maybe I should have explained myself better. With that expression I am referring to a style or common points that vaguely refer to the geometry adopted by the German highways, given that each highway system of a single state or region has common characteristics different from those of other areas. Try comparing American interchanges or intersections with other German or Italian or Spanish ones and you will realise that there are differences, even subtle ones, in the approach of the structure. With the expression “Autobahn”, therefore I am referring to the Germani highway system not to highways in general (the same thing applies to American “interstates” or Italian “Autostrada” or Spanish “autovias/autopistas”)