"With Flowgraphs it is possible as i described above, but realtime vehicle avoidance detection would require LUA coding, which is not my specialty."
Funnily enough, that's precisely what I'll be doing probably later this year. I've created a complete flight simulator programmed with Lua. When taxiing, the aircraft can detect other aircraft in front or to the side and they will stop and wait in order to avoid collisions. I intend to use similar techniques for wheeled vehicles and they will have proper traffic avoidance etc.
But I'm amazed that the standard AI don't seem to have any traffic avoidance at all....