Can angles be used to make cars treat intersections as "1-way" intersections? For example at a 90 degree intersection cars would be able to go straight, turn left or right, but at a 45 degree one they would only go straight or toward the lesser turn angle.

Also have noticed sometimes cars will stop and never move again if you delete a round-about while paused then re-start.

Yes, that is why I formed the post in the form a question. I am asking if it can be done.

no, cars will do a u turn to use the 45 degree angled road if they want to