Is it obligatory to obey the directions of a policeman who has identified himself with an appropriate certificate?

1. No. you must only obey a traffic policeman who directs traffic in an intersection.
2. Correct answer: Yes, even if his directions contradict those of a road sign.
3. Generally not.
4. Yes, but only concerning traffic directions that are given within the intersection.

WhyYou obey a plain-clothes officer who showed ID even when the directions contradict the signs. A person's directions override a sign.