How many meters should be reserved at the entrance and exit of road greening zoning?

I think the question you asked is called "sight distance" in our professional field. I won't go into details about the specific principle and why it should be set up. Let's help you solve the problem directly.

See Article 4.3.3 of Code for Design of Urban Road Intersections (CJJ 152-20 10).

I hope I can help you! Adopt it if possible!