What does the railing at the entrance of the community mean by one car and one post?

After passing a car, the brake lever will be raised and automatically put down after the car leaves.

One car and one pole in a residential area can help property management, automatically identify the license plate number, judge whether it is a residential vehicle, and automatically release it. After a vehicle passes, the brake lever automatically drops, and so does the next vehicle, so it is called one lever for one vehicle.