Why do some buses make the sound of "ding, ding, ding" halfway?

Buses in Guangzhou, FAW Bus, Tram Company, and some buses in Bus No.2 will play "Ding Ding" when they reach a certain speed, reminding drivers to pay attention to the speed and drive safely. "Ding Dong" single ring means that the intelligent terminal receives a short message from the engine room, and "‘ing ONG'" means that the intelligent terminal of the vehicle starts to shift gears and the vehicle is about to be sent out.

Now the new welfare bus, Yitong bus, floodlight company, Sanqi company and Zhenbao bus will change their voices to' Please pay attention to safety, please pay attention to the speed, please slow down'.

In addition, some latitude and longitude landmarks will be added, and tips such as "Please pay attention to safety in complex sections, please pay attention to your own way, speed limit ahead, please pay attention to electronic eyes ahead" will be played.