What is the maximum speed when the visibility is within 50 meters on the expressway?

When the visibility is less than 50 meters on the expressway, the maximum speed shall not be higher than 20 kilometers per hour.

According to the Regulations for the Implementation of the Road Traffic Safety Law, the provisions are as follows:

When a motor vehicle is driving on an expressway, it shall abide by the following provisions when it encounters low visibility meteorological conditions such as fog, rain, snow, dust and hail: when the visibility is less than 50 meters, turn on fog lights, low beam lights, position lights, front and rear position lights and hazard warning flashlights, and the speed shall not exceed 20 kilometers per hour, and leave the expressway as soon as possible from the nearest exit.

Extended data:

Driving in foggy days must be highly concentrated, driving slowly, driving second and driving third. Most of the serial traffic accidents in foggy days are caused by blindly following cars or being too close to them. Once the visibility is too low in foggy days, you should immediately slow down and drive to the right, park your car in a safe area and turn on the width light and emergency light, and then continue driving after the fog clears.

When driving in foggy weather, when overtaking a parked vehicle, you should honk your horn at the right time, and make a low-speed detour from the left side when it is confirmed that there is no intention to start and there is no car coming from the opposite side. Also pay attention to carefully keep an eye on the lane separation line in the road, and don't run in the lane, otherwise you will be in danger of colliding with the opposite car.

Baidu Encyclopedia-Regulations for the Implementation of the Road Traffic Safety Law of the People's Republic of China

People's Network-Safety First Helps You Drive in Fog.