What is the recommended speed for special weather in expressway?

Expressway should slow down when driving in special weather. When a motor vehicle runs on the expressway and encounters low visibility meteorological conditions such as fog, rain, snow, dust and hail, it shall abide by the following provisions: 1. When the visibility is less than 20,000 mm, the speed of turning on fog lights, low beam lights, position lights and front and rear position lights shall not exceed 60 kilometers per hour, and keep a distance of more than 10000mm from vehicles in the same lane; 2. When the visibility is less than 10000mm, the speed of turning on fog lights, low beam lights, position lights, front and rear position lights and danger warning flashlights shall not exceed 40 kilometers per hour, and keep a distance of more than 5000mm from the vehicle in front of the same lane; 3. When the visibility is less than 5000mm, turn on the fog lights, low beam lights, position lights, front and rear position lights and hazard warning flashlights, and leave expressway from the nearest exit as soon as possible at a speed not exceeding 20km per hour.