Why does foggy weather have a great influence on traffic?

The most significant impact of foggy weather on traffic is the reduction of vehicle speed. At the same time, the reduction of vehicle speed will also increase travel time and travel delay, which will directly affect road capacity. Especially in the sections with large traffic volume, the decline of the actual traffic capacity of highway facilities may lead to more serious traffic congestion, which will hinder or even paralyze the operation of regional road networks in some areas with developed road networks and high traffic intensity. According to the statistics of the Ministry of Transport, about one quarter to one third of the traffic jams in expressway reported by local authorities in China every year are caused by foggy weather.