Influence of weather is observable in everyday life. In the area of motorized individual traffic this influence is twofold. A change in infrastructure (e.g. due to rain or snow) could lead to highly modified driving behaviour and on the other hand traffic demand is influenced. The latter is because weather is influencing attractiveness of transportation modes (e.g. in terms of safety or comfort) and locations (e.g. less outdoor trips due to rain). With the progress of society, people have put forward higher requirements for traffic networks, especially the service levels and the adaptability to changes in sudden traffic problems. The adhesion coefficient of roads that are covered by snow and ice is low, therefore, the braking distance increases, climbing property reduces, and the traffic capability reduces greatly. Also, the running speed of vehicles reduces, which not only lowers the capacity of roads and aggravate traffic congestion, but also especially easily form chain crowding effects, thus causing local congestion in road network. This study aims at finding the effect of Snow and Potholes on the determination of Passenger Car Units of different vehicle categories.