The Road Condition Model is the central part of the Winter Model. The reason for this is that it produces input data for most of the models that describe effects of different kinds, such as accident risks, travel times, fuel consumption and environmental impact. The road condition model supplies a condition assessment for a winter in the form of a road condition description on an hourly basis. According to the requirements of the client, the road condition model is confined to describing road conditions for two-lane roads with oncoming traffic in rural areas. At this stage, the model is also confined to describing road conditions in the traffic lane. No account is thus taken of hard shoulders, if any. The aim of the project is to develop a working prototype to the definite road condition model. The road condition model consists of the following sub models. The first five are related to maintenance measures taken and the last four to traffic and weather. 1. Anti-icing treatment. - 2. Snow ploughing combined with anti-icing treatment. - 3. Snow ploughing. - 4. Gritting. - 5. Grading. - 6. Rut development in hard-packed snow or thick ice. - 7. Condensation. - 8. Splashing from a wet road. - 9. Drying of a moist road.