Road users are concerned with ice and snow on roads and streets. The main problems are increased accident risk and impaired accessibility. To prevent-or at least decrease-the difficulties, road administrators perform various maintenance actions. The actions are advantageous for road users but involve costs for the road administrators and negative effects for the environment. To optimize maintenance efforts, the use of management systems should be applied. The winter model project will result in a model for assessing the most important effects and the monetary value of alterations to winter maintenance strategies and operations in Sweden. The effects are assessed for road users, road administrators, and the environment. For road users, the main effects concern accessibility (in terms of vehicle speed and flow) and safety. By using simultaneous monitoring of road surface conditions and traffic, the relationship between speed and different roadway conditions has been established. The speed reductions due to seven specified roadway conditions (moist, wet, ice, or snow) relative to the speed at dry bare conditions are generally significant. The reduction can be as great as 20%. No relationship for traffic flow could be established. The average accident rate (accidents per million vehicle kilometers) during a winter season can be 16 times larger in black ice conditions than in dry road conditions. The accident rate in ice and snow conditions has an exponential relation to the duration of the condition-for example, the shorter the duration, the higher the accident rate.