The advantages and limitations of an expert system for winter road maintenance in Sweden, as well as how to create an expert system that is effective, are discussed. An expert system will support the decision making of the maintenance manager in real time. It is primarily intended for inexperienced maintenance management personnel. An effective expert system must render advice on what action should be taken, when it should be carried out, and, if necessary, how much and what type of chemical should be used on a road. Another important use for an expert system is the education and training of maintenance managers. Information for developing an expert system was gathered in part from literature studies, but the main informational source was interviews with experts. In-depth interviews with six experienced maintenance managers concerning winter maintenance activities took place during February, March, and April 2000. The interviews were based on examples in which present and forecast weather were given along with the time of day. The setting was the managers' actual area of operation along with the actual available equipment. Based on these examples, the managers were asked what action they would take and why. In order to obtain the best possible result, a follow-up was conducted, documenting what actions had been taken during conditions that matched the weather examples used in the interviews. A short discussion then took place as to why particular decisions were made. After the interviews were concluded, information was compiled and key parameters identified. Rules of best practice could then be formulated stating what action should be taken under conditions defined by temperature, wind, precipitation, and forecast. Actions were placed into three categories: plowing, sanding, and salting. Three types of salting were defined: dry, prewetted, and brine. The best practice rules also prescribe the correct amount of salt for spreading over a road. Preliminary results show that brine spreading is preferred over prewetted salt in most situations. Dry salt should never be used. For preventive salting, normal recommended amounts are 10 g of brine/sq m (124 lb/lane-mi) or 7 g of prewetted salt/sq m (87 lb/lane-mi). These best practice rules will later be incorporated into the expert system.