Weather descriptions and compensation model for winter road maintenance

This paper describes how a good compensation model for regulating costs for winter maintenance between client and contractor requires two well-functioning sub-models. A sub-model that describes the weather during the winter season and a sub-model that links the weather descriptions to the need to take measures/set in resources. Both the client and the contractors have called the quality of weather descriptions used now into question. The basis for the weather is data collected from individual station in the Swedish National Road Administration system for road weather information (RwiS). By using special definitions the data are translated into eight weather situations at an hourly levels. Examples of weather situations are: snowfall, drifting snow and risk of slipperiness caused by rain or sleet on a cold road. The hour-by hour weather descriptions are summarized into clearly defined weather occurrences, for instance drifting snow during a 6-hour period or a snowfall lasting at least 20 hours. The final result of weather descriptions for a winter is a number clearly defined weather occurrences. The compensation model is based on the number of weather occurrences for each RwiS station chosen as representative for a certain maintenance area. The paper describes the developments, which are intended to improve the quality of weather descriptions as well as the compensation model. The implementation of weather descriptions and compensation model will also be reported.