Exact weather forecasts for the next 2-8 hours are a precondition for effective winter road maintenance. Because local prediction of meteorological parameters for large scale models is not very satisfactory, energy balance models are used to predict road surface temperature at individual points over the next few hours. Winter service deployment requires minimum warning of 3-4 hours. Swedish and Austrian tests show that the slow lane on a motorway can be warmer than fast lane. It is also found that the reliability factor in favourable conditions at night is plus or minus 1 degree Centigrade, and significantly higher errors occur during the day. As an overall system in combination with additional detailed information from national weather centres, these forecasts are an important factor in efficient planning of winter services. Many systems are now on trial, and comprehensive installations will be implemented after analysis of experiments. An explicit warning must be given against overoptimism since the problems are extremely complex.
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