To be successful in the winter road maintenance work it is of greatest importantance to have a reliable weather information system. The Swedish RWIS (road weather information system) is owned and supported by SNRA, the Swedish National Road Administration. The system is built up in collaboration with four partners, and one of them is SMHI, the Swedish Meteorological and Hydrological Institute. SMHI, has supported SNRA for many years with both meteorological and technical knowledge. Most of the information delivered from SMHI, the latest decade, has been presented in a Windows based PC system, today extended to a web version.
The winter road maintenance work in Sweden is carried out both by the Production Divison of SNRA and private contractors and good winter statistics is very important already in the tendering process of the maintenance contracts. From mesoscale analysis produced at SMHI it is possible to get good basic data. In these analysis, information from 650 road stations is included together with data from our meteorlogical station network and weather radars.
During the winter season SMHI provides forecasts and consultancy to one of the most comprehensive road weather systems of the world. We supplies forecast maps produced in FreeHand, textual forecasts and special cloud and air temperature forecasts to a forecast model to evaluate road surface temperature the next 7 hours. These cloud and temperature forecasts are produced in a 1-dimensional high resolution limited area model with input data from mesoscale analysis. Other products are, radar and satellite images, automatically produced short term precipitation forecasts based on data from weather radars and direct model output from numerical forecasts. Twice a day, in the morning and in the evening, SMHI arrange weather briefings on telephone with the personnel at SNRA Traffic Management Centres and contractors for road maintenance. In complicated weather situations these regular briefings are followed up with extra contacts around the clock.
As the information from the road stations is of significant importance, SMHI every night makes a quality control of the data from all 650 road stations. This control is done to discover stations which deliver odd data and therefore need service. It is also important to have high quality of station data as adjustments of the contract sum is based on data from road stations and data showing the amount of snowfall taken out from mesoscale analysis. Finally this winter service is completed with an important education programme for the users of the road weather information system.