Road Weather Information System in Finland

The weather has a significant impact on winter traffic. It affects directly by causing poor visibility or indirectly by causing poor driving conditions (e.g., slipperiness due to snow, slush or ice on the road), multiplying the risk of an accident. To decrease the risk of an accident and to improve the safety and flow of traffic, Finnish National Road Administration (Finnra) has developed a Road Weather Information System (RWIS). The purpose of the RWIS is to provide the road maintenance staff with information about prevailing road and weather conditions on the road network in winter. With the help of the system, road maintenance measures, salting and plowing, can be timed better and the amount of anti-slipping agents can be optimized to a minimal level. Another growing function of the system is to provide information to road users.

The system’s operation is based on automated road weather stations equipped with measuring devices. Approximately 270 road weather stations located along the main roads throughout the entire country are currently connected to the system. The road weather stations collect data about air, road surface and dew point temperatures, wind, humidity, rain, visibility and road conditions on the surface of the road. The RWIS retrieves data from the road weather stations every 15 - 60 minutes.

All road weather data is centrally stored in a common, national database. New weather and road condition data is written to the database at a rate of approximately nine rows a second around the clock. Database queries are processed about every other second. Road weather data is viewed using the RWIS’s workstation software. The user can view road weather data in map, table and graphic windows.

In addition to road weather data, the RWIS includes image products, such as rain radar and cloud satellite images. Finnra purchases also map, table and text-based road weather predictions. Finnra has about 130 driving condition cameras located along the main roads.

As the road weather system has improved and expanded, it has become sensible to centralize monitoring duties in winter. First experiments were made during the winter 1991-92 in the southern parts of the Finland. The experiences obtained were so positive that Road Weather Monitoring Centres were set up in the autumn of 1993 covering the whole country. Besides, Finnra has ten Traffic Information Centres. TIC’s task is to serve road users via telephone, local radio stations, text-TV, and the like. In winter the information concentrates on weather and road conditions, while in summer the focus is on roadworks and any resulting obstacles to traffic.

Driver information services linked to data produced by the RWIS can be roughly divided into two different categories. Information provided before a trip and information provided during a trip. Information provided before a trip can be used to plan the timing of the trip (possibly even postponing the trip to a better time), to possibly select an alternate route, and to reserve enough of extra time for the trip. Information channels include TV, radio, Internet, special info signs etc.