Located on the southern coast of Finland, the Uusimaa road district started to reduce the amount of salt applied to roads to prevent slippery conditions on roads located in areas with ridges. The latter are sand and gravel formations that are highly permeable to water. The combined length of the roads selected for the salt reduction experiment during the first winterwas 162 km and during winter 2004-05 319 km. The purpose of the experiment was to determine what the chances are of reducing the application of salt as a means to combating slippery conditions. Simultaneously, the surfacefriction requirement for the roads was decreased from 0.30 to 0.25. The aim is to prevent a rise in the chloride concentration of groundwater. Natural chloride levels in Finland in typical ground water area formations areless then 10 mg/litre. On the roads used for the experiment, the effects of reduced salt application on ground waters have been studied by measuring the chloride concentrations in 45 water intake wells over a four-year period during the years 1999-2003. In majority of the water intake wells thechloride concentration had decreased or remained at the same level as before the experiment. On the roads used for the experiment the amount of salt applied is reduced by approximately 55 % compared to the average over the previous winters. An average of 4.1 tons of salt per road kilometre was applied in 2003. No changes at all are discernible in the number of accidents compared to the years used as the control years for the experiment. Changes in speeds are extremely slight. In conjunction with the experiment, feedback was surveyed using questionnaires in 2001 and 2003. The majority felt that the amount of salt ought to be reduced. For the covering abstract see ITRD E143097.
Abstract