For winter salt treatments, roads authorities in Europe and North America are increasing their use liquid only spreading to prevent ice forming on roads. In Scotland most authorities spread dry salt while the trunks roads are treated with a pre-wetted salt.
Recent studies from Europe have compared the durability of liquid brine only spreading to pre-wetted salt. They concluded that for precautionary salt treatments, especially on dry and moist surfaces that sodium chloride brine only spreading requires less salt and stays longer on the surface.
Transport Scotland have promoted this research, along with the Highways Agency (now Highways England), through the National Winter Service Research Group (NWSRG). Three live trials were undertaken in the UK during the 2014/15 winter season.