In the United Kingdom, the primary method of preventing ice from forming on road surfaces is to spread rock salt with purpose-built spreaders that regulate both the rate of spread and the spread pattern. British Standards Institution Standard BS3247 requires that the rock salt contain no more than 4% moisture by weight. Although salt is an effective deicing chemical, its extensive and intensive use on roads has been found to corrode vehicles, damage highway structures, cause detrimental effects to vegetation, and increase groundwater pollution. Prewetted salt is under trial on minor roads by local authorities in England and Scotland. The U.K. Highways Agency commissioned TRL Limited to review the use and to determine the potential benefits of prewetted salt. The use of prewetted salt has been compared with the use of dry rock salt in terms of their environmental effects as well as their cost. Factors such as salt loss due to trafficking and climatic conditions, potential hazards and damage to structures, and safety issues arising from the use of prewetted salt have been investigated. Field trials are in progress in the winter of 2000-2001 to determine the efficacy of prewetted salt as a precautionary treatment. The trials will be used to assess specifications for materials and equipment, the cost and method of retrofitting brine tanks to a spreader, the accuracy of spread width and pattern, and salt residue on the road and verge. The final results of this study will enable the Highways Agency and local authorities to determine whether to introduce prewetted salt on U.K. roads and, if so, the climatic conditions under which it should be used.