Road slipperiness can contribute to car accidents. In 1997, over 53,000 accidents were caused by slippery roads in the United Kingdom out of an estimated 4,000,000 accidents (or approximately 1.3 per cent) .[6] A small change in road slipperiness can have a drastic effect on surface friction: decreasing the coefficient of friction from 0.45 to 0.35, equivalent to adding a dusting of wet snow, increased the accident rate by almost 1000%.[2] As such, road agencies have a number of approaches to decreasing road slipperiness.