Since the 1990 prohibition of the use of studded tyres, the quantity of anti-freezing admixture spread to guarantee safe winter road traffic in Japan has risen steadily. The principal chemicals used for this purpose have been sodium chloride and calcium chloride, because they are the most effective and economical available. The appropriate use of these chemicals is an extremely effective winter road traffic safety measure. Because in heavy snowfall regions, anti-freezing admixture that has been spread on the roads is removed along with snow during the frequent snow removal operations performed in these regions, in order to limit the rise in the quantity spread, it is necessary to clarify the actual state of the spreading of anti-freezing admixture in order to study and develop more effective and more efficient spreading methods. With regards to non-chloride anti-freezing admixture, the effectiveness of acetate compounds in advance spreading has been confirmed, but it is necessary to continue to evaluate their effectiveness by studying more cases where road surface conditions and meteorological conditions differ.