The National Institute for Road Research has, following requests from various South African road authorities, undertaken a study of the effects on roads of abnormally heavy vehicles. The aim was to develop improved procedures to assist the road authorities in deciding whether, in a particular case, a permit should be issued for an abnormally heavy vehicle to make a specified number of journeys over a given road. An extensive survey of existing local and overseas practices revealed that no completely satisfactory method exists. However, some of the methods that are being used are briefly descriptionbed. Although this report is mainly concerned with pavements, bridges and high fills are also mentioned.