In 1969, a research-type, skid-test trailer was acquired, U.S. routes were surveyed in 1970 and 1971, and the interstate and toll-road systems were surveyed in 1971. The data were used for research purposes and have been reported. The interstate and toll-road systems were surveyed again for research purposes in 1974. Since October 1974, surveys have been performed under highway safety project grants (interaccounted to 108, subsection OSKID). Primary and principal secondary roads, involving 4,613 miles (7,427 km), were surveyed in 1975. A second skid tester, a survey-type, was acquired in April 1976; and survey-testing of major, rural collector roads continued during 1976. This included 5,074 miles (8,166 km) of state secondary roads and 788 miles (1,268 km) of rural secondary roads. In 1977, the interstate and toll-road systems were re-surveyed, and a total of 1,576 miles (2,537 km) of predominately rural secondary roads were tested. The 1977 survey data are reported.

Statewide surveys represented 57 percent of the mileage of rural, state-maintained roads; and 99 percent of all traffic on rural, state-maintained roads travel those roads. About 5 percent of the interstate mileage, about 4 percent of the toll-road mileage, about 19 percent of the primary mileage, and about 16 percent of the secondary mileage may be considered slippery. A small percentage of both state primary (3.7 percent) and secondary (5.0 percent) roads were classified as very slippery. These sections, in particular, have been flagged for de-slicking.

Trends from analyses of accidents on wet pavements from 1969 through 1977 are reported. Description and evaluation of the resurfacing program from the standpoint of de-slicking of pavements is also presented. In addition, results of high-accident location testing and evaluation are included.

Report Date


Report Number

No. 512

Digital Object Identifier



The contents of this report reflect the views of the authors who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Bureau of Highways or the National Highway Safety Administration or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation.