California Skid Resistance Studies

A Correlation between skid test valus and surface texture measurements was attempted. the modified sand patch test exhibited poor correlation and poor repeatability. the outflow meter test exhibited fair to good correlation with high-speed skid number on PCC pavement, and this test showed good to excellent repeatability. further testing and evaluation is recommend in order to establish outflow meter requirements for the surface texture of new PCC pavements. None of the texture measuring methods correlated with Skid Number Gradients. Coefficient of friction measurements were taken for the entire width of PCC traffic lanes. the coefficient of friction in the wheel tracks was found to be substantianly lower than that for the rest of the lane width, indicating that localized polishing of the traffic lanse in the wheel tracks is a typical occurences on PCC pavements. The rightmost (truck) lanes are subjected to a greater polishing action in the wheel tracks than the wheel tracks in the adjacent lanes. A small scale laboratory wear and polishing device proved to be unseccessful. Before and after studies of a pavement overlaid with calcined bauxite chip seal showed a dramatic increase in skid number, but no significant change in the accident frequency.