Current UK standards for skidding resistance and texture depth are based on studies carried out in the 1970s, which showed that low-speed skidding resistance depends upon the microtexture of the road surfacing, but as speed increases, the skidding resistance falls, depending on the texture depth. In 1995, the Highways Agency commissioned further research in order to reassess the earlier work, particularly the influence of texture on the relationship between high- and low- skidding resistance, for the wide range of surfacings now used on UK trunk roads. A K J Law T1290 Pavement Friction Tester (PFT) was purchased by the Highways Agency, for this new study. The equipment has been used to make measurements of locked-wheel friction over a range of speeds from 20 to 130 km/h. Measurements have been made on more than 130 sites covering a wide range of types of surfacing, levels of texture and skidding resistance. The report presents the results of the first phase of analysis, which show clearly the loss of friction with increasing speed and confirm that this is more marked for surfacings with low texture depth. Significant findings were that texture has a greater impact on loss of friction at lower speeds than previously thought and that the effect is similar for both random-textured and transverse-textured impermeable surfacings. (A)

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