Seasonal variability of skid resistance in paved roadways

Abstract

Skid resistance is relevant for road safety. Past research studies have shown that in the long term, skid resistance oscillates around a trend value. Weather conditions, traffic, microtexture, macrotexture and polishing aggregate susceptibility are factors that contribute to this behaviour. Present models simulate this oscillatory pattern by considering a fixed wavelength adjusted to a calendar year, for a limited number of test sections and considering only heavy traffic. In the present study, an analysis of the long-term fluctuations of skid resistance was performed. Seventeen models were calibrated with different macrotexture levels, traffic and types of pavement surface. The investigation applied the concept of a polishing equivalence factor for traffic modelling in order to evaluate a truck as an equivalent car in terms of polishing. Models were based on a survey of skid resistance and macrotexture developed in the Chilean paved road network. It was concluded that asphalt surfaces were highly sensitive to factors that followed the seasonal pattern. The fluctuation obtained ranged between 0·08 and 0·25. In contrast, fluctuation was valued between 0·04 and 0·11 in cement concrete surfaces. Therefore, skid resistance values should be adjusted considering the season of the year in which they were measured and the type of pavement surface to obtain a value that can be compared with thresholds.