Assessement of time-dependant models of pavement skid resistance

Abstract

Skid resistance is an indicator of the adherence provided by a pavement. It is affected by the physical characteristics of the pavement such as environmental conditions, traffic and road geometry. The effects of these variables over the skid resistance vary over time on how each of these interacts between one another. The empirical evidence shows that skid resistance decline monotonic and asymptotically over time. This behavior was conceptually developed by Diringer and Barros (1990). Two phases over the pavement life were defined by them: a transient phase presenting an accelerate loss of skid resistance over time and a permanent phase, where an equilibrium skid resistance level is reached and a periodical oscillation is observed near this value. Three representative models of skid resistance temporary behavior were studied in this paper. The objective of the present study is to analyze the strengths and weaknesses of the skid resistance time-dependant models, in order to formulate new predictive models based on them. This study considers the Highway Research Board (HRB) absolute model, the HDM-4 incremental model and the seasonal model developed by Jayawickrama and Thomas (1998). The study concluded that the three analyzed models present weaknesses that can be improved. Particularly, the HRB and HDM-4 models do not correlate explicitly their variables and parameters to the type and characteristics of the pavement. With this, models lose predictive capacity although they gain generality. The Jayawickrama and Thomas model is strongly dependant on the environmental measurement conditions. For this reason, is difficult to estimate accurately the tendency of skid resistance and to calibrate the model.