Assessment of New Methods for Determining the Threshold Level of Skid Resistance and Comparison with Single Point Methods and the NUS Model

Skid resistance threshold (TL) is a method that is widely used in road pavement management as a minimum standard for activating the maintenance of each section of the pavement with less resistance to skidding than this threshold. Different methods are used to determine the threshold level of skid resistance in different countries (depending on their climatic conditions). Determining the precision of the skid resistance threshold is important, and its timely implementation will prevent many accidents. So far, various methods have been used to determine the threshold of skid resistance in different countries of the world, including: the three-point curve method, the statewide method and hierarchical tree grouping, etc. A single-point measure of skid resistance is not acurate to show the skid resistance performance on a surface of the pavements. Therefore, this major limitation of single-point models can be remedied using the two-parameter slip resistance models, the Peen State slip resistance model, the PIARC International Friction Index (IFI) model and the CRR-SN nationwide model. The NUS model is one of the latest models to be used more precisely for threshold determination. The application of each of these is analyzed in this paper.