This report contains guidelines and recommendations for managing and designing for friction on highway pavements. The contents of this report will be of interest to highway materials, construction, pavement management, safety, design, and research engineers, as well as others concerned with the friction and related surface characteristics of highway pavements.

Real-time measurement of the tire-road friction coefficient is extremely valuable for road-maintenance operations and highway safety management. This paper presents a systematic framework to predict skid resistance of wet pavement with a non-contact method, which could be a potential approach for real-time measurements of pavement friction. The grip potential of pavement is estimated according to the measured pavement texture based on theoretical simulation of the complete hysteresis and partial adhesive effects during tire sliding on wet pavement. Such a method could be potentially used for the purpose of harmonization analysis of skid resistance and potential capability of optimization of pavement surface texture.

This volume highlights the latest advances, innovations, and applications in bituminous materials and structures and asphalt pavement technology, as presented by leading international researchers and engineers at the RILEM International Symposium on Bituminous Materials (ISBM), held in Lyon, France on December 14-16, 2020. The symposium represents a joint effort of three RILEM Technical Committees from Cluster F: 264-RAP “Asphalt Pavement Recycling”, 272-PIM “Phase and Interphase Behaviour of Bituminous Materials”, and 278-CHA “Crack-Healing of Asphalt Pavement Materials”. It covers a diverse range of topics concerning bituminous materials (bitumen, mastics, mixtures) and road, railway and airport pavement structures, including: recycling, phase and interphase behaviour, cracking and healing, modification and innovative materials, durability and environmental aspects, testing and modelling, multi-scale properties, surface characteristics, structure performance, modelling and design, non-destructive testing, back-analysis, and Life Cycle Assessment. The contributions, which were selected by means of a rigorous international peer-review process, present a wealth of exciting ideas that will open novel research directions and foster new multidisciplinary collaborations.

The ability of a driver to stop on a wet pavement surface has been shown as a relationship between a tire and the pavement surface texture. For a number of years, the Ontario Ministry of Transportation and Communications has been classifying pavement surface textures and correlating these textures with the skid number of the surface, as measured by a brake-force trailer. The skid trailer number can be explained now in terms of the pavement surface texture. This paper contains a summary of the test procedure, a discussion of the texture classification system, and the relationship of the six texture parameters is discussed in terms of the equation used to generate a skid number at 100 km/h (62 mph). The advantages of using this system as a complement to present skid testing procedures are outlined, with particular attention to its use in those areas which cannot be tested by the brake-force trailer and in the area of mix design studies. The paper concludes with a discussion of some potential uses for the test method in future research work in Ontario, including the semiautomation of the interpretation procedure.

Innovations in Road, Railway and Airfield Bearing Capacity – Volume 1 comprises the first part of contributions to the 11th International Conference on Bearing Capacity of Roads, Railways and Airfields (2022). In anticipation of the event, it unveils state-of-the-art information and research on the latest policies, traffic loading measurements, in-situ measurements and condition surveys, functional testing, deflection measurement evaluation, structural performance prediction for pavements and tracks, new construction and rehabilitation design systems, frost affected areas, drainage and environmental effects, reinforcement, traditional and recycled materials, full scale testing and on case histories of road, railways and airfields. This edited work is intended for a global audience of road, railway and airfield engineers, researchers and consultants, as well as building and maintenance companies looking to further upgrade their practices in the field.

This synthesis report will be of interest to pavement design, construction, management, and research engineers, highway safety officials, and others concerned with pavement friction characteristics. It describes the current state of the practice and discusses the methods used for evaluating wet pavement friction characteristics of new and restored pavements. This synthesis reviews models used for measuring and evaluating friction and texture, causes for friction changes over time, and aggregate and mix design to provide adequate friction. Also presented are construction and surface restoration practices for providing good pavement surface characteristics. In addition, considerations of noise and ride quality are discussed when compromise may be required.