scope:

This Guide for Pavement Friction was prepared under NCHRP Project 1-43 to provide highway pavement practitioners with guidance in designing, constructing, and managing pavement surfaces-as part of both new and rehabilitation projects-that meet the public's demand for safe friction levels, while recognizing and considering the effects of noise generation and other pavement- tire interaction issues (e.g., splash and spray, tire wear).

The guide contains recommendations and tools for upper-level administrators and policy-makers, as well as front-line pavement designers and managers. These recommendations are intended to supplement but not replace an agency's normal structural and/or mix design practices. The guide covers the following topics:

• Characteristics of pavement materials and surfaces that contribute to adequate wet-weather friction;
• Friction-testing methods, equipment, and indices;
• Methods for establishing friction levels that signify (a) design of new pavement surfaces, (b) increased potential for skid-related crashes, and (c) the immediate need for friction restoration; and
• Guidance for aggregates, mixtures, and surface types that result in long-lasting, high-quality friction surfaces, with proper consideration of noise, economics, and other friction-related issues (e.g., splash and spray, hydroplaning, tire wear).

The guide addresses both asphalt (i.e., flexible and semi-rigid) and concrete (i.e., rigid) pavements associated with both original construction (i.e., new construction and reconstruction) and maintenance and rehabilitation (M&R) treatments. It does not address winter maintenance issues (i.e., snow and ice removal/treatment) and does not deal with unpaved surfaces or nonhighway pavements.