Relationship between Skid Resistance Numbers Measured with Ribbed and Smooth Tire and Wet Accident Locations

Abstract

Due to the recent strategic initiative adopted by the Ohio Department of Transportation (ODOT) to reduce highway crashes, there is a current need to determine if surface friction testing results can be correlated to wet weather crash data in Ohio. The establishment of such correlations would allot ODOT to develop a proactive wet-pavement accident reduction program that would effectively predict locations where wet-pavement crashes may likely occur. Under this study, research was conducted to determine if surface characteristic measurement can be correlated to wet-weather accidents and guidance was provided on the identification of desirable or target friction numbers as a function of site categories and friction demand. A comprehensive literature review was first conducted on pavement surface characteristics, including a review of international research activities. This was followed by a field testing program to evaluate smooth- and ribbed-tire surface friction, as well as pavement macrotexture and roughness, at 90 locations through the state. The 90 sections that were selected represent three site categories: signalized intersections, unsignalized intersections, and congested freeways. These site categories were considered to have the most potential to reduce rear-end crashes. The surface characteristics data from the 90 pavement sections were then analyzed with regards to crash data using both trend analysis and regression modeling techniques. Based on the finding from the field testing program and the available information in the literature, preliminary recommendations were developed for ODOT to consider in its quest for improving the safety of its roadway network. The main body of this report includes an abbreviated summary of the extensive literature search of both U.S. and international studies, a detailed description of the field testing program, a summary of data analysis procedures, a summary of the findings and conclusions, and a summary of the final recommendations for implementation.