THE INTERNATIONAL ROAD ROUGHNESS EXPERIMENT: A BASIS FOR ESTABLISHING A STANDARD SCALE FOR ROAD ROUGHNESS MEASUREMENTS

Abstract

With the general lack of equivalence between the many methods and measures by which road roughness is characterized, standardized indices offer the means to achieve a time-stable data base that can be utilized by all. The International Road Roughness Experient (IRRE) was organized in Brasilia, Brazil, to find a suitable index and to quantify the relationships between different equipment and roughness indices in use. Roughness measurements were made on 49 test sites by diverse types of equipment in common use. The data were analyzed to determine the equivalence between the roughness measures that could be obtained with each type of equipment and whether one common measure was applicable to all. The results from the IRRE showed that a standard roughness index is practical and measurable by most of the equipment in use today, whether of the profilometer or road meter type. As a result of the IRRE, a standard index was selected that is based on the quarter-car analysis method with standard parameter values and a reference speed of 80 km/h. Provided in this paper is the background on the fundamental of roughness characterization that guided the selection of the standard road roughness index.