Relationship between Surface Profile Characteristics and the Need for Localized Roughness Correction

The Texas Department of Transportation is implementing a smoothness specification based on inertial profile measurements. This specification includes a localized roughness provision to locate defects on the final surface based on measured surface profiles. To identify defects, the existing method checks deviations between the average profile and its 25-ft moving average against the specified threshold of 150 mils. Stations at which deviations exceed 150 mils in magnitude are considered defect locations. Although this method provides an objective approach to identification of defects on the basis of profile data, some districts have taken the additional step of using a bump rating panel to select bumps and dips to be corrected based on the panel's opinion of the defects' severity from the point of view of ride quality. Clearly, a standard method needs to be developed to maintain consistency in ride quality assurance testing. This paper presents results of a study in which bump rating panel data were used to investigate the need to correct defects identified from surface profile measurements.