Numerical determination of pavement mean texture depths at different degrees of traffic polishing-induced wear

Abstract

All existing digital image-based numerical mean texture depth (MTD) calculation methods are unable to achieve a consistent level of acceptable accuracy for MTD values calculated at different degrees of pavement polishing. To solve this problem, a novel procedure is proposed to determine MTD as a function of degree of polishing represented by a texture statistic ‘directional wear index’ DWI. First, a relationship is established between DWI and the elevation H eq that defines the equivalent top surface of MTD. H eq is derived from 3-D digital image based on the concept of planation surface. Through studying laboratory specimens and field pavements polished to different degrees, a well-defined relationship between DWI and H eq was established. Knowing H eq from the H eq–DWI relationship, MTD is calculated as the mean depth of the voids between H eq and the test surface. The digital image-based procedure is able to concurrently determine MTD and the surface's degree of polishing.