Determination of Mean Texture Depth of Pavement Using 3D Digital Image

Mean texture depth (MTD) of pavement is a 3D texture parameter that has been found by pavement engineers and researchers to be useful for providing an assessment of a pavement’s performance in a number of aspects, including (i) the ability of pavement to drain surface runoff effectively during rainfall, (ii) the ability to maintain an adequate skid resistance for safe vehicle operations in wet weather, and (iii) the ability to keep tire-pavement noise caused by traffic within an acceptable limit. Hence, it is important to maintain the MTD of pavements at a sufficiently high level at the road network level. Currently it is not possible to determine MTD continuously at traffic speed for network level monitoring. Instead, mean profile depth (MPD) has been measured for the purpose of estimating MTD. Unfortunately, MPD being a 2D texture parameter along a linear profile, cannot provide a perfect representation of MTD. Studies have found that the relationship between MPD and MTD vary from one mixture type to another. This presents a major problem for network level monitoring of MTD. To overcome this limitation, direct determination of MTD from 3D digital images is preferred. This paper describes the limitations of currently available method for numerical MTD determination based on 3D digital images, and proposes possible approaches to overcome those limitations. Through comparison of the different methods, recommendations are given for the preferred approach and method for direct MTD determination at road network level.