Methodology for Accurate AASHTO PP67-10-Based Cracking Quantification Using 1-mm 3D Pavement Images

Quantification of cracking is crucial to assessing overall cracking condition, monitoring cracking propagation, and other pavement design and managerial decision-making purposes. For a majority of the highway agencies, the cracking width and length are the two most important indicators representing severity and extent of cracking, respectively. However, due to limitations in pavement data collection technology and vague protocols, cracking length and width were mostly estimated or simply summed or averaged instead of accurately measured over the past two decades. In recent years, accurate cracking map can be derived in a consistent manner with the advance of the three-dimensional (3D) data collection systems. Nonetheless, rare effort has been dedicated to rigorous cracking length and width measurement, which has slowed the progress of cracking measurement. Although the AASHTO PP67-10 protocol specifies new requirements for automated cracking measurement, cracking quantification remains immature in current practice, which affects the reliability of pavement maintenance and design modeling. In this research, a rigorous methodological framework for accurate cracking length and width measurement is developed. Methods are introduced and demonstrated effective at extracting the desirable cracking skeleton, which is used for accurate cracking length measurement. Based on the cracking skeleton and contour, an orthogonal projection method is developed in this study to calculate the continuous cracking width for each pixel along the cracking skeleton. This study provides insight into how to derive reliable and consistent cracking data from 3D images. Findings from this research would further improve the practice of cracking measurement based on the new AASHTO PP67-10 protocol. (C) 2016 American Society of Civil Engineers.