Crack Detection and Measurement Using PTZ Camera–Based Image Processing Method on Expressways

Abstract

Cracks commonly develop in expressways owing to repeated vehicle loads and environmental impact. Therefore, timely and accurate detection of minor cracks can help prevent severe and expensive rehabilitation efforts as well as assist in inspections to avert significant transportation system failures. Consequently, crack detection and measurement in expressways has been extensively researched. Traditional two-dimensional approaches present challenges, as they typically require distance measurement data and large workload. A pan–tilt–zoom (PTZ) camera–based crack detection and measurement method based on deep learning to obtain the size measurement of detected cracks is proposed in this paper. A YOLOv5-based crack recognition model is first trained to detect and classify crack images captured by PTZ cameras. Our previously proposed crack size estimation method is then applied on these crack images to estimate length and width. The proposed approach successfully detects and measures cracks on highway pavements; the YOLOv5-based crack recognition results yield 87.7% mean average precision and more than 90% average precision for crack real size measurement on 12 cracks. Case studies conducted in the G4/Jingshi Highway demonstrate the applicability of the method and enable tuning of the measurement algorithm parameters, confirming the viability of our proposal. Cracks in highway pavement are among the most critical problems in expressway maintenance. Crack detection and measurement not only have severe consequences in relation to expressway safety and decide maintenance timing, but can also prevent the rapid development of crack disease. Owing to ITS development of an expressway network in China, PTZ camera–based crack detection and measurement using YOLOv5 networks is proposed. We train a crack recognition model using YOLOv5 to classify cracks before length and width estimation. Case studies conducted in the G4/Jingshi Highway in the Hebei province of China demonstrate that the proposed method was able to detect and quantify cracks in a cost-effective manner, providing objective and timely guidance for preventive maintenance. This method shows its promise in real-world civil engineering applications for network-level highway maintenance engineering.