Pavement distress seriously affects the quality of pavement and reduces driving comfort and safety. The dropped objects from vehicles have increased the risks of traffic accidents. Therefore, automatic detection of urban pavement distress and dropped objects is an effective method to timely evaluate pavement condition. Firstly, this paper utilized a portable platform to collect pavement distress and dropped objects to establish a high-quality dataset. Six types of pavement distresses: transverse crack, longitudinal crack, alligator crack, oblique crack, potholes, and repair, and three types of dropped objects: plastic bottle, metal bottle, and tetra pak were included in this comprehensive dataset. Secondly, the real-time YOLO series detection models were used to classify and localize the pavement distresses and dropped objects. In addition, segmentation models W-segnet, U-Net, and SegNet were utilized to achieve pixel-level detection of pavement distress and dropped objects. The results show that YOLOv8 outperformed YOLOv5 and YOLOv7 with a MAP of 0.889. W-segnet showed an overall MIoU of 70.65% and 68.33% on the training set and test set, respectively, being superior to the comparison model and being able to achieve high-precision pixel-level segmentation. Finally, the trained models were performed on the holdout dataset for the generalization test. The proposed methods integrated the detection of urban pavement distress and dropped objects, which could significantly contribute to driving safety.

In south China, suffering from the rainiest climate, porous asphalt mixtures have been receiving increasing attention. However, with the increase in the application of pavement and the growth of service life, the importance of the recycling application of old reclaimed porous asphalt pavement (RPAP) has gradually become prominent. Based on this, this paper established RPAP content ranging from 0% to 30% in increments of 5% and designed experimental groups with and without regenerating agent to investigate the effects of RAP content and regenerating agent addition on the high-temperature stability, low- and normal-temperature crack resistance, moisture susceptibility, drainage capacity, and mechanical properties of PAC-13 reclaimed porous asphalt mixtures. Subsequently, the practical performance of PAC-13 RPAP was verified through a pavement test. The results indicate that, as the RPAP content increases, the high-temperature stability and mechanical properties of the recycled mixture improve. Specifically, as the planer content is increased to 30%, the dynamic stability of the regenerated porous asphalt increases by 61.1%, and the dynamic modulus at 25 Hz also shows an increase of 25.3%. However, the crack resistance, moisture susceptibility, and drainage capacity at both low temperatures and room temperature exhibited accelerated weakening. When the RPAP content increases to 30%, the reduction in failure strain of regenerated PAC-13 reaches 41.8%, and the reduction in submergence stability reaches 21%. Simultaneously, the water permeability coefficient, void ratio, and interconnected void ratio all demonstrate significant reductions of 23.5%, 6.5%, and 10.0%, respectively, indicating a diminished drainage capacity in the recycled porous pavement mixture. Then again, with the addition of the regenerant, the high-temperature stability of the regenerated porous mixture is reduced by 10.8%, and the mechanical properties are reduced by 6.48%, while the crack resistance at low temperature and room temperature, moisture susceptibility, and drainage ability are enhanced. The verification results of the test section demonstrate the feasibility of utilizing reclaimed asphalt pavement (RAP) material in the porous asphalt mixture. Additionally, it is recommended to select RAP material with a particle size of 4.75 mm or larger while ensuring that the proportion of RAP does not exceed 20%. The research findings of this paper are anticipated to offer guidance for the preparation of PAC-13 reclaimed porous asphalt mixtures while facilitating the recycling and large-scale utilization of old porous pavement materials.