Spatial-temporal correlation between surface distress and internal damage in pavement structure

A recurrent phenomenon is the reappearance of distress conditions on the same road section, both before and after maintenance interventions. The maintenance work essentially addresses the superficial symptoms rather than the root causes, since the internal relationships between various forms of distress remain unclear. This study quantitatively evaluates the correlation between surface distress and internal defects based on field detection data and statistical methods, effectively complementing existing qualitative analytical method. Approximately 200 defect locations data were collected from the RIOHTrack full-scale ring road, and targeted evaluation metrics reflecting pavement performance were proposed. Then, the Ripley's K-function was employed to analyze the spatial aggregation of surface and internal cracks, and to further verify their macroscopic correlation during the spatio-temporal evolution process. Next, kernel density estimation and relative risk assessment were used to investigate the relationships between the surface distress and internal defects. Experimental results reveal that the loading position significantly affects surface distress, but exhibits no obvious correlation with hidden damage, and there is also no spatial aggregation phenomenon between them. However, for semi-rigid base asphalt pavement, internal cracks and surface cracks show a strong correlation, while demonstrating only a weak association with loading position. Finally, a sensitivity analysis was performed based on the results obtained at different distance thresholds, and r = 0.5 m was designated as the optimal spatial correlation distance threshold. This threshold was then used to determine the pavement structure offering the best crack resistance performance, providing a key reference for the design and maintenance of heavy-duty highway pavements. This study provides a reference for road active maintenance and supports the transformation of maintenance strategies from passive response to active intervention.