To overcome the limitations inherent in traditional road network-level models for predicting pavement damage decay on ordinary national and provincial trunk lines, this investigation draws on comprehensive detection and evaluation data from A province in eastern China, spanning from 2014 to 2020. Utilizing advanced data classification and statistical induction techniques, the study delves into the decay performance of the Pavement Condition Index (PCI). The analysis reveals that enhancing the thickness of the surface layer is a critical factor in decelerating PCI attenuation. Road sections that are 3 years old experience a pronounced decline in PCI, necessitating a focus on minor repair and maintenance with preventive maintenance as a secondary measure. For sections aged 6 to 7 years, the PCI decline rate is notably high, advocating for a strategy that prioritizes preventive maintenance and includes minor repair and maintenance. Road sections older than 8 years enter a phase of rapid PCI decline, at which point comprehensive repair and maintenance become imperative. The ‘predictionworksheet’ model, characterized by its low residual sum of squares (RSS) and minimal absolute and relative errors, has been identified as an effective tool for predicting PCI attenuation on ordinary national and provincial trunk lines in A province. This model exhibits strong applicability and accuracy in forecasting the damage and decay trends of road network-level trunk roads, providing a solid foundation for informed decision-making in road maintenance and management.