Perpetual Pavements: Review of International Design Methodologies, Costs, and Sustainability Criteria

Perpetual pavements have been proposed as a long-life alternative capable of preserving structural integrity for several decades while limiting maintenance to the upper layers. However, their implementation varies widely across regions due to differences in traffic, climate, subgrade conditions, materials, design methods, and maintenance strategies. This study presents a structured critical review of international perpetual pavement practices, with emphasis on structural configurations, design criteria, field performance, life-cycle costs, and environmental impacts. Peer-reviewed studies, technical reports, and documented case studies were comparatively analyzed to identify common principles and context-dependent decisions. The reviewed evidence shows that perpetual pavement should be understood as a performance-based design philosophy rather than a fixed structural section. Although horizontal tensile strain at the bottom of the asphalt layers and vertical compressive strain at the top of the subgrade remain widely used design indicators, commonly adopted limits should not be treated as universal thresholds. Field studies also suggest that increased pavement thickness does not necessarily produce proportional improvements in performance, particularly when foundation support, interlayer bonding, material durability, and construction quality are not adequately considered. From an economic and environmental perspective, perpetual pavements may provide favorable life-cycle outcomes when higher initial resource use is compensated by fewer and less intensive rehabilitation activities. These benefits are most likely under heavy traffic and long analysis periods, but remain sensitive to maintenance assumptions, discount rates, system boundaries, and local material conditions. Overall, the review suggests that the future of perpetual pavement design lies in achieving structural durability with the minimum reasonable use of materials, costs, and future interventions.