What is the perpetual pavement design concept?

Perpetual pavement is a long-life design concept where structural layers never require rehabilitation - only periodic surface renewal. Design principles: (1) Rich bottom layer (high binder, 4%+ air voids) for fatigue resistance - strain below endurance limit (~70 microstrain), (2) Intermediate layer for rutting resistance - stiff mixture, (3) Surface for friction and noise - renewable wearing course, (4) Total thickness typically >300mm depending on traffic. Life cycle analysis shows lower total cost despite higher initial cost. Requires quality construction and materials. Applicable for high-volume facilities.