Evaluation of traffic induced subgrade stresses in flexible airfield pavements

During the first series of traffic tests at the Federal Aviation Administration's (FAA's) National Airport Pavement Test Facility (NAPTF), the flexible pavement test sections were trafficked using a simulated six-wheel Boeing 777 (B777) landing gear and a simulated four-wheel Boeing 747 (B747) gear simultaneously until the test sections failed. Soil pressure cells (PC) installed within the test sections recorded the load-induced vertical subgrade stresses. The main objective of this paper is to analyze the PC-measured vertical subgrade stresses over the duration of traffic testing and present some interesting findings regarding the comparative effect of B777 and B747 traffic loading on subgrade stress and its relation to the rutting performance of the NAPTF test sections. The results showed that, in general, the subgrade stresses induced by the B777 and B747 traffic loading do not differ significantly.