This paper summarizes research conducted at the Federal Highway Administration (FHWA) to validate and calibrate two different flexible pavement mechanistic permanent deformation models. The research uses internal calibration method and demonstrates applications of the method using rutting performance data generated from selected full scale accelerated pavement tests.

Since 1970, the FHWA has sponsored research both nationally and internationally on a wide variety of topics dealing with flexible pavement performance modeling. Some of these efforts led to the development of the VESYS mechanistic flexible pavement analysis system. This system is capable of performing pavement primary response analysis and performance prediction. A recent version, VESYS 5, includes two flexible pavement rutting models, "system rutting" and "layer rutting" models, along with other pavement performance models to predict pavement performance for different pavement materials under daily traffic loading and under different climatic seasons. Also under the FHWA sponsored programs, several full-scale pavement testing programs have been developed to better understand and quantify pavement performance under controlled tragic loads. Among those full-scale testing programs, a permanent, outdoor Accelerated Loading Facility (ALF) was constructed at FHWA and has been in operation since 1986. The ALF tests are conducted under controlled conditions, therefore, it provides a valuable source of data for validating, calibrating and improving currently used flexible pavement performance models.

In this study, selected sets of field performance data from FHWA's ALF testing program were used to validate and calibrate the two flexible pavement rutting models used in VESYS 5. A procedure for mechanistic model calibrations using of full-scale test data was established. It was further shown that the calibrated rutting model can be used to predict the rutting performance of other flexible pavements.