This paper summarizes research conducted at the Federal HighwayAdministration (FHWA) to validate and calibrate two differentflexible pavement mechanistic permanent deformation models. Theresearch uses internal calibration method and demonstrates applicationsof the method using rutting performance data generated from selectedfull scale accelerated pavement tests.

Since 1970, the FHWA has sponsored research both nationallyand internationally on a wide variety of topics dealing with flexiblepavement performance modeling. Some of these efforts led to thedevelopment of the VESYS mechanistic flexible pavement analysissystem. This system is capable of performing pavement primaryresponse analysis and performance prediction. A recent version,VESYS 5, includes two flexible pavement rutting models, "systemrutting" and "layer rutting" models, along withother pavement performance models to predict pavement performancefor different pavement materials under daily traffic loading andunder different climatic seasons. Also under the FHWA sponsoredprograms, several full-scale pavement testing programs have beendeveloped to better understand and quantify pavement performanceunder controlled tragic loads. Among those full-scale testingprograms, 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, calibratingand improving currently used flexible pavement performance models.

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