Evaluation and verification of two systems for mechanistic structural design of asphalt concrete pavements in Nebraska

The VESY-3-A mechanistic design system for asphalt pavements was field verified for three pavement sections at two test sites in Nebraska. PSI predictions from VESYS were in good agreement with field measurements for a 20 year old 3 layer pavement located near Elmwood, Nebraska. Field measured PSI values for an 8 in. full depth pavement also agreed with VESYS predictions for the study period. Rut depth estimates from the model were small and were in general agreement with field measurements. Cracking estimates were poor and tended to underestimate the time required to develop observable fatigue cracking in the field. Asphalt, base course and subgrade materials were tested in a 4.0 in. diameter modified triaxial cell. Test procedures used dynamic conditioning and rest periods to simulate service conditions.