CalME,a Mechanistic–Empirical Program to Analyze and Design Flexible Pavement Rehabilitation

A computer program known as CalME has been developed for analysis and design of new flexible pavements and rehabilitation of existing pavements. The paper describes the overlay design procedure and the calibration of the models for reflection cracking and permanent deformation through heavy vehicle simulator (HVS) tests. To simplify the input process, the program includes databases for traffic loading, climatic conditions, and standard materials. A companion program was developed for backcalculation of layer moduli, and the results may be automatically imported into the CalME database. The program incorporates the existing, empirical California Department of Transportation design methods as well as an incremental–recursive analysis procedure based on the mechanistic–empirical method. The effects of different pavement preservation and rehabilitation strategies on pavement damage may be studied with several options for triggering timing of placement. The influence of within-project variability on the propagation of damage can be evaluated using Monte Carlo simulation. The program also permits importation of the results of HVS or track tests into the database and simulation of the experiments on the computer. This feature is useful for the calibration of the mechanistic–empirical models but may also be used for in-depth interpretation of accelerated pavement testing results. An HVS experiment that was used for calibration of the reflection cracking and the permanent deformation models is described.