An increasing responsibility of highway and transportation agencies is the maintenance, rehabilitation, and management of highways that have been built. Particularly with regard to asphaltic concrete pavements, this requires the use of efficient and economical methods for determining the structural properties of existing pavements. Use of nondestructive testing (NDT) data with associated analysis methods is an excellent tool for determining these pavement structural properties. Several types of NDT equipment were evaluated, and the falling weight deflectometer was judged to be preferred for use on either a network or project basis. An analysis procedure to quickly back-calculate pavement layer moduli values, called MODULUS, was developed during this project. To assist engineers in the use of MODULUS, an expert system, called PASELS, was also developed for preprocessing and post-processing the data, focusing on local conditions.

Research has been completed, and the project report has been published as: NCHRP Report 327, "Determining Asphaltic Concrete Pavement Structural Properties by Nondestructive Testing." The report contains users manuals for the computer programs MODULUS and PASELS. The computer programs themselves are available through McTrans at the University of Florida.