1. Transport Infrastructures Section, Dept. of Civil and Environmental Engineering, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan, Italy (corresponding author).
2. Nottingham Transportation Engineering Centre, Univ. of Nottingham, Pavement Research Bldg., University Park, Nottingham NG7 2RD, U.K.
3. Royal Melbourne Institute of Technology, School of Engineering, Civil and Infrastructure Discipline, 376-392 Swanston St., Melbourne, VIC 3001, Australia.