1. Associate Professor, National Technical Univ. of Athens (NTUA), Dept. of Transportation and Planning and Engineering, 5 Iroon Polytechniou, Zografou Campus, Athens 157 73, Greece. E-mail: aloizos@central.ntua.gr
2. Research Fellow, Laboratory of Highway Engineering (NTUA), 5 Iroon Polytechniou, Zografou Campus, Athens 157 73, Greece. E-mail: vpapavas@central.ntua.gr