1. Professor, Dept. of Civil Engineering, Univ. of Thessaly, Volos, 383 34 Thessaly, Greece (corresponding author).
2. Postdoctoral Researcher, Univ. of Thessaly, Volos, 383 34 Thessaly, Greece.
3. Project Director, Attiko Metro S.A., 191 Mesogeion Ave., 11525 Athens, Greece.