1. Ph.D. Candidate, School of Civil Engineering, Iran Univ. of Science and Technology, Tehran 16765, Iran.
2. Professor, Dept. of Civil and Environmental Engineering, Univ. of Auckland, Transportation Research Centre, 20 Symonds St., Auckland 1142, New Zealand (corresponding author).
3. Associate Professor, School of Civil Engineering, Iran Univ. of Science and Technology, Tehran 16765, Iran.