1. Associate Professor, College of Urban Railway Transportation, Shanghai Univ. of Engineering Science, Longteng Rd., Shanghai 201620, P.R. China.
2. Assistant Professor, College of Transport and Communications, Shanghai Maritime Univ., 1550 Haigang Ave., Shanghai 201306, P.R. China.
3. Assistant Professor, Dept. of Civil and Environmental Engineering, Univ. of Wisconsin-Milwaukee, P.O. Box 784, Milwaukee, WI 53201-0784 (corresponding author).
4. Professor, College of Urban Railway Transportation, Shanghai Univ. of Engineering Science, Longteng Rd., Shanghai 201620, P.R. China.
5. Ph.D. Candidate, Research Assistant, Dept. of Civil and Environmental Engineering, Univ. of Wisconsin-Milwaukee, P.O. Box 784, Milwaukee, WI 53201-0784.