1. Associate Professor, College of Transportation Science and Engineering, Nanjing Univ. of Technology, Nanjing, Jiangsu 210009, China (corresponding author).
2. Professor, Glenn Dept. of Civil Engineering, Clemson Univ., Clemson, SC 29634.
3. Associate Professor, Key Laboratory of High-Speed Railway Engineering, Ministry of Education, Southwest Jiaotong Univ., Chengdu, Sichuan 610031, China.
4. Postgraduate Student, College of Transportation Science and Engineering, Nanjing Univ. of Technology, Nanjing, Jiangsu 210009, China.