1. Ph.D. Candidate, School of Transportation, Southeast Univ., 2 Sipailou, Nanjing, Jiangsu 210096, China.
2. Professor, School of Transportation, Southeast Univ., 2 Sipailou, Nanjing, Jiangsu 210096, China (corresponding author).
3. Professor, School of Transportation, Southeast Univ., 2 Sipailou, Nanjing, Jiangsu 210096, China.