1. Ph.D. Candidate, Lyles School of Civil Engineering, Purdue Univ., 550 Stadium Mall Dr., West Lafayette, IN 47906.
2. Ph.D. Candidate, School of Transportation, Southeast Univ., 2 Sipailou, Nanjing 210096, China.
3. Graduate, School of Transportation, Southeast Univ., 2 Sipailou, Nanjing 210096, China.
4. Professor, School of Transportation, Southeast Univ., 2 Sipailou, Nanjing 210096, China (corresponding author).