1. Ph.D. Candidate, School of Transportation, Jiangsu Key Laboratory of Urban ITS, Southeast Univ., Nanjing 210096, China.
2. Professor, School of Transportation, Jiangsu Key Laboratory of Urban ITS, Southeast Univ., Nanjing 210096, China (corresponding author).
3. Professor, Dept. of Civil and Environment Engineering, Univ. of Wisconsin–Madison, Madison, WI 53706.