1. Associate Professor, Key Laboratory of Road and Traffic Engineering of the Ministry of Education, Tongji Univ., 4800 Cao’an Highway, Shanghai 201804, China (corresponding author).
2. Master Student, Key Laboratory of Road and Traffic Engineering of the Ministry of Education, Tongji Univ., 4800 Cao’an Highway, Shanghai 201804, China.
3. Associate Professor, Dept. of Civil and Environmental Engineering, Univ. of Wisconsin, Milwaukee, P.O. Box 784, Milwaukee, WI 53201-0784.
4. Professor, Dept. of Civil and Environmental Engineering, Univ. of Wisconsin, Madison, 1212 Engineering Hall, 1415 Engineering Dr., Madison, WI 53706.