1. School of Transportation Engineering, Tongji University, 4800 Cao'an Road, Shanghai 201804, China.
2. Safe Transportation Research and Education Center, University of California, Berkeley, 2614 Dwight Way, Mail Code 7374, Berkeley, CA 94720-7374.
3. School of Transportation Engineering and Key Laboratory of Road and Traffic Engineering of the Ministry of Education, Tongji University, 4800 Cao'an Road, Shanghai 201804, China.