1. Beijing Key Laboratory of Traffic Engineering, Beijing University of Technology, Beijing, China
2. Department of Mechanical and Traffic Engineering, Ordos Institute of Technology, Ordos, China
3. Department of Civil and Environmental Engineering, University of North Carolina at Charlotte, EPIC Building, Room 3366, 9201 University City Boulevard, Charlotte, NC 28223-0001, United States
4. School of Civil and Transportation Engineering, Beijing University of Civil Engineering and Architecture, Beijing, China
5. Institute of Transportation Engineering and Geomatics, Tsinghua University, Beijing, China