1. Department of Electronic Engineering, The Hong Kong Polytechnic University, CF622, Hung Hom, Kowloon, Hong Kong
2. School of Transportation, Nantong University, No. 9 Seyuan Road, Nantong, Jiangsu Province, China
3. Key Laboratory of Road and Traffic Engineering of the Ministry of Education, Institute for Advanced Study, Tongji University, Shanghai, China
4. Department of Civil and Environmental Engineering, University of Wisconsin–Milwaukee, P.O. Box 784, Milwaukee, WI 53201-0784, USA
5. School of Transportation Science and Engineering, Harbin Institute of Technology, Harbin, China