1. Transportation Research Center, Beijing University of Technology, 100, Ping Le Yuan, Chaoyang District, Beijing, 100124 China.
2. China Academy of Urban Planning and Design, 9, Sanlihe Road, Haidian District, Beijing, 100037 China.
3. Transportation College, Southeast University, 2, Sipailou, Nanjing, Jiangsu, 210096 China.