1. Beijing Key Laboratory of Traffic Engineering, Beijing Engineering Research Center of Urban Transport Operation Guarantee, Beijing Univ. of Technology, No. 100 Pingleyuan, Chaoyang District, Beijing 100124, China.
2. Beijing Key Laboratory of Traffic Engineering,Beijing Engineering Research Center of Urban Transport Operation Guarantee, Beijing Univ. of Technology, No. 100 Pingleyuan, Chaoyang District, Beijing 100124, China.