1. Jiangsu Key Laboratory of Urban ITS, Southeast Univ., Nanjing, Jiangsu 211189, China; Jiangsu Province Collaborative Innovation Center of Modern Urban Traffic Technologies, Southeast Univ., Nanjing, Jiangsu 211189, China; School of Transportation, Southeast Univ., Dong Nan Da Xue Rd., Nanjing, Jiangsu 211189, China.