1. Guangdong Key Laboratory of Intelligent Transportation System and Research Center of Intelligent Transportation System, School of Engineering, Sun Yat-Sen University, Guangzhou, Guangdong 510275, P. R. China
2. School of Civil Engineering and Transportation, South China University of Technology, Guangzhou, Guangdong 510640, P. R. China
3. Xinjiang Communications Construction Group Co., Ltd, Urumqi, Xinjiang 830016, P. R. China
4. College of Transportation, Jilin University, Changchun, Jilin 130025, P. R. China