1. Faculty of Transportation Engineering, Kunming University of Science and Technology, Kunming, Yunnan, China
2. State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, Beijing, China
3. Department of Civil and Environmental Engineering, University of South Carolina, Columbia, SC, USA
4. School of Safety Engineering and Emergency Management, Shijiazhuang Tiedao University, Shijiazhuang, Hebei, China