1. School of Maritime Economics and Management, Dalian Maritime University, Dalian, People's Republic of China
2. School of Traffic & Transportation Engineering, Dalian Jiaotong University, Dalian, People's Republic of China
3. School of Civil & Environmental Engineering, Nanyang Technological University, Singapore, Singapore
4. State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, Beijing, People's Republic of China