1. Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China
2. National Rail Transit Electrification and Automation Engineering Technology Research Center (Hong Kong Branch), Hong Kong 999077, China
3. School of Civil Engineering, Central South University, Changsha 410075, China
4. Center for Railway Infrastructure Smart Monitoring and Management, Central South University, Changsha 410075, China
5. Department of Civil and Environmental Engineering, University of Massachusetts, Amherst, MA 01003, USA
6. School of Business Administration, Capital University of Economics and Business, Beijing 100026, China
7. School of Geosciences and Info-Physics, Central South University, Changsha 410075, China