1. School of Transportation, Fujian University of Technology, Fuzhou, 350108, China
2. School of Transportation, Southeast University, Nanjing, 210036, China
3. School of Modern Posts, Nanjing University of Posts and Telecommunications, Nanjing, 210023, China
4. College of Transportation Engineering, Tongji University, Shanghai, 201804, China
5. Department of Civil and Environmental Engineering, University of California, Berkeley, 94131, USA