1. Zhejiang Scientific Research Institute of Transport, Zhejiang Provincial Key Lab for Detection and Maintenance Technology of Road and Bridge, Hangzhou, Zhejiang 311305, China
2. School of Transportation, National Demonstration Center for Experimental Road and Traffic Engineering Education, Southeast University, Nanjing, Jiangsu 211189, China
3. Department of Civil and Environmental Engineering, University of California, Davis, Berkeley, CA 95616, USA