1. Department of Civil and Environmental Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706.
2. Department of Civil and Environmental Engineering, Rutgers University, CoRE Building, 96 Frelinghuysen Road, Piscataway, NJ 08854.
3. School of Transportation, Southeast University, 2 Si Pai Lou, Nanjing 210096, China.