1. Zachry Department of Civil Engineering, Texas A&M University, 3136 TAMU, College Station, TX 77843–3136.
2. Research Institute of Highway, Ministry of Transportation, 8th Xitucheng Road, Haidian District, Beijing 100088, China.
3. Department of Civil and Environmental Engineering, University of Washington, 133B More Hall, Box 352700, Seattle, WA 98195-2700.