1. Assistant Professor, Dept. of Civil and Environmental Engineering, Univ. of Alaska, Fairbanks, AK 99775-5900 (corresponding author).
2. Associate Research Scientist, Texas Transportation Institute, 508D CE/TTI Building, Texas A&M Univ., College Station, TX 77843-3135.
3. Professor, Zachry Dept. of Civil Engineering, 503E, CE/TTI Building, Texas A&M Univ., College Station, TX 77843-3136.