1. Graduate Research Assistant, Dept. of Civil and Environmental Engineering, Univ. of Washington, Box 352700, Seattle, WA 98195-2700.
2. Associate Professor, Dept. of Industrial and Systems Engineering, Dept. of Civil and Environmental Engineering, Univ. of Washington, Box 352650, Seattle, WA 98195-2650 (corresponding author).
3. Assistant Professor, Dept. of Civil and Environmental Engineering, Univ. of Washington, Box 352700, Seattle, WA 98195-2700.