1. Research Assistant, Dept. of Civil and Environmental Engineering, Univ. of Illinois, 205 N. Mathews Avenue, Urbana, IL 61801 (corresponding author).
2. Research Assistant, Dept. of Civil and Environmental Engineering, Univ. of Illinois, 205 N. Mathews Avenue, Urbana, IL 61801.
3. Professor, Dept. of Civil and Environmental Engineering, Univ. of Illinois, 205 N. Mathews Avenue, Urbana, IL 61801.
4. Professor, Dept. of Industrial and Enterprise Systems Engineering, Univ. of Illinois at Urbana-Champaign, 104 S. Mathews Ave., Urbana, IL 61801.