1. Assistant Professor, Dept. of Construction Science, Texas A&M Univ., 3137 TAMU College Station, TX 77843.
2. A. James Clark Chair Professor, Dept. of Civil and Environmental Engineering, Univ. of Maryland, College Park, MD 20742.
3. Associate Professor, Dept. of Decision Sciences, George Washington Univ., Washington, D.C. 20052 (corresponding author).