1. Assistant Professor, Dept. of Construction Management, Colorado State Univ., Fort Collins, CO 80523.
2. Vecellio Professor, Dept. of Civil and Environmental Engineering, Charles E. Via, Jr., Virginia Tech, Blacksburg, VA 24061 (corresponding author).
3. R.H. Boggle Professor, Grado Dept. of Industrial and Systems Engineering, Virginia Tech, Northern Virginia Center, 7054 Haycock Road, Falls Church, VA 22043-2311.