1. Assistant Professor, Dept. of Civil, Architectural, and Environmental Engineering, Univ. of Colorado at Boulder, Boulder, CO 80309 (corresponding author).
2. Professor Emeritus, Dept. of Civil and Environmental Engineering, Stanford Univ., Stanford, CA 94305.
3. Vice President and Chief Learning Officer, Kiewit Corp., 3555 Farnam St., Omaha, NE 68131.