1. Graduate Research Assistant, Dept. of Civil Engineering, North Carolina State Univ., Campus Box 7908, Raleigh, NC 27695-7908.
2. Professor, Dept. of Civil Engineering, North Carolina State Univ., Campus Box 7908, Raleigh, NC 27695-7908 (corresponding author).
3. Dept. of Planning and Public Works, 292 West Beamer St., Woodland, Yolo County, CA 95695.
4. IEM, 4277 Pamona Ave., Palo Alto, CA 94306.