1. Construction Safety Supervisor, Hoffman Construction Company, Portland, OR 97205.
2. Associate Professor, Dept. of Civil, Construction, and Environmental Engineering, Oregon State Univ., 220 Owen Hall, Corvallis, OR 97331 (corresponding author).
3. Assistant Professor, Dept. of Technology Systems, East Carolina Univ., 231 Slay Hall, Greenville, NC 27858.