1. Associate Professor, Dept. of Civil and Environmental Engineering, Bucknell Univ., 1 Dent Dr., Lewisburg, PA 17837 (corresponding author).
2. Student, Bucknell Univ., 1 Dent Dr., Lewisburg, PA 17837.
3. Lead Safety Statistical Analyst, Amtrak, 1 Massachusetts Ave. NW, Washington, DC 20001.