1. Graduate Research Assistant, Center for Sustainable Transportation Infrastructure, Virginia Tech Transportation Institute, Charles E. Via, Jr. Dept. of Civil and Environmental Engineering, Virginia Tech, 200 Patton Hall, Blacksburg, VA 24061 (corresponding author).
2. Director, Center for Sustainable Transportation Infrastructure, Virginia Tech Transportation Institute, Charles E. Via, Jr. Dept. of Civil and Environmental Engineering, Virginia Tech, 200 Patton Hall, Blacksburg, VA 24061.
3. Professor, Dept. of Civil and Environmental Engineering, Univ. of Delaware, 301 DuPont Hall, Newark, DE 19716.