1. Research Scientist, Virginia Tech Transportation Institute, 3500 Transportation Research Plaza, Blacksburg, VA 24061.
2. Associate Professor, Charles Via Dept. of Civil and Environmental Engineering, Virginia Tech; Leader, Transportation Systems and Operations Group, Virginia Tech Transportation Institute, 3500 Transportation Research Plaza, Blacksburg, VA 24061 (corresponding author).
3. Graduate Student, Virginia Tech Transportation Institute, 3500 Transportation Research Plaza, Blacksburg, VA 24061.