1. Assistant Research Scientist, Texas Transportation Institute, 1100 NW Loop 410, Suite 400, San Antonio, TX 78213 (corresponding author).
2. Research Scientist, Texas Transportation Institute, Gilchrist, Room 380, 3135 TAMU, College Station, TX 77843-3135.
3. Senior Research Engineer, Texas Transportation Institute, Gilchrist, Room 360, 3135 TAMU, College Station, TX 77843-3135.