1. Research Fellow, Center for Transport Infrastructure Investment, Korea Transport Institute, 2311 Daewha-dong Ilsanseo-gu Goyang-si, Gyeonggi-do 411-701, Korea.
2. Engineering Associate, HDR/WHM Transportation Engineering, 504 Lavaca St., Suite 1175, Austin, TX 78701-2817.
3. Assistant Professor, Dept. of Civil and Environmental Engineering, Univ. of Virginia, 351 McCormick Rd., Thornton Hall, P.O. Box 400742, Charlottesville, VA 22904-4742 (corresponding author).