1. Assistant Professor, Dept. of Transportation Technology and Supply Chain Management, Kainan Univ., S209, No.1 Kainan Rd., Luzhu Shiang, Taoyuan 33857, Taiwan.
2. Assistant Professor, Dept. of Civil and Environmental Engineering and Transportation Center, Northwestern Univ., 2145 Sheridan Rd., A335, Evanston, IL 60208 (corresponding author).