1. Professor and Chair, Dept. of Traffic Engineering, Chang’an Univ., P.O. Box 487, Xi’an, P.R. China 710064.
2. Graduate Research Assistant, Dept. of Traffic Engineering, Chang’an Univ., P.O. Box 487, Xi’an, P.R. China 710064.
3. Associate Professor, Dept. of Civil, Architectural and Environmental Engineering, Illinois Institute of Technology, 3201 South Dearborn St., Chicago, IL 60616 (corresponding author). E-mail address:
4. Fellow and Managing Director, DeVoe L. Moore Center, Florida State Univ., 150 Bellamy Building, Tallahassee, FL 32306.
5. Vice President, Reason Foundation, 3415 South Sepulveda Blvd., Suite 400, Los Angeles, CA 90034.