1. Ph.D. Student, School of Transportation Science and Engineering, Beihang Univ., Beijing 100191, China.
2. Assistant Professor, Humphrey School of Public Affairs, Univ. of Minnesota, Minneapolis, MN 55455.
3. Professor, School of Economics and Management, Beihang Univ., Beijing 100191, China.
4. Professor, School of Transportation Science and Engineering, Beijing Advanced Innovation Center for Big Data and Brain Computing, Beihang Univ., Beijing 100191, China (corresponding author).