1. Professor, Dept. of Transport Engineering, Chang’an Univ., Xi’an 710064, China.
2. Dept. of Transport Engineering, Chang’an Univ., Xi’an 710064, China (corresponding author).
3. Graduate Student, Dept. of Transport Engineering, Chang’an Univ., Xi’an 710064, China.
4. Professor, Faculty of Architecture, Building and Planning, Univ. of Melbourne, VIC 3010, Australia.
5. College of Urban and Environmental Sciences, Northwest Univ., Xi’an 710064, China.