1. Professor, Highway College, Chang’an Univ., Xi’an, Shaanxi 710064, China.
2. Lecturer, College of Civil Engineering, Xi’an Univ. of Architecture and Technology, Xi’an, Shaanxi 710055, China (corresponding author).
3. Lecturer, Highway College, Chang’an Univ., Xi’an, Shaanxi 710064, China.
4. Master, Anhui Transport Consulting and Design Institute Co., Ltd., Wutong Rd., Hefei, Anhui 230000, China.