1. Gansu Transportation Planning, Survey and Design Institute Co., Ltd., Lanzhou 730030, China
2. Gansu-Highway Traffic Construction Group Co., Ltd., Lanzhou 730000, China
3. School of Civil Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
4. Key Laboratory for Special Area Highway Engineering of Ministry of Education, Chang’an University, Xi’an 710064, China