1. School of Highway, Chang’an University, Chang’an University Middle-section of Nan’er Huan Rd., Xi’an, Shaanxi 710064, PR China
2. School of Highway, Chang’an University, Chang’an University Middle-section of Nan’er Huan Rd., Xi’an, Shaanxi 710064, PR China (Corresponding author), e-mail: zgfeng@chd.edu.cn, https://orcid.org/0000-0001-9342-861X
3. Shandong Transportation Institute, 1877 Gangxi Rd., Jinan, Shandong 250100, PR China
4. School of Highway, Chang’an University, Chang’an University Middle-section of Nan’er Huan Rd., Xi’an 710064, Shaanxi, PR China (Corresponding author), e-mail: leexinjun@gmail.com