1. School of Highway, Chang’an Univ., Xi’an, Shaan’xi 710064, China.
2. School of Highway, Chang’an Univ., Xi’an, Shaan’xi 710064, China; Henan Univ. of Urban Construction, Pingdingshan, Henan 467036, China.
3. Henan Urban and Rural Planning and Design Research Institute Co. Ltd., Zheng-zhou, Henan 450044, China.