1. Professor, School of Transportation Engineering; and Key Laboratory of Road and Traffic Engineering of the Ministry of Education, Tongji Univ., 4800 Cao’an Rd., Shanghai 201804, P.R. China (corresponding author).
2. School of Transportation Engineering; and Key Laboratory of Road and Traffic Engineering of the Ministry of Education, Tongji Univ., 4800 Cao’an Rd., Shanghai 201804, P.R. China.