1. School of Transportation Engineering, Tongji University, 4800 Cao'An Road, Jia-Ding District, Shanghai 201804, China.
2. School of Transportation Engineering, Tongji University; Department of Urban and Regional Planning, University of Florida, P.O. Box 115706, Gainesville, FL 32611-5706.
3. School of Economics and Management, Tongji University, 1239 Siping Road, Shanghai 20092, China.
4. School of Traffic and Transportation Engineering, Central South University, 932 South Lu-Shan Road, Changsha 410083, China.