1. Jiangsu Key Laboratory of Urban Intelligent Transportation Systems, Southeast University, Si Pai Lou No. 2, Nanjing 210096, China
2. Public Transport Research Group, Institute of Transport Studies, Department of Civil Engineering, Monash University, Building 60, Clayton, Victoria 3800, Australia
3. Department of Civil and Environmental Engineering, College of Engineering, University of Washington, 201 More Hall, Box 352700, Seattle, WA 98195-2700