1. College of Metropolitan Transportation, Beijing University of Technology, Beijing, P. R. China
2. College of Civil and Environmental Engineering, Imperial College London, London, UK
3. Beijing Key Laboratory of Traffic Engineering, College of Metropolitan Transportation, Beijing University of Technology, Beijing, P. R. China
4. School of Traffic and Transportation, Beijing Jiaotong University, Beijing, P. R. China
5. Centre for Transport Studies, Imperial College London, London, UK