1. Institute for Transport Planning and Systems, ETH Zurich, 8092 Zurich Switzerland;
2. College of Business Administration, University of Illinois at Chicago, Chicago, IL 60607;
3. Department of Industrial Economics and Technology Management, Norwegian University of Science and Technology, 7491 Trondheim, Norway;
4. Department of Economics, Mathematics and Statistics, Birkbeck University of London, London WC1E 7HX, United Kingdom;
5. Department of Management Engineering, Technical University of Denmark, 2800 Kongens Lyngby, Denmark