1. Texas Transportation Institute, Texas A&M University System, 3135 TAMU, College Station, TX 77843-3135.
2. Department of Transport, Technical University of Denmark, Bygningstorvet 116 Vest, K-2800 Kongens, Lyngby, Denmark.
3. School of Public and International Affairs, Virginia Polytechnic Institute and State University, 207 Architecture Annex (0113), Blacksburg, VA 24061.
4. Institute for Transport Studies, University of Leeds, Leeds LS2 9JT, United Kingdom.