1. Transport Research Laboratory, Crowthorne, Berkshire RG45 6AU, United Kingdom
2. Department of Rural and Urban Planning, University of Zimbabwe, Box MP167, Mount Pleasant, Harare, Zimbabwe
3. Association of State Road Transport Undertakings, 7/6 Sirifort Area, New Delhi 110 049, India
4. Department of Civil Engineering, University of Dar es Salaam, Box 35131, Dar es Salaam, Tanzania