1. Assistant Lecturer and Ph.D. Student, Dept. of Civil and Environmental Engineering, School of Engineering, Makerere Univ., Technology Rd., P.O. Box 7062, Kampala, Uganda (corresponding author).
2. Assistant Professor, Dept. of Transport and Planning, Faculty of Civil and Geosciences, Delft Univ. of Technology, Stevinweg 1, 2628 CN Delft, Netherlands.
3. Associate Professor, Dept. of Civil and Environmental Engineering, School of Engineering, Makerere Univ., Technology Rd., P.O. Box 7062, Kampala, Uganda.
4. Guest Professor, Dept. of Transport Science, School of Architecture and the Built Environment, KTH Royal Institute of Technology, Teknikringen 72, 1tr, 100 44 Stockholm, Sweden; Professor, Northeastern Univ., Boston, MA 02115.