[1] Univ Botswana, Fac Engn & Technol, Dept Civil Engn, Gaborone, Botswana
[2] Natl Univ Malaysia UKM, Fac Engn, Dept Civil Engn, Selangor, Malaysia
[3] Univ Johannesburg, Fac Engn & Built Environm, Dept Civil Engn Technol, Johannesburg, South Africa