1. Dept. of Highway and Transportation Engineering, Al-Mustansiriyah Univ., 10053 Baghdad, Iraq; Ph.D. Candidate, Dept. of Civil Engineering, Univ. Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia (corresponding author).
2. Professor, Dept. of Civil Engineering, Univ. Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia.
3. Assistant Professor, Dept. of Civil Engineering, Univ. Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia.
4. Lecturer, Dept. of Civil Engineering, Univ. Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia.