1. Professor, Dept. of Environmental Engineering Sciences, Univ. of Florida, 218 Black Hall, Gainesville, FL, 32611 (corresponding author).
2. Doctoral Candidate, Dept. of Civil and Environmental Engineering, Louisiana State University, 3418 CEBA Building, Baton Rouge, LA 70803.
3. Research Professor, Dept. of Roads and Transportation Engineering, Bari Polytechnical Univ., Bari 70125, Italy.