1. Associate Transportation Engineer, Dowling Associates, Inc., 428 J St., Suite 500, Sacramento, CA 95814.
2. Professor, Dept. of Civil and Environmental Engineering, Univ. of Tennessee, Knoxville, TN 37996 (corresponding author).
3. Professor, Dept. of Civil, Construction, and Environmental Engineering, North Carolina State Univ., Raleigh, NC 27695-7908.
4. Associate Professor, Dept. of Statistics, Univ. of Tennessee, Knoxville, TN 37996.