1. Associate Research Engineer, Texas A&M Transportation Institute, College Station, TX 77843.
2. Senior Transportation Engineer, California Dept. of Transportation, 1120 N St., Sacramento, CA 95814.
3. Transportation Engineer, Texas Dept. of Transportation, 9500 N Lake Creek Pkwy., Austin, TX 78731.
4. Research Engineer, Texas A&M Transportation Institute, College Station, TX 77843 (corresponding author).