1. Transportation Analyst, Oregon Dept. of Transportation, 555 13th St. NE Ste 2, Salem, OR 97301.
2. Associate Professor, Texas A&M Univ., CE/TTI 301-A, 3136 TAMU, College Station, TX 77843 (corresponding author).
3. Associate Professor, Texas A&M Univ., CE/TTI 301-G, 3136 TAMU, College Station, TX 77843.