1. Graduate Research Assistant, Dept. of Civil Engineering, Univ. of Arizona, Tucson, AZ 85712-0072.
2. Professor, Dept. of Civil and Environmental Engineering, Arizona State Univ., Temple, AZ 85787-5306.
3. Research Associate, Dept. of Highway Research, The Korea Transport Institute, 2311 Daehwa-dong, Ilsan-gu, Goyang-si, Gyeonggi-do 411-701, Republic of Korea.