1. Lecturer in Civil Engineering, Griffith School of Engineering, Gold Coast Campus, Griffith Univ., QLD 4222, Australia.
2. Associate Professor, Dept. of Transportation Engineering, College of Urban Sciences, The Univ. of Seoul, 90 Jeonnong-dong, Dongdaemun-gu, Seoul 130-743, Korea.
3. Associate Professor, Dept. of Transportation, Chonnam National Univ., San 96-1 Dundeok-dong, Yeosu-si, Jeollanam-do 550-749, Korea (corresponding author).