1. Associate Professor, Graduate School of Engineering, Hokkaido Univ., N13, W8 Kita-ku, Sapporo 060-8628, Japan (corresponding author).
2. Associate Professor, Faculty of Civil Engineering and Geosciences, Delft Univ. of Technology, 2600 GA Delft, The Netherlands.
3. Professor, Dept. of Urban Management, Kyoto Univ., Cluster C1-3, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8540, Japan.
4. Ph.D. Student, Graduate School of Kyoto Univ., Cluster C1-3, Kyoto-Daigaku-Katura, Nishikyo-ku, Kyoto 615-8540, Japan.