1. Division of Field Engineering for the Environment; Faculty of Engineering; Hokkaido University; Sapporo Japan
2. Department of Civil Engineering; School of Engineering; The University of Tokyo; Tokyo Japan
3. Division of Computer Science and Information Technology; Graduate School of Information Science and Technology; Hokkaido University; Sapporo Japan
4. International Center for Urban Safety Engineering (ICUS); Institute of Industrial Science; The University of Tokyo; Tokyo Japan