ABSTRACT
This paper presents an overview of the underground space use in Japanese large cities where people are living very densely. Due to the limited available land in those cities, it is becoming very difficult to acquire the land required for infrastructure on surface. Also, in recent years environmental concern has become vital issues for people including general public who have not direct stake. Therefore, underground has been used as essential space for infrastructure in recent years. Even in the case that underground alternative selected for the reason of minimum impact on environment and the community around the project, strict constraints such as restricted ground settlement, limited construction space are imposed. To cope with those difficulties more sophisticated technologies are needed in densely populated large cities. The paper describes about the special technical aspects pertaining to urban underground construction works, introducing major urban underground projects and new technologies employed in Japan.
The paper also describes the new legal system employed to carry out underground project without consent of landowners in special condition.
