“Tokyo underground: taking property development to new depths: With demand for commercial and residential space increasing on the surface in Tokyo, developers are exploring new ways to utilize space underground”, by Jun Hongo
“Confident that space under Tokyo can be better utilized, the government has shown signs it is finally ready to tackle the problem. With space in the capital becoming difficult to find, the Diet passed a new law in 2001 on the use of daishindo (extreme underground), or the areas located below 40 meters.
Under the law, developers seeking to create public-service grids such as roads, subways and sewage systems can to some extent work freely under that depth in certain areas in Kanto, Chubu and Kinki. Such areas are described as “a valuable space” on the land ministry’s website. Developers can also skip negotiations with landowners and construct a route that requires the shortest distance.
Developers have already taken advantage of the 40-meter rule, and a new water-pipe system in Kobe is scheduled to be completed next year. Because it is located more than 40 meters below ground, construction costs have been cut by ¥2 billion and the project is expected to be finished five months ahead of schedule.”
- 大深度地下の公共的使用に関する特別措置法（平成十二年五月二十六日法律第八十七号） Special Measures Law on the public use of deep underground (2000 years May twenty-six days law eighty-seventh issue)
- Japanese Wikipedia page for 大深度地下 （だいしんどちか） (daishindo-chika)
- シミズの大深度地下開発への取組み Shimizu’s deep underground (dai-shindo chika) development efforts