is a Japanese concept for the public use of deep underground, enabled by a 2001 law. It was first thought of in the late 1980s as Japan faced ever increasing land values in the economic bubble

Japanese asset price bubble

The was an economic bubble in Japan from 1986 to 1991, in which real estate and stock prices were greatly inflated. The bubble's collapse lasted for more than a decade with stock prices initially bottoming in 2003, although they would descend even further amidst the global crisis in 2008. The...

, to allow the utilization of heretofore unused deep underground for necessary water and utility ducts

Common utility duct

A common utility duct, sometimes called a common utility conduit, is any structure – above, on, or below ground – that carries more than two types of public utility lines...

 and other city tunnel

Tunnel

A tunnel is an underground passageway, completely enclosed except for openings for egress, commonly at each end.A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal. Some tunnels are aqueducts to supply water for consumption or for hydroelectric stations or are sewers...

s.

However, due to technical difficulties in ventilation, emergency procedures and other safety-related issues and also relatively high cost, no projects utilizing deep underground have been completed as of 2010.

Definition

• Depth greater than 40 meters or
• Depth 10 meters greater than the layer on which deep foundation
  Deep foundation
  A deep foundation is a type of foundation distinguished from shallow foundations by the depth they are embedded into the ground. There are many reasons a geotechnical engineer would recommend a deep foundation over a shallow foundation, but some of the common reasons are very large design loads, a...
  
   rests

In the case of public use, no compensation to the land owner is required.

Projects utilizing the law

• Underground water mains in Kobe
  Kobe
  , pronounced , is the fifth-largest city in Japan and is the capital city of Hyōgo Prefecture on the southern side of the main island of Honshū, approximately west of Osaka...
  
   (Chūō-ku, Kobe
  Chuo-ku, Kobe
  is one of 9 wards of Kobe City in Japan. It has an area of 28.37 km², and a population of 119,768 .The Consulate-General of Panama in Kobe is located on the eighth floor of the Moriyama Building in Chūō-ku.-Related matters:*Port of Kobe*Port Island...
  
  )
  • Project approved on June 19, 2007 (first ever in Japan).
• Tokyo Gaikan Expressway
  Tokyo Gaikan Expressway
  The is a national expressway in Japan. It is owned and operated by East Nippon Expressway Company.-Overview:The name Gaikan refers to the route's status as an outer ring road for Tokyo. The expressway is also referred to simply as Gaikan for short...
  
   (Tōmei Junction - Ōizumi Junction/Interchange)
  • Project status elevated to construction stage on April 27, 2009.

Projects anticipated to utilize the law

• Capacity expansion of Chūō Main Line
  Chuo Main Line
  The , commonly called the Chūō Line, is one of the major trunk railway lines in Japan. It runs between Tokyo and Nagoya, although it is the slowest direct railway connection between the two cities; the coastal Tōkaidō Main Line is slightly faster, while the Tōkaidō Shinkansen is the fastest rail...
  
   (extension of Keiyō Line
  Keiyo Line
  The is a railway line connecting Tokyo and Chiba, Japan, running mainly along the edge of Tokyo Bay. It is operated by the East Japan Railway Company .It provides the main rail access to the Tokyo Disney Resort and the Makuhari Messe exhibition center...
  
   from Tokyo Station
  Tokyo Station
  is a train station located in the Marunouchi business district of Chiyoda, Tokyo, Japan, near the Imperial Palace grounds and the Ginza commercial district....
  
   to Mitaka Station
  Mitaka Station
  is a railway station in Mitaka, Tokyo, Japan, operated by the East Japan Railway Company .-Lines:Mitaka Station is served by the Chūō Main Line, acting as the terminus for all-stations Chūō-Sōbu Line services from , with Chūō Line limited stop services from...
  
  )
• Extension of Tsukuba Express from Akihabara Station
  Akihabara Station
  is a railway station locatedin Tokyo's Chiyoda ward. It is at the center of the famous Akihabara shopping district specializing in electronic goods.-Lines:JR East:* Keihin-Tōhoku Line* Yamanote Line* Chūō-Sōbu LineTokyo Metro:...
  
   to Tokyo Station
• Chūō Shinkansen
  Chuo Shinkansen
  The is a planned maglev line connecting Tokyo, Nagoya, and Osaka, Japan. The only part of the line that exists is the Yamanashi test track, which is currently being extended from 18.4 km to 42.8 km. The line is proposed to connect Tokyo and Nagoya in the first stage in 40 minutes, and eventually...
  
   (a total of 100 km of deep underground track in Tokyo, Nagoya and Osaka areas)
• Hanshin Expressway
  Hanshin Expressway
  The is a network of expressways surrounding Osaka, Kobe and Kyoto, Japan. Operated by , it opened in 1962.Portions of the Hanshin Expressway collapsed during the Kobe earthquake on January 17, 1995. These sections were rebuilt by 1996...
  
   Route 2 Yodogawa-Sagan Line third phase (extension from Toyosaki, Kita-ku, Osaka
  Kita-ku, Osaka
  is one of 24 wards of Osaka, Japan.-Economy:West Japan Railway Company has its headquarters in Kita-ku. Nihon Bussan has its headquarters in Kita-ku. Dentsu and Yomiuri Shimbun have branch offices in Kita-ku. Mazda has an office in the Umeda Sky Building Tower East. Air France has an office on the...
  
   to Hiejima, Kadoma
  Kadoma, Osaka
  is a city located in Osaka, Japan.As of 2010, the city has an estimated population of 128,034 and the density of 10,430 persons per km². The total area is 12.28 km²....
  
  )

External links

• Law on Special Measures for the Public Use of Deep Underground (大深度地下の公共的使用に関する特別措置法 dai-shindo chika no kōkyō-teki shiyō ni kansuru tokubetsu sochihō or 大深度地下使用法 dai-shindo chika shiyōhō)
• Ministry of Land, Infrastructure, Transport and Tourism page on the utilization of deep underground
• Group plans to bury Tokyo's elevated 'shuto'