title: Deep underground
text: # Deep underground
  
  Deep underground (大深度地下, dai-shindo chika) 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, to allow the use of heretofore-unused deep underground for necessary water and utility ducts and other city tunnels.
  
  However, due to technical difficulties in ventilation, emergency procedures and other safety-related issues and the relatively high cost, no projects using 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 rests
  
  In the case of public use, no compensation to the land owner is required.
  
  ## Projects using the law
  
  * Underground water mains in Kobe (Chūō-ku, Kobe)
     * Project approved on June 19, 2007 (first ever in Japan).
  * Tokyo Gaikan Expressway (Tōmei Junction - Ōizumi Junction/Interchange)
     * Project status elevated to construction stage on April 27, 2009.
  
  ## Projects anticipated to use the law
  
  * Capacity expansion of Chūō Main Line (extension of Keiyō Line from Tokyo Station to Mitaka Station)
  * Extension of Tsukuba Express from Akihabara Station to Tokyo Station
  * Chūō Shinkansen (a total of 100 km of deep underground track in Tokyo, Nagoya and Osaka areas)
  * Hanshin Expressway Route 2 Yodogawa-Sagan Line third phase (extension from Toyosaki, Kita-ku, Osaka to Hiejima, Kadoma)
  