The Tokyo bay tunnel of the Trans-Tokyo bay highway

The Trans-Tokyo Bay Highway project is the first phase of an ambitious plan to connect Kawasaki and Chiba by a 15-km crossing of Tokyo Bay, The crossing involves a 5-km bridge, a IO-km undersea tunnel, and two manmade islands in the middle of the bay. The construction method for the undersea tunnel must take into account the large external diameter of the primary lining (approx, 14 m); the extremely soft ground under the sea; the extremely high water pressure to which the tunnel will be subjected; and active seismic conditions in the Tokyo Bay area. This paper discusses the state-of-the-art in planning, engineering and construction of the tunnel.