| SR 99 tunnel boring machine |
Manufacturer: Hitachi Zosen Corp. in Japan
Size: 326 feet long, 5,500 tons
External diameter: 57.3 feet
Schedule: Crews started manufacturing the tunnel boring machine in late 2011. It will be fully assembled and tested in Japan later this year, then disassembled and shipped to Seattle in early 2013. |
Seattle Tunnel Partners, our design-build contractor for the SR 99 tunnel, selected Hitachi Zosen Corporation to supply the machine that will construct the tunnel. Hitachi Zosen is responsible for designing, manufacturing, assembling, testing and commissioning the 57-foot-diameter machine, as well as training Seattle Tunnel Partners’ personnel.
Located in Osaka, Japan, Hitachi Zosen has successfully built a number of large-diameter tunnels including the Tokyo Metropolitan Expressway (45 feet in diameter) and the Tokyo Bay Highway Tunnel (47 feet in diameter). They supplied the tunnel boring machines for Sound Transit’s Link Light Rail Capitol Hill Station to Pine Street segment. Hitachi Zosen has manufactured more than 1,300 tunnel boring machines.
How does a boring machine work?
A tunnel boring machine (called a TBM) is a cylindrical machine with a cutter head at the front. It contains a system to mine the soil and transport it out of the tunnel. As the soil is removed, pre-cast concrete segments are placed to form the tunnel structural liner. View our boring machine animation on YouTube or download a Windows Media Player version.
This boring machine was used to dig the Calle M30 tunnel in Madrid. The red and yellow circles are the cutter heads.
The back end of the Calle M30 tunnel boring machine.