Light rail update: A look at the machines that will dig twin tunnels under Capitol Hill

After a nearly year-long process of designing and manufacturing, Hitachi Zosen Corp. of Osaka, Japan is about to ship one of the giant tunnel boring machines that will dig the tunnels connecting the Capitol Hill light rail station to the University District and downtown Seattle.


Sound Transit says the Hitachi machine is due to be shipped later this month and will be trucked in sometime in early April. The Daily Journal of Commerce reports that the TBM is nicknamed ‘Brenda.’

Sound Transit’s Geoff Patrick says this machine will handle the Capitol Hill to downtown twin tunnels:

The Hitachi TBM will be used for the segment between Capitol Hill and downtown. It will be launched in the third quarter of this year for the first trip. Once that is completed it will be disassembled, returned to Capitol Hill, reassembled and re-launched for the second tunnel.

Brenda (Image: Sound Transit)

This machine will be one of three that will bore tunnels from Montlake, under Volunteer Park and through to Broadway and from Broadway to downtown as part of the $1.9 billion project. You can see the tunneling routes and more about the tunnel boring machines, here.

Brenda’s sisters — pictured to the left and at the bottom of this post — are being assembled in Fife. “The two tunnels between UW and Capitol Hill will be bored concurrently by the two machines in the [Fife photo],” Patrick said.

Tunneling begins from the University of Washington station site near Husky Stadium this summer but isn’t planned to reach Capitol Hill until sometime in 2012. Meanwhile, on Broadway, this tunnel boring machine will begin working its way from Capitol Hill to downtown.

In its latest project update, Sound Transit says the current phase of construction for the Capitol Hill Light rail station involves pouring the concrete slab that forms the bottom of the station. Sound Transits contractor JCM completed the first of five major concrete pours on Saturday, February. 26. It took more than 20 concrete trucks per hour to get the 900 cubic yards of concrete needed to pour the slab, Sound Transit notes.

Sound Transit also reports that excavation of the “TBM retrieval shaft” continues at Pine St downtown next to the Paramount Theater. The shaft has been excavated down to about 20 feet deep and excavation will continue until early summer.

(Image: Sound Transit)

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8 thoughts on “Light rail update: A look at the machines that will dig twin tunnels under Capitol Hill

  1. How on earth are they going to deliver this machine to the Cap Hill construction staging area?! That alone is worthy of a parade!

  2. the old TMNT cartoon. Shredder and his peeps were always traveling underground in these vehicles w/ giant drills on the front. Digging tunnels wherever they went.

  3. The North route for the Light Rail should have followed/intertwined with the I5 corridor north and saved Millions of Dollars.