If you don’t like tunneling projects by the bushelful, then you certainly won’t get too excited about Seattle construction news.
While Seattle most definitely has some shiny new construction projects relating to buildings and can make a splash with the replacement of the world’s longest floating bridge (see what I did there?), transportation projects involving tunneling quite often buries all the other news (I’m on a roll here, aren’t I?).
And while the political back-and-forth of the Alaskan Way Viaduct tunnel makes the news in a flash and cost overruns on any project turns a few heads, one tunneling project plodding along with precision and uncanny ease has Sound Transit excited about the turnaround of its earth-pressure balance tunnel-boring machine, Brenda.
As part of the $1.9 billion (spending money on transit has turned quite vogue in western Washington) U-Link project that will connect Seattle’s relatively new downtown light rail system to the University of Washington campus by 2016, crews must tunnel two lanes between downtown and Capitol Hill and also connect Capitol Hill to the Montlake campus with a different tunneling project.
The 21-foot diameter machine started boring the one-mile tunnel heading from Capitol Hill toward downtown five months ago and just this month popped out from underground ready to go back and do it all over again. Crews extracted Brenda downtown and will now take apart the 679,000-pound mammoth and haul it back to Capitol Hill. Poor Brenda—named after the project manager’s wife—will simply get dropped back into the Seattle earth to keep digging, going south for the second straight time. No rest for the weary here.
Check out this Sound Transit YouTube video of Brenda’s removal.
Brenda, which can eat about 40 feet of dirt and rock each day, is about the length of a football field and is on schedule for completing both tunnels within 18 months—as planned—for tunnel contractor JCM U-Link Joint Venture, consisting of Jay Dee Contractors of Michigan; Frank Collucio Construction Co. of Seattle; and Michaels Corp. of Wisconsin.
Sound Transit has said that dealing with retaining walls on Capitol Hill and dropping just 15 feet below Interstate 5 were both engineering feats they are happy to have gotten past.
The new light-rail line will stretch 3.15 total miles, with the twin-bored tunnels from downtown to a Capitol Hill station and then north from Capitol Hill to a new University station. With U-Link such a tunnel-happy project, two other TBMs are already churning the dirt between Husky Stadium (itself undergoing renovations) and Capitol Hill.
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