Let’s give these tunnel ideas a hand
While Bertha sits stuck, Seattle’s engineers are coming out of their garages with ideas to finish the Highway 99 tunnel.
Seattle Times staff columnist
One thing I love about Seattle is its tradition of “garage engineers” — those technical tinkerers, cultivated here first by Boeing, who moonlight from their scientific day jobs to try to make the city a better place.
Lately these volunteers have focused their magnifying glasses on a vexing question: What should we do about Bertha?
The official plan is: Fix it (then proceed to multiple rounds of litigation.) But since the world’s largest and lamest tunneling machine broke down in December, I have received about a dozen back-of-the-napkin proposals for other ways the state might salvage its tunneling project.
Some came from real engineers (featuring diagrams for grout curtains and so forth), and some not. The tunneling companies are going with their fix-it plan. If that doesn’t work, consider these “plan Cs.” From the people.
One with a Luddite appeal comes from an “armchair miner” in Kenmore. He’s actually an electrical engineer, but has a passion for old mines (seriously, that’s his hobby.) He got to wondering: If Bertha won’t work, why can’t people dig the tunnel?
“Some 500 modern miners could dig the tunnel using modern tools while Rube Goldberg ‘Bertha’ is disassembled, studied, fought over, etc.” he proposed.
He pointed out the contractor is hiring miners to dig special shafts to service Bertha. How about they dig the tunnel instead?
It sounds far-fetched, but some tunnels are still dug this way. In 2013, miners using machines called “road-headers” completed two three-fourths-of-a-mile-long highway tunnels in Devil’s Slide, Calif. They used modern stabilizing techniques, but the digging was old-school.
The problem for us is that our tunnel is both huge and deep. There’s so much groundwater pressure 200-feet down that tunneling with human crews would mean first pumping out “rivers of water,” as one engineer described it.
Former state transportation director Doug MacDonald said he once oversaw a tunnel project in Boston in which the drill couldn’t complete the job. Workers really did step in to finish with “an excavator, shovels and old-fashioned timber supports.”
“But that was a 14-foot diameter tunnel,” he said. “This one is 57 feet. It would take forever to do this one by hand.”
True, but forever might be better than never? I would also point out, again, that under downtown Seattle there is a mile-long, 30-foot diameter, 100-foot-deep train tunnel that was dug in a year and half by 350 workers with pickaxes and wheelbarrows. In 1904.
Another idea was sent in by multiple readers. Bertha cost $80 million new, but it will allegedly cost $125 million to dig her up and fix her. So why not order a new Bertha and drill from the opposite end?
“Then we avoid the possibility of discovering next March that Bertha is a lemon,” one proposal concluded.
Said MacDonald: “Now that’s a crazy idea that might not be totally crazy.”
Something similar worked a few years ago on the Brightwater sewage tunnel. After a drill broke down, the tunnel was finished from the other end in what was called “a tough, high-stakes decision.” Getting a new Bertha — named Greg? Christine? — would likely take a year. It would need a launch pit and would also have to be dug out after it tunneled up to a busted Bertha.
“Everyone believes they’ll be able to fix the machine,” a spokesman for the state demurred. “That’s the plan. So nobody’s entertaining backup ideas.”
I’m glad the people are. This project needs all the backup it can get.
Speaking of that, did you read how the guy who runs the tunneling firm Tutor Perini is lawyering up to stick us with the cost overruns? He seemed a lot more confident than our guy from the state. Probably because he knows he has better lawyers.
Garage engineers are cool. But it’s 2014. What Seattle really needs are some garage courtroom sharks.
Danny Westneat’s column appears Wednesday and Sunday. Reach him at 206-464-2086 or firstname.lastname@example.org
About Danny Westneat
Danny Westneat takes an opinionated look at the Puget Sound region's news, people and politics. Send tips or comments to email@example.com. His column runs Wednesday and Sunday.
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