Bertha is on pace to emerge into daylight in a few days and push its way into a pit in South Lake Union, where the one-time world’s biggest tunneling machine will be cut apart and trucked away.

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Bertha has made it to the finish line.

The celebrity boring machine’s arrival near Seattle Center, some 29 months late, guarantees a Highway 99 tunnel bypassing downtown. And the Alaskan Way Viaduct that roars over Seattle’s bay front, while affording an Olympic Mountains view to the common people on wheels, will truly be demolished.

Within a few days, the giant drill likely will nestle its cutterhead against a concrete retaining wall, grind another 5 feet to daylight and push into a cube-shaped vault near Thomas Street and Sixth Avenue North to be cut apart and trucked away over the next several months.

The 9,270-foot dig ranks among the trickiest megaprojects in history: Bertha was the largest drill on Earth when it entered the ground nearly four years ago, and it pushed through glacial soils that were abrasive and sloppy.

“You see it, and you’re just kind of overwhelmed by what humans can do, what they can accomplish,” said former Gov. Chris Gregoire, who ended an eight-year, $160 million process quagmire by proposing the giant tunnel in January 2009 to replace the old viaduct.

This week she reiterated the benefits of replacing the earthquake-imperiled viaduct, and delivering “a first-class waterfront” for public use after the tunnel opens to traffic in early 2019.

Nonetheless, she fell short on two promises. The state demolished only the Sodo half of the viaduct by Gregoire’s self-imposed deadline of 2012 despite the purported safety hazard.

And after then-Mayor Mike McGinn predicted in 2010 that Seattle residents would get stuck paying cost overruns, Gregoire argued, “It’s a hypothetical; it has no bearing. There’s no reason to expect cost overruns.”

As it turns out, residents statewide will almost certainly cover, through gas taxes, some fraction of a potential half-billion dollars in delay costs.

Losses could have been far worse, had Bertha stalled 200 feet below the Pike Place Market, for example, instead of along the waterfront lot where it overheated in late 2013. Even there, the industry’s top engineers, piledrivers and lifting specialists barely managed to create an access vault stronger than Seattle’s groundwater pressure to remove and fix Bertha’s damaged parts.

Gary Brierley of Denver, a famed tunnel engineer known as Dr. Mole, said the contractors at Seattle Tunnel Partners (STP) and drilling-machine builder Hitachi Zosen went beyond the call of duty by reviving Bertha without an assurance of being repaid.

Bertha timeline

How did we get here? A look back on Seattle’s tunnel machine Bertha


More on Bertha

Digging has been nearly flawless since last April 29, when Bertha passed under the viaduct at Yesler Way.

“Quite frankly, I was not at all certain that even after they fixed it, the machine would make it,” Brierley said. “That ground is phenomenally unforgiving. Over time, this is going to go down as a major accomplishment in the tunneling industry.”

Like the Big Dig in Boston, he said, “the residents of Seattle 10 years from now are going to be very happy they have the SR 99 tunnel,” he said. “Go to Boston and try to find someone who wants to give the Big Dig back.”

McGinn says he’s glad Bertha finished, rather than stalling again and failing, and that people will appreciate a viaduct-free shoreline.

But like many environmentalists, he still thinks a $2 billion-plus underground highway was the wrong choice in an age of global warming, and that it won’t even improve traffic congestion.

“The Nisqually earthquake was in 2001,” McGinn said. “Imagine if we’d spent that intervening time to build transit to West Seattle and Ballard, instead of getting hung up on the highway.

“It’s a missed opportunity.”



Carving Bertha

The journey will end with Bertha’s front end — at least 4 million pounds — being carved like a wheel of cheese into hundreds of smaller portions to be trucked away.

That is time-consuming work, done within the tight vault using torches, scaffolds and power tools. Pieces will be sliced vertically and extracted at awkward angles.

Exact positions of these cuts are still being reviewed, said STP manager Chris Dixon. Engineers must locate the center of mass for each steel piece to determine where fastening loops should be welded, for a balanced lift.

That’s different from the repair operation in 2015, when the cutterhead, bearings and drive axle were lifted to the surface as one piece by a red Mammoet tower crane. Dixon said conventional cranes lifting smaller pieces will be cheaper than another tower crane, which would require additional land, ground reinforcement and assembly time.

The steel cutting disc will be carved into eight sections, one for each spoke. Those sections then must be further chopped to meet the 20-ton limit for transport on city streets.

To remove the entire front end will take four to five months, said Dixon. The rear two-thirds of the 330-foot-long Bertha, including catwalks and utility lines, will be pulled nearly two miles, out the tunnel’s south end in Sodo.

The same union workers who operate Bertha now will disassemble the machine while road-deck construction continues to the south, Dixon said, employing 600 people.

The job took so long that some people who started as apprentices have advanced to journeymen, said Lee Newgent, executive director of the Washington State Building Trades Council.

Pieces that many Puget Sound-area residents have come to know — the 57-foot, 4-inch diameter cutting disc, the ring-shaped bearing, the white steel shell — will probably be melted and recycled. One possible destination is the Nucor steel mill in West Seattle, said Hitachi Zosen.

Other parts, including the 24 giant electric motors deep inside the machine and the movable arms that position the concrete tunnel rings in back, should be reusable. So should miles of hoses, wires and conveyor belts.

Hitachi Zosen says it would gladly consider leaving part of Bertha in Seattle as a public artifact. The Museum of History & Industry (MOHAI), “is exploring options about that, in some way,” executive director Leonard Garfield said Wednesday.



The road ahead

The end of drilling doesn’t mean the project is nearing completion. The double-decker road, lights, ventilation and signals must be finished inside the tunnel over the next year and a half.

The tunnel has no downtown or Belltown exits, so commuters who now exit at Seneca Street or Western Avenue will have to find new routes. An estimated 35,000-plus vehicles per day are forecast to use the new waterfront boulevard.

But for about two years in 2019-20, even that road will be choked by closures and detours to demolish the old viaduct and build the surface boulevard.

Toll rates are undetermined. The state hopes that tolls would cover $200 million in construction costs plus tunnel operations, but planners face a dilemma — a rate high enough to do all that might divert some traffic and worsen congestion.

An advisory committee previously suggested a $1.25 peak rate, rather than $3, so motorists would stay on Highway 99. A financial study of toll income is due within weeks, and the state Transportation Commission will start planning from scratch.

Among the project’s detractors, Thom Neff, a Boston megaproject executive turned consultant, made a bold prediction during the tunnel machine’s repairs in 2015: “Given the evidence to date, my opinion is that Bertha will not finish the tunnel, but that some other machine, or process might.”


But he accurately called the work “beyond precedent” and said it would go over budget.

“I may have to eat some crow,” Neff said this week. But he argued that Hitachi Zosen essentially built a new machine during repairs by making the front end tougher.

“Originally they didn’t understand what they were getting into, but they figured it out,” he said.

Soichi Takaura, Hitachi Zosen’s general manager of tunnel-boring machines, has said Bertha as launched July 30, 2013, would have gone all the way to South Lake Union if it hadn’t struck a steel pipe Dec. 3 that year. It overheated and failed three days later.

In written answers to The Seattle Times, the Japanese company lamented that rather than settle differences in “a businesslike manner,” the parties are litigating, an unusual spot for Hitachi Zosen.

“The fact that the repaired TBM (tunnel-boring machine) was able to complete the remainder of the tunnel as quickly as it did, after tunneling resumed, is testimony to the fundamental soundness and durability of the TBM,” the firm said.

Bertha’s original quality is a key issue being disputed among lawyers and technical witnesses, in the case of who will pay what shares of $480 million in STP damage claims against the state or insurers.

The Washington State Department of Transportation (WSDOT) expects to spend another $149 million for its own engineers, administration and land costs due to the delays.

In the unlikely event WSDOT were completely defeated in court and had to pay $500 million or so in overruns, that would equate to roughly 1 cent a gallon in gas taxes for two or three decades.

But if WSDOT only spends the $149 million, that could be handled by shifting items in future budgets, said House Transportation Committee Chairwoman Judy Clibborn, D-Mercer Island.

“I feel confident in the end we’re going to be OK, we’re not going to be slammed with billions,” she said.

Asked about the overruns, Gregoire said she couldn’t comment because she’s stopped following the project closely four years ago since leaving office.

Gov. Jay Inslee said litigation is impossible to predict, but he believes the state will prevail while Hitachi Zosen and STP end up arguing about who pays for Bertha’s delay and repairs.

State analysis in 2008 guessed a huge single tunnel might be $800 million cheaper than a more routine project with smaller twin tubes — a projected savings that could be partially erased.



Future Berthas

Will there be another Bertha?

Hitachi Zosen says it would still consider other huge bores. Its rival Herrenknecht of Germany drilled through soft earth in Hong Kong last year using a machine 5 inches wider than Bertha, and previously built a 62-foot machine for a Russian project that was canceled.

But with every foot of diameter, the soil volumes, torque to spin the cutter, and the drill’s own weight grow geometrically.

“I’m not sure they can get much bigger,” said Mark Woodson, of Flagstaff, Arizona, past president of the American Society of Civil Engineers (ASCE). Besides the bulk, larger drilling machines lead to more conflicts with utilities, and more risk of delays, he said.

Only one mega-tunnel is even being discussed in North America. A 60-foot-wide Interstate 710 tube near Los Angeles is listed as “under study,” in a national roster kept by the Underground Construction Association.

Neff, the Boston consultant, has criticized that proposal. Highway 99 demonstrated that mega-tunnels cost more and take longer than boosters advertise, he said. Perhaps more crucial is a philosophical shift in cities toward mass transit, which requires less space, he said.

The ASCE’s latest report card gives U.S. bridges a C+ and roads a D rating. Much of this is Eisenhower-era infrastructure that’s crumbling, not only in the U.S., but in Europe, said Woodson.

Elevated roads are no longer welcome in cities, which makes tunneling attractive, Woodson said.

“I think we’re going to see more of this in the future. Hopefully we’re going to use this for purposes in addition to cars,” he said. “Light rail, commuter rail, mass transit.”