Under surveillance: Elaborate monitoring program watches downtown Seattle as Bertha drills

Under surveillance: Elaborate monitoring program watches downtown Seattle as Bertha drills
"Cyclops" moves its eye back and forth, silently scanning a downtown Seattle building, making sure that nothing moves.

In this era of National Security Agency jitters, the strange lens has startled at least one guest at the Alexis Hotel.

Hotel staffers had to explain that Cyclops is part of a vast array of devices - one of the largest such monitoring networks ever placed in the U.S., installers say - beaming real-time data on nearly 200 structures that are about to have a giant drill carve a 1.7-mile tunnel under many of them.

The $2.05 billion tunnel is the heart of the Alaskan Way Viaduct Replacement Program, whose total cost is a staggering $3.14 billion. Seattle has seen few projects this transformative since the early 20th century, when workers used water cannons and steam-powered claws to slice Denny and Jackson hills and fill in the waterfront with their dirt and debris.
Now contractor Seattle Tunnel Partners will grind through this very same waterfront landfill to start creating an underground highway.

The men who took down Denny Hill didn't have today's lasers and satellites to guide them. But even high-tech gadgets don't shield big public projects from nasty, expensive surprises.

Which is why, for the next 14 months, data from Cyclops and kindred devices will be transmitted to a crew of engineers, technicians and surveyors from Paris-based contractor Soldata, who will be gathered on the second floor of an old garment factory kitty-corner from Safeco Field.

Also watching for trouble will be another task force that meets each day at 6 a.m. in "T1," the high-powered-sounding name of a construction trailer at the tunnel launch pit, near CenturyLink Field. There, Seattle Tunnel Partners will combine the above-ground data with performance readings from within the mammoth tunnel-boring machine known as Bertha, to guide Bertha's course and speed.

Even with all those watchers and that technology, Linea Laird, the Washington State Department of Transportation (WSDOT) engineer in charge of the viaduct replacement project, doesn't discount the risks - from the "incredibly challenging soils" to the dense urban environment under which Bertha will grind.

But, she said, "I think this project is going to be really successful." The state is two years into the overall project and - when it comes to the work completed so far - "we are on time and on budget."

Next comes the drilling. Bertha's job is to chew out a double-decker highway tube that will pass under parts of the viaduct itself, and below several high-rises and near the landmark Pike Place Market.

It will be up to Laird's team and Seattle Tunnel Partners to make sure things go smoother than for King County Metro's Brightwater sewage tunnel near Bothell, or for Seattle's Beacon Hill Sound Transit light rail tunnel. Work on Brightwater stopped for months in 2009 when a tunnel-boring machine was damaged. At Beacon Hill, construction worker Michael Merryman died in a 2007 accident, and the digging opened "voids" in the earth and caused house foundations to crack.
Seattle Tunnel Partners says it's deploying lessons from those projects to avoid problems on the tunnel to be carved by Bertha's 57.5 foot-diameter rotating cutting head. One of the Seattle Tunnel Partners is Tutor Perini Corp., a Sylmar, Calif.-based general contractor. The other member of the joint venture is Dragados USA, whose Spanish parent company successfully bored a nearly 40-foot-diameter tunnel beneath the famed La Sagrada Familia cathedral in Barcelona.

Now, it's downtown Seattle's turn.

(Bertha's journey)

Setting out south of King Street near CenturyLink Field, Bertha will start slowly, going only about six feet a day as "she" bores through the fill along the waterfront where the water table is high and the soils particularly unstable.

Here, the project team has fortified both the soil and some of the buildings above. Techniques range from injecting grout into the soil to building subterranean support structures near Yesler Way, where Bertha will burrow beneath the viaduct itself. (Officials have not yet decided whether they'll close the elevated roadway while Bertha tunnels underneath).

To further protect property along the route, subcontractor Soldata, a geotechnical monitoring company, has installed the sensing equipment on the viaduct and outside and inside nearly 200 buildings. It also has placed more than 700 monitoring instruments in streets and sidewalks along the tunnel route.

"Monitoring points" on the buildings, ranging from the size of a nail head to a 6-inch square prism, already are being read by automated survey machines, the Cyclopses, which are collecting data around the clock.

Gauges that will measure changes in the size of existing building cracks also have been installed in some buildings. If any movement is detected, Department of Transportation officials say, the tunneling team will be alerted immediately.

Complementing these readings will be satellite images. Pictures were taken before construction to create reference points, and more will be taken as Bertha advances. This will allow crews to monitor the tunnel route, as well as areas beyond the instrumented monitoring area.

(The watchers)

Checking readings from Cyclopses at the old garment factory, up to 20 people will use cell phones and laptops hooked up to Soldata's database management program called Geoscope.

The size of this team likely will decrease as the project goes on and the team gets more comfortable with operations, said Seattle Tunnel Partners Project Manager Chris Dixon. But Soldata, whose North America West office is in Seattle, says this is one of the largest such monitoring operations ever undertaken in the country.

In case of power or cellular outages, the readings will be backed up locally, as well as in Paris and at Soldata's East Coast office in the Pittsburgh area.

Some of the Soldata data also will be fed to Seattle Tunnel Partners' launch-pit trailer. There, up to eight experts on the task force also will keep a close eye on readings from Bertha itself, such as grouting volumes and the weight of the excavated material. A software program called Arigatya will display data and recommend how to tweak what Bertha does.
These precautions, along with several years of outreach by WSDOT, have allayed the concerns of Jenne Neptune, general manager of the 121-room Alexis Hotel.

Initially, Alexis staff members worried that the early-20th-century buildings that house the hotel would be susceptible to settling, but those concerns dissipated after frequent conversations with Department of Transportation representatives over the last several years.

By the time Bertha reaches the Alexis, she'll be about 150 feet below ground.

"I think we feel very comfortable that the impact is going to be pretty much none, minimal," Neptune said.

Just to make sure, the transportation department recently wrote to Neptune and others who live and work along the tunnel route to remind them that the structures could settle some, and that it's possible they'll "hear some noise or feel slight vibrations." Officials asked how they could contact building managers day or night should their structures start to settle.

"Everyone we've worked with has been so helpful," said Neptune, "and they're so communicative."

Nor is Ron Mayers on pins and needles about the coming of the world's largest tunnel-boring machine.

His family owns a pair of century-old office buildings, the six-story Western and Polson buildings at Columbia Street and Western Avenue. These will be the first buildings that Bertha tunnels under.

Mayers doesn't even plan to monitor the situation when Bertha is below. He'll leave the watching to the professionals, who will have equipment that is "far more sophisticated and accurate" than the observations of a layman such as himself.

This is not to say the 14 months of drilling will necessarily go without a hitch, said Laird, the 31-year WSDOT veteran who leads the project.

There will be challenges, she said, adding the key is "how we communicate these challenges. It's really just managing the expectations of a project as complicated as this."

But still one wonders what would happen if Bertha, like one of the Brightwater drills, gets stuck.

Would the earth above Pike Place Market or a high-rise have to be opened up? Or could Bertha be backed out of the tube? That would be hard to do, since the cutter head is bigger than the rest of Bertha. Laird said the team would instead work to move Bertha ahead, though the machine could be cut into smaller pieces if need be.

Laird said the plan is to keep Bertha moving, and "drive (her) right out the other end as anticipated on Sixth Avenue."
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