Underneath Seattle: Steering Bertha

There’s no GPS underground, so how will Bertha, the SR 99 tunneling machine, hit a precise target nearly two miles from her launch point at the south end of downtown Seattle? One of the tunnel boring machine (TBM) operators takes you underneath Seattle to show how it’s done.

[@irvinwittmeier5208]

It takes a real man to be in charge and give all the credit to every one else!;-) nice job

[@StationBambu]

It takes a real feminist to take credit for a real man's accomplishment.

[@artsbest1]

An incredible engineering feat.

[@weedandwine]

Built an 8 mile Cascade mountain rail tunnel 1925 to 1929. Working from each end they met up perfect in the middle. No computers or laser guided controls, just dynamite and shovels. They have some cool stuff nowadays but it must have been much more work back then. That tunnel is still used daily by many trains.

[@riparianlife97701]

The ring is built against a movable sleeve that trails the TBM. And as that sleeve moves forward, it leaves a small space between the outside soils and the outside of the tunnel rings. That appears to be the only chance for settling.

[@riparianlife97701]

If this works out, we need a pair of express tunnels the same size running under I-5 from the 405 to the 405.

[@jrno93]

Docktor Jim thatll take a good 35-50 years

[@dovemfg]

They forgot to mention that it’s powered by a nuclear reactor

[@702Demon]

Does this machine make a disturbingly loud sound when it hits certain rocks?

[@wsdot]

The machine hasn't been used for six years but I don't recall anyone mentioning anything like that while the project was happening.

[@jaredrizzo8343]

Does anyone notice the concrete cracking when they are pushing on it from 2:10-2:11? I'm no expert, but that can't be great as it's damaging the material.

[@irvinwittmeier5208]

Jared Rizzo good eye and i though i was paying attention !;-)

[@iap6647]

Ha, how’d you catch that? I wonder if it’s moisture being pushed out of the concrete from all the pressure being pushed on to it.

[@MIKExDILL0N]

I’m pretty sure that’s just water dripping on it from above. Definitely not a crack.

[@MossPalone]

It does crack sometimes due to the immense pressure the machine applies on the segments.

[@WilliamAlanPhoto]

*sings Every push you make We'll will build a ring...

[@heru-deshet359]

Bet they were paid more than minimum wage.

[@xx5zi]

Cheap labor is no bargain.

[@Levi-qu8yl]

What if a car gets in an accident inside the tunnel and explodes? Will the fire spread and trap everyone inside, ultimately killing them. Doesn't seem so safe.

[@3DGEM3]

Levi are you serious, tunnels are nothing new. This one is only two miles, Switzerland just finished a thirty mile tunnel, I'm sure humans know how to build safe tunnels.

[@wsdot]

Safety is our top priority. The tunnel will have state-of-the-art ventilation and fire suppression systems, as well as emergency exits throughout the structure. If a fire were to occur in the tunnel, sprinklers would help the fire department fight the fire and keep the temperature down while the ventilation systems remove smoke. Read more about tunnel safety in this fact sheet: www.wsdot.wa.gov/Projects/Viaduct/Media/Default/-NewDocuments/Library/2016_0223_TunnelSafety_nm.pdf

[@Jemalacane0]

Use "ABC" chemical fire extinguishers.