Gadgets will keep Seattle buildings safe during tunnel dig
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SEATTLE -- Workers are getting ready to dig a massive tunnel underneath downtown Seattle as part of the Alaskan Way replacement project, and transportation officials hope some new high-tech gadgets will keep the city's historic buildings from being damaged.
Crews won't start digging the new tunnel for a few months, but Washington State Department of Transportation officials are already installing high-tech measuring devices on dozens of downtown businesses. The gadgets are part of a $20 million plan to protect the buildings while the tunnel is being dug.
When the enormous tunnel boring machine moves underneath the city, it will rattle the ground and buildings as it goes by, and that could create dangerous sinkholes.
That's what WSDOT officials hope to avoid, and that's why workers are already drilling a 200-foot-deep hole on First Avenue to install sensitive measuring devices to guard against giant unintended gaps underneath the buildings.
"We want to detect those early so we can deal with them at the point of source down deep before it has any chance of doing any damage -- architectural or cosmetic damage -- to the buildings," said Matt Preedy, the tunnel project's deputy administrator.
The devices being installed now will twirl every few seconds, aiming their lasers at hundreds of tiny reflectors that are precision-mounted on 200 buildings. The lasers will be able to detect if a building moves even an inch as the boring machine moves underneath.
What workers want to avoid is what happened when a tunnel was dug on Beacon Hill. That project damaged some buildings and caused headaches for homeowners, who were later compensated millions of dollars by the contractor.
Crews won't start digging the new tunnel for a few months, but Washington State Department of Transportation officials are already installing high-tech measuring devices on dozens of downtown businesses. The gadgets are part of a $20 million plan to protect the buildings while the tunnel is being dug.
When the enormous tunnel boring machine moves underneath the city, it will rattle the ground and buildings as it goes by, and that could create dangerous sinkholes.
That's what WSDOT officials hope to avoid, and that's why workers are already drilling a 200-foot-deep hole on First Avenue to install sensitive measuring devices to guard against giant unintended gaps underneath the buildings.
"We want to detect those early so we can deal with them at the point of source down deep before it has any chance of doing any damage -- architectural or cosmetic damage -- to the buildings," said Matt Preedy, the tunnel project's deputy administrator.
The devices being installed now will twirl every few seconds, aiming their lasers at hundreds of tiny reflectors that are precision-mounted on 200 buildings. The lasers will be able to detect if a building moves even an inch as the boring machine moves underneath.
What workers want to avoid is what happened when a tunnel was dug on Beacon Hill. That project damaged some buildings and caused headaches for homeowners, who were later compensated millions of dollars by the contractor.
And so does "big dig part deux" begin. Hold onto your seats, gonna be a bumpy ride
The contractor on Beacon Hill---Obayashi. A bunch of dirtbags. Lots of shortcuts.
@bagsofdirt As someone who worked on that project I can wholeheartedly agree with your statement.
Would it have been cheaper to bore two tunnels using a smaller tunnel boring device instead of the "worldâs largest" one?
 @timdog no thats twice the work
@Jaaee Howuthinkigotthat Teeaa @timdog And twice the risk of settlement
They will not keep anything safe, only reveal when the drilling is destroying existing structures.
 @contraryjim What they WILL do is detect the slightest movement of the building/soil - in time to take the corrective measures needed to prevent a problem.
You know, anybody who has taken the Seattle Underground Tour can tell you that the waterfront is largely made up of sawdust and Denny Regrade fill. Is this REALLY the kind of terrain you want to put a tunnel through?
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Oh well. Speaking as a native of Tacoma and the toll bridge that our friends and neighbors in the Imperial Emerald bequeathed us a few years ago, well, good luck with that. *snort*
@svensson the tunnel will be well below the "sawdust"...much like the rail tunnel that already exists
@madminer15Â That's correct. The new tunnel, except for the entrance, will be well below the fill dirt laid down by the city's forefathers. And along much of the route, it will be 200-250 feet below the streets. Watch my story updated for 6pm.
please build a suspended roadway ABOVE ground at 1/20 the cost. do we really have billions to throw away right now on this silly tunnel in a tsunami zone?
@dorimonsonfan Except this isnt in a tsunami zone.
@dorimonsonfan Construction is well underway. Tunnel boring commences in June.
@dorimonsonfan give it up dori we're well past that now