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Bertha breaks through: Watch the tunnel boring machine’s cutterhead emerge

Breakthrough day is here

The disassembly pit, pictured in March 2017, awaits Bertha, the tunnel boring machine digging the SR 99 tunnel.
WSDOT/Flickr

1:30 p.m.: The cutterhead has stopped spinning, and Bertha’s work is done. The next step is for crews to remove the braces supporting the walls of the pit, which could take several days, but will be visible on the live stream.

12:15 p.m.: Much of the dust is cleared, and live stream on WSDOT’s website shows the cutterhead more clearly than ever.

Several seconds from WSDOT’s live feed show the spinning cutterhead behind braces in the disassembly pit.
WSDOT

11:50 a.m.: We have breakthrough. The live stream shows a spinning cutterhead through the portal to the breakthrough pit—that’s Bertha emerging from the tunnel.

Bertha’s full cutterhead is visible in the disassembly pit
WSDOT

11:45 a.m.: The dust is starting to clear a little, and WDOT’s live stream clearly shows the rubble making way for Bertha.

WSDOT’s live feed shows the cutterhead emerging.
WSDOT

11:30 a.m.: The bottom of the tunnel boring machine’s cutterhead is visible at the site, according to WSDOT, although it’s kicking up a large amount of dust that’s obscuring the view from the live stream.

KIRO 7 has a live camera hovering above the pit, which provides a better context for what’s happening right now.

April 4, 10:25 a.m.: Bertha started drilling through the five-foot-thick concrete wall along the disassembly pit at 8 a.m., and WSDOT has posted a dedicated blog with the live stream.

In updates on Twitter around 10:20 a.m., WSDOT said that some water and soil conditioner from the machine are starting to flow into the pit.

Original post, April 3: Bertha’s had a pretty busy 24 hours. As of Sunday, the tunnel boring machine digging the Alaskan Way Viaduct replacement tunnel was less than 100 feet from the finish line—and on Monday afternoon, the Washington State Department of Transportation (WSDOT) announced that the drill is only 30 feet away and is scheduled to break through Tuesday.

To get to the disassembly pit near Seattle Center, the drill first needs to break through a concrete wall. WSDOT expects that the machine will reach the wall sometime today, and crews will spend the evening prepping Bertha for that last push. It could take several hours for Bertha to dig through the concrete.

Because Bertha’s about to see the light at the end of that tunnel—literally—a live stream is imminent. Both an embedded live stream and a time-lapse camera are posted on the WSDOT project website.

A series of images show Bertha’s progress into the disassembly pit
A series of images from WDOT show Bertha’s agenda for the next few weeks.
WSDOT

Bertha has a busy few weeks lined up. Once the cutterhead breaks through, crews will spend several days removing some braces before the machine proceeds forward. WSDOT says “it will be weeks” until Bertha’s in final position and disassembly can start.

Bertha’s last push has been uncharacteristically ahead of schedule; previous project estimates put the breakthrough date in May and, more recently, mid-April.

The whole project was initially estimated to be completed by December 2015, but project delays, including a two-year halt for repairs from December 2013 through December 2015, have pushed the tunnel’s opening date by a few years.

WSDOT estimates the tunnel should be ready for traffic in 2019. When it’s ready, the tolled tunnel will replace the ailing Alaskan Way Viaduct.

This article has been updated multiple times since its original publication with information about the live video stream.