Becoming Bertha: the journey begins for the world’s largest tunneling machine

Bertha’s Twitter profile photo. More photos of her and construction in Seattle are posted
regularly on Flickr. A 10-foot-long interactive model of Bertha is on
display at Milepost 31, the project’s information center in Pioneer Square.
For more information about the SR 99 Tunnel Project, visit
Before you buy a car, you take it for a spin to see how it runs. 

Same goes for the world’s largest-diameter tunneling machine. With that in mind, leaders from the SR 99 Tunnel Project flew to Japan this week to visit Bertha, the five-story tall behemoth that will begin tunneling beneath downtown Seattle next summer.

They spent the day at the Sakai Works factory in Osaka, watching major components of the $80 million machine rotate, extend, retract and move. The goal? Make sure Bertha – whose name was chosen earlier this month as part of a contest for school-aged kids across Washington – is running smoothly before she boards a ship to Seattle.

“This machine is incredibly innovative,” said Linea Laird, WSDOT’s administrator for the Alaskan Way Viaduct Replacement Program. “Using technology like this allows us to create a new highway 99 while keeping the viaduct open to traffic.”

With so much riding on Bertha, it’s no wonder Laird and others made the long trip. Seattle Tunnel Partners, WSDOT’s contractor for the project, will authorize shipment of the machine after testing is completed next month. Crews will then prepare the machine for its eventual departure to Seattle.

They will spend the early part of next year disassembling Bertha into 41 separate pieces – the largest weighing up to 900 tons – and loading them onto a single ship. After a month-long trip across the Pacific Ocean, Bertha will land at the Port of Seattle’s Terminal 46, to the west of CenturyLink Field. Crews in Seattle will transport the pieces a few hundred yards east to an 80-foot-deep pit where the machine will be reassembled and launched beneath downtown next summer.

When Bertha arrives in Seattle, she’ll bring with her plenty of excitement. But the project she’s a part of has already brought something very important to Washington: jobs. Construction to replace the Alaskan Way Viaduct is boosting the local and regional economies, sustaining more than 3,900 jobs at the height of construction. Evidence of that can be found near Bertha’s launch pit, where crews are busily preparing for her arrival.

Bertha’s preparing too, according to her recently established Twitter profile. Step 1: get her travel documents in order.

“So nice to finally have an identity,” @BerthaDigsSR99 tweeted shortly after her name was announced. “Maybe now the passport agency will take my application.”

Laird and others are counting on that as Bertha’s journey to – and eventually beneath – Seattle draws closer.